Dissertationen zum Thema „Harbours and marinas“
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Varenne, Alix. „Étude de la diversité des nurseries artificielles dans les zones portuaires et de leur connectivité trophique avec les écosystèmes adjacents“. Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ5044.
Der volle Inhalt der QuelleCoastal development modifies shorelines by introducing man-made habitats, which significantly impact coastal biodiversity and ecosystem functioning. Ecological engineering solutions, such as artificial fish habitats (AFH), can help rehabilitate extremely modified areas, including ports, by offering shelter for fish. As a side effect, AFH provide a substrate to benthic invertebrates and macroalgae, that could improve ecosystem functioning. The effects of AFH may also extend beyond ports and modify trophic exchange with adjacent habitats via fish feeding hydrodynamics. This thesis investigates the patterns of distribution of invertebrate biodiversity associated with AFH and explores the exchange of biomass between marinas and adjacent Posidonia oceanica meadows along the French Mediterranean coast where these habitats are often adjacent.The objectives are: (1) evaluating how taxonomic diversity and composition of benthic invertebrates vary with AFH immersion time, (2) understanding how AFH types and environmental context modify benthic assemblages, and (3) exploring the exchanges of organic matter between marinas and adjacent meadows. I focused on Biohut® AFH (ECOCEAN), made of a metal cage filled with oyster shells, attached to docks or under pontoons in harbours and marinas.In chapter 1, I examined the role of immersion time in determining the diversity and composition of invertebrate assemblages colonising AFH in 3 commercial harbours. The findings indicated significant variations in invertebrate composition from 6 to 18 months, with increased abundance, taxonomic richness, and evenness over time. In chapter 2, I focused on the geographical and within-port variability in taxonomic composition and diversity of invertebrates dwelling in AFH. The study revealed differences in taxa composition between 2 large regions, characterised by different nutrient loads and correlations between assemblage composition and chlorophyll-a, a proxy for nutrient concentration. The number of taxa was the highest in the nutrient-enriched region. Additionally, invertebrate assemblages varied according to port habitats where the AFH were placed, possibly due to differences in light availability. In chapter 3, I investigated trophic connectivity between P. oceanica meadows and adjacent marinas at 4 sites where both habitats are present. Two marinas were equipped with AFH and the remaining 2 were not. At the unequipped sites, the δ15N values of the particulate organic matter within the marina were the highest indicating human-derived nutrient enrichment. The values decreased within the meadow, gradually according to the distance. This suggests a spill of nutrients over the portion of the meadow adjacent to the inlet. Fish relied on resources from both the seagrass meadow and the marina, similarly among the 4 sites, however, the trophic niches of fishes (Diplodus spp.) captured within the equipped marina were slightly larger than those within unequipped ones and overlapped less with the trophic niches of the fish captured outside. Fish faeces were also part of the organic matter sedimenting within meadows. In chapter 4, I reported initiatives developed with other scientists. They include species functional diversity and trophic relations within AFH, acoustic signatures of organisms dwelling in AFH and biodiversity comparison between ports and marine reserves using environmental DNA.My work has highlighted several aspects that could improve the effectiveness of AFH as ecological engineering solutions. Immersion time, local environmental conditions, and specific locations within ports need particular attention. Although I did not find clear differences in cross-habitat exchange related to AFH, they seemed to play a role in reducing nutrient enrichment. Moreover, since fish play an important role in cross-habitat exchanges and find refuge within AFH, this ecological engineering solution could indirectly contribute to change trophic connectivity
Fruth, Lizabeth Lepp. „A guide for small craft harbor and marina managers in coastal California“. Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28253.
Der volle Inhalt der QuelleGous, Werner. „Configurations of a piled row breakwater for a protected shallow water marina“. Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86710.
Der volle Inhalt der QuelleENGLISH ABSTRACT: For the safekeeping or harbouring of small craft, whether for leisure or commercial use, a tranquil basin is the principle requirement in designing a functional harbour facility. Waves transmitted through the perimeter structures of a marina result in agitation of the basin and thereby a reduction in tranquillity. Similarly, waves reflected off the perimeter structures that line entrance channels could result in difficulty when manoeuvring through the entrance channel water areas. An alternative to the conventional breakwater becomes a necessity when the conventional mass-filled or caisson breakwaters are not feasible in technical or financial terms. One of the alternative options could be to consider a piled row breakwater. In broad terms, this consists of closely spaced piles that attenuate wave energy whilst not forming an impermeable barrier, allowing for currents and sediment to pass through. When comparing the different options for creating a piled row breakwater the quantity of material used to achieve a desired level of wave dissipation could be the most important aspect in considering possible alternatives, as this would relate directly to construction costs and time when considering implementation. A literature review revealed multiple references to theories that predicted the transmitted and reflected waves for various breakwater porosities and wave conditions. However, there is limited coverage in literature enabling prospective designers. For example, literature describing the applicable ranges of shape configurations that one should start off with when developing concepts is not readily available. This thesis study used physical modelling to compare the wave transmission properties of breakwaters comprised of three different piled element shapes, namely round, square and diagonal square piles. The pile element shapes are compared for varying porosity values over a range of input wave parameters. A comparison of the transmission incurred by these configurations with previous work is presented and it was found that the physical model experiment closely simulated the predicted values. The tests were scaled from actual conditions in possible marina locations and therefore the performance criteria measured could be applied in reverse to potential site locations. From analysis of the physical model results, it was clear that the highest energy loss was found, in general, to occur with low porosities (below 10%), as could be expected. For a fixed screen configuration in terms of pile element shape and porosity, the performance is heavily dependent on wave steepness, the steeper waves incurring a lower transmission coefficient than the less steep waves. For a given porosity, circular piles performed the best (transmit the least) followed by square piles and then diagonal square. When comparing the material used, diagonal square piles yielded better performing breakwaters due to the expanded cross section gained in elevation. The work has provided useful insight into the performance of piled row breakwaters in restricting transmission of wave energy. Design guidance has been provided when considering the parameters for deriving conceptual layouts for piled row breakwater structures. Recommendations were put forward for further work in this field, including potential study areas, data gathering, and study methods, as well as more applied uses of piles, for example in combination with other elements in a marina.
AFRIKAANSE OPSOMMING: die veilige bewaring van klein vaartuie, hetsy vir ontspanning of kommersiële gebruik, is die hoofvereiste in die ontwerp van 'n funksionele hawe fasiliteit dat die beskermde hawegebied ‘n rustende water oppervlak sal moet handhaaf. Golwe wat oorgedra word deur die omtrek golfbrekers van ‘n hawe deur middel van transmissie veroorsaak oppervlak versteurings in die hawe bak en dus ook ongewensde versteurings in die vasmeer kondisies. Op ‘n soortgelyke wyse, veroorsaak golwe wat gereflekteer word vanaf die toegangs kanaal golfbrekers problematiese kondisies vir die navigeer van bote deur die kanaal. Die behoefte aan 'n golfbreker alternatief vir die konvensionele oplossing word genoodsaak wanneer die konvensionele stortrots of caisson golfbrekers nie haalbaar is nie as gevolg van tegniese of finansiële aspekte (Park et al. 2000). Een van die opsies wat oorweeg kan word as 'n alternatief is ‘n heipaal-ry tipe breekwater. In breë terme, bestaan dit uit naby gespasieërde heipale om golf energie te breek, sonder om ‘n ondeurdringbare versperring te vorm. Wanneer die verskillende opsies vir die skep van 'n heipaal-ry tipe breekwater vergelyk word, kan die hoeveelheid konstruksie materiaal benodig per opsie die belangrikste vergelykende parameter word. Die rede hiervoor is die direkte verwantskap aan konstruksie kostes sowel as tyd aspekte wat gepaardgaan met die konstruksie materiaal hoeveelhede. Vanuit die literatuurstudie is verskeie verwysings geïdentifiseer waarin vorige teorieë oor oordrag en refleksie van golwe evalueer word vir wisselende porositeit waardes en intree golf waardes. Daar is egter 'n beperkte dekking in die literatuur wat ontwerps-riglyne betref. Byvoorbeeld, die toepaslike omvang van die vorm konfigurasies wat oorweeg moet word wanneer konsep ontwerp gedoen word, is nie geredelik beskikbaar nie. Hierdie tesis vergelyk, deur middel van fisiese skaal model toetse, drie heipaal-ry element vorms, naamlik ronde, vierkantige en diagonal geroteerde vierkante vir verskillende porositeit waardes oor 'n verskeidenheid van golf inset parameters. 'n Vergelyking is getref tussen die toetsdata en vorige werk en daar is bevind dat die fisiese model eksperiment die voorspelde waades uit die literatuur redelik akkuraat kon naboots. Die toets kondisies is geskaal vanaf werklike moontlike marina terreine en dus kon die toets resultate toegepas word in die ontwerp van potensiële terreine. Vanuit die data-analise, is waargeneem dat die hoogste energie verliese oor die algemeen plaasvind by laer porosititeit waardes (onder 10%) soos wat verwag kon word. Vir 'n gegewe golfbreker opset, in terme van die heipaal element vorm en porositeit, is die verrigting hoogs afhanklik van die golf steilheid, met hoër verrigting by steiler golwe. Vir 'n gegewe porositeit, sal ronde heipaal elemente die beste verrigting gee, gevolg deur vierkante heipale en laastens diagonal geroteerde vierkante. Vir soortgelyke hoeveelheid heipale, sal diagonal geroteerde vierkante beter verrigting lewer moontlik as gevolg van die verlengde deursnit dimensie in vooraansig. Hierdie navorsing het goeie insig verskaf oor golfdeurlaatbaarheid en weerkaatsing van heipaalry breekwaters. Ontwerp riglyne word ook verskaf wat betref die parameters wat gebruik kan word vir die konsep ontwikkelings fase vir heipaal-ry breekwaters. Aanbevelings word gemaak vir verdere navorsingswerk in hierdie veld, insluitend moontlike studie-areas, data insameling, studie metodes, sowel as vir meer toegepasde situasies, byvoorbeeld waar die heipaal elemente in kombinasie met ander marina komponente ontwerp moet word.
Karanci, Ayse. „Statistical And Spatial Approaches To Marina Master Plan For Turkey“. Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613087/index.pdf.
Der volle Inhalt der QuelleMcCandless, Andrew Wright. „Mooring Impacts on Zostera marina Meadows and Associated Epifauna in Nantucket Harbor, Massachusetts, USA“. Thesis, Portland State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10751923.
Der volle Inhalt der QuelleSeagrass ecosystems are some of the most productive in the world and provide a variety of ecosystem services but are facing global decline chiefly due to anthropogenic disturbance. Mechanical disturbances to seagrass meadows from anchoring, propeller scars, and mooring scars result in losses or damage to both shoots and the underlying rhizome. I conducted a literature synthesis on the extent of, recovery from, and ecological impacts of these mechanical disturbances to seagrass meadows. The literature suggests that anchoring damage tends to be worst in deeper water where larger vessels anchor and can cause large (>100m2) loss per anchoring and recovery may take decades to over a century. Propeller damage is of largest concern in shallow (<2m) areas experiencing heavy boat traffic because propeller damage can only occur where the propeller can come close to the seagrass. Mooring damage is highly variable depending on the type of mooring used (<10m2 to >1000m2 scoured per mooring). Seagrass patches experiencing these mechanical disturbances have, in some studies, been found to have lower seagrass percent cover and shoot density than reference areas. This indicates scars can have ‘halos’ of impacted seagrass meadow. Some seagrass systems cannot recover within a century (e.g. Posidonia oceanica meadows at the extent of their depth tolerance) while others recover annually from some disturbances (e.g., anchor scars <1m2). Systems face altered species composition when scars are preferentially recolonized by certain species and patterns of recovery are affected by altered biogeochemical conditions following disturbances. Additionally, mooring, anchoring, and propeller scarring frequently alter meadow density, cover, patch size, patch shape, patch isolation, edge area, and ratios of edge to interior meadow leading to changes in faunal community structure. Correlations between these disturbances and faunal abundances, densities, and richness in seagrass ecosystems are complex, vary temporally (sometimes on the scale of days), and may result in species showing positive, negative, or no responses to a wide range of disturbance regimes.
To explore the connections between mooring scarring, the surrounding seagrass meadow condition and epifaunal community, in the second part of this thesis I measured 30 mooring scars to determine average scar size. To explore any potential ‘halo’ effect around mooring scars for seagrass or epifauna and to seek any difference in epifaunal community between mooring and reference sites I also sampled paired sites at eight locations in Nantucket Harbor, Massachusetts three times each in the summer of 2015. Each location consisted of a meadow site actively experiencing mooring scarring and a reference site without moorings. My conservative sampling methods of the 30 sampled mooring scars found scars to average 21.1m2. Across my paired sites, seagrass was found to have lower cover and lower canopy height in mooring versus reference sites. Seagrass cover and canopy height were lower in the first few meters (typically 2-3m) surrounding each scar in comparison to paired reference quadrats indicating a ‘halo’ effect of each scar. I did not detect a difference in epifaunal community composition or density per blade between mooring and reference sites; however, the relatively constant per blade concentration of epifauna combined with the differences in seagrass biomass between the mooring versus reference sites indicate an overall increase in the total amount of epifauna in areas with less disturbance. Epifaunal community composition was different and between locations and sampling dates indicating these factors are more important than proximity to mooring scarring in determining epifaunal abundance and richness. When considering scar area and the ‘halo’ of each scar I estimate that at least 32ha (2%) of Nantucket Harbor was impacted by mooring scarring. Given that the estimates of seagrass do not include areas previously denuded of this plant and that my measurements were conservative, likely a larger portion of this harbor’s potential seagrass habitat is impacted. Combined with the findings of loss due to these direct boat-related physical disturbances of seagrass meadows worldwide across regions, this halo effect is likely to also be found for moorings globally. I encourage management of the issue by employing and fine-tuning mooring methods (such as deploying moorings with anchor connections that do not drag on the sea floor) to minimize these unintentional but strong effects of mooring on the recipient habitat.
Rezende, Jozrael Henriques. „Um estudo sobre a gestão de resíduos e efluentes em marinas, terminais hidroviários de passageiros e embarcações de turismo e lazer no Reservatório de Bariri/Hidrovia Tietê-Paraná“. Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-01082007-172554/.
Der volle Inhalt der QuelleThe environmental aspects related to the daily operations in small craft inland harbors, in passenger waterway terminals, in leisure and tour vessels, in addition to other supporting facilities such as fluvial shipyards, indicate the need for adoption of sustainable models of management of such organizations, due to the fact that their activities are directly related to water bodies and to river banks and reservoirs, which are strategic areas for the aquatic ecosystems balance and protected by a strict environmental legislation. This study focus on technological options and proposes the implementation of a management program of waste and sewage in order to adapt the facilities and the operation of the marinas, passenger terminals and recreational boating to the ISO 14000 serial rules and to the environmental legislation in relation to the destination of solid wastes, oily residues and sewage effluents. The proposals were based on data from an investigation about the current situation of the facilities, the equipment, and the waste and sewage management, carried on both a marina and a tour navigation company which operate in the Bariri reservoir in the Tietê-Paraná Waterway. The results of this study demonstrate the importance of the implementation of programs for training and controlling the waste and sewage produced in shore and off-shore activities. These programs are based on the reduction of the production of waste, on the segregation, on the reutilization and the recycling of the materials, as well as on environmental education and on the treatment and final destination of waste and sewage. This way, they may prevent, control and act against water resources pollution besides making business more attractive and the places safer and more appealing for users and workers.
Tang, Zhaoxiang. „Evaluation of an approximate method for incorporating floating docks in harbor wave prediction models“. Texas A&M University, 2005. http://hdl.handle.net/1969.1/2686.
Der volle Inhalt der QuelleGrasselli, Ferrante. „Meiofauna assemblages associated with mussel beds along an urban harbor“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Den vollen Inhalt der Quelle findenDi, Bitonto Matteo. „Combined effects of substratum enhancement and seeding techniques on assemblages in artificial harbor habitats“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Den vollen Inhalt der Quelle findenMugnai, Francesco. „Exploring the distribution and underlying drivers of native and non-native mussel and oyster species in harbour environment“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14697/.
Der volle Inhalt der QuelleCailloux, Damien. „Les Mystères de l'Ouest : les représentations des bas-fonds portuaires dans l'ouest de la France (XIXe-XXe siècles)“. Thesis, Paris 1, 2016. http://www.theses.fr/2016PA01H099/document.
Der volle Inhalt der QuelleThe image of ill-reputed harbour is a common pattern in modern culture. It's built on harbour's slum, sailor's bender, prostitutes and docks, that define the representation of this area. This image echoes other places of misery, vice and crimes. The representation of those harbour's slums, that occupy specific neighborhoods in cities, are created by writers and journalists in mid-19th century. This image is also the legacy of negative vision of port, of buccaneering's stories and sailor's distrust. The harbour's slum is part of a broader universe : sailors with deviant behaviour, ill-reputed neighborhood, backward and dangerous province. During the first part of the 19th century, some places of the coastline have rough reputation but in the 1880's, the novelists, who discover sailor's bender, focus on ports. At the same time, journalists, social commentators and authorities focus on misery and insecurity. Seafarers, who claim his belongings to the slums, prostitutes, soldiers, the poor and criminals play a central role in the fascination and the condemnation of the harbour's slum. During the inter war period, the harbour's slum is seen as dying out. As the mystery vanishes, the nostalgia begins, that lasts after World War II
Errani, Francesca. „Viral investigation in the Ravenna's harbor: mussels as bioindicators for the presence of Norovirus, Hepatitis A virus and Nervous Necrosis Virus“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17425/.
Der volle Inhalt der QuellePerriquet, Marie. „Characterization of the hydrodynamics and saltwater wedge variations in a coastal karst aquifer in response to tide and precipitation events (Bell Harbour catchment, Co. Clare, Ireland)“. Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20042/document.
Der volle Inhalt der QuelleLow-lying coastal areas in the west of Ireland, such as the Galway and Clare coasts, have seen recent increases in flooding frequencies coupled with overall increases in sea level. The impacts of these changes are most strongly felt in coastal karst catchments and this study focuses on one such area, the Bell Harbour catchment (~50 km²), where there is a clear interaction between rainfall inputs and tidal influences, to create a terrestrial salt water wedge. Data (specific conductivity and water levels) have been collected at two coastal springs, six boreholes, three lakes, and from discrete locations in the middle of the bay, using dedicated loggers over extended periods. Two approaches that provided consistent results were used to explain the different hydrodynamic behaviours identified in the boreholes (conduits, fissures and matrix flows). Specific conductivity variations and water chemistry measured inland allowed for assessment of the spatial extent of the saltwater wedge into the aquifer as a function of both karst recharge and tidal movements at high/low and neap/spring tidal cycles. The extent of the saltwater wedge depends on the intrinsic properties of the aquifer but also on the relative influence of the recharge and the tide on groundwater levels, which induce opposite behaviours. This dynamic between recharge and the tide thus controls the seawater inputs, hence explaining temporal and spatial changes in the saltwater wedge in this coastal karst aquifer. Strong tidal amplitudes seems to be the motor of sudden saltwater intrusion observed in the aquifer near the shore while the relative elevation of the groundwater appears to influence the intensity of the salinity increase. The magnitude of annual recharge in the area is high enough to limit saltwater intrusion to no more than about one kilometre inland from the shore. Given the anticipated decreases in summer precipitation (~10 percent), coupled with anticipated sea level rises, the extent of the saltwater wedge into the aquifer is likely to increase in coming decades
Quinn, Jason Matthew. „The adequacy of project based EIA for a complex coastal development : the Glenelg/West beach study“. Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09ENV/09envq44.pdf.
Der volle Inhalt der QuellePerrier, Amandine. „Le commerce maritime grec en Méditerranée orientale et en mer Noire aux Vème et IVème s. av. J.-C“. Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM3024.
Der volle Inhalt der QuelleIn this present thesis concerning Greek Archaeology, I undertook to work on the organization of Greek maritime commerce in Eastern Mediterranean and Black Sea during the 5th and 4th century BC. I worked mostly on the trade's nature and intensity occurring in this part of the Mediteranean in this time. In order to carry out my work properly, I established a new catalog of greek shipwrecks, that I then confront with textual, epigraphic and archaeological sources. The careful study of the ship's cargo takes part in a better understanding of the commercial actors, trading network and above all of the importance of Athens at this time
Planque, Yann. „Écologie trophique de deux espèces sympatriques de phoques en périphérie de leur aire de répartition“. Thesis, La Rochelle, 2021. http://www.theses.fr/2021LAROS032.
Der volle Inhalt der QuelleHarbour seal (Phoca vitulina) and grey seal (Halichoerus grypus) are two sympatric marine mammal species that are increasingly considered as potential competitors, especially at their European core distributions. The objective of this PhD was to study the foraging strategies and trophic ecology of these species at the limit of their range (Baie de Somme, Eastern English Channel, France), and to investigate the hypothesis of potential interspecific competition. Biotelemetry devices were fitted on 49 individuals to document their movements and dives at sea.The analysis of surface locations and diving behaviour, completed recently by the detection of Prey Capture Attempts (accelerometry), allowed for a better understanding of the two seal species’ foraging strategies and improved the detection of their foraging areas. Trophic niches of the two seal species were then characterised with the analysis of diet, stable isotopes (in the whiskers of the same captured individuals), and foraging areas. A high interspecific trophic overlap was identified between these niches, resulting from the consumption of benthic flatfish in coastal areas, and we suggest that it provides here the basis for potential competition between both species. This study also showed the key role of individual foraging strategies on the ecological conclusions at the scale of the species/sub-population, including that the potential competition may be due to some individual grey seal strategies. Continuing these studies is essential to detect any potential ecological changes that could be trophically-induced
Bélisle-Desmeules, David. „La Babylone des marins : Marins hauturiers à Montréal 1851-1896“. Thèse, 2016. http://hdl.handle.net/1866/20143.
Der volle Inhalt der QuelleStalder, Dominique Sabina. „Influence of environmental drivers on the movement behaviour of harbour porpoises in the North Sea“. Master's thesis, 2019. http://hdl.handle.net/10400.3/5137.
Der volle Inhalt der QuelleO boto e um pequeno predador marinho com um elevado estatuto de conservação nas águas europeias. Para uma proteção eficaz desta espécie é importante ter conhecimentos detalhados das respostas comportamentais as mudanças das condições ambientais. Neste estudo, investiguei a influência das condições ambientais sobre a variação do comportamento de deslocação de grande escala da população de botos no Mar do Norte. Foram analisados dados de deslocações de 57 indivíduos rastreados por satélite num período de 19 anos. Para cada relocalização, estimou-se o estado comportamental subjacente do indivíduo (residência ou em deslocação) recorrendo a processos de modelação do estado espacial (State-space modelling, SSM). Estes estados comportamentais foram então correlacionados com variáveis ambientais estáticas e dinâmicas através de regressões logísticas. Estimou-se que os botos estão cerca de 81% do seu tempo em áreas circunscritas, passando apenas uma pequena parte do seu tempo (6%) em rápidas deslocações de longa distância, classificadas como estado de deslocação. Esses movimentos de curta duração e longas distâncias refletem provavelmente deslocações entre áreas de procura de alimentação. As restantes relocalizações (13%) não puderam ser atribuídas sem ambiguidade a nenhum destes estados comportamentais. Foram encontradas diferenças individuais consideráveis na extensão destas deslocações, com máximos variáveis entre 24 km e 867 km, relativamente à posição inicial. Consequentemente, a proporção de tempo gasto no estado de deslocação rápida (variando de 0,5% até 20,0%) e no estado residente (variando de 50,5% ate 99,5%) foi altamente variável entre indivíduos. O estado residente foi associado com baixos níveis de salinidade, temperatura e velocidade da corrente; com altas concentrações de clorofila-a em relação à media sazonal; e com declives intermédios do fundo. Estes resultados indicam indiretamente que as presas dos botos provavelmente se agregaram em áreas com as condições ambientais referidas, servindo, portanto, como área de alimentação. Estudos anteriores sobre a distribuição e abundância dos botos suportam a importância desses fatores ambientais. Os conhecimentos adquiridos neste estudo podem ser usados para melhorar os modelos populacionais espaciais que estão atualmente a ser desenvolvidos para estudar o impacto do ambiente marinho em mudança, e com as crescentes perturbações antrópicas, que afetam a dinâmica da população de botos.
ABSTRACT: The harbour porpoise is a small marine predator with a high conservation status in European waters. In order to protect the species effectively, it is crucial to acquire detailed knowledge on behavioural responses to changing environmental conditions. Here, I investigated the influence of environmental conditions on variation in large-scale movement behaviour of the harbour porpoise population in the North Sea. The movement tracks of 57 satellite- tracked individuals tagged over a total period of 19 years were analysed. For each relocation, the underlying behavioural state (area-restricted or transient state) of the individual was estimated using a state-space modelling (SSM) approach. The behavioural states were then modelled as a function of multiple static and dynamic environmental variables by means of a logistic regression. Harbour porpoises were estimated to spend about 81% of their time in area-restricted state (i.e. movements within feeding areas), while they spent only a small amount of their time (6%) in making fast and long-ranging movements, classified as transient state. These short movement bursts over long distances likely reflected transient movements between foraging grounds. The remaining relocations (13%) could not be assigned unambiguously to either state. Considerable individual differences in the extent of movements were found, with the maximum net displacement from the first location ranging from 24 km to 867 km. Accordingly, the proportion of time spent in transient state (ranging from 0.5% to 20.0%) and resident state (ranging from 50.5% to 99.5%) was highly variable among individuals. The area-restricted state was associated with low levels of salinity, temperature and current velocity; with high levels of chlorophyll a concentrations relative to the seasonal mean; and with intermediate sea bottom slopes. These results indirectly indicate that prey species may aggregate in areas where such environmental conditions are found, therefore serving as feeding grounds to harbour porpoises. Earlier studies on harbour porpoise distribution and abundance support the importance of these environmental drivers. The findings from this study can be used to better inform spatially explicit population models that are currently being developed to study the impact of a changing marine environment with increasing anthropogenic disturbance on harbour porpoise population dynamics.