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1
Kahlert, Maria. "Biomass and Nutrient Status of Benthic Algae in Lakes." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-5097-0/.
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Shamsudin, L. B. "The benthic algae of the River Itchen with particular reference to epilithic algae and epilithic algae on selected macrophytes." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375372.
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Novitski, Linda Nicole. "BENTHIC ALGAL COMMUNITY STRUCTURE ALONG AN ELEVATIONAL AND CHEMICAL GRADIENT IN THE HAZEL CREEK WATERSHED, GREAT SMOKY MOUNTAINS NATIONAL PARK." Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1155742200.
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McGee, Dorien Kymberly. "Morphologic comparisons of shallow and deepwater benthic marine diatoms of Onslow Bay, North Carolina /." Electronic version (PDF), 2005. http://dl.uncw.edu/etd/2005/mcgeed/dorienmcgee.pdf.
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Adams, John Anthony. "Benthic calcareous algae as Jurassic marine temperature indicators in Western Europe." Thesis, Cardiff University, 2004. http://orca.cf.ac.uk/55372/.
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The determination of calcareous chlorophyte distributional limits is via temperatures---namely isocrymal limits, because the green algae are very susceptible to cold temperatures. The calcereous green algae are today and were in the past, one of the most sensitive and useful environmental indicators. As well as being useful in distribution analysis, they are a useful part of biotic analysis in general. Calcareous green algae are mostly, but not wholly tropical in nature---they are found in shallow marine environments up to their range extent of just into temperate water masses (12°C isocrymal). The Dasycladales were dominated form of calcareous alga in the Jurassic (today their role has been largely taken over by the Halimidaceae). It can be seen that in the Upper Jurassic (where there are enough datapoints to form a reasonable limit, as opposed to the Lower or Mid Jurassic) that the Halimedaceae appeared to terminate at a line slightly southwards of the Dasycladales (this compares with the modern situation of a shared termination limit). Modern calcareous Chlorophyta distributions can delimit in the 12°C isocrymal water temperature boundary, and this limit can be imposed on the Jurassic Chlorophyta distribution dataset for palaeothermometry purposes. Together with selected isotope values, it is possible to estimate Jurassic isocrymes across Western Europe. This suggests the possibility of creatures such as belemnites (which are used for isotopically derived palaeotemperatures) having recorded summer temperatures in their isotopes rather than annual average. Modern algal temperature value differences (isocrymal versus summer maximum) is by ∼10°C and this change in values for the Jurassic Chlorophyta produces temperature figures equivalent to a majority of the isotopically derived temperature values.
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Roberts, Emyr Martyn Tomas. "Tidal modulation of seabed light and its implications for benthic algae." Thesis, Bangor University, 2015. https://research.bangor.ac.uk/portal/en/theses/tidal-modulation-of-seabed-light-and-its-implications-for-benthic-algae(9842ea2e-2c3f-47c7-8a2e-2f0af199b393).html.
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The light climate at the seabed of shallow, tidal seas is extremely variable, and light is, therefore, often the most important abiotic factor pertaining to primary production in coastal benthic ecosystems. The influence of the tide on seabed light, and thus photosynthesis, has received limited attention in the scientific literature, despite being potentially very substantial. In this thesis, three physical aspects of tidal modulation of seabed light are investigated: (1) temporal (i.e., springs-neaps) patterns induced by the tide in daily total seabed light; (2) the net effect of the tide (e.g., amplification or reduction) on seabed light integrated over a range of timescales; and (3) the potential of the tide to modify the spectrum of seabed light. The implications of these three aspects for benthic algae are explored theoretically. Observations of seabed light were made over springs-neaps cycles in winter and summer at the Menai Strait (North Wales, U.K.). At this turbid, macro-tidal site, low waters occur at about midday and midnight during neap tides, and at about 6am and 6pm during spring tides. Neap tides hosted the largest daily totals of seabed light in both seasons. A `switch' to spring tides hosting the largest daily totals in the summer months (by virtue of both morning and evening low waters occurring within the longer daylengths), as predicted by Bowers et al. (1997), did not occur. The general increase in turbidity in the strait at spring tides, and the marked increases at low waters of spring tides, were shown to be responsible. Observations at the Bay of Brest (Brittany, France), a macro-tidal site diametrically opposite to the Menai Strait in terms of the times of low waters at neaps and springs, indicated a peak at springs throughout the year. Analytical and graphical tools were developed that permit the nature of springs-neaps patterns in daily total seabed light and the occurrence (or non-occurrence) of seasonal 'switches in sense' to be predicted for sites of interest. Comparison of measured light levels with literature values for the saturation of photosynthesis in example algal species indicated that corresponding springs-neaps cycles may be induced in daily total benthic primary production. The net effect of the tide on seabed light integrated over daily intervals was described theoretically by Bowers and Brubaker (2010). Observations of the effect from the Bay of Brest (Brittany, France), made using a novel mooring configuration, showed good agreement with predictions based on the existing theoretical framework, confirming that the important parameters are the time of low water, tlw, the tidal amplitude, b, the diffuse attenuation coefficient, kPAR, and the daylength, L. The results of a simple numerical modelling study indicated that depthintegrated annual totals of irradiance and photosynthesis are amplified by the tide in the Bay of Brest, despite annual total photosynthesis being reduced by the tide at the shallowest sub-tidal positions, owing to light-saturation and photoinhibition effects. The results also suggested that differences in the areal extent, primary productivity, and vertical zonation of benthic algal communities from site to site may be partially attributable to differences in the values and temporal behaviour of tlw, b, kPAR, and L between the sites, through their influence on seabed light. Time-series observations of the spectral distribution of light at the seabed, made during winter at the Menai Strait, revealed that the most strongly attenuated wavelengths (i.e., blue and red in coastal waters) were preferentially amplified by the tide over a springs-neaps cycle. Further analysis indicated that the observed 'tidal flattening' of the spectrum of time-integrated irradiance would not significantly benefit one example species more than another (i.e., one red alga, one brown) on the basis of their different pigment compositions and photosynthetic action spectra. This was considered to be true at the mean depth of the observations, but it was predicted that at shallower depths the effect would confer a photosynthetic advantage on brown algae such as species of kelp, perhaps contributing to their dominance amongst benthic vegetation in the shallow sub-tidal zone. This study has shown that the tide has significant and predictable effects on the temporal behaviour, quantity and spectral quality of seabed light, which should be accounted for when modelling benthic marine primary productivity, interpreting the results of ecological field studies, and predicting the response of coastal benthic ecosystems to environmental change.
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Mills, David Kevin. "Productivity and distribution of benthic microalgae in the Forth estuary." Thesis, Heriot-Watt University, 1985. http://hdl.handle.net/10399/1649.
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Manzoni, Ginevra. "Possible effects of the invasive algae Caulerpa cylindracea on the benthic assemblages." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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In the Mediterranean Sea, the spread of the invasive algae Caulerpa cylindracea appears to be one of the most severe threat to the biodiversity of the coralligenous benthic communities. The magnitude of its effects may be modulated by the features of recipient communities, considering the high variability in species composition and relative abundance that characterize these biogenic reefs. The structure of benthic assemblages, taxa abundances and species diversity were investigated using a manipulative approach at three study sites in Elba Island and applying a multifactorial experimental design. Benthic assemblages’ structure, abundance and diversity were investigated in relation to the possible effects of both presence and absence of C. cylindracea and of the gorgonian Paramuricea clavata. Being C. cylindracea widely spread in the study sites, its absence in the specifically intended plots was maintained by periodical manual removals, while appropriate plots with and without P. clavata were selected for proper experimental setup. The coverage of P. clavata was comparatively low and, except a slightly but significant increase of benthic species richness in presence of the gorgonian, no other effects of its presence on the benthic assemblages among sites nor in relation to the presence of C. cylindracea were detected. Overall, Corallinaceae encrusting algae, turfs and sediment dominated in term of percent cover both in presence and absence of C. cylindracea. The effects of the presence of C. cylindracea on the structure of benthic assemblages appeared moderate and site specific. That is probably due to high heterogeneity of environmental conditions and different invasiveness of C. cylindracea at the investigated spatial scales.
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Liess, Antonia. "Nutrient Stoichiometry in Benthic Food Webs – Interactions Between Algae, Herbivores and Fish." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6933.
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Johnson, Vivienne R. "A study of marine benthic algae along a natural carbon dioxide gradient." Thesis, University of Plymouth, 2012. http://hdl.handle.net/10026.1/1230.
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Increasing atmospheric CO2 is causing unprecedented changes in seawater chemistry, yet the uncertainty of the ecological response to these projected changes, termed ‘ocean acidification’, remains considerable at present. To predict the effects of these changes, we need to improve our understanding of the responses of marine primary producers since these drive biogeochemical cycles and determine the structure and function of benthic habitats. The majority of experiments on the effects of ocean acidification on photoautrophs to date have mainly focused on oceanic microalgae, leaving benthic assemblages largely overlooked. Carbon dioxide vents are providing a means for examining and predicting the impacts of ocean acidification on marine ecosystems. In this thesis a temperate CO2 volcanic vent gradient was used to investigate the responses of benthic microalgal assemblages (periphyton, epilithic, epipelic, epipsammic and endolithic) and macroalgae (a calcified phaeophyte, crustose coralline algae and turf algae) to increasing pCO2. The photosynthetic standing crop of microphytobenthic assemblages increased significantly with elevations in CO2 indicating that the productivity of shallow water habitats may be promoted over the course of this century. Some benthic diatoms appear to benefit in naturally CO2 enriched environments whilst benthic cyanobacteria in this study appear to be relatively insensitive to the levels of increase predicted for this century. Dramatic shifts in epilithic macroalgae assemblages were observed along the CO2 gradient and a calcified phaeophyte was revealed as an unexpected ecological winner under ocean acidification scenarios. These observations suggest that benthic algal assemblages have the potential to dramatically alter as CO2 levels continue to rise; this would have profound consequences for the structure and function of benthic ecosystems.
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Martín, Martín Rafael Pablo. "Benthic marine algae from South Shetland Islands (Antarctica): biodiversity and evolutionary patterns." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673828.
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The present work focuses on different aspects related to the Antarctic seaweed. As the main primary producers of the coastal areas of Antarctica, this group of organisms play a key role in shaping the biological communities and the ecological dynamics of Antarctic shores. However, compared to other groups of Antarctic organisms or the seaweed communities of other regions of the world, Antarctic macroalgae remain less studied. This is especially true in several areas of knowledge as their actual biodiversity, their evolutionary history and patterns, some aspects of their ecology or the total extent of their relations with other Antarctic organisms and their environment. Aiming to address the lack of knowledge of these areas, we aimed to extend it by focusing our work in several key aspects of Antarctic seaweed biology. As so, we tried to respond several specific questions regarding the topics above mentioned. In this context, we studied biodiversity of seaweed communities that are present in the South Shetland Islands. For that, we tried to identify the composition and influencing factors of the seaweed assemblages present in Deception Island. We also studied how seaweed biodiversity affects Antarctic epiphytic diatoms richness, studying the composition of them, both from Deception and Livingston islands. Moreover, we tried to expand the data with evolutionary relevance by analysing the nuclear DNA content and ploidy levels (C values), as well as the nuclear developmental patterning of some common Antarctic seaweed species with no previous data for those characters. This was achieved by using a fluorimetry technique that sets a reference for comparison for future studies on those parameters. Additionally, we condensed the latest knowledge on the chemical ecology of seaweeds and other organisms from Antarctica, and tried to expand it by investigating the potential antimicrobial activity of these seaweeds. For this, we tested their natural extracts against several Antarctic microorganisms and identified several species that were active chemically. Also, we tested the same extracts for antimicrobial action against several microorganisms that are common human pathogenic surrogates and identified potential human interest in these seaweeds on the search for new sources of antibiotics. Finally, we reported our findings on the role seaweed have in the context of climate change in the Antarctic region. Those findings include the identification of non-native kelp rafts that arrived to the maritime Antarctica, and presented several passenger species that have potential invasiveness in the Antarctic. Regarding that, we classified and explored the possible roles that the rafts themselves and the species travelling with them may play in futures scenarios of climate change in Antarctica.
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Basic, Dunja. "Grazer control on benthic algae in the Berg River, Western Cape, South Africa." Bachelor's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/26088.
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Benthic environments in streams are areas of high biological activity where primary producers and consumers interact with each other and the environment. Various factors such as light, nutrient availability and temperature affect algal biomass accumulation however disturbance factors and grazing lead to biomass losses as well as changes in the species composition and densities of algae. There are little, if any, studies done on the effects of grazers on benthic algae in South African rivers and as such, this experiment was done in the Berg River, in the Western Cape of South Africa. The aim was to ascertain the effects of herbivores on benthic algae within the river and lit was hypothesized that periphyton biomass would be higher where grazer densities were lower and that the differences observed in biomass of periphyton between treatments would increase over time. It was also hypothesized that there would be a lower diversity of algae where there were lower herbivore densities. A randomized block design experiment was set up in the Berg River and treatments of 'excluded herbivores' and 'included herbivores' were set up, with two pairs of each treatment spread across four replicates. Stones from the stream were randomly selected and placed in the boxes. After five days half of the boxes were sampled and after eight days, the remaining half was sampled. Stones were scrubbed to remove periphyton from the stones and a sub-sample of 50ml was removed from each for later algal species identification. Invertebrates were removed from the boxes, preserved in ethanol and later identified to family level. Chl-a and AEDW (mg/m²) were determined from the samples as were invertebrate and algal densities. The results showed that there were no herbivore density effects on biomass most likely due to the season of sampling and the length of the experiment. However, the effect on algal densities was more pronounced as there was a higher variety of algal forms present where herbivore densities were lower. To get a better idea of how herbivores affect periphyton other factors need to be taken into account like experimental time period, season and different environmental conditions.
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McKenny, Claire. "The Diversity of macroinvertebrate grazers in streams relationships with the productivity and composition of benthic algae /." Click here to access, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060308.131239.
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Zacher, Katharina. "Effects of UV radiation on Antarctic benthic algae : with emphasis on early successional stages and communities = Effekte von UV-Strahlung auf antarktische benthische Algen : mit schwerpunkt auf jungen Entwicklungsstadien und Gemeinschaften /." Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 2007. http://www.loc.gov/catdir/toc/fy0804/2008422507.html.
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Tsoi, Wing Ying. "Community Dynamics of the Benthic Algae in Cobble Based Streams in South-East Quensland." Thesis, Griffith University, 2014. http://hdl.handle.net/10072/367032.
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Benthic algae are largely present within a polysaccharide matrix called ‘biofilm’ where they coexist as a community with heterotrophs such as bacteria, fungi and other organic matter that attaches to substrates. In upland stream ecosystems, benthic algae serve as a basal food source in riverine food webs and immobilise nutrients from the water column via the processes of assimilation and remineralisation. From a conservation biodiversity perspective, upland benthic algal assemblages are not only a biodiversity hot spot for rare, endangered and endemic freshwater species but also a source of propagules for downstream reaches.
Diatoms (Division Bacillariophyta) are the most abundant and diverse taxonomic group commonly dominating the benthic algal communities in upland streams, and are major contributors to primary productivity providing a particularly high quality food source compared to other benthic algal taxa and terrestrial matter. The quantity and quality of benthic diatoms as food sources for consumers in streams change spatially and temporally can cause resource shortages and dietary shifts in consumers which, in turn, track these changes to the upper food webs consumers and the benthic food web patterns. Despite their ecological importance and previous study by taxonomists and ecologists world-wide, patterns of benthic diatom taxonomic composition and their underlying factors are largely unexplored in Australian subtropical upland river ecosystems. Therefore, identification of the biodiversity, distribution and abundance of diatom taxa that sustain river food webs, is of fundamental importance in understanding how rivers function as ecosystems.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Spears, Bryan M. "Benthic-pelagic nutrient cycling in shallow lakes : investigating the functional role of benthic microalgae." Thesis, University of St Andrews, 2007. http://hdl.handle.net/10023/371.
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Microbes, living on the boundary between the sediment and the water-column in lakes, can play a pivotal role in governing the magnitude and frequency of nutrient cycling. The purpose of this research was to focus on the role of benthic microalgae in regulating such processes and to identify spatial and temporal characteristics in their function. Approaches included the quantification of sediment nutrient concentrations (particularly P fractionation), estimates of equilibrium phosphate concentrations (EPC0) (resuspended and undisturbed sediment estimates), and assessment of the benthic microalgal community composition, biostabilisation capacity, and its ability to regulate diffusive-nutrient flux. This thesis highlighted the importance of biological regulation of benthic/pelagic nutrient cycling, especially the role of benthic microautotrophs. Release sensitive sediment-P fractions were observed to be highly variable (both with depth and season) and correlated well with indicators of benthic photosynthesis (e.g. DO, chlorophyll, pH). Understanding the seasonality of whole-system P partitioning can enhance future lake management programmes. EPC0 estimates were significantly higher during undisturbed as opposed to disturbed sediment conditions. Epipelon constituted < 17 % of the total sediment chlorophyll signal and was highest in the clearer winter months and at intermediate depths at which a trade off between wind-induced habitat disturbance and light limitation existed. In intact core experiments, the benthic microalgal community significantly reduced the diffusive nutrient (especially PO₄-P and SiO₂) flux. NH₄ -N release was highest under light conditions at high temperatures. The mechanisms for regulation included direct uptake, photosynthetic oxygenation of the sediment surface, and regulation of nitrification/denitrification processes. Sediment stability increased with colloidal carbohydrate concentration (extruded by benthic microbes) at 4.1 m water-depth but not at 2.1 m overlying water depth, probably indicating the role of habitat disturbance in shallow areas acting to reduce epipelic production. Additionally, in an ecosystem comparison, the nature and extent of the biotic mediation of sediment stability varied between freshwater and estuarine ecosystems.
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Schwinnen, Chad Robert. "Impacts of a Herbivorous Fish, Campostoma anomalum (central stoneroller), on Nitrogen Fixation by Benthic Algae." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1284993489.
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Bray, Jonathan Peter. "The ecology of algal assemblages across a gradient of acid mine drainage stress on the West Coast, South Island, New Zealand." Thesis, University of Canterbury. Biological Sciences, 2007. http://hdl.handle.net/10092/1492.
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Physicochemical factors, algal diversity, taxonomic composition and standing crop were investigated across a broad gradient of AMD stress in streams and rivers. 52 sites were surveyed in the vicinity of Greymouth, Reefton, Westport and Blackball, on the West Coast, South Island. Seven sites in the Reefton area were sampled from April 2006 - February 2007 to establish changes over time in benthic algal communities of AMD and reference streams. Longitudinal change and ecosystem recovery were also investigated by sampling eight sites down Devils Creek, Reefton, and two of its tributaries. AMD has negative impacts on algal diversity, generally increases the dominance of certain taxa and, where metal oxide deposition or hydraulic disturbance are not great, can lead to algal proliferations. These proliferations were chlorophyte dominated, predominantly by filamentous Klebsormidium acidophilum. From the general survey a total of 15 taxa were identified from the most severely impacted sites (pH <3.6), which included both acidophiles and acidotolerant algae. Multivariate analyses strongly suggest that pH was the dominant factor controlling taxonomic occurrence of diatoms, macroalgae and the structure of the total assemblage. Other factors such as conductivity, metal oxide deposition, temperature, depth, month, geographic location and altitude were also important. Algal communities changed over time and this became more marked as AMD impact decreased. This was presumably due to AMD stressors reducing diversity, and thus the available scope for assemblage change. Longitudinal differences in assemblage structure within Devils Creek appeared to be in response to dilution of AMD in upper reaches and to changes in natural physical features such as gradient in mid and lower reaches. After a distance of 7.2 km the physicochemical effects of AMD and suspended clay inputs were minimal. At this site and at several previous sites, the assemblage exhibited a degree of recovery towards that found at unimpacted sites. A range of algae found in the broad scale-survey are potentially useful 'sensitive' indicators. These included: Heteroleibleinia purpurascens; Achnanthes oblongella; Oedogonium sp. and Spirogyra sp. In contrast: Euglena mutabilis; Navicula cincta; K. acidophilum; Microspora quadrata and Microthamnion kuetzingianum may be useful 'tolerance' indicators. These data show that AMD has a range of negative impacts on algae, and algae may be a useful tool for monitoring these impacts in West Coast streams.
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Yang, Yao. "The ecology of a herbivorous fish (Pseudogastromyzon myersi: balitoridae) and its influence on benthic algal dynamics in four Hong Kong streams." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41508646.
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Pye, Karen. "The effects of eutrophication on the marine benthic flora of Langstone Harbour, South Coast of England." Thesis, University of Portsmouth, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343337.
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McKenny, Claire. "The Diversity of Macroinvertebrate Grazers in Streams: Relationships With the Productivity and Composition of Benthic Algae." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/368092.
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There has been much interest in the last decade concerning the factors that influence diversity, especially how diversity and ecosystem processes may be linked. This study was based in small, cobble streams in South East Queensland. Its aim was to determine how the diversity and composition of consumers (the grazer guild) is influenced by both the production and composition of benthic algae, at different spatial scales. It also aimed to ascertain whether this response differs among grazer sub guilds with different dispersal capabilities. Ten sites in the Upper Brisbane and Mary catchments were sampled. The sites were selected to provide a range of productivity and composition. Grazers from these sites included snails and elmids, and larval mayflies, moths, and caddisflies. Grazer diversity and composition appeared to be structured by catchment scale influences, but environmental variables also affected which animals colonised patches and microhabitats (cobbles) within catchments. Primary productivity and algal composition could not be separated, with highly productive reaches also having a high cover of filamentous algal taxa. Grazer diversity displayed strongly positive, linear relationships with algal variables at the reach scale. It had a negative relationship with filamentous algae at the cobble scale, and a non-significant hump-shaped relationship with primary productivity. Survey data alone could not separate whether grazers were responding to habitat or food-related drivers, or to variations in productivity. Experimental manipulation of algal variables at the patch scale, using light and nutrients, also could not clearly uncouple the relationship between primary productivity and filamentous algal cover. Once reach scale variation was removed, grazer diversity displayed hump-shaped relationships with algal variables, including algal diversity. Much of this variation was due to patterns in mobile grazers, as sedentary grazers did not respond to algal variation at this scale. The density of the more mobile taxa showed similar patterns to those at the cobble scale (hump-shaped). A second field experiment was carried out in order to further investigate the responses of invertebrates to algal community composition at the cobble scale. Data from all three chapters suggested that as sites shifted to a dominance of filamentous algae, often with an associated increase in GPP, there was also a shift in the grazer community towards more sedentary grazers and away from the more mobile taxa. This also occurred at the cobble scale in the second experiment. The gut analysis and diet studies in the third chapter indicated that while many grazers consumed filamentous algae, it was not assimilated. This suggests that the preferences for sedentary taxa for cobbles and reaches dominated by filamentous algae are likely to be due to some other, possibly habitat-related, factor such as flow or predation refuge. The study provides a rare examination of relationships between primary productivity and consumer diversity in freshwater streams, and finds support for the pattern found in other systems of monotonic relationships of these two variables at large scales and hump-shaped relationships at smaller scales. It emphasises the importance of understanding other, potentially confounding, aspects of communities of producers, and investigates the possible roles of the most important of these (community composition) in structuring consumer communities in the small cobble streams of South-East Queensland.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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Stephens, Sonia H. "Effects of light and nutrients on the community composition of Benthic Algae in a Hawaiian stream." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7014.
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McKenny, Claire, and n/a. "The Diversity of Macroinvertebrate Grazers in Streams: Relationships With the Productivity and Composition of Benthic Algae." Griffith University. Australian School of Environmental Studies, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060308.131239.
Full textAbstract:
There has been much interest in the last decade concerning the factors that influence diversity, especially how diversity and ecosystem processes may be linked. This study was based in small, cobble streams in South East Queensland. Its aim was to determine how the diversity and composition of consumers (the grazer guild) is influenced by both the production and composition of benthic algae, at different spatial scales. It also aimed to ascertain whether this response differs among grazer sub guilds with different dispersal capabilities. Ten sites in the Upper Brisbane and Mary catchments were sampled. The sites were selected to provide a range of productivity and composition. Grazers from these sites included snails and elmids, and larval mayflies, moths, and caddisflies. Grazer diversity and composition appeared to be structured by catchment scale influences, but environmental variables also affected which animals colonised patches and microhabitats (cobbles) within catchments. Primary productivity and algal composition could not be separated, with highly productive reaches also having a high cover of filamentous algal taxa. Grazer diversity displayed strongly positive, linear relationships with algal variables at the reach scale. It had a negative relationship with filamentous algae at the cobble scale, and a non-significant hump-shaped relationship with primary productivity. Survey data alone could not separate whether grazers were responding to habitat or food-related drivers, or to variations in productivity. Experimental manipulation of algal variables at the patch scale, using light and nutrients, also could not clearly uncouple the relationship between primary productivity and filamentous algal cover. Once reach scale variation was removed, grazer diversity displayed hump-shaped relationships with algal variables, including algal diversity. Much of this variation was due to patterns in mobile grazers, as sedentary grazers did not respond to algal variation at this scale. The density of the more mobile taxa showed similar patterns to those at the cobble scale (hump-shaped). A second field experiment was carried out in order to further investigate the responses of invertebrates to algal community composition at the cobble scale. Data from all three chapters suggested that as sites shifted to a dominance of filamentous algae, often with an associated increase in GPP, there was also a shift in the grazer community towards more sedentary grazers and away from the more mobile taxa. This also occurred at the cobble scale in the second experiment. The gut analysis and diet studies in the third chapter indicated that while many grazers consumed filamentous algae, it was not assimilated. This suggests that the preferences for sedentary taxa for cobbles and reaches dominated by filamentous algae are likely to be due to some other, possibly habitat-related, factor such as flow or predation refuge. The study provides a rare examination of relationships between primary productivity and consumer diversity in freshwater streams, and finds support for the pattern found in other systems of monotonic relationships of these two variables at large scales and hump-shaped relationships at smaller scales. It emphasises the importance of understanding other, potentially confounding, aspects of communities of producers, and investigates the possible roles of the most important of these (community composition) in structuring consumer communities in the small cobble streams of South-East Queensland.
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Brandt, Michael. "Factors limiting benthic algal abundance in Virginia streams of the Coastal Plain." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1878.
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Algae are important components of stream food webs and often used in biomonitoring assessments. Little is known regarding the factors that limit their abundance in streams of the VA Coastal Plain. The surficial geology of the Coastal Plain is predominately sandy deposits which comprise the dominant substrate in streams of this region. In a comparative study of five streams located near the VCU Rice Center, we quantified substrate composition, light availability, and nutrient concentrations to assess their relative importance in determining benthic algal abundance. The proportion of stream area comprised of hard substrates was a significant predictor of variation in benthic algal abundance (r²=0.66). An experimental component comparing algal colonization on artificial hard substrates (tile) to the natural substrate reinforced the importance of substrate stability. Hard substrates which included gravel and aggregated clay likely provided greater stability for algal colonization relative to sand and silt deposits, resulting in lower mortality from scouring and sedimentation. Incident solar radiation was a secondary factor affecting algal abundance with shaded streams exhibiting lower benthic chlorophyll. Where substrate and light conditions were favorable, relationships between benthic algal abundance and dissolved phosphorus concentrations were observed. Seasonal fluctuations were ameliorated by high light conditions and constant disturbances at sites lacking hard substrates which kept CHLa at consistently low levels. The mean proportion of FBOM C derived from benthic algae ranged from 10 to 24%. In spite of the consistently low observed benthic algal abundance at sandy unstable Coastal Plain streams, benthic algae are an important source of benthic organic matter.
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Tan, Xiang. "Environmental Influences on Benthic Algal Communities and their Application for Biomonitoring of Australian and Chinese Rivers." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/367601.
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Benthic algae a re one of the most important primary producers i n lotic ecosystems, and changes i n their community structure and function (e.g., metabolism) will influence other organisms at higher trophic levels or even the entire aquatic ecosystem through bottom-up effects. Since they are known to be sensiti ve to changes i n ambient conditions, benthic algae and especially diatoms have been widely used as i ndicators of environmental changes in aquatic ecosystems, particular ly i n E urope , through developi ng diatom-based indices. However, these indices have not been widely used i n other continents. Applications of such i ndices in Asia and Oceania first require testi ng to see whether the y can perform as reliable bioindicators across time and space, considering that aquatic systems are constantly changing in terms of their ambient environment such as water physical and chemical conditions. Nevertheless, few studies have been carried out to compare the environmental influences on benthic algal communities among different geographic regions, nor the influences at different spatial scales (e.g., catchment, reach, and habitat). F urthermore, few studies have considered how diatom indices perform compare with other commonly used bioindicators of aquatic ecosystem health.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment.
Science, Environment, Engineering and Technology
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Thomas, Evan William. "THE ROLE OF WAVE DISTURBANCE ON LENTIC, BENTHIC ALGAL COMMUNITY STRUCTURE AND DIVERSITY." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1178127686.
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Bambakidis, Theodore. "Changes in Benthic Algal Community Structure Following an Unpredictable Stream-Wide Desiccation Event." Bowling Green State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1245682807.
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Smith, Francine Mary Jorna. "Investigating Cyanotoxin Production by Benthic Freshwater Cyanobacteria in New Zealand." Thesis, University of Canterbury. Chemistry, 2012. http://hdl.handle.net/10092/6932.
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Cyanobacteria can form nuisance proliferations and produce large concentrations of toxins that pose a health hazard. This thesis investigates cyanotoxin production by New Zealand benthic cyanobacteria. Cyanobacteria were sampled from lakes, reservoirs, streams, and rivers. Thirty-five strains were isolated into culture and screened for genes involved in the biosynthesis of common cyanotoxins. Positive results were confirmed and cyanotoxin concentrations quantified using analytical chemistry techniques.
Genes involved in anatoxin a/homoanatoxin a biosynthesis were detected in nine out of ten Phormidium cf. uncinatum strains isolated from a single mat. Anatoxin a was confirmed in these strains by LC–MS/MS at concentrations from 0.3 to 6.4 mg kg⁻¹. One strain also produced homoanatoxin-a. Anatoxin-a variation between strains may explain the wide range in anatoxin a concentrations previously observed in New Zealand.
The sxtA gene involved in saxitoxin biosynthesis was identified in Scytonema cf. crispum strains. Saxitoxin was confirmed in strains and environmental samples by Jellett PSP Rapid Test and HPLC–FD. Gonyautoxins, neosaxitoxin, and decarbamoyl derivatives were also detected. This study is the first identification of these compounds in Scytonema and in New Zealand cyanobacterial strains. These strains were isolated from recreational and pre-treatment drinking water reservoirs, highlighting the risk benthic cyanobacteria pose to human and animal health.
Experiments were undertaken using cultures of Phormidium and Scytonema to determine how growth influences cyanotoxin production. The effects of iron and copper stress on P. autumnale were also investigated. High iron concentrations disrupted attachment mechanisms. Iron and copper had a significant effect on growth, without significantly affecting anatoxin a production. However, the maximum anatoxin a quota was consistently observed during early exponential growth. Scytonema cf. crispum produced higher saxitoxin quota throughout exponential growth than during the stationary phase. Both the Phormidium and Scytonema growth experiments indicate that high toxin quota can be expected early in benthic mat development, making early detection of these proliferations important.
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Chinnock, Paul. "Calcareous benthic invertebrates and algae of the cool-water shelves of W.A. and S.A. : their significance in paleoecological studies /." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09SB/09sbc539.pdf.
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Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1997?Australian National Grid reference SF-49 - 12,16;SG -49 - 4,8,12; ; SG - 50- 5,9,13 SH - 49 - 4; SH - 50-1,5,9,14; SI - 50- 5,9,12,14,15 SI - 51- 7,10,11; SI -52- 1,2; SI - 53- 16 SI - 54- 9,13 1:250 000. Includes bibliographical references (leaves 47-51).
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Vasconcelos, Francisco Rivera. "Effects of warming and browning on benthic and pelagic ecosystem components in shallow lakes." Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-133327.
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The majority of lakes on Earth are shallow, unproductive and located at high latitudes. These lakes are experiencing big changes due to climate change, where two environmental drivers operate simultaneously, browning and warming. How they affect lake ecosystems is not well understood. Here, I addressed this issue by using a theoretical and an experimental approach. In particular, I generated model predictions and compared them with the results of a realistic large-scale experiment, where browning and warming were manipulated in a factorial design. In addition, model outcomes were compared with data from 12 unproductive lakes sampled along a gradient of browning. Another novelty of my thesis is that it integrates benthic and pelagic food web components in the model and experimental approaches. I found that browning affected the resources availability for benthic and pelagic producers in the model and in the experiment. With browning, benthic primary producers became increasingly light limited and declined, while pelagic producers became less nutrient limited and increased. Pelagic nutrient limitation was alleviated by two non-exclusive mechanisms. Browning directly enriched the water with nutrients, and browning indirectly increased the nutrient flowing from the sediment to the pelagic habitat via suppression of benthic producers. To tease apart these two mechanisms I applied structural equation modeling (SEM). The indirect evidence by SEM suggests that both mechanisms contributed equally to the pelagic nutrient concentration in the experiment. Interestingly, a model food web with only primary producers shows similar qualitative behavior as a food web with grazers and carnivores included. This happens because carnivorous fish exert strong top-down control in the more productive habitat, which relaxes grazing pressure on primary producers and increases resource limitation in the adjacent habitat. Biomass of benthic and pelagic consumers followed the same pattern as their resources. The lake data were largely congruent with model expectations and supported the findings of the experiment. Furthermore, the model also predicted a negative relationship between total phosphorus and both primary and fish production, which was observed across the 12 lakes. Warming effects were more complex. The model predicts that warming effects should depend on browning and are expected to be strongest in the more productive of the two (benthic and pelagic) habitats. For example, at low levels of browning the biomasses of benthic algae and fish are expected to decline with warming, which was observed in the experiment. In contrast, observed warming effects at high levels of browning deviated from model expectations. The mechanisms by which browning and warming interactively affect lake food webs are still poorly understood. This thesis offers a conceptual foundation for their further study through the integration of within- and between-habitat interactions.
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Vigilant, Veronica Lynn. "The occurrence of the harmful algae bloom toxin, domoic acid, in nearshore and offshore benthic communities of Monterey Bay, California /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2007. http://uclibs.org/PID/11984.
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Andersson, Eva. "Benthic-Pelagic Microbial Interactions and Carbon Cycling in Clearwater Lakes." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5798.
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Yang, Yao, and 楊瑤. "The ecology of a herbivorous fish (Pseudogastromyzon myersi: balitoridae) and its influence on benthic algal dynamics in four HongKong streams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41508646.
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Krenz, Robert John III. "Organic Matter Processes of Constructed Streams and Associated Riparian Areas in the Coalfields of Southwest Virginia." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73430.
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Central Appalachian headwater streams in coalfield areas are prone to mining disturbances, and compensatory mitigation is required in cases of documented impacts. Stream construction on reclaimed mines is a common mitigation strategy. Streams constructed as compensatory mitigation are meant to restore structural and functional attributes of headwater streams and are often evaluated by measuring structural ecosystem characteristics. However, replacement of stream ecosystem functions is essential for mitigation of mining disturbances from an ecosystem perspective. This research compared selected structural and functional measures in eight constructed streams on mined areas to those of four forested reference streams across two years. Three organic matter functions were evaluated: riparian litterfall input, leaf breakdown, and periphyton accrual. Constructed streams were typically warmer than reference streams and also had elevated specific conductance, elevated oxidized nitrogen concentrations, depressed benthic macroinvertebrate richness, and lower levels of canopy cover. Functionally, litterfall input and total leaf breakdown means for constructed streams were approximately 25% and 60% of reference means, respectively. Leaf breakdown in constructed streams appeared to be inhibited as a result of reduced processing by benthic macroinvertebrates as well as inhibition of microbial and physicochemical pathways. Constructed streams with total breakdown rates most similar to reference-stream levels had the coldest stream temperatures. Areal periphyton biomass, benthic algal standing crop, and senescent autotrophic organic matter in constructed streams were roughly quadruple, double, and quintuple those of reference streams, respectively. Indicator ratios also suggested stream-type differences in periphyton structure. Mean algal accrual was greater in constructed streams than in reference streams during leaf-on seasons. My results suggest that light is likely the primary factor driving accrual rate differences during summer and fall, but that temperature may also be important during fall. Planting a diverse assemblage of native riparian trees and ensuring their successful development can inhibit benthic irradiance and thermal energy inputs while providing similar quantity and quality of OM to constructed streams, thereby fostering replacement of reference-like OM functions in some streams.Ph. D.
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Armenio, Patricia. "Nutrient contributions from Dreissena spp. to Lyngbya wollei and Cladophora glomerata." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1294506836.
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Davis, Katie S. "Use of a Towed Camera System along the west Florida shelf: A Case Study of the Florida Middle Grounds Benthic Marine Communities." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7494.
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As technologies advance the study of ocean dynamics, new approaches to vexing problems of scale and process are becoming more widely available. Originally conceived as a tool primarily for indexing the abundance of near-bottom fishes, the Camera-based Assessment and Survey System (C-BASS) may also be an effective tool for monitoring benthic invertebrate resources vulnerable to natural and anthropogenic perturbations, and for characterizing the composition of benthic communities to inform spatial management. Using still images derived from the C-BASS video of benthic transects within the Florida Middle Grounds, I documented the abundance of benthic habitat-forming functional groups—sponges, algae, and corals—and noted taxa that were present in a SCUBA and ROV study conducted a decade earlier. Images were pre-processed using MATLAB computer programming language to correct for light attenuation and scattering in seawater at depth, and examined using ImageJ software and Coral Point Count software or rapid visual assessment methodology to assess image quality and percent cover, respectively. Exploratory data analysis (dissimilarity profile) delineated five habitat types in the northern Florida Middle Grounds, and discriminating benthic cover was identified using similarity percentage analysis: soft corals, fleshy macroalgae, low-relief algae, encrusted rubble, and sand. Hard corals and sponges represented relatively low area cover. A canonical analysis of principle components of in situ environmental measurements, chlorophyll a, turbidity, salinity, slope, and depth highlighted the association of the sand habitat type with greater depths and least amount of slope. Fleshy macroalgae were associated with greater slope, which reflected its presence in transitional areas between sand and reef. Soft coral habitat type was correlated with shallower depths, but also to lower temperature and lower salinity, highlighting the limitations of one-time environmental measurements to the condition of that time and space. A distance-based redundancy analysis of fish species abundance revealed that sponges, soft corals, and hard corals explained some of the variation of Holocentridae spp., angelfishes, and porgy, and that gray snapper appeared to associate with higher measurements of chlorophyll a. A comparison of C-BASS measurements with a coincidental stationary camera survey revealed that a slight shift in view, either from the seafloor to the water column, or from two slightly different positions in the water column, can obscure or reveal benthic cover to varying degrees, suggesting that more imaging could provide more complete representations of the benthic cover. Continued surveys of the benthic composition of the west Florida shelf could elucidate the range of environmental conditions and facilitate further investigations into the fish species associations with biotic cover in these benthic communities.
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Ralston, S. "A study of the ecology of benthic algae using artificial substrates in an irrigation canal of the Breede River, Western Cape, South Africa." Thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/25987.
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Schneck, Fabiana. "Efeitos da rugosidade de substratos, distúrbios físicos e organismos pastejadores na estruturação de assembleias de algas bênticas e na biomassa perifítica em um riacho subtropical : uma abordagem experimental." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/49267.
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Os estudos apresentados nesta tese tiveram como objetivo compreender aspectos da organização de assembleias de algas bênticas em riachos. Foi avaliado especificamente o efeito da heterogeneidade de habitat na escala de rugosidade de substratos e sua interação com distúrbios hidrológicos e organismos pastejadores (grazers). Utilizou-se uma abordagem experimental in situ com substratos lisos e rugosos (com fendas) constituindo os tratamentos. Os experimentos foram conduzidos no Rio do Marco, um riacho de quarta ordem na região dos Campos de Cima da Serra, em São José dos Ausentes, Rio Grande do Sul. Após uma introdução geral acerca do assunto são apresentados os capítulos com os estudos. O Capítulo 1 avaliou os efeitos da rugosidade de substratos sobre a riqueza de espécies, densidade, composição e padrões de distribuição de assembleias de algas bênticas. Assembleias em substratos rugosos foram mais ricas que assembleias em substratos lisos, porém esse resultado diferiu entre grupos com diferentes formas de vida, assim como as diferenças na composição de espécies, indicando que somente alguns grupos foram beneficiados pela ocorrência de refúgios em substratos rugosos. Observou-se também que diferenças na composição da assembleia entre substratos lisos e rugosos resultaram de aninhamento e substituição de espécies. No Capítulo 2 foi testada a hipótese de que substratos rugosos abrigam assembleias mais persistentes que substratos lisos. Os resultados encontrados confirmaram esta hipótese e foram atribuídos ao efeito da rugosidade per se após a exclusão de alguns fatores de confundimento, como estabilidade física dos substratos e diferenças na riqueza de espécies. Concluiu-se que o mecanismo mais plausível para explicar a maior persistência em substratos rugosos é a maior disponibilidade de refúgios em relação a substratos lisos. O objetivo do Capítulo 3 foi avaliar o efeito da rugosidade de substratos sobre assembleias de algas frente a um distúrbio hidrológico experimental, testando especificamente se a resistência e a resiliência de algas é maior em substratos rugosos que em substratos lisos e se a resposta de diferentes formas de vida é distinta. Os resultados indicaram que a rugosidade de substratos não apresenta efeitos pronunciados sobre a resistência e a resiliência de algas bênticas. Porém, grupos de algas com distintas formas de vida diferiram quanto à resistência e resiliência, de forma que o padrão observado está relacionado a atributos biológicos que conferem habilidades para suportar distúrbios. Os resultados deste estudo em conjunto com os resultados obtidos no Capítulo 2 e resultados obtidos por outros autores permitiram que fosse proposto que a importância da heterogeneidade de habitas e de refúgios é mediada pela intensidade de distúrbios. No Capítulo 4 foram avaliados os efeitos independentes e as interações de rugosidade de substratos, peixes pastejadores e tipos de mesohabitats (corredeiras e remansos) sobre a biomassa algal, matéria orgânica e peso seco total. O efeito de peixes pastejadores não foi mediado pelos mesohabitats, sendo que a exclusão de peixes causou aumento nas três variáveis resposta, independente do tipo de mesohabitat. Por outro lado, houve uma interação entre mesohabitats e substratos para determinar o acúmulo de peso seco total, sendo que substratos rugosos acumularam maior quantidade de material em remansos que em corredeiras, enquanto substratos lisos acumularam quantidades similares entre os dois tipos de mesohabitats. Já a biomassa algal e matéria orgânica apresentaram maior acúmulo nos substratos rugosos em relação aos lisos, independente do mesohabitat. Os resultados encontrados indicam que a perda de organismos pastejadores pode afetar o acúmulo de biomassa algal e material orgânico, importantes recursos alimentares em riachos. Finalmente, na última seção são apresentadas as considerações finais.The studies presented in this thesis aimed at understanding some aspects of the organization of benthic algal assemblages in streams. Specifically, the studies evaluated the effect of habitat heterogeneity on the scale of substrate roughness and its interaction with hydrological disturbances and grazing organisms. An experimental in situ approach was used, in which the treatments were constituted by smooth and rough (with crevices) substrates. The experiments were conducted in the Marco River, a fourth-order stream at the region of Campos de Cima da Serra, São José dos Ausentes, Rio Grande do Sul, Brazil. After a general introduction on the subjects of this thesis, the chapters with the studies are presented. The Chapter 1 describes a study to evaluate the effects of substrate roughness on species richness, density, composition and distribution patterns of benthic algal assemblages. Algal assemblages on rough substrates were richer than on smooth substrates, but this result differed among algal life forms. Similarly, results on species composition also differed among life forms, indicating that only some groups were benefited by the occurrence of refuges on rough substrates. It was also observed that differences in the composition of assemblages between rough and smooth substrates resulted from nestedness and turnover. The Chapter 2 describes a study in which was tested the hypothesis that rough substrates harbor more persistent assemblages than smooth substrates. The results confirmed this hypothesis and were attributed to the effect of roughness per se after the exclusion of some confounding factors, such as the physical stability of substrates and differences in species richness. It was concluded that the most plausible mechanism that could explain the higher persistence in rough substrates is the greater availability of refuges in relation to smooth substrates. The main aim of the study described in Chapter 3 was to evaluate the effect of substrate roughness on algal assemblages in the face of an experimental hydrological disturbance. Specifically, it was tested if the resistance and resilience of algae is higher on rough than on smooth substrates and if algal life forms differ in their response to disturbance. The results indicated that substrate roughness had no pronounced effects on benthic algal resistance and resilience. However, algal life forms differ in their resistance and resilience, and the observed pattern was mostly related to biological traits that confer abilities to support disturbances. The results of this study, in addition to the results obtained in Chapters 1 and 2, allowed us to suggest that the importance of habitat heterogeneity and refuges is mediated by the intensity of disturbances. The Chapter 4 describes a study that evaluated the independent and interacting effects of substrate roughness, grazing fish and mesohabitats (pools and riffles) on algal biomass, organic matter and total dry mass accrual. The effect of grazers was not mediated by mesohabitats, and their exclusion caused an increase in the three response variables, regardless of mesohabitat. On the other hand, mesohabitats and substrates interacted to determine the accrual of total dry mass, since rough substrates accumulated greater amounts of dry mass in pools than in riffles, while smooth substrates accumulated similar amounts in both mesohabitats. Algal biomass and organic matter showed greater accrual on rough than on smooth substrates, independently of mesohabitat. These results indicate that the loss of grazers may affect the accrual of algal biomass and organic matter, which are important food resources in streams. Finally, in the last section are presented the concluding remarks.
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Astill, Helen Lee. "The role of benthic macroalgae in sediment-water nutrient cycling in the Swan-Canning estuarine system, Western Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2000. https://ro.ecu.edu.au/theses/1344.
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This study documented the macroalgal assemblages of the Swan-Canning Estuarine System (SCES) over a two year period, and the influences of several environmental parameters on the assemblages. In addition, the Impacts of unattached macroalgal accumulations on benthic nutrient fluxes and microbial communities were investigated. Benthic macroalgal assemblages and physico-chemical regimes were monitored in the SCES, to determine temporal and spatial changes in macroalgal communities and the influence of environmental factors in these changes. Physico-chemical regimes demonstrated strong seasonal changes, which revolved around the onset and cessation of freshwater flows in winter (May to September). In the months after freshwater flows, strong spatial variability in physico-chemical profiles was observed. However, by summer the system was essentially marine. Macroalgal biomass and species richness was lowest in winter. Species number was maximal during periods of greatest hydrological variability in the estuary (spring and autumn). It may be inferred from results of statistical analyses that substrate type (i.e. hard/soft) and waterflow were the most Influential factors over temporal and spatial distribution of macroalgal species in the SCES. These factors ware reflected by the patchiness of macroalgal distribution in the system- attached macroalgal species distributed unevenly according to availability of limited hard substrate and presence/absence of unattached macroalgal species corresponding to seasonal freshwater flows. One species, Gracileria comosa, dominated macroalgal biomass and was the most widespread species and commonly occurred as extensive, unattached accumulations. As G. comosa was the most abundant unattached macroalga, accumulations of this species were investigated to determine the characteristics and behaviour or accumulations in the Swan-Canning Estuarine System. Accumulations were characterised by seasonally measuring height and biomass of accumulations in three regions or the estuarine system over one year. The height of accumulations was generally between 5 and 25cm, regardless of water depth, location, or season. Biomass was highly variable, but generally between 100 and 500 dw/m2 . The persistence of macroalgal accumulations was monitored at 28 sites within 10 estuarine regions, over a three month period, during which the first freshwater flows were recorded. Accumulations persisted between one week and one month, depending on the region, with accumulations persisting for longer periods in areas of low flow such as embayments and the regulated Canning River, and for shorter periods In regions of higher flow such as the channalised Swan River. Field and laboratory studies were performed to determine If the presence of G. comosa accumulations had an Impact on sediment-water nutrient exchange. Field studies established that accumulations affected benthic nutrient fluxes within a 24 hour period. However, this effect was site-dependent, occurring at an estuarine site of relatively high sediment organic content, but not at a site of relatively low sediment organic. Diurnal changes in water quality inside algal accumulations corresponded to photosynthetic/respiratory activity of the macroalgae - most notably, Increases In orthophosphate and ammonium fluxes from the sediment after approximately 8h of darkness. Since this effect was on time scales less than the period of persistence (weeks to months), It was concluded that macroalgal accumulations have an impact on benthic nutrient fluxes from sediments of relatively high organic content in the system. Laboratory studies investigated the effect of depth and density of an algal layer on sediment- water nutrient exchange. The experimental results concurred with field observations; water column concentrations of inorganic nutrients were significantly higher in sediment cores overlain by an algal layer over a 7 day period. In addition, Inorganic nutrient concentrations increased With Increasing height of the layer and ammonium concentrations increased with increasing density of the algal layer. Additional laboratory experiments tested the effect of an algal layer on sediment denitrification rates, and the composition and distribution of benthic microbial populations, Benthic nitrogen (N2) release rates were low irrespective of the presence of macroalgae and sediment types (less than 1mmo N/m2/d). However, release rates were significantly higher in sediment cores covered by algae than in comparable bare sediment cores, provided the algal layer was relatively high (5cm in height} and sediment organic content was high. The presence of an algal layer did not have a significant effect on the composition or distribution of microbes in the sediment. In all cases, microbial populations contained relatively few denitrifiers/nitrate reducers compared to nitrifiers and ammonifiers. High ammonium release rates from the sediment to the water column, and the low release rates of elemental nitrogen, suggested that even II the nitrate reducing bacteria were active they were not reducing nitrate to nitrogen, suggesting the possibility of Dissimilatory Nitrate Reduction to Ammonium (DNRA). Subsequent analysis confirmed that the nitrate reducers were reducing nitrate to nitrite, a result compatible with the hypothesis that the main microbial processes occurring were ammonification, nitrification, and DNRA, but not denitrification. These processes, regardless of the presence of a benthic algal layer, contribute to high ammonium flux rates from the sediment and provide a mechanism of internal inorganic nitrogen regeneration. In conclusion, this study has established that unattached macroalgal accumulations are a prominent component of the macroatgal community in the Swan-Canning Estuarine System. Accumulations may remain within an estuarine region for up to one month, particularly in regions of low water flow. In seasons and regions of relatively high water flows (e.g. the Swan River), accumulations become highly transient, if present at all. At times, and in regions where they may persist, algal accumulations of 5cm or more in depth have an impact on benthic nutrient fluxes. In particular, their presence over sediments of high organic content appears to exacerbate the release of ammonium from the sediment to the overlying water column. Of note, the benthic process Dissimilatory Nitrate Reduction to Ammonium appears to dominate in summer while denitrification rates are minimal, regardless of the presence of a macroagal layer. From these findings, it is recommended that high fluxes of ammonium in the system be recognised In water quality management and nutrient budgets for the system, as It appears that Internal ammonium regeneration Is a large source of Inorganic nitrogen for organisms In the overlying water body, and may support algal blooms In summer. In addition, it appears that the most appropriate method of managing macroalgal distribution and biomass in the system is ensuring strong freshwater flushes during winter periods when macroalgal biomass is largely removed. If seasonal flushes were inhibited, it is predicted that macroalgal biomass and distribution would increase, extending the period that thsy can influence benthic nutrient cycles. The physical removal of macroalgae as a management option in such a scenario would require much time and effort, as the Swan-Canning Estuarine System is such a large system, and macroalgae are spread throughout. Therefore, in modifying river flows into the estuarine system, the quantity, composition and distribution of macroalgae, and possibly other flora and fauna, will be altered. This is already evident in the Canning River, which is regulated and suffers management problems, such as altered species composition, bathymetric changes, toxic algal blooms, and eutrophication.
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Lange, Erik David. "Investigation of Microcystis Cell Density and Phosphorus in Benthic Sediment and Their Effect on Cyanobacterial Blooms on Western Lake Erie in the Summer of 2009." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1272581269.
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Spångfors, Helena. "Malformation in different species of benthic diatoms in three herbicide polluted streams in southern Sweden." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-34915.
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Målet med den här studien var att undersöka kiselalger och dess eventuella missbildningar i tre vattendrag i södra Sverige - Höje å, Skivarpsån och M42. Kiselalger används som bioindikator för vattenkvalitet i hela Europa, men de befintliga kiselalgsindexen visar inte eventuell förekomst av miljöfarliga ämnen. Det har dock visats att en förekomst > 1 % av missbildade kiselalger indikerar påverkan av miljöfarliga ämnen, såsom pesticider och tungmetaller. Denna studie är en av få som har undersökt kiselalgers missbildningar i vattendrag som är mer eller mindre påverkade av herbicider. Sex prov från varje vattendrag analyserades - kiselalger räknades och identifierades till artnivå och missbildningar dokumenterades och kategoriserades. Vattendragen delades in efter PTI (Pesticide Toxicity Index), där Höje å hade lägst PTI och ansågs minst påverkad av herbicider. Skivarpsån och M42 hade högre PTI, och ansågs därför ha en högre herbicidpåverkan. Det fanns en signifikant skillnad i missbildningsfrekvens vattendragen emellan, den kunde dock inte kopplas till PTI. Både Höje å och M42 hade > 1 % missbildningar. Skivarpsåns missbildningsfrekvens var < 1 % trots vattendragets relativt höga PTI. Det är möjligt att missbildningsfrekvensen bättre hade reflekterat PTI om herbicidprovtagningen skett någon månad tidigare, då herbicidhalter kan variera och kiselalger har visat sig kunna spegla ett vattendrags mående upp till tre månader bakåt i tiden. En annan förklaring till en varierande missbildningsfrekvens kan vara en lika varierande artsammansättning. Vissa arter är mindre “benägna” att missbildas än andra - ett prov som domineras av sådana skulle därför kunna innehålla få missbildningar trots eventuell miljögiftspåverkan. Det krävs dock ytterligare studier för att bättre förstå kiselalgers missbildningar i förhållande till herbicider.
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Katona, Leon R. "Diversity and Function of Algal Biofilms in the Laurentian Great Lakes." Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1622215756216238.
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Nauman, Callie A. "The Spatial and Temporal Distribution and Environmental Drivers of Saxitoxin in Northwest Ohio." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1589644025246293.
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Hooper, Garnet James. "Effects of algal structure on associated motile epifaunal communities." Thesis, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268881.
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McLenaghan, Natalie Ann. "Benthic macroinvertebrate diversity in a shallow estuary : controls on nutrient and algal dynamics /." Online version of thesis, 2009. http://hdl.handle.net/1850/9704.
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Walker, Robert A. "Photosynthesis and Respiration in Five Species of Benthic Foraminifera that Host Algal Symbionts." Scholar Commons, 2004. https://scholarcommons.usf.edu/etd/1287.
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Oxygen production and consumption were measured in five species of benthic foraminifers using a "Clark-type" oxygen electrode. Net photosynthesis and respiration were calculated and normalized to both μg Chl a and mm² upper surface area for the chlorophyte-bearing soritid foraminifers, Archaias angulatus and Cyclorbiculina compressa, and the diatom-bearing amphisteginids, Amphistegina gibbosa, A. lessonii and A. radiata. Photosynthesis/Irradiance curves were generated by fitting data to the hyperbolic tangent equation P = Pmax tanh (α I/ Pmax). Derived photosynthetic parameters, Pmax, α, Ik were found to correspond to the general responses of the endosymbiont taxa. Chlorophyll concentration was found to be significantly lower in Cyclorbiculina compressa than in the other four species. Maximum O2 production (Pmax) when normalized to Chl a was 3-4 times higher in soritid species than in amphisteginids. Photosynthetic efficiency (α) was significantly higher in Amphistegina gibbosa and A. lessonii than in the soritids. Mean Ik, which indicates approaching light saturation, was 13 and 26 μmol photon m-2sec-1 respectively for A. gibbosa and A. lessonii compared with 95 and 119 μmol photon m-2sec-1 respectively for Archaias and Cyclorbiculina. Calculated P/I data were to variable for Amphistegina radiata to estimate reliable α and Ik values. Factorial metabolic scope, which indicates potential for activity was only 2-6 for amphisteginids versus 9-16 for soritids. Annual primary production was estimated to be 285 mmoles O2 m-2 of habitat for A. angulatus, 9.3 mmoles O2 m-2 of habitat for C. compressa and 15.3 mmoles O2 m-2 of habitat for Amphistegina lessonii. Pmax values for Amphistegina gibbosa fluctuated at the compensation point and did not indicate significant oxygen production. Pmax values for Amphistegina radiata failed to reach the compensation point and net oxygen production was not recorded.
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Rull, Jordi. "Algues bentòniques marines de Namíbia." Doctoral thesis, Universitat de Barcelona, 1999. http://hdl.handle.net/10803/673149.
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Aquest treball no pretén ser un estudi exhaustiu sobre la flora bentònica marina de Namíbia, sinó simplement una base per portar-lo a terme en un futur. El que sí pretén, en canvi, és oferir una recopilació de tota la informació que hi ha fins a aquest moment sobre el tema i contribuir al coneixement de la flora bentònica marina de Namíbia, proporcionant-ne noves dades sobre la composició i biogeografia, a part de descripcions detallades i valoracions crítiques de moltes de les especies que la integren.
En una època en què les noves tecnologies fan orientar la botànica cap a l'estudi de les relacions filogenètiques entre les espècies, amb la consegüent reconsideració de la seva classificació taxonòmica, o cap a la realització de revisions sistemàtiques de grups concrets, potser resulta anacrònic presentar un treball de les característiques del que ara ens ocupa. No obstant això, el fet que la major part de les espècies de la flora marina de Namíbia no estiguin degudament documentades, cosa que obliga sovint a recórrer a les descripcions originals o a les obres clàssiques, creiem que ho justifica.
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Comeaux, Jay Louis. "Effects of copper on benthic communities in artificial microcosms." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/40317.
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Portune, Kevin Joseph. "Examinations on harmful algal cyst distribution, germination, and reactive oxygen species production within Delaware's Inland Bays, USA." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 210 p, 2008. http://proquest.umi.com/pqdweb?did=1601513961&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Witte, Andrew Dennis. "Benthic algal communities of shallow reefs in the Eastern Cape: availability of abalone habitat." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/12032.
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Marine ranching has been identified as an alternative to traditional aquacultural rearing and growing organisms for consumption. In the Eastern Cape, abalone ranching is a new and experimental industry. The aims of the research were to: first develop a GIS model to assist management in site selection for abalone seeding; and secondly to develop and standardize the sampling methodology in order to ground truth the sites, and assist in the monitoring and habitat identification of abalone. The GIS model developed in Chapter 3 was created using an unsupervised classification and fuzzy logic approach. Both vector and raster datasets were utilized to represent 7 different layers. Predominantly satellite imagery was used to classify the different substrate groups according to pixel colour signatures. The basic process was to apply a fuzzy rule set (membership) to rasters which gave an output raster (Fuzzification). The membership output rasters were overlaid which creates a single model output. It was found that model accuracy increased significantly as more layers were overlaid, due to the high variability within each of the individual layers. Model ground-truthing showed a strong and significant correlation (r2 = 0.91; p < 0.001) between the model outputs and actual site suitability based on in situ evaluation. Chapter 4 describes the investigation towards the optimal sampling methods for abalone ranching habitat assessments. Both destructive sampling methods and imagery methods were considered as methods of data collection. The study also evaluated whether quadrat and transects were going to be suitable methods to assess sites, and what size or length respectively they should be to collect the appropriate data. Transect length showed great variation according to the factor assessed. A transect of 15 metres was found to be optimal. Abalone counts showed no significant (p = 0.1) change in the Coefficent of Variance (CV) for transect lengths greater than 15m, and had a mean of 0.2 abalone per metre. Quadrat size showed a significant difference in functional group richness between quadrat sizes of 0.0625m2, and 0.25m2 but no difference between 0.25m2 and 1m2 quadrats for both scape and photographic quadrats. It was also found that between 5 and 10 replicates (p = 0.08) represents the functional groups appropriately using quadrats and that a 0.25m2 quadrat is most suitable for sampling. Chapter 5 describes the benthic community structure of Cape Recife shallow water reefs. Using the standardized methodology previously mentioned, 45 sites were assessed to identify the community structure. These sites were grouped into 5 different groups influenced by depth and substrate, as well as functional group composition according to a Wards classification. The community structure showed that depth and substrate play a significant role (p < 0.05) in the community type. There is also a significant relationship (p < 0.05) between complexity, rugosity, abalone presence and substrate. During this study the basic protocols for site selection and benthic community monitoring have been developed to support the abalone ranching initiative in the Cape Recife area. It has also provided a baseline of the benthic community in the ranching concession area which will be used as a benchmark for future monitoring efforts. The site selection, sampling, and monitoring methods developed during the course of this work have now been rolled out as Standard Operating Procedures for the ranching programme in this area.