Dissertations / Theses on the topic 'Aquaculture impacts'

Suspension-feeding bivalves produce biodeposits (faeces and pseudofaeces) that have much higher sinking velocities than their constituent particles. Consequently they cause sedimentation of material that might otherwise not be deposited. The benthic remineralisation of biodeposits increases sediment oxygen demand and nutrient regeneration, thus enhancing the benthic-pelagic coupling of nearshore ecosystems. In New Zealand the mussel Perna canaliculus has a high natural abundance and is also intensively cultured. This thesis examines the dispersal and remineralisation characteristics of mussel P. canaliculus biodeposits and the impacts of sedimentation from a mussel farm in the Firth of Thames on sediment biogeochemistry by combining laboratory, field and modelling studies. Dispersal characteristics were examined in the laboratory by measuring sinking velocities and erosion thresholds of biodeposits produced by mussels of a wide size range fed three experimental diets. The results show that biodeposit dispersal is a function of mussel diet and size and thus could differ significantly between locations and seasons. Estimates of dispersal distances based on these results demonstrated that the initial dispersal of biodeposits produced by cultured mussels is not far. Depending on the hydrodynamic conditions, secondary dispersal via resuspension potentially plays a more important role in the dispersal of biodeposits from mussel farms than initial dispersal and almost certainly serves as the major means of transport of biodeposits from natural mussel beds. Biodeposit mineralisation was studied by incubating coastal sediments with added biodeposits and measuring oxygen and nutrient fluxes as well as sediment characteristics over an 11 d period. Sediment oxygen consumption and ammonium release increased immediately after biodeposit addition and remained elevated compared to control cores without additions for the incubation period. A biodeposit decay rate (0.16 d-1) was calculated by fitting a first-order G model to the observed increase in oxygen consumption. This rate is 1 - 2 orders of magnitude higher than published decay rates of coastal sediments without organic enrichment or plant material. Nutrient fluxes during the incubation period illustrated that biodeposit remineralisation alters the stoichiometry of the nutrients released from the sediments which may potentially be more significant than the changes of the individual fluxes. To determine the impact of a mussel farm in the Firth of Thames I measured sediment oxygen and nutrient fluxes by deploying benthic chambers, sediment characteristics by collecting sediment cores and sedimentation rates by deploying sediment traps in four seasons. Oxygen consumption and sediment nutrient release rates were generally higher under the farm compared to a reference site, demonstrating the typical response to increased organic input. Unusually low nitrogen release rates measured in summer may indicate enhanced denitrification under the farm. A simple budget demonstrated the importance of benthic nutrient regeneration in maintaining primary production in this region and that mussel culture can lead to a redistribution of nutrients. This study showed that site-specific hydrodynamic and biogeochemical conditions have to be taken into account when planning new mussel farms to prevent excessive modifications of nutrient dynamics. Results of the laboratory and field studies conducted in this thesis were used to parameterise, calibrate and validate models of mussel biodeposit dispersal and remineralisation. A particle tracking model showed that the maximum initial dispersal of faecal pellets from the mussel farm is approximately 300 m and that pellets can be transported several times this distance via resuspension. The remineralisation model was able to simulate the increased nitrogen fluxes from the sediments well and highlighted the need for thorough calibration and parameterisation of the model. This thesis contributed to the current understanding of the ecosystem impacts of mussel culture and provided numerical models and model parameters that will assist in the assessment of mussel culture sustainability and the contribution of mussels to the nutrient cycling in nearshore ecosystems.

Thesis (Ph. D.)--Ohio State University, 2003.<br>Title from first page of PDF file. Document formatted into pages; contains xvii, 114 p.; also includes graphics. Includes abstract and vita. Advisor: David A. Culver, Dept. of Evolution, Ecology, and Organismal Biology. Includes bibliographical references (p. 103-114).

Ricefield based fish seed production (RBFSP) in irrigated spring (boro) ricefields after initial introductions by external promoters has spread among farmers in parts of Northwest Bangladesh. This approach to producing juvenile fish, rather than by specialised geographically clustered hatchery and nursery enterprises, has been recognised as a strategy for decentralised production that makes large high quality seed available locally and supports food fish production. RBFSP has been promoted by the international NGO CARE as part of a process to improve rice-based livelihoods of farming households using a farmer field school (FFS) approach in two consecutive projects between 1993 and 2005. The approach is technically simple and is based on the stocking of common carp (Cyprinus carpio) eggs and Nile tilapia (Oreochromis niloticus) broodfish in ricefields. As a new approach to farmer level fish seed production, its livelihood impacts on the farming households as well as associated actors; its adoption, adaptation and rejection process in farming households; and its cost-effectives for dissemination at farmer level were not well understood. This thesis mainly applies the concept of the sustainable livelihood approach (SLA) using tools and processes of the growing family of participatory research. A systems approach was used to ensure that the key stakeholders including households, community and extension organizations were included. The study was initiated with a well-being analysis of community households to identify poorer households before exploring impacts of RBFSP on poorer producing households (RF) compared to non-producing (NRF) households based on one-off and longitudinal surveys. Livelihoods impacts on other actors linked directly and indirectly with RBFSP were also investigated. The adoption process of RBFSP at the household level and the cost-effectiveness of its promotion were assessed. Impact studies at the household level showed that RF households were significantly larger and had lower levels of formal education than NRF. Adoption of RBFSP had improved practical skills and hence substantially improved human capital in RF households. RF households tended to have more of their ricefish plots located adjacent to their households. Poor and intermediate adopters had smaller riceplots than better-off households but higher seed production efficiencies (poor-315.1 kg fingerlings/ha; intermediate-419.1 kg fingerlings/ha) than better-off households (294.6 kg fingerlings/ha). In addition to direct consumption of large fingerlings, RF households restocked them for further growth in their household ponds in doing so increasing yields by 60%. Fish consumption increased substantially in RF households based on their own production reducing their dependency on purchase from markets. The year round longitudinal survey revealed that activities for RBFSP were compatible with their existing rice-based agriculture activities for household members including men, women and children. The relatively limited income from fingerling production improved cash flow in the low income months. Consumption of large size fingerlings from ricefields provided nutrient dense food in the ‘hungry gap’ months when supplies of wild fish were poor, smoothing consumption. Apart from RF households, RBFSP extended its livelihoods impacts to a wide range of actors in and around the seed producing community. Poor fry traders were found to be key actors in the spread and support of RBFSP. On average fry traders supplied fingerlings to 35 foodfish producers within a mean distance of 5 Km from producing households in a community where RBFSP was well established. The end users (foodfish producers) included households with their own ponds, ponds with multiple ownership and larger waterbodies leased by small groups. Locally available RFBSP juveniles were attractive to each of these groups, supplementing hatchery derived seed. A large number of complex socio-cultural and technical factors were related to household level adoption of RBFSP. The major factors included use of cash generated to prevent distress sales of rice; lack of requirement to use pesticide in ricefields; meeting the household consumption demand; capacity to restock fingerlings in ponds; lack of any negative effects on rice production; increased non-stocked fish production in riceplots; simplicity of the technology; ease of fish harvest from riceplots; increased ability to gift fingerlings/foodfish to relatives and neighbours; more efficient use of both riceplot and irrigation pumps. The most important reasons for households not attempting or quickly rejecting RBFSP were labour conflicts with other activities. However, lost access to the riceplots through changes in tenure was the most common cause of late rejection by households who had practiced RBFSP for several years after withdrawal of CARE support. Location of fish seed producing plots close to the homesteads facilitated household women to contribute to seed production activities through feeding and looking after fish. Women were able to decide and control resources generated from fingerling sales as well as choosing to gift fingerlings to their relatives. Informal transfer of fingerlings in this way stimulated spread of RBFSP. Decentralised fish seed production was promoted through FFS very cost effectively. The introduction of an improved strain of Nile tilapia (GIFT) broodfish greatly enhanced the returns from decentralised seed production based on common carp alone. High levels of secondary adoption improved benefits from promoting RBFSP. The major benefit derived from the improved returns to food fish farmers using locally produced seed. Higher levels of net present value (NPV) and benefit cost ratio (BCR) were achieved based on promotion of mixed-sex tilapia in RBFSP than mono-sex tilapia produced in a large scale central hatchery. Cost-effectiveness in terms of multiplier development impacts on ramification of secondary adopters and, income of fry traders and foodfish producers, RBFSP also showed better performance than a mono-sex tilapia hatchery.

Salmon aquaculture can be a potential solution to bridge the gap between declining capture fisheries and increasing seafood demand. However, the environmental impacts it creates have generated criticism. The overall objectives of this dissertation are to examine the economic consequences of environmental issues associated with salmon aquaculture, and to explore policy implications and recommendations for reducing environmental impacts. These objectives are addressed in five main analyses. The growth of salmon aquaculture is analyzed based on farmed salmon production in the four leading producing countries and the sector as a whole. Analyses indicate that salmon aquaculture is unlikely to continue to grow at its current pace. A joint production function approach is used to estimate pollution abatement costs for the salmon aquaculture industry. Results reveal that pollution abatement costs vary among observations and models. On average, pollution abatement cost is estimated at 3.5% in terms of total farmed salmon production, and 6.5% in terms of total revenue of farmed salmon. The ecological and economic impacts of sea lice from salmon farms on wild salmon population and fisheries are also studied. Analyses suggest that these effects are minor when the sea lice induced mortality rate is below 20%, while they can be severe if the mortality is greater than 30%. Sea lice have greater ecological and economic impacts on pink salmon than on chum salmon. These effects are greater under a fixed exploitation rate than under a target escapement policy. The economic performance of open netcage and sea-bag production systems for salmon aquaculture is compared. Netcage systems appear to be more economically profitable than sea-bag systems when environmental costs are either not or only partially included. Sea-bag systems can be financially profitable only when the salmon they produce can achieve a price premium. Finally, policy implications are explored and recommendations are made for sustaining salmon aquaculture in a holistic manner based on the results from previous chapters. Technologies, economic-based instruments and more stringent environmental policies can be employed to reduce environmental impacts. However, there is no single solution to solve these environmental impacts, and a combination of policy options is needed.

Increased domestic and international demand for aquatic foods have greatly enhanced aquaculture practices and production in Bangladesh, which is reflected in the national economy. However, the impacts of a fast growing aquaculture sector through the involvement of stakeholders, poorer sections throughout the value chain and broader rural livelihoods are largely underdeveloped and have frequently been ignored. The present study explores the impacts of dynamic aquaculture sector on stakeholders at production level and supply chain and test the hypothesis that aquaculture is enhancing rural livelihoods and benefiting the poor. Three aquaculture production systems in three areas of Bangladesh were selected for the study. These were prawn production in gher system in Jessore, pond fish culture in Mymensingh and rice-fish farming in Dinajpur. This selection allowed analysis both the impacts of domestic and export marketing of aquaculture products. Participatory research data collection tools; focus group discussions and participatory mapping were commonly used along with questionnaire surveys to ensure participation of stakeholders. Aquaculture, in general, found to have had significant impacts on rural livelihoods. The greatest effect of aquaculture on farming households were observed in income and consumption. Integrated aquaculture systems were the regular source of fish and vegetables and constitute more than half of the fish and vegetables consumed by farming households. While income from aquaculture was the highest among the several household income sources, the main cash crop differed between the systems studied. Prawn, fish and rice was the main cash earning crops for gher farming, fish farming and rice-fish farming respectively. Qualitative investigation suggested that aquaculture not only increased income through greater production volume, but also improved farmers’ assets through income diversification to farm and non-farm sources. The other important outcomes of aquaculture were the enhancement of social safety nets through increased sharing of inputs and labour among farmers. Commonly the aquaculture systems were found to be more intensive with an increasingly commercial attitude over the last ten years, which affected the intra-household labour distribution leading to a greater role for women in production management. While the three activities; fish feed preparation, feeding and growing vegetables performed by vast majority of women could be attributed to their inherent involvement with agriculture, hard physical work like harvesting ponds and pond construction were mostly carried out by the women from poor households as a strategy to reduce hired labour cost. The women’s’ increased involvement in aquaculture not only increased their overall workload, but also empowered them in household decision making to some extend. However, involvement in decision making was related to the level of involvement in production activities. The impacts of aquaculture spread beyond the farming households to the broader rural livelihoods. Wage labourers and fishers (harvesting teams) two of the poorest groups of people directly involved were benefited most over the last ten years. Intensification of aquaculture increased the demand for hired labour leading to a structural shift in the agricultural wage labour market in farming communities. About half of the agricultural labourers were found part-time employed in aquaculture activities in Jessore and Mymensingh. In Dinajpur intensification of rice cultivation had a much higher effect on the demand for labour than aquaculture. Increased employment in rural areas increased real labour wages by about one fifth over the last ten years and subsequently improved livelihood outcomes. Declining fish catch due to both decreased natural fish stocks and more restricted property rights, professional fishers benefited by diversifying their livelihoods into the aquaculture sector. While, many of the fishers permanently changed their profession to prawn marketing in Jessore, the rest were full-time or part-time employed in harvesting ponds and/or retailing fish in markets. Such diversification of income greatly reduced seasonal vulnerability and improved livelihood outcomes. The role of fish marketing, which is a critical institution in rural livelihoods, was found to facilitate the growth of the aquaculture sector. High demand of aquatic products and the diverse options of marketing fisheries enabled farmers to meet their initial requirements. More commercial operations of aquaculture increased farmers’ awareness and linkages to markets. However, typically the worse-off farmers were the slowest to capture new market opportunities, often due to their poor resources and human capital. Fish marketing was found to be run by the private sector and government provided the infrastructure facilities, except prawn processing plants, which were developed by private sector. While the fish market transactions were fairly efficient, markets facilities and infrastructure were commonly poor and need of government investment for improvement. A gradual growth of fish and markets in the rural areas was observed in the study; this was driven by the increased demand for fish through increased population and supply from aquaculture. The marketing intermediaries provided important services despite their small share of consumers’ price and ensured a fair share for farmers. The auctioneers provided a vital role in running the supply chain with investment and credits, which ensured fair competition in the pricing process. Marketing of aquatic products was not only a mechanism of product transaction, but also provided critical livelihoods for rural poor. On average about one hundred people, including retailers were involved in auction markets and eight people in prawn depots. Importantly the number of people in marketing was found to have increase over the years. Access for different groups of poor people to marketing jobs was found to be significant in rural livelihoods. The asset base and daily earning indicates that more than three quarters of the marketing intermediaries were poor; some of them were from poorest and low cast Hindu society. Greater flexibility of entry and exit to the jobs enabled the poorer sections to diversify their livelihoods, which enabled to cope with seasonal variability of opportunities and stable income. The marketing employment provided then increased livelihood welfare and social security. Finally, it can be concluded that the promotion of aquaculture not only increased much needed food availability but also generated critical livelihoods and marketing is not just a mechanism of product flow, but also providing livelihoods welfare to poorest sections of the society. The micro level findings of the study regarding impacts of aquaculture indicate that aquaculture production and marketing have significant impacts on enhancing rural livelihoods in Bangladesh.

The potential impacts of marine aquaculture operations on the environment are reviewed. The reported effects of suspended mussel farms on the benthic environment are examined and the potential impacts discussed. A framework to assess the impacts of suspended mussel farms is presented. The use of simulation models to predict the impact of fish farm wastes on the benthic environment is discussed and the mathematical theory supporting such models is presented. The applicability of these models to mussel farming is discussed and the data required to undertake such modelling identified. The effect of increased sedimentation on the macrobenthic community, physical structure and biogeochemistry of the surficial sediment around three suspended mussel farms are examined. At one site, the benthic community was subjected to bulk sedimentation, organic enrichment and reduced macrobenthic infaunal diversity. Elevated levels of organic carbon were recorded close to the farm. At the remaining two sites, benthic impacts were less clear and not demonstrably due to the mussel farms. The settling velocity of mussel faeces and pseudofaeces was required to enable modelling of particles ejected from the farm sites. An experiment was devised to measure this parameter.- The settling velocity of mussel faeces (~0.5 cms-I ) was less than pseudofaeces (~1 cms-I ). Differences in these settling velocities were attributed to the organic content and particle size of the excreted matter. The particle tracking model DEPOMOD (Cromey et at., 2000a) was used as a platform from which to develop a simulation model predicting the benthic impact of suspended mussel farms. Parameters within the model were modified to be represent a mussel farming scenario. Data from the three sites surveyed were applied to the model. Although the model results compared favourably with the field data, the model tended to overestimate the benthic impact as measured by the Infaunal Trophic Index. The results of the model are discussed and improvements and further experiments are identified.

The dynamics of demersal fish species assemblages and stocks on the continental shelf of Ghana, West Africa were investigated using data from trawl surveys conducted between 1963 and 1990, and in relation to marine environmental and nearshore forcing factors. Time series analysis was used to examine the dynamics of the marine environment. Classification and ordination methods were used to identify fish assemblages and to identify factors that determine assemblage formation and dynamics. The response of the identified assemblages to changes in the Ghanaian shelf ecosystem were assessed. Between 1964 and 1992, three distinct environmental time blocks (ETBs) in the continental shelf ecosystem off Ghana were recognised. In the first ETB (i. e. before 1972) sea surface and bottom temperatures were relatively high and salinity was low. The second ETB (1972 - 1982) was characterised by low temperatures, high but stable salinity, reduced rainfall and freshwater input into the sea. In the third ETB (1982 - 1992), the system bore a resemblance to the first block with rising temperatures and decreasing salinity. Six fish species assemblages were identified, namely the supra-thermocline sciaenid and lutjanid assemblages, two sparid assemblages (shallow and deep elements), the deep shelf assemblage and the upper slope assemblage. During ETB I and ETB3, the assemblages were easier to identify using ordination techniques, than during ETB2. Species diversity also decreased during ETB2 especially in waters between 10 and 50 m deep. This behaviour of the assemblagesis attributed to the increase in abundance of Balistes capriscus, a species that dominated the ecosystem for nearly 20 years from about 1971, and the observed environmental changes. The estimated density of demersal fish was higher in the upwelling season than in the thermocline season and decreased from 50 kg ha-1 in 1963-64 to 32.4 kg ha-1 in 1990. The density reached its lowest value of 22.5 kg ha-1 in the period between 1973 and 1977. The potential yield of the total demersal biomass (excluding triggerfish) is estimated to be 36,000 - 55,000 mt per annum. With landed catches exceeding 60,000 mt in some years, it is apparent that the resource is over-exploited. A number of policy options are discussed and recommendations for the management of the fishery are made.

Through the implementation of in vivo feeding trials, the efficacy of three wheat gluten (WG) products, vital (Amytex®), hydrolysed (Merripro®) and soluble hydrolysed (Solpro®) wheat gluten as replacement of soy protein concentrate, and scFOS prebiotic (Profeed®) supplementation were analysed to assess their impacts on intestinal health and production of juvenile rainbow trout. Microbial community analysis in experiment one revealed a degree of diet based modulation with 7.5% and 15% inclusions of wheat gluten (WG) products. Bacterial species diversity was significantly reduced with 15% hydrolysed wheat gluten (HWG) inclusion compared to the plant protein control and 15% vital wheat gluten (VWG) treatments, with sequenced OTUs dominated by the phylum Firmicutes and possible promotion of probiotic species. No detrimental effects were observed on intestinal morphology. These findings led onto a longer duration feed trial with a more holistic, higher resolution approach. Experiment two revealed modulation of the allochthonous intestinal microbiota, with increased proportions of Enterococcus and Weissella in the 10% and 20% VWG treatments. Bacillus and Leuconostoc relative abundances were significantly increased with 10% HWG and soluble hydrolysed (Sol) wheat gluten inclusions. HSP 70 transcripts were significantly down-regulated in all WG treatments compared to the basal soy protein concentrate treatment (SPC) and increased intraepithelial leukocyte counts were observed with 10% VWG inclusion. Growth performance was unaffected by 10% dietary inclusions of WG, however, FCR’s were significantly improved in the 20% VWG treatment compared to the 10% HWG and Soluble treatments. This led to the investigation of increased inclusion levels of WG products in experiment three. All WG treatments in experiment three yielded significantly improved growth performance. Somatic indices were significantly increased with 30% blended WG inclusion compared to the SPC treatment. Modulation of allochthonous intestinal microbiota was observed to a lower degree than the previous experiments, with a dose response observed with increasing blended WG inclusion. In the final experiment two basal diets (SPC and 20% Blended) and two scFOS supplemented diets (SPC + FOS and 20% Blended + FOS) were investigated for the effect on growth performance, gut health and allochthonous microbial population. Growth performance was unaffected, however, modulation of the allochthonous microbial population was observed with an apparent synergistic effect of scFOS supplementation in WG diets. This synergistic trend was also observed in the transcription level expression of immune relevant genes. 20% WG inclusion with additional scFOS supplementation observed significant down regulation of the pro-inflammatory cytokine TNF-α, as well as HSP 70, CASP 3 and Glute ST compared to the 20% Blend treatment. The present research demonstrates dietary inclusions of WG products, solely or blended, at the expense of soy protein concentrate to modulate the allochthonous microbial population, potentially promoting probiotic species, whilst reducing the levels of intestinal stress in juvenile rainbow trout. Supplementation of the prebiotic scFOS modulated the microbial populations, enhancing the proportion of potential probiotic species, and combined with WG inclusions, reduce intestinal and oxidative stress and inflammation biomarkers, with no observed deleterious effects.

During the 1990s, shellfish hatcheries operating on the Eastern Shore of Virginia noticed an increase in mortalities of their clam larvae; it was suspected that this was a result of the deteriorating quality of the estuarine water used by aquaculture hatcheries. Many hatcheries obtain their facility process water directly from nearby streams and estuaries. During the same time period, there was also an increase in the use of plastic mulch on some of the vegetable fields on the Eastern Shore. The increased runoff commonly associated with these plastic-covered fields often contains copper-based bactericides that are used on the crops. The plasticulture fields were often located adjacent to the same estuaries from which the shellfish hatcheries draw their water. High levels of copper were measured in multiple surface water locations near these fields. Runoff associated with the plasticulture fields contained up to 238 ug/L dissolved copper, well in excess of the copper concentration of 16.4 ug/L dissolved copper known to affect the mortality of larval clams. Surface water samples collected from nearby unimpacted water bodies contained less than 4 ug/L dissolved copper. Sorption studies conducted with synthetic estuary water quantified the dissolved copper sorption capacities of eight sorbents, including GACs, zeolites, a greensand, and an ion exchange resin, Amberlite IRC-718. These isotherm studies showed that all sorbents removed soluble copper, and that increased salinity and a greater contact time were shown to increase sorption. Utilizing the Freundlich isotherm, the capacity of the eight sorbents studies ranged from 25 to 221 ug/g with a 24-hour contact time. Column studies with an influent concentration of 300 ug/L dissolved copper showed that using 10 grams of a GAC sorbent, a flow rate of 5 mL/min maintained the target effluent concentration of less than 16.4 ug/L for approximately 100 hours. A similar column using 10 g of resin sorbent at a flow rate of 12.5 mL/min maintained the target effluent concentration for approximately 300 hours. The high removal capacity of the resin makes it a desirable treatment for controlling copper in estuarine water used for aquaculture. Utilizing the sorbent capacities obtained from the Freundlich isotherm and a batch treatment, a typical 500 gallon tank used for clam aquaculture would require approximately four pounds of a GAC sorbent, or two pounds of the resin sorbent to reduce a source water that contains 300 ug/L of dissolved copper to below the larval clam toxicity level. Both sorbents would require a 24-hour contact time.<br>Master of Science

The Philippines is a food extractive enclave in the bust stage of export-oriented aquaculture, and this globalization agenda has had several negative impacts. Aquaculture has not expanded fish and marine foods but threatens national food security by integrating Philippine aquatic resources into the globalized food chain. Following structural adjustment policies imposed beginning in the 1980s, the Philippines shipped massive levels of animal protein to world markets, but this country has grown less food self-sufficient. During the decades that shrimp aquaculture has boomed and busted in the Philippines, the living conditions of Filipino families have steadily worsened. This study of three Panguil Bay fishing communities of Northern Mindanao demonstrates that the survival of subsistent artisan fisher households is now threatened because export-oriented producers have severely degraded the ecosystem upon which they rely. Moreover, women and children are inequitably threatened by the ecological and economic changes that have accompanied the Philippine global aquaculture agenda. In reality, capitalist commodity chains of export-oriented aquaculture externalize to households and to nature much of the true cost of producers and of ecological degradation. As a result, malnourished and impoverished Philippine fishing households subsidize global aquaculture commodity chains. While Filipino fisher households can no longer afford local food costs, their hidden inputs into capitalist commodity chains keep prices of luxury seafoods cheap in rich core countries.<br>Ph. D.

Human uses and abuses of rivers have grown and diversified over the last few centuries with increasing urban development. With increasing population growth, there has been increasing demand for the use of rivers to satisfy a diverse range of human needs including solid waste disposal and the discharge of industrial, sewage and mining effluents. Rivers have been abstracted for agricultural and potable water supply and river channels have been modified for navigation, flood defences and hydro-electric power generation. These modifications to the river system disrupt the fabric of the aquatic ecosystem and diminish its integrity, affecting equally the capacity of fish and other organisms to survive. Fish depend on undamaged interactive pathways to enhance their survival, growth and recruitment.The Don, Rother and Dearne catchment in South Yorkshire and North East Derbyshire has suffered from a legacy of pollution and land contamination that dates back to the Industrial Revolution. These rivers have been grossly polluted from industrial, sewage, and mining effluents and from the disposal of solid wastes in the catchment. Much of the lengths of these rivers were fishless into the mid 1980s.Fish populations in the catchment remain low and species diversity is poor at most locations in the Don sub-catchment. Brown trout and coarse fish species are present in the Don catchment, with the salmonid populations confined to the upper reaches. Most tributaries of the River Don provide brown trout recruits to the main rivers but poor water quality and degraded habitats have prevented the successful colonisation of the waters by the species. Coarse fish, where present, were found at the middle and lower reaches of the river.Fish populations and species diversity in the River Dearne are generally poor due to serious water quality problems. Limited numbers of brown trout and coarse fish were found at few locations in the catchment, reflecting the widespread nature of poor water and habitat quality. The sub-catchment receives diverse discharges from sewage, industry and abandoned mines. This is exacerbated by various pollution incidents, the causes of some of which remain unidentified.The River Rother has low fish population densities, and many stretches of the river are fishless due mainly to poor water quality and lack of suitable habitats. Some tributaries of the River Rother, particularly the River Hipper, Redleadmill Brook and Brookside Beck hold considerable numbers of brown trout. The Rother sub-catchment also receives sewage, industrial and mine effluents which impact on the water quality.The benthic macroinvertebrate fauna of the sites studied were mainly pollution-tolerant taxa with low species diversity reflecting poor water quality. Heavy metal levels were generally low and declining which, possibly, relate to the decline in steel and coal industry in the catchment.A concerted programme to improve effluent discharges from major sewage treatment works and industries serving the catchment area coupled with a decline in the coal, steel and manufacturing industries has resulted in marked improvements in water quality of the rivers. Reductions in ammonia and BOD levels have been achieved since 1991 due mainly to improvements to sewage treatment works. As a consequence the fisheries of the rivers have shown some evidence of recovery. Unfortunately these improvements are localised and the fish populations suffer periodic setbacks because of isolated pollution incidents.Despite considerable efforts by the Environment Agency and its predecessors (the National Rivers Authority and Yorkshire Water), to improve the fish populations through stocking and some habitat improvement measures, the general status of the fisheries remains poor particularly in the Rivers Dearne and Rother. A strategic Aquatic Resources Management Plan (ARMP) targeting the bottlenecks to recovery and improvement in the water quality and fisheries habitat is proposed for the long-term sustainable improvement of the fisheries. Project Concept Notes and Logical Project Frameworks have been developed to address the water quality, habitat and fisheries rehabilitation problem. These constitute draft proposals for which additional information would be needed before projects can be progressed.

Many studies have investigated the impacts of marine cage fish farming on seabed sediments. Most of these studies have focused on organic loading or toxic chemicals used for the treatment of disease, normally for a single or a small number of sites over short time periods. Only very rarely has there been the opportunity to use large data sets consisting of a large number of fish farm sites over a long time scale. In Scotland, localised nutrient impacts have been well documented for marine cage salmon farms, but mixed effects of nutrient and chemicals such as SLICE (the active ingredient of which is emamectin benzoate) have not been investigated in the long term. The aim of this project was to investigate the ecological impacts on sediments from farming activities using very large spatial and temporal data to investigate the long term effects of nutrient and chemical waste. This was achieved using a metadata set collected from 403 sampling stations at 31 fish farms on the west coast of Scotland over a 9 year period. Data consisted of sediment macrofauna, carbon and nitrogen levels, redox potential, particle size for sediment characterisation and sediment concentrations of SLICE. The data was analysed for trends using statistical and multivariate analysis to look for changes in sediment community and related conditions, and the relationships between these parameters were investigated. At sampling stations that were less than 50 metres from the sea cages, 72% of the macrofauna communities were correlated with regard to their species composition and abundance. A significant relationship between the concentration of SLICE and sediment characteristics was represented as: SLICE= 0.000644*(median size particle size) + 0.0311*(C %) – 0.00213*(redox potential) + 1.453. Annelids were the most sensitive to the presence of emamectin benzoate, with the sipunculid Phascolion strombi, the echinoderm Ophiura affinis, and the custaceans Iphinoe, Diastylis and Iphimedia also showing sensitivity. During the data period, there was a clear change in species composition associated with improved seabed conditions. This correlated with biomass changes at the relevant sites, where there was a consequent decrease in nutrient input and SLICE usage. The statistical comparison of the AMBI and ITI indices indicated a 68.9% correlation, but they differed in their ability to indicate levels of organic disturbance. AMBI was shown to correlate more closely with conditions and thus a more reliable index when working with large databases. Univariate and multivariate analysis indicated that a combination of abundance (N), Shannon Wiener (H’) and AMBI, as biological indices for describing the status of the ecological level associated with the carbon percentage and redox potential of sediments gave the most reliable representation of environmental change over a series of sampling stations. In conclusion, the overall results suggest that, in the long-term, sampling stations which contained significant levels of SLICE had a higher impact status than those affected only by nutrient inputs. The accuracy of multiple regression models were increased by adding biotic and abiotic parameters, though fish biomass at the sites were not considered be as important factor for the prediction of impacts. However, this model could be sensitive to natural environmental conditions and variations. In light of these results and conclusions, recommendations can be made both for updating the existed environmental regulation of marine fish farms and in the development of meaningful models to relate sediment conditions to accurate estimations of overall environmental impacts.

L'etude de la parasitofaune des poissons marins mediterraneens des cotes francaises du languedoc-roussillon et de la baie de kotor (adriatique) en yougoslavie, a revele la presence de 45 especes de myxosporidies, dont huit nouvelles pour la science. Plusieurs aspects de la biologie de ces parasites sont abordes. L'impact de ces parasites en aquaculture a ete etudie a travers le modele thelohanellus nikolskii responsable d'epizooties dans les elevages de carpes d'europe centrale et d'asie. La pathologie liee a cette espece, ainsi que les stades initiaux de la sporogenese ont ete precises. Les affinites des myxosporidies avec le parasite pkx et les marteilia nous a amene a etudier egalement le cas de ces deux autres parasitoses: l'hepatonephrite parasitaire des salmonides (pkd), ainsi que la marteiliose de l'huitre plate ostrea edulis. Les premieres approches moleculaires de ces organismes ont permis la construction d'une banque genomique de m. Refringens et la caracterisation d'une premiere sonde nucleique specifique. L'etude preliminaire de celle-ci a ete realisee, et son utilisation comme outil epidemiologique et de diagnostic, est abordee

Among efforts to develop sustainable approaches towards the intensive rearing of finfish within open marine waters, is the development of integrated aquaculture techniques. Integrated Multi-Trophic Aquaculture (IMTA), has been promoted as a way to reduce unwanted environmental impacts associated with the intensive production of marine finfish within net-pens. The principle aim of this concept, is the bioremediation of nutrient discharges from fish aquaculture. This is to be achieved by integrating fish cultivation with the growing of species from lower trophic levels, which use the nutrient discharges as a food source. Many studies have been performed that investigate the ability of various species of macroalgae to remove dissolved nutrient discharges, and the ability bivalves to remove solid-bound nutrients, presented as either fish faeces, or an enhanced production of phytoplankton that may be promoted by nutrients emitted by fish-farms. IMTA has also been suggested as a means to improve overall productivity per unit of feed applied to fish, through the conversion of nutrient emissions into additional biomass, such as the tissues of macroalgae or bivalves. Within the research community which focuses upon the environmental impacts of aquaculture, there is a growing awareness that sustainable solutions to aquaculture production cannot be realised through a focus restricted to the growing-phase, and to a limited set of environmental impacts which may this activity may produce. This is because changes to a specific production phase often promote changes at phases located elsewhere along a products value chain. Life-Cycle Assessment (LCA), is a method employed for modelling the environmental impacts that may potentially be generated across the value chain of a product. It is particularly useful for identifying instances of environmental impact shifting; a term used to describe situations where efforts to reduce the contribution of a specific production phase towards one or more environmental impacts, has the effect of either displacing this contribution to another phase, or increases the contribution of production towards different environmental impacts. Despite its apparent suitability, LCA has not previously been fully applied to the environmental impact modelling of open-water IMTA systems. The work presented in the following thesis advances this research front, by using LCA to explore the potential for environmental problem shifting occurring as a consequence of replacing intensive monoculture production, with IMTA. Comprehensive datasets have been acquired from the Chilean aquaculture industry, describing the production of aquafeed and Salmo salar, as well as for the production of the Phaeophytic macroalga, Macrocystis pyrifera, and the molluscan bivalve, Mytilus chilensis. Using LCA methodology, the production of salmon feed, and the production of S.salar, M.pyrifera and M.chilensis, have been assessed for their capacity to contribute towards a variety of global-scale, environmental impacts. IMTA consisting of either S.salar and M.pyrifera, S.salar and M.chilensis, or all three of these species, and combined at ratios required for a bioremediation efficiency of 100 %, 50%, or 20 % of either nitrogen or phosphorous emission from fish, is compared to the monoculture production of S.salar. The comparison is based upon a standardised functional unit, with each species produced through IMTA, being modelled as part of the reference flow required to fulfil the functional unit. Monoculture is compared to IMTA upon the basis of nutritional function, by using a functional unit of mass-adjusted protein content, and mass-adjusted economic value. The use of economic value is based upon the ‘best-case’ assumption, that it serves as a proxy for the total nutritional function that each product offers to human society. The LCAs presented in this study have produced a number of results. Salmon ingredients derived from agricultural crops and animals account for the majority (between 71 % to 98 %) of contributions towards the impacts of compound salmon feed. In general, agricultural crops ingredients contribute more to these impacts than do agricultural animal ingredients, and account for between 31 % and 87 % of the contributions from all ingredients and inputs. In contrast, the combined supply of fish meal and fish oil from capture fisheries is responsible for between 0.13 % and 11 % of all impacts. Vegetable oil accounts for the vast majority of contributions from ingredients derived from agricultural crops. Vegetable oil is modelled as a 50 : 50 blend of sunflower oil and rapeseed, oil, but sunflower oil accounts not only for most of the contributions from vegetable oil, it is responsible for over 50 % of the contributions that all agricultural crop based ingredients contributes towards some impact categories. Replacing sunflower oil with rapeseed oil reduces the contributions of salmon feed by between 6 % and 24 % across 10 out of the 11 impact categories. When compared upon the basis of equal weight, the contributions of fish oil are between 18 % and 99 % lower than those from rapeseed oil. The production of feed is responsible for the majority of contributions (between 32 % and 86 % ) to all impacts of salmon grow-out production. The production of salmon-smolts accounts for between 3 % and 18 %. The majority (64 %) of contributions towards the eutrophication potential of salmon production are from nutrient emissions, which are the result of fish metabolism, whilst nutrients released through the production of feed, the majority of these being from the agricultural production of crop and animals, account for 32 %. Feed production is also a major contributor to the impacts of land-based smolt production, but these contributions (between 12 % and 37 % across all impact categories) are of a lower magnitude than those from the supply of feed to the grow-out phase. Inputs of salt, and inputs of both electricity produced in a diesel power generator and obtained from the national electricity network, are also notable contributors (between 5 % and 67 %, 4 % and 29 %, and 2 % 47 %, respectively) towards the impacts of smolt-production. The main contributors towards the potential impacts of kelp grow-out production (excluding eutrophication potential) are the supply of infrastructure (between 14 % and 89 %), operation of a diesel-powered motorboat for maintenance purposes (between 1 % and 89 %), and the supply ‘of seeded cartridges’ (between 9 and 49 %). The major contributors from the production of ‘seeded cartriges’ in a land-based facility are the supply of electricity from the national electricity network, the supply of fresh water, and the treatment of waste water. The impact potentials of producing seed in this facility might be reduced if the scale of operation is increased. Removal of nitrogen and phosphorous upon the harvesting of kelp is calculated based upon kelp tissue contents of these nutrients. The harvesting of 200 tonnes ha / yr-1, results in a eutrophic potential with a negative value (-376.51 kg of phosphate equivalents). The removal of such a quantity of nutrients might be beneficial if the local marine environment is at risk of hypernutrification, but when no such problem is present, the potential for undesirable consequences of nutrient sequestration should be considered. The major contributor towards the impacts of mussels is the provision of infrastructure (between 25 % and 99.5 %, excluding eutrophication potential). Infrastructure is also responsible for the majority of contributions from mussel seed production. The provision of cotton mesh bags, which are used to aid attatchment of seed to drop-ropes in the grow-out phase, account for between 37% and 99 % of the contributions from the infrastructure from the grow-out phase. This result suggest that either the impacts of mussel production can be reduced by using an alternative material with lower environmental impact potentials, or the inventory data describing the producing of cottonmesh bags requires some improvement. The outcomes of the LCAs of the different IMTA scenarios, are interesting. The results show that choice of species, and the ratios of their combination as required for the different efficiencies of bioremediation, can have a significant effect upon the comparison between IMTA and monoculture.<br>The study demonstrates a potential for environmental problem shifting as being a consequence of IMTA, especially when the functional unit is mass-adjusted economic value. As bioremediation efficiency increases, contributions towards eutrophication decrease. However, this reduction is achieved at the cost of increasing the contributions of IMTA towards those impact categories, such as ‘ozone layer depletion,’ for which it has a greater contribution than does monoculture. In general, it cannot be concluded from these results that open-water IMTA represents a more sustainable alternative to the monoculture production of Atlantic salmon. The sustainability of IMTA is shown to be dependent upon a variety of trade-offs, between individual environmental impacts, and between these impacts and the nutritional function that the system is capable of providing.

Basé sur deux études de cas aux Philippines (Pampanga) et au Pérou (Tumbes), cette thèse avait pour objectif d'analyser le développement de l'aquaculture à travers l'étude des causes initiales de ce développement, de son développement spatial et des impacts socio-économiques découlant de l'activité. La méthodologie a associé des traitements d'images satellites au travail de terrain. L'élaboration de plusieurs méthodes de détection des étangs ont permis une cartographie fine de ces infrastructures. La méthode s'est en particulier appuyée sur l'articulation d'un traitement multispectral et d'un traitement utilisant la morphologie mathématique. Le travail de terrain a reposé sur l'emploi de questionnaires, d'entretiens, de récolte de données de seconde main, l'observation directe et la participation aux activités quotidiennes. Un système multi-agent a enfin été élaboré à partir des données récoltées sur le terrain philippin, dans le delta de Pampanga, dans le but d'explorer l'influence d'une ensemble de facteurs, à la fois sociaux et environnementaux, sur l'évolution du paysage<br>Based on two case studies in the Philippines (Pampanga) and Peru (Tumbes), the goal of this thesis was to analyze the development of aquaculture with an emphasis on the initial causes of aquaculture, its history, its spatial development, and on its socioeconomic impacts at a range of space and time scales. The methodology associates satellite image processing with fieldwork. Several pond mapping methods based on a combination of multispectral classification techniques and mathematical morphology were tested and compared. Field investigation methods involved questionnaires, interviews, harvesting of second-hand data, direct observation, and a participation in daily activities of various stakeholders. Finally, I crafted a multi-agent model based on empirical data collected in the Pampanga delta with the aim of exploring the influence of a range of environmental and social parameters on landscape evolution

Poor salmonid spawning habitat due to excessive fine sediment inputs has been identified as a major factor limiting survival in chalk rivers. A lack of knowledge about the complex processes and factors affecting survival was the driver for this study and gaps in the research were identified concerning the sources of fine sediment and the impact organic material had on salmonid survival in chalk streams. Consequently the main objectives of this study were to characterise spawning habitat quality of a chalk catchment, assess the sources of sediments accumulating within artificial redds, describe the composition of organic sediments using emerging technology and to create a novel method to assess the sediment oxygen consumption of those sediments. Methods were based around a catchment wide field based monitoring programme, consisting of artificially constructed spawning gravels which allowed hyporheic measurements to be taken, and sediment analysis and sediment oxygen consumption methods were carried out using different laboratory methods. Spawning habitat characteristics of the chalk catchment were found to exhibit; low sediment accumulation rates although original levels of fine sediment were high, high organic matter content, variable intra-gravel flow and intra-gravel oxygen concentrations and groundwater influences. Primary sources of fine sediment accumulating in spawning gravels and suspended sediments were found to be attributed to catchment surface sources, namely pasture (50-68%) and arable (32-50%) using inorganic and organic parameters. Organic composition of redd gravels was found to be dominated by protein material rather than humic substances, the more commonly found fluorescent compound in freshwater systems and the sediment oxygen consumption of sediments varied throughout the catchment and was found to consume the greatest oxygen in <63μm size fraction. Application of sediment oxygen consumption rates to existing parameter based models that predict salmonid survival, highlighted the need to address the sensitivity of current models to rivers experiencing low sediment accumulation rates. Outcomes of this study further the knowledge of the sources, organic composition and sediment oxygen consumption capacity of fine sediments accumulating in spawning gravels which can lead to appropriate mitigation on chalk rivers to improve salmonid spawning habitat.

Predator populations can have significant impacts on prey recruitment success and prey population dynamics through consumption. Young, inexperienced prey are often most vulnerable to predation due to their small size and limited evasion capabilities. to reduce the risk of predation, new recruits and young juveniles typically settle in structured nursery habitats, such as seagrass beds, which promote higher survival by acting as refuges from predators. Thus, successful recruitment to the adult portion of the population is often dependent on the availability of suitable nursery habitat. In this thesis, I used field tethering experiments and gut content analyses to assess the role of habitat, body size, finfish predation, and cannibalism on the survival of one of the most ecologically and economically important species in Chesapeake Bay: the blue crab Callinectes sapidus. In field tethering experiments, survival probability of juvenile blue crabs in York River nursery habitats (i.e. seagrass beds, sand flats) increased significantly and additively with crab size and SAV cover. Images of predation events during tethering experiments revealed cannibalism by adult blue crabs to be a major source of juvenile mortality. Gut content analyses from three field studies identified seven predators of juvenile blue crabs in lower Chesapeake Bay nursery habitats: adult blue crabs, striped bass Morone saxatilis, red drum Sciaenops ocellatus, silver perch Bairdiella chrysoura, weakfish Cynoscion regalis, Atlantic croaker Micropogonias undulatus, and oyster toadfish Opsanus tau. Using frequency of consumption and diet proportion metrics, I determined striped bass, red drum, and silver perch to be the most impactful finfish predators on juvenile mortality, in addition to cannibalism. Atlantic croaker and oyster toadfish play minor roles in juvenile mortality in Chesapeake Bay nursery habitats. The probability of juvenile crabs being present in a predator’s gut was also significantly higher in seagrass beds than in unvegetated sand flats. Food web dynamics are an important aspect of ecosystem-based fisheries management. Understanding the ecological interactions between populations, and their environment, can provide insight into natural population fluctuations of valuable fishery species such as the blue crab. This thesis demonstrated the positive effects of body size and SAV cover on juvenile crab survival, indicating the importance of seagrass nursery habitat for blue crab population dynamics in Chesapeake Bay. However, despite the predator refuge offered by SAV, high densities of predators and prey in seagrass beds resulted in greater consumption of juveniles in those habitats. Key predators of juvenile blue crabs were also identified and their relative impacts were estimated. The predator-prey relationships revealed in this thesis were integrated into a revised food web for blue crabs in Chesapeake Bay, in the hopes of informing future ecosystem-based management efforts.

Le Chili, deuxième pays d'élevage de saumons au monde, est celui qui utilise le plus d'antibiotiques et de pesticides, qui peuvent être nocifs pour l'environnement et l'homme. Ces composés ont tendance à être séquestrés par les particules en suspension, transportés par les courants et finalement déposés dans les sédiments, où ils sont finalement consommés par la communauté benthique. Des changements dans les communautés bactériennes, l'émergence de gènes de résistance et les impacts écologiques ont été décrits pour les antibiotiques et les pesticides, bien que la plupart se concentrent sur l'impact local de la salmoniculture. Le present travail vise à comprendre la dynamique et le devenir des antibiotiques dans le fjord de Puyuhaupi, à caractériser la partition des antibiotiques florfénicol et fluméquine par une approche expérimentale simulant les températures moyennes du fjord en hver et été. En outre, la présence des pesticides deltaméthrine et cyperméthrine dans les particules en suspension et les organismes benthiques filtrants (bivalves et éponges) dans le fjord de Puyuhuapi a été évaluée. Enfin, une expérience d’exposition des organismes vivants dans la colonne d'eau et dans les sédiments marins d'une zone sans activité aquacole (baie de Banyuls, France) a été réalisée pour évaluer si la présence d'antibiotiques et de pesticides affecte le processus de minéralisation de la matière organique, à travers des changements dans la respiration de la communauté et les composants reminéralisés. Nos résultats montrent de faibles concentrations de florfénicol (de trace à 23,1 ng L-1) et de fluméquine (niveau de trace) détectées après 180 et 360 jours (respectivement) depuis leur dernière médication à une distance comprise entre 2 et 23 km des sites d’aquaculture. Le modèle de fugacité utilisé dans notre zone d'étude, associé au modèle de décomposition, prévoit que la fluméquine peut rester dans les sédiments pendant plus de deux mois à des concentrations d'inhibition subminimales (sub-MIC). Cette situation peut favoriser la sélection bactérienne pour la résistance aux antibiotiques et, à terme, constituer un risque pour la santé humaine lié à la consommation de fruits de mer. Les valeurs des constantes de partage Kd et KOC, obtenues par des expériences en lots dans notre étude, suggèrent que la capacité d'adsorption de la fluméquine est deux fois supérieure à celle du florfénicol (Tableau 2, section 3.2), ce qui implique que la fluméquine a une plus grande tendance à être adsorbée et absorbée par les sédiments. D'un point de vue environnemental, le devenir de la fluméquine sera plus associé aux processus affectant les particules, comme leur transport et leur déposition sur le fond marin, alors que la concentration de florfénicol sera contrôlé par des processus hydrodynaques, comme la dilution et le transport par les courants. En conséquence, une fraction plus élevée de fluméquine pourrait être stockée dans les sédiments des zones côtières d'élevage de saumons. Les pesticides deltaméthrine et cyperméthrine ont été utilisés dans des bains de saumon pour contrôler les foyers d'infection de Caligus (Caligus rogercresseyi). De très faibles concentrations de deltaméthrine ont été détectées dans les particules en suspension (0,01 à 0,05 ng L-1), ce qui n'aurait aucun effet sur les organismes (NOEC, LC50 et EC50) ou au niveau écologique (NOEAEC). Cette occurrence peut traduire la remise en suspension des sédiments ou un apport externe provenant de zones adjacentes, dans lesquelles des sites d’aquaculture sont actifs. Bien que la cyperméthrine n'ait pas été utilisée dans le fjord de Puyuhuapi, de faibles concentrations ont été détectées dans les bivalves et les éponges (0,04 et 0,05 ng g-1, respectivement) avec des valeurs comparables à celles mesurées dans des saumons sauvage capturé pour la consommation humaine (0,04 ng g-1). [...]<br>Chile, as the second largest salmon farming country in the world, reports the highest use of antibiotics and pesticides, which can be harmful to both the environment and humans. These compounds tend to be sequestered by suspended particles, transported by currents and finally deposited in sediments, where they are later consumed by the benthic community. Changes in the bacterial community, emergence of resistance genes and impacts at the ecological level have been described for antibiotics and pesticides, although most focus on the local impact of salmon farming. This study sought to understand the dynamics and fate of antibiotics throughout the Puyuhaupi Fjord and to understand the partitioning behavior of the antibiotics florfenicol and flumequine through adsorption experiments that simulate the average temperature of the fjord. In addition, the occurrence of deltamethrin and cypermethrin in total suspended solids and filtering benthic organisms (bivalves and sponges) in the Puyuhuapi Fjord was evaluated. Finally, an experiment of respiration in the water column and marine sediments obtained in an area without aquaculture activity (Banyuls Bay, France) was developed to evaluate if the presence of antibiotics and pesticides can affect the degradation process of organic material, through changes in community respiration and remineralized components.Our results show low concentrations of florfenicol (from trace to 23.1 ng L-1) and flumequine (trace level) detected after 180 and 360 days (respectively) since their last medication at a distance between 2 and 23 km from the culture sites. The fugacity model used in our study area, together with the decay model, predicts that flumequine can remain in sediments for more than two months at sub-minimum inhibition concentrations (sub-MIC). This condition may promote bacterial selection for antibiotic resistance and eventually pose a risk to human health from the consumption of seafood products. The values of the partition constants Kd and KOC, obtained by bacth experiments, suggest that the adsorption capacity of flumequine is twice that of florfenicol (Table 2, section 3.2), implying that flumequine has a greater tendency to be adsorbed and absorbed by sediments. From an environmental point of view, our results may imply that the fate of flumequine will be related to processes affecting particles, suspension transport and seafloor deposition, whereas florfenicol concentration be controlled by hydrodynamic processes such as dilution and transport by currents. In turn, a higher fraction of flumequine may be stored in the sediments in coastal areas housing salmon farming centers.The pesticides deltamethrin and cypermethrin were incorporated through dips to control outbreaks of caligus (Caligus rogercresseyi) infection. Very low concentrations of deltamethrin were detected in total suspended solids (0.01 to 0.05 ng L-1), which value would not have an effect on organisms (NOEC, LC50 and EC50) or at the ecological level (NOEAEC), which may come from sediment resuspension or external input from adjacent areas with active salmon culture centers. Although cypermethrin was not used in Puyuhuapi Fjord, low concentrations were detected in bivalves and sponges (0.04 and 0.05 ng g-1, respectively), values comparable to wild salmon caught for human consumption (0.04 ng g-1). These results suggest an indirect exposure of the compound may be associated with external input from adjacent fjords or unreported treatments because cypermethrin can remain for more than two years in sediments with high organic material and low oxygen content. [...]<br>Chile, como segundo país con mayor producción en el cultivo de salmones a nivel mundial, reporta el mayor uso de antibióticos y pesticidas, lo que puede ser perjudicial tanto para el medioambiente como para el hombre. Estos compuestos tienden a ser secuestrados por las partículas suspendidas, transportados por las corrientes y, finalmente son depositadas en los sedimentos, donde eventualmente son consumidos por la comunidad bentónica. Cambios en la comunidad bacteriana, aparición de genes de resistencia e impactos a nivel ecológico han sido descritos para antibióticos y pesticidas, aunque la mayoría se enfocan en el impacto local de la actividad salmonera. Este estudio buscó entender la dinámica y el destino de los antibióticos en todo el fiordo Puyuhaupi y conocer el comportamiento particional de los antibióticos florfenicol y flumequina a través de experimentos de adsorción que simular la temperatura promedio de fiordo. Junto con esto se buscó evaluar la ocurrencia de deltametrina y cipermetrina en los sólidos totales suspendidos y los organismos bentónicos filtradores (bivalvos y esponjas) en el fiordo Puyuhuapi. Finalmente se desarrolló un experimento de respiración en columna de agua y sedimentos marinos obtenidos, una zona sin actividad acuícola (bahía Banyuls, Francia), para evaluar si la presencia de antibióticos y pesticidas pueden afectar el proceso de degradación del material orgánico, a través de cambios en respiración comunitaria y en las componentes remineralizadas.Nuestros resultados muestran bajas concentraciones florfenicol (desde traza a 23.1 ng L-1) y flumequina (nivel traza) detectados después de 180 y 360 días (respectivamente) desde su la última medicación a una distancia de entre 2 y 23 km de los centros de cultivo. El modelo de fugacidad utilizado en nuestra área de estudio, junto con el modelo de decaimiento, predicen que flumequina puede permanecer en los sedimentos más de dos meses a concentraciones de inhibición sub-Mínima (sub-MIC). Esta condición puedo promover la selección bacteriana por resistencia a los antibióticos y, eventualmente representar un riesgo para la salud humana por el consumo de productos marinos. Los valores de constantes de partición Kd y KOC, obtenidos experimentalmente en nuestro estudio, sugieren que la capacidad de adsorción de flumequina es dos veces mayor que la de florfenicol (Tabla 2, sección 3.2), lo que implica que flumequina tiene una mayor tendencia a ser adsorbido por los sedimentos. Desde el punto de vista ambiental, nuestros resultados pueden implicar que el destino de la flumequina estará más asociado a procesos como el transporte de partículas y la deposición en el fondo marino, mientras que el florfenicol debería estar másxxiiirelacionado con procesos acuáticos como la dispersión y el transporte por las corrientes, lo que sugiere que, eventualmente, una mayor fracción de flumequina puede quedar almacenada en los sedimentos en la zona con centros de cultivo de salmones.Los pesticidas deltametrina y cipermetrina se incorporaron a través de baños para controlar brotes de infección por caligus (Caligus rogercresseyi). Concentraciones muy bajas de deltametrina se detectaron en los sólidos totales suspendidos (0.01 a 0.05 ng L-1), cuyo valor no tendría un efecto sobre los organismos (NOEC, LC50 y EC50) o a nivel ecológico (NOEAEC), los que pueden provenir de la resuspensión de sedimentos o por aporte externo de áreas adyacentes con centros de cultivo activos. A pesar de no ser utilizada cipermetrina en fiordo Puyuhuapi, bajas concentraciones se detectaron en bivalvos y esponjas (0.04 y 0.05 ng g-1, respectivamente) valores comparables a salmones silvestres capturados para consumo humano (0.04 ng g-1)

In questo lavoro di tesi sono stati analizzati campioni di orate (Sparus aurata) da acquacoltura allevate con differenti diete, commerciali o innovative, con lo scopo di verificare se le diverse formulazioni dei mangimi hanno un effetto sul profilo molecolare dei pesci. A tal proposito, è stata utilizzata la spettroscopia di Risonanza Magnetica Nucleare (1H NMR) accoppiata ad un approccio metabolomico poiché, rispetto ad altre tecniche, consente la determinazione simultanea di un’ampia classe di metaboliti che caratterizzano il campione attraverso la generazione di spettri che contengono un ampio spettro di informazioni. Questo lavoro di tesi si sposa bene con l’attuale tendenza di sviluppo dell’acquacoltura, che viene vista come uno strumento interessante per fornire cibo e migliorare la sicurezza alimentare, ma allo stesso tempo esso è in accordo anche con la sempre più elevata attenzione verso sostenibilità, qualità e conformità alle richieste dei consumatori, che sono oggi le principali tendenze nel settore alimentare. Negli ultimi anni si è assistito ad un ampio sviluppo dell’acquacoltura e questo ha portato alla necessità di ricercare strategie per migliorare l’efficienza, la produttività, ma anche la sostenibilità di questi sistemi. Questo ha condotto ad un elevato aumento delle ricerche riguardanti questi aspetti dell’acquacoltura, e l’impatto che la dieta ha sul metabolismo dei pesci è uno di questi. I dati spettroscopici sono stati interpretati attraverso analisi statistica multivariata, nello specifico attraverso l’analisi delle componenti principali, PCA, per individuare eventuali differenze significative tra i tre gruppi a seguito della diversa tipologia di alimentazione. Dal presente lavoro di tesi è stato possibile concludere che i campioni vengono distribuiti e classificati in funzione della dieta. Inoltre, è stato possibile individuare i metaboliti che maggiormente determinano questa separazione.

The toxin-producing harmful algal bloom (HAB) species Alexandrium monilatum has long been associated with finfish and shellfish mortalities in the Gulf of Mexico. In the summer of 2007, A. monilatum re-emerged as a bloom-forming species in the Chesapeake Bay. Over the last decade, late summer blooms of A. monilatum have been expanding in range in the lower Chesapeake Bay and have reached record-high densities, particularly in the lower York River. This dinoflagellate species overwinters in the sediments as a resting cyst, and upon excystment under suitable environmental conditions produces blooms the following summer. The research presented here includes the first mapping and quantification of resting cysts of A. monilatum in surface sediments in the Chesapeake Bay using quantitative real-time polymerase chain reaction (qPCR) assays. A systematic grid sampling design was employed to collect pre-bloom sediments in the southwestern portion of the Chesapeake Bay each year from 2014-2016. Cysts were widespread in the bottom sediments and sediment cyst density increased from 2014-2016, reaching as high as 90,000 cysts/cc in the York River channel. A multiple linear regression was used to model cyst density using environmental parameters. Sediment type was a strong predictor of cyst density, with higher cyst densities found at sites with more fine sediments (silts and clays). Laboratory HAB toxicity bioassay methods were used to investigate potential adverse health impacts of A. monilatum on adult triploid eastern oysters, Crassostrea virginica. Oyster behavior and mortality were monitored and routine paraffin histology was performed to analyze tissue damage. Oysters did not exhibit mortality or tissue damage in a 48-hour fed toxicity bioassay. However, a 96-hour unfed toxicity bioassay led to 67% mortality, and erosion of the gill and mantle epithelial tissues in 94% of oysters exposed to A. monilatum (live cell or lysate). In the summer of 2015, oysters were deployed in the lower York River to assess effects of exposure before, during, and after a natural A. monilatum bloom. A subsample of six live oysters was collected weekly for two months and processed for histology. There was no mortality of deployed oysters, but minor epithelial erosion of the mantle was seen in half of the oysters sampled during the peak of the A. monilatum bloom from early to mid-August. Field and laboratory results showed that C. virginica did occasionally consume A. monilatum, and exposure of C. virginica to live A. monilatum or lysate could lead to epithelial erosion of external tissues and mortality. It is clear from the findings of this research that A. monilatum has established itself in the York River region of the Chesapeake Bay and that at least under laboratory conditions, persistent exposure to A. monilatum (live or lysate) can have serious potential health impacts on adult oysters.

Rainfed areas in the Dry-Zone of Sri Lanka are characteristic of extensive marginal agro-ecosystems known as the semi-arid tropics (SAT) populated by poor farming communities. In the Dry-Zone and elsewhere, the traditional response to seasonal water scarcity was to construct rainfall-harvesting devices known as ‘tanks’; created by building earthen dykes across ephemeral streams in undulating terrain. Most are held in common ownership by adjacent communities, who use them for multiple functions including irrigation, bathing and fishing. Storage efficiency is enhanced by arranging tanks in cascading sequence within watersheds so that drainage waters can be re-used. The aim of this study was to evolve improved collective strategies for the management of seasonal water bodies (focussing on aquatic production) in order to reduce the vulnerability of the poorest groups. Understanding of these complex systems requires a holistic approach which integrates hydrological, biological and socio-economic factors on a suitable (watershed) scale. Work commenced with a comprehensive situation analysis, culminating with the formulation of a participatory research agenda for action research based on low-input stocking enhancements. Village livelihoods have traditionally revolved around paddy cultivation as the primary tank function; however, in recent times, water-use strategies have responded to a range of demographic, economic and environmental pressures with implications for the sustainable management of natural resources, especially living aquatic organisms. Natural fish production in the most seasonal tanks relies on intermittent spill-events which link successive tanks; these provide migration routes which permit recruitment of stocks from lower perennial tanks. Rehabilitation initiatives that increase the storage / irrigation capacity of tanks or poorly designed surplus weirs that impede migration have negative impacts on fisheries, though they are rarely considered by planners. The fundamental concept of the purana complex (PC) as the smallest logical sub-component of the watershed for intervention is introduced. Within PC boundaries discrete community groups bound by ties of kinship and caste, control access to private and commonly held natural resources. PCs in the uppermost reaches of watersheds are distinguishable by the highly seasonal nature of their tanks and poor physical infrastructure relative to lower watershed communities. Such areas are also often buffer zones between as yet uninhabited hinterlands and settled areas where cultivation potentials are further restricted due to wild animal incursions. Consequently, these groups exhibit the greatest dependence on exploitation of the natural resource base. This often includes less seasonal tanks in lower PCs where fisheries are of less significance to local livelihoods. Such low-level ‘poaching’ is generally well tolerated, but potential for conflict exists where development efforts restrict hitherto free access to these resources. These findings were the basis for two phases of action research which involved the stocking of ten tanks belonging to seven communities in North West Province (2000-2001). Phase 1 trials encompassed a range of social and physical and settings from lower to upper watershed. Results indicated that the use of costly hatchery-produced seed was unlikely to be sustainable given (1) a background of highly erratic natural production (2) uncertain returns to individual effort and (3) a low priority accorded to fish production from village tanks given the availability of low-cost commercial production from perennial reservoirs. The second phase was restricted to low-caste communities in upper watershed areas and relied entirely on wild-fish stocks captured from perennial reservoirs lower in the watershed. Also emphasis was on intermittent ‘staggered’ harvesting using hook and line gears rather than the single intensive ‘collective harvests’ adopted in phase 1 trials. High yield potentials were demonstrated in the smallest tanks (<4ha) which were devoid of fish stocks during two pervious drought years. Results also indicate that sustainable adoption will be likely only where there is strong social cohesion and representative village leadership. An adaptive learning process which can demonstrate the net benefits of staggered harvesting in seasonal tanks is described. These stocking strategies combined with tank rehabilitation sympathetic to preservation of upstream hydrological linkages, are highly complementary enhancement steps. Results clearly show that together they have potential to maintain the wider aquatic ecosystem on which the poorest groups depend.

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2007.<br>Small farm dams (< 20 ha) in the Western Cape Province provide adequate water conditions for intensive cage production of rainbow trout (Oncorhynchus mykiss). A major environmental concern of cage aquaculture, however, is the high inputs of nutrients via commercial diets and the subsequent eutrophication of the water source. Eutrophication can result in the degradation of the general water quality (increasing pH levels, oxygen depletion, increased hydrogen sulphide and free ammonia) and shifts in the phytoplankton structure (increased biomass, single species dominance). Deterioration of water quality will affect the success of the fish farming enterprise as well as the performance of irrigation equipment by increasing the risk of clogging and corrosion. Water quality, phytoplankton and zooplankton compositions were monitored at four sites from June 2005 to November 2006 to determine the effects of cage culture on the farm dam environment, its associated biota as well as irrigation water quality. The distribution of nutrients, nitrogen and phosphorus, was mainly influenced by the stratification and mixing regime of the water bodies. Nutrient concentrations increased during the winter mixing period while in the summer months, they seem to settle to the lower part of the water column. Nutrient concentrations of production sites and reference sites were comparable except for the ammonia levels that were significantly higher at the production sites. Phytoplankton corresponded with nutrient availability resulting in high biomass during winter. In terms of biomass, phytoplankton was approximately two times more abundant in production sites compared to reference sites. Assemblage dominance by cyanophytes (Anabaena circinalis, Microcystis spp.) was found more often in production sites, while reference sites were dominated by dinophytes (Ceratium hirundinella, Peridinium spp.). Zooplankton biomass concurred with high phytoplankton biomass in winter. Zooplankton assemblages in production sites sustained much higher biomass. Effects of cage culture on irrigation water quality are evident from increased algal biomass and shifts in species composition. These results indicated that at its present production level, cage culture had impacts on the farm dam environment and irrigation water quality. The most significant evidence was given by increased plankton biomass and single species dominance in production sites. However, these findings can not solely be ascribed to the introduction of aquaculture as various other factors may also contribute to the water quality of these ecosystems.

Made available in DSpace on 2014-12-17T14:52:57Z (GMT). No. of bitstreams: 1 OrildoSOS.pdf: 487861 bytes, checksum: 000c581381b10a9543619587412d4f6e (MD5) Previous issue date: 2006-05-19<br>O objetivo desse trabalho foi investigar a contribui??o social da atividade econ?mica denominada de carcinicultura, para o munic?pio de Canguaretama no Rio Grande do Norte, a partir da vis?o dos moradores do citado munic?pio, sendo enfocados aspectos ambientais, aspectos de produ??o, consumo de energia, gera??o de empregos e renda, e investimentos na ?rea social, para a melhoria de vida da popula??o local. Foi realizada uma pesquisa amostral do tipo Survey com 234 pessoas daquele munic?pio de um universo de 27.011 habitantes. Foi escolhido esse munic?pio porque o mesmo ? um dos principais produtores de camar?es no Estado, al?m de contar com as principais fazendas de cria??o e laborat?rios de melhoramento gen?tico dessa cultura. O instrumento de pesquisa utilizado, foi o question?rio com perguntas abertas e fechadas. Resultados mostram que grande maioria declarou pouco conhecimento com rela??o ao processo produtivo da atividade da carcinicultura e reconheceram como principal benef?cio da mesma, a gera??o de empregos. Em termos de associa??o entre vari?veis, n?o se verificou relacionamento entre as vari?veis investigadas do grupo perfil e a vari?vel dependente que expressa a opini?o do entrevistado quanto aos benef?cios sociais gerados pela atividade. Ou seja, em termos de g?nero, n?o h? diferen?a de percep??o entre homens e mulheres sobre os benef?cios sociais advindos da carcinicultura. De forma an?loga, n?o se observa diferen?a de percep??o sobre os benef?cios sociais da atividade entre as diferentes faixas de escolaridade, idade e renda familiar da popula??o entrevistada

Sutchi catfish (Pangasianodon hypophthalmus) – known more universally by the Vietnamese name ‘Tra’ is an economically important freshwater fish in the Mekong Delta in Vietnam that constitutes an important food resource. Artificial propagation technology for Tra catfish has only recently been developed along the main branches of the Mekong River where more than 60% of the local human population participate in fishing or aquaculture. Extensive support for catfish culture in general, and that of Tra (P. hypophthalmus) in particular, has been provided by the Vietnamese government to increase both the scale of production and to develop international export markets. In 2006, total Vietnamese catfish exports reached approximately 286,602 metric tons (MT) and were valued at 736.87 $M with a number of large new export destinations being developed. Total value of production from catfish culture has been predicted to increase to approximately USD 1 billion by 2020. While freshwater catfish culture in Vietnam has a promising future, concerns have been raised about long-term quality of fry and the effectiveness of current brood stock management practices, issues that have been largely neglected to date. In this study, four DNA markers (microsatellite loci: CB4, CB7, CB12 and CB13) that were developed specifically for Tra (P. hypophthalmus) in an earlier study were applied to examine the genetic quality of artificially propagated Tra fry in the Mekong Delta in Vietnam. The goals of the study were to assess: (i) how well available levels of genetic variation in Tra brood stock used for artificial propagation in the Mekong Delta of Vietnam (breeders from three private hatcheries and Research Institute of Aquaculture No2 (RIA2) founders) has been conserved; and (ii) whether or not genetic diversity had declined significantly over time in a stock improvement program for Tra catfish at RIA2. A secondary issue addressed was how genetic markers could best be used to assist industry development. DNA was extracted from fins of catfish collected from the two main branches of the Mekong River inf Vietnam, three private hatcheries and samples from the Tra improvement program at RIA2. Study outcomes: i) Genetic diversity estimates for Tra brood stock samples were similar to, and slightly higher than, wild reference samples. In addition, the relative contribution by breeders to fry in commercial private hatcheries strongly suggest that the true Ne is likely to be significantly less than the breeder numbers used; ii) in a stock improvement program for Tra catfish at RIA2, no significant differences were detected in gene frequencies among generations (FST=0.021, P=0.036>0.002 after Bonferroni correction); and only small differences were observed in alleles frequencies among sample populations. To date, genetic markers have not been applied in the Tra catfish industry, but in the current project they were used to evaluate the levels of genetic variation in the Tra catfish selective breeding program at RIA2 and to undertake genetic correlations between genetic marker and trait variation. While no associations were detected using only four loci, they analysis provided training in the practical applications of the use of molecular markers in aquaculture in general, and in Tra culture, in particular.

The overarching aim of this research was to improve understanding of the synergies and trade-offs between economic and domestic food security benefits associated export-oriented shrimp and prawn aquaculture in a fragile developing country environmental context. The research scope covers the entire ‘seafood system’ incorporating production, distribution, trading and consumption in the south-west coastal region under greater Khulna District, Bangladesh. The primary research objective was to understand causal factors in variation of seafood nutritional quality and health outcomes, exploring correlations with seafood consumption across a range of agro-ecological, aquatic farming systems and socio-economic conditions. The study also focused on differences in intra-household allocation with a special focus on adolescent girls, being amongst the most vulnerable members of society. These objectives necessitated a highly inter-disciplinary approach to understand complex interactions between biophysical aspects (e.g. where and which species are most effective in supplying essential nutrients) and the social norms of food allocation. Fieldwork was conducted in Satkhira, Khulna, and Bagerhat Districts of Khulna Province over 17 months during 2012 to 2015. Four villages across a peak-annual surface water salinity gradient; high saline (>10 ppt), medium saline (>5<10 ppt), low saline (<5 ppt) and freshwater (<0.5 ppt) were selected for case-studies. The thesis begins with a literature review of the evolution of shrimp and prawn farming in Bangladesh and the wider region and identification of knowledge gaps. Research resolved from district to community to household level. Key informant (KI) interviews were used to establish well-being criteria (based on a range of 5 social and economic assets) at community level. In each community a census of households (n=1082 households) were derived from the same interviews and KIs asked to ranked households on the established well-being criteria. Results were validated through a short interview of all the identified households (HH). This sample-frame provided the based for two concurrent survey efforts. Stratified-random selection of 160 HH on two well-being categories (better-off and worse-off) for ‘farm level’ analysis using a semi-structured questionnaire. Key topics included inputs/outputs characteristics, economic benefits and the fate of farmed products were evaluated. Another 240 households with single adolescent girls were selected from the same frame, again with randomized-stratified sampling based on well-being categories for ‘intra-household’ analysis. This resulted in selection of 60 HH per community consisting of 30 ‘better-off’ and 30 worse-off households (further analysis was conducted on a range of secondary sampling outcomes based on livelihood options, intra-household food distribution and aquatic farming assets). A 24-hour food recall method, food frequency questionnaire, food photography and measuring cup sets were used to estimate individual members’ food consumption at the household level. Anthropometric measures (stunting, wasting, BMI, MUAC) and biomarkers (omega-3 index in RBC and LC n-3 PUFA/LC PUFA in whole blood cell) were used to assess food security outcomes of adolescent girls (n=200 subject). In an entirely separate effort, samples of shrimp/prawn and fish polyculture species (57 species and 9 by-products, 1 live feed; n=672) were collected from the major agro-ecologies (four saline gradients; HS, MS, LS and FW) and culture systems (extensive, semi-intensive, intensive, organic and pocket gher). At least 3 sites from each saline gradient (3×4=12 sites) were selected for sampling and pooled samples to represent all the culture system in the region. The major macro and micronutrients of the collected species were analysed and these datasets were used to know the nutritional distribution among the family members in household level study. Two aggregate indices of wealth (or well-being) and aquaculture were developed based on a range of quantitative (ordinal and interval) measures. Principle Component Analysis (PCA) was used to understand how aquaculture influences on wealth gain. Wealth index of the same social well-being did not differ among the agro-ecologies. However, the aquaculture index was varied in agro-ecologies. Most of the households (60-80%) were involved directly in aquaculture however, a majority portion of the households was worse-off (48-64%). Both HS and LS area had more livelihood options due to their proximity to mangrove forest Sundarbans and city amenities, respectively compared to MS and FW area. Ownership of the land did not influence any involvement in aquaculture and yields but he willingness and risk-absorbing capacity of the farmers were the main factor to get involve in aqauculture. In aquatic farming system the importance of export-oriented shellfish yield gradually decreased from HS to FW area (55-20% by volume). The intentional stocking of finfish and PLs were common across the saline areas however the wild caught juveniles and hatchery originated fingerlings were usual in higher and lower saline areas, respectively. The low priced tilapia took the place of wild recruited mangrove fishes in MS area. Diseases, especially the devastating white spot virus (WSSV), frequency were higher in higher saline areas. The indicators like wild recruitment, salinity, water productivity and water management also a vital factor to gain yield. The integration of aquatic and terrestrial crops (rice and dyke crop) in the lower saline areas provide higher yield compared to higher saline areas. However, the net economic returns were largely determined by the aquatic products. The income of ghers in FW and MS area was sensitive to the lower prices of freshwater finfish and tilapia. The protein content in shellfish was higher than the other finfish, however, lower in other essential nutrients. Species living in the higher saline areas contained higher total n-3 PUFA (in weight) and LC n-3 PUFA/LC-PUFA compared to the same species living in lower saline areas. Small Indigenous Species (SIS) and Self-Recruiting Species (SRS) were proven to provide higher micronutrients and total n-3 PUFA than larger fish. Seafood that destined for the international markets contained less n-3 PUFA and micronutrients in comparison to the domestically consumed fish. Customary intra-household food distribution disparity (mainly fish) still exists at household levels where females, especially adolescent girls, were deprived. Fish consumption (>77 g /capita/day) and fish originated protein supply (>25% of total protein intake) was higher than the other part of Bangladesh. The protein consumption of adolescents was 2-3 times higher than the Recommended Nutritional Intake (RNI). However, the energy intake was lower than the required level. High protein, low energy consumption was not reflected in body mass. Micronutrients (zinc) consumption was above the RNI level. However, iron and calcium consumption was less than the RNI. The n-3 PUFA in RBC of adolescent girls accurately reflected their access to, and availability of, oily fish. In the omega-3 index (n-3 PUFA in red blood cell) both HS and MS areas, adolescent females were in the intermediate stage (4-8%), and rest of the two areas were in the undesirable stage (<4%). The n-3 LC-PUFA was around 20-30% of total LC-PUFA content in whole blood and gradually decreased from higher saline to lower saline areas. The thesis concludes that the gher based aquatic animal farming in S-W Bangladesh is a dynamic system operated by both rich and poor. The salinity level and the presence of mangrove forest make the farming system dynamic. The holistic scenario suggested aquaculture in ghers is a family driven small scale polyculture where varieties of aquatic foods are produced both for global and local value chain. Higher amounts of valued products (both in terms of nutrition and price), less disease susceptibility, more alternative livelihood options both in HS and LS were found in better position than the other two sites, however the nutritional content of fish and its manifestation in adolescents strongly mirrors agro-ecologies irrespective of social position of households. The thesis provides an important, grounded importance of the system and the linkage of the community people for livelihoods, food production and food security. The dynamic systems were understood and effective messages formulated for the policy makers. In doing so, the thesis contributes to an understanding of how small-scale polyculture equally benefited local food security and macroeconomic growth of a developing country.

Marine Protected Areas (MPAs) have been suggested as one of the solutions to coral reef fisheries management. It is thought that their effects on biomass, species diversity and habitat could improve surrounding fisheries yields through fish migration and increased recruitment. However, MPAs' benefits on surrounding fisheries are difficult to establish due to the lack of historical data. Furthermore, the lack of involvement of stakeholders have led to a number of failures. MPAs in the form of No Take Zones (NTZ), which aim to promote the sustainable use of fisheries resources, might contribute to the successful management of coral reef fisheries. However, few studies have considered their benefits from the point of view of surrounding fishing communities. It is evident that if stakeholders are to be further involved in MPA management, they need to perceive the benefits. The hypothesis tested was that if NTZs are of benefit to surrounding communities, their food security situation would be improved. The fieldwork was carried out in Southern Kenya with five fishing communities located around a long established MPA. The study showed that a range of food security indicators gave good information on MPAs' benefits to the surrounding communities. It was found that these benefits were highly affected by distances. Thus, although fishing households were the least food secure, they were better off if they fished nearer the protected reefs. Households dependent on MPA-related tourism were the most food secure but this dependency decreased with the communities' distance from the main tour operators. The results showed that MPAs' benefits were not equally shared by the communities bearing most of the costs. In addition, it was also found that tourism seasonality does not always compensate for the seasonality of other activities. Furthermore, tourism could not be assumed to develop around MPAs and provide reliable alternative employment.

L'aquaculture et la pêche impactent l'environnement, les ressources et le fonctionnement des écosystèmes. L’un des enjeux en écologie est de placer ces activités anthropiques dans un cadre de développement durable. Afin de quantifier et de limiter ces impacts, différentes méthodes d’évaluation environnementale ont vu le jour. L’Analyse de Cycle de Vie (ACV) est une méthode pertinente pour évaluer le bilan environnemental d'un produit en prenant en compte l’ensemble de ses étapes de vie, "du berceau à la tombe", depuis l’extraction des matières premières et leurs transformations pour l'élaboration du produit, jusqu’à la fin de vie. Cette thèse porte sur l’adaptation de l’ACV au domaine de l'aquaculture et de la pêche en Tunisie. Son objectif est d'explorer les perspectives offertes par cette méthodologie afin de mieux caractériser le fonctionnement des systèmes de production de poissons et leur lien avec l’environnement. Cette étude a montré que les pratiques aquacoles et la production d'aliment de poisson sont les contributeurs majeurs aux impacts environnementaux, ceci est expliqué par l'utilisation de farine et d'huile de poisson dans la fabrication de l'aliment. Les résultats ont également montré que les impacts du chalutage de fond sont proportionnels à la quantité de carburant nécessaire pour la production. Ce travail a permis d'étudier et comparer les impacts environnementaux de l'activité aquacole et de la pêche au chalutage de fond en Tunisie. Les résultats de cette thèse ont un intérêt pour les gestionnaires en proposant des voies d'amélioration et des recommandations stratégiques de gestion pour améliorer les deux secteurs afin de les placer dans un contexte de développement durable<br>The main goal of ecology is to place human activities within a framework of sustainable development by enhancing their economic benefits, their social attractiveness and their environmental performances. Ecosystems that support fisheries and aquaculture are subject to several alterations of significant relevance to their functioning and to their abilities to provide goods and services. Therefore, the long-term sustainability of fishing and aquaculture is a major concern from an environmental and ecological viewpoint. Both activities carry risks of negative environmental impacts because of its close relation with the immediate environment. To better understand environmental impacts and ensure the sustainability of fishing and aquaculture, it is necessary to develop an integrative sciencebased approach to impact assessment. Life Cycle Assessment (LCA) has emerged as a robust method to estimate potential environmental impacts associated with a product. It allows the assessment of environmental impacts “from cradle to grave”, taking into account all stages of a product’s life. This thesis focuses on the adaptation of LCA to demersal trawling and aquaculture in Tunisia. The goal is to explore how LCA improves the environmental evaluation of seafood production systems and how it helps to better understand their links with the environment. Results revealed that rearing practices and fish feed were the greatest contributors to the impacts studied due to the production of fish meal and oil and the low efficiency of feed use. The study also showed that impact intensity of demersal trawling was proportional to the amount of fuel consumed. LCA is a valuable tool for assessing how to improve environmental sustainability of demersal trawling and aquaculture

<p> Environmental activists are questioning the management strategies of the invasive Indo-Pacific lionfish (a species complex of <i>Pterois volitans </i> and <i>P. miles</i>) in the western North Atlantic, due to the species' rapidly expanding invasion and steadily growing population. The invasive lionfish species ecological effects are of great concern, as impacts on marine and terrestrial ecosystems trigger population and biodiversity declines. Awareness and research supporting the need for better managerial techniques and response strategies are surfacing among academic groups, forcing critical thought on the best methods of containment and population management.</p><p> In response to the lack of information on the marketability of the lionfish species, I propose a thesis that focuses on the creation of a privately funded non-governmental organization (NGO) that will offer a more promising solution for the control of lionfish through the application of effective marketing and educational outreach strategies. An NGO design and program provides more options and greater flexibility than the federal response to date, which as previously mentioned has not been efficient in the management of the lionfish invasion, as it is incredibly difficult for federal agencies to conduct the public promotion and supply-chain building necessary to properly found this operation. The NGO will work to initiate interest in the lionfish through public education and cooperation and incentivize its capture and consumption, by appealing to the supply and demand ends of the culinary market. The overarching goal is to demonstrate how an NGO can successfully alleviate environmental impacts and increase sustainability through the use of market-based initiatives and inter-party cooperation.</p>

Links between the pond and surrounding land for horticulture is a distinctive feature of farming households in Bangladesh. It was hypothesised that the role of fishponds in integrated aquaculture systems has potential towards improving livelihoods and poverty alleviation. Rural and peri-urban settlements in Mymensingh District, Bangladesh were selected for assessing the importance and role of pond-dike systems on the livelihoods of households of different socio-economic level. The study was carried out in view of the sustainable livelihood approaches of the Department for International Development, U.K. Participation of all levels of stakeholders was ensured in the first and last phase of the study. The combination of quantitative and qualitative analysis at community and household level was a major strength and challenge of the study, and was used to explore the potential of integrated farming and factors that undermine such potential to contribute to a sustainable livelihood. The research commenced with a comprehensive situation appraisal and baseline survey to explore the context and characterize farming systems, followed by a longitudinal household survey to understand the effect of seasons on livelihoods. Households with access to ponds were identified as active or passive integrators based on a simple set of criteria and their resources and livelihoods assessed in comparison with non-pond households. During the last phase of the study a farmer participatory research (FPR) trial, based on a priority issue identified during the 1st phase of the study, was launched to investigate the potential of the integrated systems. The situation appraisal conducted within four communities revealed the effects of gender, well-being and location on farmers' regular activities and food consumption patterns. Fish culture was equally important as an enterprise among richer and poorer men, whereas vegetable cultivation was more important to men than women but wealth and location also affected its importance. Lack of knowledge was a particular problem for farmers growing fish and vegetables in the rural areas. Fish disease, high price of input, lack of money were also identified as constraints by fish producers. The expected use and current use of ponds, problems and benefits associated with fish culture were also found to be affected by groups emphasising vegetable, orchard and fish culture within their systems. The role of the pond for family use, which was a major objective for pond construction, was found to be significantly different between rural and peri-urban areas. Fish culture is now the dominant use of ponds for households irrespective of their focus on vegetable, orchard or fish production and they are utilised less for general domestic use. Ponds are relatively more important as a source of irrigation water in rural than in peri-urban communities. Significant differences were observed between locations and well-being categories for the percentage of fish retained for consumption and that sell. Rice bran was the most commonly used pond input (80% of all pond households) but active integrated farmers applied rice bran more frequently than passive groups (91 compared to 63 times/season). ‘Ease of production’ was a major incentive for farmers to integrate fish and vegetable production and this opinion was related to household type i.e. active integrators were more aware and confident about the practice. The literacy levels of household heads, access to information and capital and contact with formal and informal institutions of active producers and the better-off households was significantly higher than other groups and poorer households respectively. It is revealed from the longitudinal households’ analysis that the consumption pattern in terms of food types and amount are linked with income, expenses and food availability in different well-being categories between seasons across locations. The empirical analysis showed that as active households’ income increased, expenditure on food purchases, agricultural labour, pond inputs and poultry per household also increased. However, on-farm contributions as a source of fish and vegetables were important during the lower income and least productive months. Performance of integrated farming systems varied by location. Resource base, accessibility to market and information played key roles in the development of integrated farming system in the study area. Active integrated households in peri-urban areas, in response to higher demand in the nearby market, produced significantly more fish and vegetables than those in the rural areas. The result showed clearly the need for due consideration of these factors while promoting IAA systems in Bangladesh. Farmer participatory research showed that production of fish could be increased by a substantial level through increasing pond nutrient inputs rather than stocking an additional species (tilapia), although this may be related to the ‘improved’ nutrition used by farmers still being well below the level required for optimal tilapia performance. Rural households benefited more than peri-urban through direct consumption of both fish and vegetables; in contrast peri-urban households benefited more through cash sales of both fish and vegetables than rural households. Higher production did not lead to increased consumption, rather households benefited financially through selling fish. Similar production levels of vegetables between groups followed different levels of fish culture practices suggesting that increased investment in fish production is complementary rather than competitive with associated vegetable production. It could be concluded that considerable potential exists for further integration and development of pond-dike systems, which could contribute towards improved livelihoods of both better off and worse off people.

Drastic alterations to the North American Southwest’s hydrology have highly influenced resident fish communities. In New Mexico and Texas, the Pecos River has been severely altered as a result of water manipulation, isolating backwaters and various habitats that were once connected to the main river. Cyprinodon pecosensis (Pecos pupfish) has been highly impacted due to the effects of anthropogenic water manipulation, as well as species introductions. Cyprinodon pecosensis populations have become isolated and scattered, residing in sinkholes, remnant lakes, and static backwaters, thus creating numerous micropopulations. The purpose of this study was to assess the morphological variation in cranial features that occur in response to varied habitats, especially in terms of environmental factors and species co-occurrence. Landmark-based geometric morphometrics was used to assess shape variation across the aforementioned micropopulations comprising four general habitat types and 27 different localities, each with varied community structure and salinity. Results from this study suggest that head and mandible morphology vary temporally, with year to year variation, as well as among different localities. The head morphology of C. pecosensis was most heavily influenced by habitat type and localities within habitat types, but was largely canalized with the exception of localities classified as deep sinkholes. Year to year variation and localities among habitat types were the most influential factors associated with mandible morphology, but there was strong overlap among the convex hulls that defined regions of morphospace for habitat types. As C. pecosensis is a threatened species, this research has important implications for future conservation and management. Additionally, these results could further aid in the understanding of preserving species in fragmented landscapes.

L'aquaculture et la pêche impactent l'environnement, les ressources et le fonctionnement des écosystèmes. L’un des enjeux en écologie est de placer ces activités anthropiques dans un cadre de développement durable. Afin de quantifier et de limiter ces impacts, différentes méthodes d’évaluation environnementale ont vu le jour. L’Analyse de Cycle de Vie (ACV) est une méthode pertinente pour évaluer le bilan environnemental d'un produit en prenant en compte l’ensemble de ses étapes de vie, "du berceau à la tombe", depuis l’extraction des matières premières et leurs transformations pour l'élaboration du produit, jusqu’à la fin de vie. Cette thèse porte sur l’adaptation de l’ACV au domaine de l'aquaculture et de la pêche en Tunisie. Son objectif est d'explorer les perspectives offertes par cette méthodologie afin de mieux caractériser le fonctionnement des systèmes de production de poissons et leur lien avec l’environnement. Cette étude a montré que les pratiques aquacoles et la production d'aliment de poisson sont les contributeurs majeurs aux impacts environnementaux, ceci est expliqué par l'utilisation de farine et d'huile de poisson dans la fabrication de l'aliment. Les résultats ont également montré que les impacts du chalutage de fond sont proportionnels à la quantité de carburant nécessaire pour la production. Ce travail a permis d'étudier et comparer les impacts environnementaux de l'activité aquacole et de la pêche au chalutage de fond en Tunisie. Les résultats de cette thèse ont un intérêt pour les gestionnaires en proposant des voies d'amélioration et des recommandations stratégiques de gestion pour améliorer les deux secteurs afin de les placer dans un contexte de développement durable<br>The main goal of ecology is to place human activities within a framework of sustainable development by enhancing their economic benefits, their social attractiveness and their environmental performances. Ecosystems that support fisheries and aquaculture are subject to several alterations of significant relevance to their functioning and to their abilities to provide goods and services. Therefore, the long-term sustainability of fishing and aquaculture is a major concern from an environmental and ecological viewpoint. Both activities carry risks of negative environmental impacts because of its close relation with the immediate environment. To better understand environmental impacts and ensure the sustainability of fishing and aquaculture, it is necessary to develop an integrative sciencebased approach to impact assessment. Life Cycle Assessment (LCA) has emerged as a robust method to estimate potential environmental impacts associated with a product. It allows the assessment of environmental impacts “from cradle to grave”, taking into account all stages of a product’s life. This thesis focuses on the adaptation of LCA to demersal trawling and aquaculture in Tunisia. The goal is to explore how LCA improves the environmental evaluation of seafood production systems and how it helps to better understand their links with the environment. Results revealed that rearing practices and fish feed were the greatest contributors to the impacts studied due to the production of fish meal and oil and the low efficiency of feed use. The study also showed that impact intensity of demersal trawling was proportional to the amount of fuel consumed. LCA is a valuable tool for assessing how to improve environmental sustainability of demersal trawling and aquaculture

With the recent growth of the hard clam aquaculture industry, sites of intensive aquaculture have emerged as large-scale agro-ecosystems where the success of aquaculture production is dynamically linked to ecosystem function. Large scale clam aquaculture operations are associated with a range of potential positive and negative feedbacks related to nutrient dynamics, water and sediment quality, proliferation of macroalgae, and carrying capacity. Quantitative modeling tools are needed to support system-level planning related to site selection, scale of operations, production capacity and ecosystem function. The purpose of this study was to develop a model for Cherrystone Inlet, VA, where one-third (1.9 km2) of the sub-tidal bottom area is held as 37 separate, private shellfish leases with an estimated 100-150 million cultured clams. A reduced complexity estuarine ecosystem model was coupled with a hard clam energetics and growth model and a watershed loading model. The linked models facilitate ecosystem-based management and enable regional spatial planning in a full ecosystem context, through coupled simulations of aquaculture activities, land use changes, nutrient loading, climate change, and estuarine response. Modeled output for hard clam growth and water column chlorophyll-o, dissolved oxygen, and dissolved inorganic nitrogen and phosphorous reproduced in situ data. Simulations with increasing clam numbers up to 500 million resulted in diminishing returns in terms of reduced growth rates, increased time to harvestable size, and reduced harvestable biomass, confirming observations by Cherrystone farmers of reduced clam growth rates above 200 million cultured clams. Modeled hard clam production capacity decreased in the absence of benthic microalgal resuspension (6%) and without the input of external production from the Chesapeake Bay (41%), and increased in simulations with increased water column chlorophyll-o (11%) and the removal of predator exclusion nets (13%). Simulations to optimize siting indicated that the highest hard clam growth rates occurred up-estuary. Model simulations with changes in land use and climate indicated that clam growth is most sensitive to increasing temperature, with rates decreasing by 37% when temperatures were increased by 5°C, while changes in land use, sea level rise and salinity did not result in large changes in hard clam production. At the system scale hard clam aquaculture was predicted to account for 14% of total nitrogen inputs to the water column between sediment recycling of clam feces (13%) and direct clam excretion (1%). The Cherrystone ecosystem model fills a critical gap on the Eastern Shore of Virginia and in similar coastal systems, providing resource managers with the most current available science in a decision-support framework to promote effective regional spatial planning and sustainability of hard clam operations and the surrounding coastal ecosystems.

The south coast of South Africa is a very dynamic, productive, high energy environment and is considered to be a generally challenging setting for in-water aquaculture. One of the largest environmental threats to aquaculture are harmful algal blooms (HABs), a natural ecological phenomenon often accompanied by severe impacts on coastal resources and local economies. There is a wide variety of potentially harmful blooming species in the region, with impacts resulting from both toxicity and the negative effects associated with high biomass. While HABs are fairly well documented around the southern Benguela area, the primary concern is the lack of long-term data showing if blooms are becoming more frequent, persistent or are having greater impact over the last decades, consistent with environmental change experienced in the region. For this study, high-resolution satellite remote sensing observations from 16 years of MODIS-Aqua (1 km) and one month of Sentinel-3 OLCI (300 m), using regionally optimised blended algorithms, were used to investigate the spatial distribution and temporal variability of chlorophyll-a (Chl-a) along the south coast of South Africa. A Chl-a threshold of 27 mg m−3 was used as an analytic to identify the occurrence of high biomass blooms in the remote sensing data. Phytoplankton count data from aquaculture farms are used to provide information corresponding to changes in phytoplankton community structure, and to investigate the distribution and seasonal trends of HABs along the south coast. To further explore the spatial and temporal distribution, phytoplankton species considered harmful for this study were identified and classified to their seasonal occurrence: some species were consistently present throughout the years, however each region showed contrasting seasonality. A second interest of this study is linked to assessing the capacity of the aquaculture industry to make profitable use of existing observational and early warning tools. The impact of HABs on the environment or in aquaculture facilities can be potentially mitigated by increasing the industry awareness and early warnings of HAB development. In this regard, the Fisheries and Aquaculture Decision Support Tool (DeST) was used in order to develop short term alerts on HAB development. The EO analyses conducted here specifically use the same methods used by this DeST to demonstrate the use of this tool for historical analysis in addition to real time alerting. In order to evaluate the effectiveness of the tool and how the aquaculture farmers use the ABSTRACT information provided on the DeST, an online user feedback was generated, and distributed to all stakeholders via email

The lack of economic analysis on export-led shrimp farming in India has become of major national importance as a result of the Indian Supreme Court's December 1996 decision to ban the shrimp farming sector. The ban was a direct result of concerns over the impact of shrimp farming-in terms of its degradation of the environment and marginalization of local people from coastal resources. In addition to questions raised with respect to the nature and extent of environmental and socio-economic externalities of this sector, recent parliamentary debate raised equally important questions regarding the sustainability of shrimp farming under a variety of production methods. However, assessment of the productive efficiency of shrimp farms under increasingly intensive production methods is lacking. Parametric and non-parametric approaches to measuring the productive efficiency of shrimp farms are applied to farm-level data collected from the Kandaleru region in India. First, technical efficiency is modelled, measured and explained by estimating a restricted translog stochastic frontier production function using maximum-likelihood methods. The variation of technical efficiency indices across the shrimp farm sample is explained using farm specific characteristics and managerial variables. Farm mechanisation, location and size are found to be significant factors explaining total inefficiency. Second, scale effects are extracted from the total efficiency index by applying Data Envelopment Analysis techniques. An inverse relationship is found to exist between farm size and efficiency. Next, social and environmental impacts facing rural inhabitants as a result of the shrimp farming sector's growth and development are assessed using primary survey data collected from twenty-six villages located adjacent to shrimp farms. The most frequently cited problem by local inhabitants is blocked access to public areas. This is followed by problems of agricultural land salinity, well water salinity, unemployment, fodder & fuelwood collection problems and health problems, respectively. The immediate policy direction is clear: larger farmers could reduce the intensity of production to maximise efficiency and minimise input slacks to reduce the risk of environmental degradation both within the aquatic pond environment and to the natural ecosystem. Similarly, they could enable free but supervised access through their farms to public areas such as the Bay of Bengal, Kandaleru creek or public pasture lands.

L'aquaculture connait un taux de croissance annuel moyen de sa production proche de 7 % depuis 50 ans. De nombreux pays, à des degrés variés, ont enregistré des augmentations de leurs productions aquacoles. Ce développement s'est accompagné d'une augmentation des surfaces terrestres et marines occupées par les différentes formes d'aquaculture : marine, saumâtre ou dulcicole. Parmi ces dernières, c'est l'aquaculture saumâtre en étangs qui a constitué notre objet d'étude, et plus particulièrement celle pratiquée dans l'espace intertropical. A partir de deux études de cas, aux Philippines (Pampanga) et au Pérou (Tumbes), cette thèse a eu pour objectif d'analyser le développement aquacole, c'est-à-dire d'identifier les facteurs et l'enchaînement des évènements qui ont contribué à la mise en place de l'aquaculture, de caractériser son développement spatial et d'identifier puis d'expliquer ses impacts, positifs et négatifs, à plusieurs échelles. La méthodologie élaborée pour répondre à ce questionnement a reposé sur l'emploi d'une méthode de traitements d'images et d'une méthode d'enquêtes. Les traitements d'images avaient trois objectifs : la cartographie des étangs, la cartographie de l'occupation du sol et la cartographie des changements d'occupation du sol. Le jeu d'images était composé de huit images satellites multispectrales pour le terrain péruvien et de neuf images satellites multispectrales pour le terrain philippin, à haute et très haute résolutions spatiales (Landsat MSS, TM, ETM+ et SPOT 5). Plusieurs méthodes ont été testées puis comparées afin de cartographier les étangs. La chaine de traitement élaborée s'est basée sur l'intégration d'un traitement multispectral et d'un traitement morphologique. La cartographie de l'occupation du sol a consisté, quant à elle, à réaliser une analyse en composante principale suivie d'une classification par un algorithme de classification non supervisée. La diachronie, enfin, visant à cartographier le changement, a utilisé la méthode dite de ‘post-classification'. Les principales méthodes d'enquêtes utilisées sur le terrain ont été les questionnaires, les entretiens directifs et semi-directifs, la récolte de données de seconde main et l'observation, participante lorsque cela a été possible. Enfin, un système multi-agent a été élaboré à partir de données empiriques sur le terrain philippin dans le but d'explorer le rôle de plusieurs facteurs sur l'évolution des paysages. Grâce à une méthode orienté-objet, de nombreux étangs aquacoles ont pu être cartographiés individuellement sur l'ensemble des images. En croisant les informations issues des cartes avec les informations d'une base de données, dite de vérité-terrain, deux mesures ont permis d'évaluer la qualité de la cartographie : les écarts de superficie entre la réalité et le produit des traitements ainsi que le nombre d'étangs correctement détectés. Il a alors été possible d'estimer les superficies d'étangs à chaque date. Les analyses diachroniques ont, quant à elles, permis d'identifier et de quantifier les occupations du sol sur lesquelles l'aquaculture s'est installée. Il a ainsi été démontré que depuis les années 1980, à Pampanga, une proportion importante des extensions aquacoles s'est réalisée au détriment des zones rizicoles. Au total, ce sont 11 000 hectares de rizières qui ont été convertis en étangs. Les changements d'occupation du sol à Tumbes, moins importants, ont majoritairement concerné des formations végétales naturelles. La mise en place de l'aquaculture et son développement résultent de nombreux facteurs qui se distinguent les uns des autres par leur nature, leur ancienneté et leur échelle d'inscription. Des séquences réunissant plusieurs de ces facteurs selon un enchaînement donné ont été mises en évidence sur les deux terrains. Au Pérou, les facteurs qui ont contribué au développement aquacole sont récents et remontent aux années 1970 alors qu'aux Philippines, les facteurs sont beaucoup plus anciens. Trois phases ont caractérisé le développement aquacole au Pérou : une première phase, dite de croissance, qui a précédé une phase dite de crise, conséquence des épizooties et d'El Niño puis une dernière, plus récente, dite d'adaptation, à la suite des changements de pratiques. Aux Philippines, l'analyse des facteurs de transition a révélé l'importance de certains facteurs historiques dans le démarrage de l'activité, qui s'expriment aujourd'hui encore sur le foncier et sur la structure sociale, et de facteurs plus récents, tel que la subsidence accélérée, qui expliquent le développement spatial au dépend des zones de riziculture. Cette thèse a aussi eu pour objectif de caractériser les systèmes aquacoles actuels par l'intermédiaire d'une analyse des systèmes agraires. Les différences et les similitudes des systèmes d'élevage et de production ont ainsi pu être caractérisées. La caractérisation des facteurs de production a rendu compte des origines et des niveaux d'utilisation très différents de facteurs tels que le capital ou le travail. L'évaluation de la performance des systèmes de production aux Philippines a permis en outre d'estimer le revenu moyen journalier des aquaculteurs dont le niveau explique en partie la pérennité de l'activité, et ceci en dépit des faibles rendements, mesurés grâce aux enquêtes agronomiques. On a enfin caractérisé les impacts de l'aquaculture sur le territoire et sur plusieurs de ses composantes sociales dont les individus et les foyers. Au Pérou, les migrations et l'emploi ont constitué les deux principaux domaines d'analyse. Les flux migratoires des ouvriers aquacoles ont ainsi pu être caractérisés et cartographiés grâce à des questionnaires. La caractérisation a permis d'établir le ‘profil type' du migrant mais a aussi mis à jour le rôle des exploitations aquacoles dans la formation et la pérennisation des flux. L'emploi local dans la filière aquacole a aussi été estimé entre les années 1980 et 2006. Celui-ci, fluctuant sur le long terme, a récemment dépassé les 2500 emplois à temps plein. La croissance de ce chiffre s'explique en partie par la mise en place récente de systèmes aquacoles intensifs, aux besoins en travail plus élevés que les systèmes extensifs et semi-intensifs. Aux Philippines, le concept de livelihood a fourni un cadre d'analyse des ressources possédées par les personnes appartenant à plusieurs catégories d'acteurs et tirant un bénéfice direct ou indirect des ressources aquacoles. Les différentes formes de capital (humain, social, financier, naturel et physique) détenues par les individus ont été évaluées, à la fois qualitativement et quantitativement. Ce cadre d'analyse a aussi permis d'identifier les stratégies élaborées à l'échelle des foyers. La description et l'explication du fonctionnement du système de glanage des ressources aquacoles a constitué un autre résultat important. L'analyse des impacts de l'aquaculture au niveau des territoires a mis en évidence l'émergence de conflits, le rôle des infrastructures et du peuplement sur le développement de la filière ou encore l'impact de l'activité sur le développement local. Le modèle multi-agent élaboré (CHANOS-CHANgement d'Occupation du Sol) a enfin permis d'explorer et de mesurer les impacts paysagers dans des scénarii où les exploitants présentent des comportements variés : rationnels, collectifs ou à rationalité limitée et où la dynamique biophysique évolue différemment. La thèse a donc permis de mieux comprendre le développement historique de l'aquaculture et ses impacts actuels sur deux territoires des pays du Sud grâce à l'emploi de plusieurs perspectives : géographique, économique et historique, et grâce au recours à une analyse s'effectuant à plusieurs échelles spatiale et temporelle. La méthode élaborée, qui intègre plusieurs outils, méthodes et faisant appel à des concepts originaires de plusieurs disciplines apparaît aussi comme un des principaux résultats.

Made available in DSpace on 2016-08-11T14:41:30Z (GMT). No. of bitstreams: 1 JanneKS_DISSERT.pdf: 1447569 bytes, checksum: 3b9a105d54e04d077ba0f4caece98db6 (MD5) Previous issue date: 2014-12-01<br>The State of Ceará after the 1990s, is now inserted in front of the Agrohidronegócio expansion through construction of a developmental project characterized by a set of structural and administrative measures for modernizing character of this agricultural capital by way of large state incentives entered in some parts of the territory of Ceará, erupting in 2003 in the Vale do Jaguaribe shrimp farming that gave rise to this research guiding question: what are the main changes occurred in the social, environmental and technological aspects in Jaguaruana- CE from the sociorestructuring produced by Agrohidronegócio the Shrimp? As the main objective of this research we proposes to analyze the socio restructuring produced in the municipality of Jaguaruana due to the expansion of the Agrohidronégocio Shrimp. Secondarily search: Display contextual way socio-spatial restructuring that allowed the expansion of shrimp farming Agrohidronégocio through the state tool; Identify the environmental, technological and social aspects that after 2003 promoted a reconfiguration Jaguaruana-CE; Understand how the subjects of communities, businesses and the government interpret / interact / coexist with the impacts of shrimp aquaculture. The research method used was the dialectical.The chosen techniques for the data collection were bibliographic, documentary research and semistructured interviews. The survey results showed that Agrohidronegócio shrimp farming has been widespread in Jaguaruana-CE without effective inspections, with government incentives and significant impacts on environmental, technological and social spheres, through the shortage of family farming, the process of deterritorialization, the rural exodus, unemployment, income concentration, the risks to human and animal health through the release of effluents into water and conflicts over water bodies felt mainly by peasant populations<br>O Estado do Ceará após a década de 1990 inserido na frente de expansão do Agrohidronegócio mediante a implantação de um projeto desenvolvimentista caraterizado por um conjunto de medidas administrativas e estruturais de caráter modernizante. O capital agrícola através de amplos incentivos estatais adentrou em alguns pontos do território cearense, eclodindo em 2003 no vale do Jaguaribe a carcinicultura que deu origem a questão norteadora desta pesquisa: Quais as principais reestruturações socioespaciais ocorridas nos aspectos sociais, ambientais e tecnológicos em Jaguaruana- CE produzida pelo Agrohidronegócio da Carcinicultura? Como objetivo principal a pesquisa propõe: Analisar a reestruturação socioespacial produzida no município de Jaguaruana decorrente da expansão do Agrohidronégocio da Carcinicultura. Secundariamente busca: Apresentar de forma contextual as reestruturações socioespaciais que possibilitaram a expansão do Agrohidronégocio da carcinicultura por meio da ferramenta estatal; Identificar os aspectos ambientais, tecnológicos e sociais que a partir de 2003 promoveram uma reconfiguração em Jaguaruana-CE; Compreender como os sujeitos das comunidades, as empresas e o poder público interpretam /interagem/convivem com os impactos da carcinicultura.Trata-se de uma pesquisa qualitativa . As técnicas escolhidas para a coleta dos dados foram pesquisa bibliográfica e entrevistas semi estruturadas. Os resultados da pesquisa evidenciaram que o Agrohidronegócio da carcinicultura vem sendo disseminado em Jaguaruana-CE sem efetivas fiscalizações, com incentivo estatal e de impactos significativos nas esferas ambientais, tecnológicas e sociais, feições de desmatamento e assoreamento no curso do rio Jaguaribe, escassez da produção agrícola familiar, processo de desterritorialização, êxodo rural, desemprego, a concentração de renda, riscos à saúde humana e animal através da liberação de efluentes em corpos hídricos e conflitos por água sentido principalmente pelas populações campesinas

Made available in DSpace on 2017-07-10T18:13:20Z (GMT). No. of bitstreams: 1 Karane A S de Moraes.pdf: 2673552 bytes, checksum: 9e0e357e3817606424cdcadc03fab744 (MD5) Previous issue date: 2014-05-27<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>This study aimed to characterize and analyze the sustainability indicators for fish farms in the city of Toledo, Paraná, Brazil, during the period September 2013 to March 2014. The research was divided into four stages: consultation of bibliographic sources, checklist inventory, case study and data analysis. The checklist was basically divided into 17 sections and 90 pertinent socioeconomic and environmental profile issues, which was applied to 25 active stakeholders involved with the activity of commercial fish farming ponds in the city of Toledo. The checklist has a number of questions pertinent to the theme of each section, where the interviewer attaches to issues the notes 0, 1, 2, 3, 4 or 5, which correspond respectively to 0, 20, 40, 60, 80 and 100% effectiveness as Answer Key proposed. Based on the responses of the interviewees has made the assessment and characterization of the projects, which resulted from: 0 to 20, 21 to 40, 41 to 60, 61 to 80 e 81 to 100%, the indexes may be defined as respectively "Critical", "Low", "Regular", "Good" or "Great" sustainability. From sections of the Checklist surveyed, 4 have generated sustainability indexes "Great", 11 "Good" and 2 "Regular". The global sustainability index obtained was 73%, a result that characterizes fish farms of Toledo, in general, "Good" social, economic and environmental sustainability. After the identification of loss-sections and the critical points, which represent 60% of total possible points, qualified as "Regular" or lower, applied the Summary Management Plan. The most deficient points located within the sections were restructured, thus setting, new strategies and practical solutions to increase the levels of sectoral and global sustainability of fish farms in the city. The application of public politics and more efficient extension services are suggested, making it necessary the implementation of technical advice to producers and development and building systems for wastewater treatment.<br>Este estudo objetivou caracterizar e analisar os indicadores de sustentabilidade para as pisciculturas do município de Toledo, Paraná, Brasil, durante o período de setembro de 2013 a março de 2014. A pesquisa foi dividida em quatro fases: consulta de fontes bibliográficas, inventário da Lista de Verificação, estudo de caso e análise dos dados. A Lista de Verificação foi dividida basicamente em 17 seções e 90 questões pertinentes ao perfil socioeconômico e ambiental, a qual foi aplicada aos 25 interessados ativos envolvidos com a atividade de piscicultura comercial em viveiros no município de Toledo. A Lista de Verificação possui um número de perguntas pertinentes ao tema de cada seção, onde o entrevistador atribui para as questões as notas 0, 1, 2, 3, 4 ou 5, que correspondem respectivamente a 0, 20, 40, 60, 80 e 100% de efetividade conforme o Gabarito proposto. Com base nas respostas dos entrevistados, fez-se a avaliação e caracterização dos empreendimentos, qual resultou entre: 0 a 20, 21 a 40, 41 a 60, 61 a 80 e 81 a 100%, podendo os índices ser definidos como respectivamente Crítica , Fraca , Regular , Boa ou Ótima sustentabilidade. Das seções da Lista de Verificação pesquisadas, 4 geraram índices de sustentabilidade Ótima , 11 Boa e 2 Regular . O índice de sustentabilidade global obtido foi de 73%, resultado que caracteriza as pisciculturas de Toledo, de um modo geral, Boa sustentabilidade social, econômica e ambiental. Após a identificação das seções deficitárias e os pontos críticos, o que representam 60% do total de pontos possíveis, qualificado como Regular ou inferior, aplicou-se o Plano Resumido de Gestão. Os pontos mais deficitários localizados foram reestruturados dentro das seções, traçando-se assim, novas estratégias e soluções práticas para aumentar os índices de sustentabilidade setoriais e global das pisciculturas do município. Sugere-se a aplicação de políticas públicas e serviços de extensão mais eficientes, fazendo-se necessário a implementação de assessorias técnicas aos produtores e elaboração e construção de sistemas para o tratamento de efluentes.

Aquaculture has great potential to help supply the nutritional needs of a growing population. To date, however, the benefits that aquaculture can have, have largely been overshadowed by the environmental degradation some segments of the industry have caused. The following body of work describes my efforts to help reduce the environmental impacts of aquaculture. By integrating aquaculture production into traditional agriculture, the impact of farming on already limited water resources and the reliance on chemical fertilizers can be reduced. Recent expansion of the aquaculture industry in Arizona has made it possible to study the integration of olive groves with marine shrimp culture. In chapter 3, I describe the characterization and evaluation of the effluent from an inland, low-salinity shrimp farm as a potential source of irrigation water. I found that 0.41 kg of ammonia-nitrogen, 0.698 kg of nitrite-nitrogen, 8.7 kg of nitrate-nitrogen and 0.93 kg of total phosphorus (TP) were made available as fertilizer each day in the effluent water. Based on the results of this first study, I decided to conduct a farm trial to quantify the effects of these shrimp farm effluents on olive trees. This work is described in chapter 4. Trees in all treatment groups grew an average of 40.1 cm over the four month study period. While growth of trees irrigated with shrimp farm effluent did not improve in respect to the other treatments, our results do indicate that irrigating with low-salinity water had no noticeable negative effects. Chapter 5 describes work conducted in Idaho, as part of a larger study aimed at reducing the effluent loads of phosphorus (P) from high density, flow-through aquaculture facilities. Research steps were taken to establish a relationship between TP and the carbon 12/13 isotope ratio (δ¹³C) and/or the nitrogen 14/15 isotope ratio (δ¹⁵N). Our findings suggest that both δ¹⁵N and δ¹³C are good better proxies for P, after correcting for P retention. A linear regression of %P (corrected) on δ¹³C and δ¹⁵N resulted in R2 values of 0.843 and 0.8622, respectively. This suggests that by tracking δ¹⁵N and/or δ¹³C through a high-density, flow-through aquaculture facility over time I will be able to determine the residence time of P with a high degree of accuracy.

A aquacultura pode gerar considerável impacto ambiental pelo alto nível de N e P produzido. Este fato reflete a necessidade de mais estudos sobre a remoção daqueles nutrientes.O objetivo deste estudo foi avaliar o uso de Azolla filiculoides na remoção de N e P de efluentes com diferentes densidades de coberturas e períodos de tempo, com e sem sedimentação prévia. Ambos os trabalhos foram desenvolvidos no Setor de Aquacultura da UFRGS.A planta Azolla filiculoides foi distribuída em proporções de 0% (controle), 25%,50% e 75% da superfície das caixas plásticas. O período do experimento foi de 10, 20 e 30 dias, com três repetições num delineamento inteiramente casualizado. O efluente foi procedente de tanque de piscicultura. O melhor tempo de duplicação (TD) ocorreu nos primeiros 10 dias com 50% de cobertura.O fitotratamento de efluentes de aquacultura com Azolla filiculoides apresentou maior remoção de nutrientes N e P com área de cobertura de 75%, devendo ser realizado em curtos períodos de tempo, isto é menores que dez dias. Para o segundo trabalho o efluente de tanque de piscicultura foi submetido a decantação por 2 horas. O sobrenadante foi coletado para o tratamento com sedimentação e mantido inalterado para o sem sedimentação, com cinco repetições por parcelas divididas. A Azolla cobriu 50% da superfície das caixas. O período experimental foi de 0, 3, 6, 9 e 12 dias. Não houve interação entre sedimentação e tempo para variável N-total. O tratamento com sedimentação removeu 49% mais N-total. Não houve diferenças significativas dos fatores sedimentação e tempo para variável fósforo. Neste estudo, o processo de sedimentação reduziu substancialmente o nutriente nitrogênio e não reduziu o fósforo do efluente.<br>The aquaculture may cause a heavy impact on the environment because of the high level of N and P produced. This fact shows the necessity of new studies about the remove of those nutrients. The objective of this study was valuating the use of Azolla filiculoides in removal of N and P of effluent with different density of covering and period of time, without and with sedimentation. Both of us the works was develop in sector of aquaculture of UFRGS. The Azolla was distributed in proportion of 0% (control), 25%, 50% and 75% placed into the plastic containers. The period of experiment was 10, 20 and 30 days, with three repetitions in delineament whole casualized. The effluent from pond of pisciculture. The best time of duplication (TD) occurred at the first 10 days with 50% of cover. The phytotreatment of effluents of aquaculture with Azolla filiculoides removal of nutrients N and P with area of covering of 75%, must carried in short periods of time, this is smaller that ten days. For the second work the effluent from pond of pisciculture was submitted the decantation for 2 hours. The surface of the water was collected for the treatment without sediments and to keep original for with the sediments, with five repetitions for in portion divide. Azolla to cover 50% of surface of boxes. The period of experiment was 0, 3, 6 and 9 days. Hasn’t interaction between sedimentation and time for variable N-total. The treatment with sedimentation removal 49% more N-total . Hasn’t different significance of factors sedimentation and time for the variable phosphorus. In this research, the process of sedimentation decreased substantial nitrogen nutrient, but it didn’t decreased the phosphorus of the effluent.

One of the main environmental impacts of salmon aquaculture activities in the Bay of Fundy is the alteration of sediment chemistry as a result of the large amount of organic waste that accumulates below fish pens. To investigate these impacts, vertical profiles of delta13C, delta 15N, Corg, Corg:Ntot, FeHC1 , MnHCl, Ptot, PHCl, SO4 2-, AVS, Hgtot, and Hgpyrite in sediment cores collected throughout the bay were acquired. These profiles were then used to identify tracers of aquaculture activities and their impact on the redox zonation of the sediment. In addition, representative samples of fish food as well as farmed and wild salmon were analyzed to determine their Hg tot content as well as delta13C, delta15N, Corg, Corg:Ntot.<br>Our results show that, as by-products of salmon aquaculture (e.g., uneaten food, feces, antibiotics, and anti-fouling agents) accumulate in the sediments, their reactive organic carbon content increases and generate a greater oxygen demand. Subsequently, an upwards migration of the oxygen penetration depth and redox boundaries in the sediment column occurs, which is confirmed on the basis of the distribution of redoxsensitive phases (e.g., authigenic metal oxides and AVS) in the sediments. High resolution voltammetric microelectrode measurements show that the FeHCl and MnHCl distributions overestimate the oxygen penetration depth in the sediments. The total phosphorus distribution in the sediment record is shown to be a suitable tracer of marine aquaculture, reflecting the recent history of residual feed and fecal matter accumulation in the sediments.<br>Elevated mercury concentrations in sediments under fish pens are explained by its strong affinity for organic carbon. Although the source of additional Hg has yet to be resolved, as the organic carbon content of the sediments increases in response to the input from fish farming activities, so does the associated Hg. Mercury also partitions strongly to authigenic pyrite in the deeper sulfidic sediments. Of the few farmed Atlantic salmon analyzed, mercury levels were not elevated compared to the concentrations of mercury in the wild salmon captured in two rivers of the Canadian east coast.

Virginia is the east coast's largest producer of eastern oysters and produces more than any other state. As the industry grows to meet increasing demand, more conflicts have arisen with other resource users, especially waterfront property owners. Some landowners claim oysters impact recreational and aesthetic uses of their property, therefore lowering the value of the home. Using a hedonic property value model, this study examines the effect of oyster aquaculture on waterfront properties by using 2,245 property sales from 16 counties and independent cities and information on aquaculture activity from 2012-2016. The results suggest that oyster aquaculture has a positive effect on waterfront property values, but a negative effect when using cage equipment.<br>Master of Science<br>Virginia is the east coast’s largest producer of eastern oysters and produces more than any other state. As the industry grows to meet increasing demand, more conflicts have arisen with other resource users, especially waterfront property owners. Some landowners claim oysters impact recreational and aesthetic uses of their property, therefore lowering the value of the home. This study examines the effect of oyster aquaculture on waterfront properties. The results suggest that oyster aquaculture has a positive effect on waterfront property values, but a negative effect when using cage equipment.