Dissertations / Theses: 'Marine fishes – Geographical distribution'

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Sampson, Mark Robert. "Modelling the distribution and abundance of several demersal fish species on the Agulhas Bank, South Africa." Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1006207.

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The Agulhas Bank supports a speciose fish community, many of which are commercially important. Despite substantial research being conducted on aspects of their biology spatial aspects of their distribution and abundance in relation to environment parameters has been ignored. This study, therefore, addressed aspects related to the distribution and abundance of representative species on the Agulhas Bank within a Geographic Information System (GIS). Four candidate species were chosen due to their importance either in numbers or unit mass to the South African demersal trawl fishery. The species also shared morphological and taxonomic similarities. The candidate species chosen were the two Cape hake species, shallow-water hake Meluccius capensis, and deep-water hake Merluccius paradoxus, and the two pleuronectiform species being Agulhas sole Austroglossus pectoralis and redspotted tonguesole Cynoglossus zanzibarensis. The use of a GIS was appropriate and allowed for hidden spatial patterns be exposed and illustrated visually, while also facilitating the quantification of the relationships between distribution/abundance and certain environmental predictors using statistical methods The Department of Marine and Coastal Management, Cape Town, supplied biological data in the form of length frequency and biomass information from spring (AprillMay) and autumn (September/October) cruises conducted between 1986 and 1993 on the R. V. Africana. The Council for National Geoscience, Cape Town, supplied sediment data for the entire southern African coastline. Initial exploratory data analysis highlighted potential relationships between environmental variables and abundance for each specie's life-history stanzas. Variations in spatial distribution were found to be significantly different between each life-history stanzas within species. Fish density as a function of the additive effects of the various environmental parameters, including temperature, depth and sediment type, was assessed using a Poisson Generalized Additive Model (GAM), while distribution was analysed with a logistic GAM. A predictive logistic model was then created, taking into consideration the importance of the predictor variables for each species, allowing for predictive estimates to be made for each species by inputting environmental information within the study area. The importance of certain environmental variables influencing distribution and abundance were noted. General patterns indicated that sediment was the most important to both the distribution and abundance of the two pleuronectiform species and juvenile life-history stanzas, while the adult gadoids' distribution and abundance appeared to be depth dependent.

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Roux, Maryanne. "The diversity and distribution patterns of intertidal fish in the Agulhas bioregion." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1019712.

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This study aimed to expand the existing knowledge on the diversity and distribution patterns of intertidal fishes in the Sardinia Bay MPA and adjacent open access areas. It focussed particularly on in intertidal fish communities along the Agulhas Bioregion coast which has been understudied, especially in recent years. Typical resident species belonging to the family Clinidae were the most abundant, conforming to previous studies. Species from the family Gobiidae were the second most abundant in this study but this family was not previously recorded as being abundant. Transient species were unimportant in the current study which is in contrast to previous studies in the region and suggests a change in species composition. Certain transient species utilised intertidal rockpools as part of their nursery areas in the Eastern Cape, as has previously been found around Algoa Bay. A decrease in species richness from east to west was recorded in this study which has been noted by previous authors and the diversity and distribution patterns of the intertidal fish in the current study conformed to patterns found previously. The position of the biogeographic boundary between the Agulhas and Natal Bioregions could not be confirmed but Wavecrest (along the Transkei coastline) appeared to be part of a transition zone rather than a fixed break. More sampling around this area is recommended to determine the location and understand the dynamic nature of this boundary. The fish species were found to be vertically distributed across the shore with most of the resident species being more abundant across the low shore while the transient species were more abundant in the middle to low shore pools. This vertical distribution has been found at many sites around the world. The volume of the pools proved to be the primary controlling factor while the effect of temperature on vertical distribution could not be demonstrated. The benefits of the Sardinia Bay Marine Protected Area on this unexploited community of fishes could not be demonstrated but the long term benefit of protection has yet to be shown. Results from this study suggest that despite the correspondence with general biogeographic trends, the intertidal fish community has changed in composition (at least in terms of transient species) during the last 30 years and the cause for these changes may in part be reduced recruitment from exploited linefish.

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Scott, Lucy Elizabeth Powell. "The development of a geographic information systems based atlas of southern African freshwater fish, and its application to biogeographic analysis." Thesis, Rhodes University, 2000. http://hdl.handle.net/10962/d1005099.

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A Geographic Information Systems (GIS) atlas of southern African freshwater fish was developed for the SADC countries from natural history collection specimens, hydrological, topographical and climatological data. The primary purpose of the development of the atlas of freshwater fish was the construction of a practical framework to transform vast amounts of existing biological data for use in research and management of aquatic resources. The database of freshwater fish collection specimens that was incorporated into the atlas, was developed in association with ALCOM (Aquatic Resources Management for Local Community Development Programme). The development of advanced computing and GIS technology has increased the scope of biological atlas projects by facilitating the integration of large amounts of spatial data to produce derived databases for specific applications. The atlas of freshwater fish was constructed using TNTmips GIS software as the most practical system available for managing and analysing biological data with a spatial component. The atlas contains 35 180 comprehensive distribution records of 735 species of fish. It has many applications as an inventory of ichthyofaunal spatial biodiversity, including those of conservation planning, environmental assessment and biogeographic research. Biogeographic studies have traditionally been subjective due to the logistical problems of working with large amounts of distribution data, although some small-scale quantitative research has been carried out in the past. The content of the atlas of freshwater fish is tested with respect to these previous studies, on known patterns of freshwater fish distributions, and the analytical capability of the atlas is tested and demonstrated with some new preliminary approaches to the analysis of freshwater fish distributions in southern Africa.

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Zapata, Fernando Alberto. "Local and regional patterns of distribution and abundance in marine reef fishes." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/184983.

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Local and regional patterns of distribution and abundance are documented in marine rocky-reef fishes. Chapter one describes limits of distribution and patterns of density variation of two fishes in a northern Gulf of California intertidal shore. The density of Sonora gobies (Gobiosoma chiquita) increases with tidal height over its intertidal range (-1.2 to 0.9 m), whereas the density of patchscale gobies (Gobiosoma sp.) decreases from the subtidal zone to 0.6 m above mean low water level. Both species exhibit higher densities during the warmer season when intertidal temperature gradients are weaker than during the colder season. Sonora gobies show a broader range of temperature tolerance than patchscale gobies but there is no evidence of shifts in distribution between seasons suggesting that the distributions of these species are not determined by temperature. Interspecific interactions may contribute to the patterns of intertidal distribution and abundance in these species despite the rigorous physical environment of the area. Chapter two documents a positive correlation between average local abundance and extent of geographic distribution in rocky-shore fishes from the Gulf of California. This correlation is not an artifact of sampling an arbitrarily defined region and is unlikely to be an artifact of sampling bias. The occurrence of this relationship in a variety of organisms suggests that the processes responsible for this pattern are likely to be similar in both terrestrial and marine environments despite fundamental differences between the two. Chapter three demonstrates that egg type and adult body size explain a considerable portion of the variation in extent of geographic range in marine reef fishes. Species with pelagic eggs have larger geographic ranges, longer larval lives, and larger body sizes than species with non-pelagic eggs. Small species with non-pelagic eggs show smaller geographic ranges than any other combination of body size and egg type. These biogeographic patterns predict a greater degree of genetic isolation among populations, and a greater species turnover over evolutionary time in clades of small species with non-pelagic eggs than in clades of species with other combinations of body size and egg type.

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Ter, Morshuizen Leslie David. "Distribution patterns of fishes in the head region of a turbid Eastern Cape estuary." Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005105.

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Two and a half years of data were collected from the Great Fish River and estuary using seine nets and gill nets to determine the fish species composition within these regions. The head region of the Great Fish River estuary was found to have a rich fish fauna, with the euryhaline marine fish component totally dominating the catch in all three regions. Gilchristella aesiuaria was the single most common species and several euryhaline marine species were captured in freshwater for the first time. Physical parameters were also measured in an effort to ascertain the possible factors which may affect the distribution and length frequency of the most common species within this area. Salinity was found to be the single most important factor affecting the species composition, and the sampling area was consequently divided into three regions, viz. river (< I ‰), head (1-4 ‰) and estuary (> 4 ‰). In addition, it was determined that river flow rate during the month prior to sampling also had a profound effect on species composition in all three regions. Based on the available evidence it is suggested that for most species this is related to conductivity levels rather than flow per se.

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Gardezi, Tariq. "Spatial scale and the ecological determinants of the distribution and diversity of fishes in Ontario lakes." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115911.

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Data on the occurrence of freshwater fishes in Ontario lakes were used to evaluate the scale of the processes that are primarily responsible for shaping their distributions and patterns of diversity. In Chapter 2 it is shown that, regardless of the scale of analysis, the most important factors structuring their distributions are climatic measures of energy, suggesting that species tend to be able to survive heterogeneous conditions falling within large areas encompassing their climatic affinities. In Chapter 3 it is shown that the relationship between species richness and energy (annual potential evapotranspiration) changes according to the scale on which it is measured. The species-energy relationship is weak at the local scale and stronger and steeper at increasing regional scales. This scale dependence is due to the ability of high energy regions to accommodate relatively large numbers of rare or infrequent species, and reflects the regional scale at which species respond to environmental gradients, particularly those related to energy. In Chapter 4 the relationship between local and regional species richness is examined. It is found that mean richness of lakes is linearly related to the species richness of the watersheds in which they reside. Together, the results point to the importance of processes that are regional in scale for shaping species' distributions and patterns of diversity.

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Manning, Jane Elizabeth. "Patterns of spatial variation : bacteria and tintinnids in the North Atlantic ocean." Thesis, Swansea University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678684.

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Dudley, Sheldon Francis John. "Snoek Thyrsites atun in South African waters : aspects of its biology, distribution and fishery." Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/22189.

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Bibliography: pages 100-108.
The snoek Thyrsites atun is an important fish predator in the southern Benguela region. It is exploited by both a handline and a demersal fishery. A survey of the Cape line fishery revealed that snoek line fishing effort is changing from the traditional harbour-based line-boat to the nomadic ski-boat. It was widely claimed that snoek catches are declining and that migration patterns are changing. Snoek constitute a by-catch of the hake-directed demersal fishery but nevertheless are seasonally important. The principle prey of snoek caught by handline off the Cape Peninsula were anchovy and mantis shrimp. Snoek caught in midwater trawls offshore were feeding primarily on anchovy, with pilchard, euphausiids and amphipods also important. Snoek trawled demersally had a more diverse diet, dominated by redeye roundberring, lightfish, lanternfish, hake, buttersnoek and euphausiids. Snoek were caught in the demersal environment throughout daylight hours, but may come off the bottom at night. The small degree of overlap between the diet of snoek caught demersally offshore and that of snoek caught in the pelagic zone, both inshore and offshore, indicates that snoek do not seem to move extensively on a diurnal basis between the two zones. Over the period 1970 to 1985 availability of snoek to the handline fishery was strongly seasonal, with catches peaking from May to July, although the traditional winter snoek run is a declining phenomenon along the South African coast. At Dassen Island, for which catch data have only been available since 1981, peak months were from November to January. The snoek seems to move offshore from July and is trawled demersally until September. The presence of snoek larvae offshore between June and September indicates an offshore spawning migration. With the exception of the summer presence in the region of Dassen Island, snoek appear to be present in the southern Benguela region between April and September. Handline catches of snoek have declined markedly since 1978, but demersal catches have remained more stable.

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Purchase, David Bryce. "Patterns of distribution, abundance and community composition of rock pool fishes in Goukamma Nature Reserve, South Africa." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/28158.

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Rock pools can be found in most rocky intertidal marine environments across the globe. Despite the vast body of literature describing the organization of ecological communities and biota inhabiting the greater rocky intertidal, very little effort has been given to rock pools. As a result they are far less understood than the adjacent emergent intertidal, particularly with respect to their fish communities. This is mostly due to the relative small size of rock pool fishes, their cryptic behaviour and morphologies, the relative difficulty in sampling intertidal fish utilizing conventional methods, and the low economic value of rock pool fishes. Rock pool fishes may have significant ecological value, as they are involved in structuring intertidal communities. Due to reduced environmental fluctuations within rock pools, these habitats may serve as crucial refuges from adjacent stressors. Furthermore, rock pools may play an important role in the early life histories of sub-littoral fish species that utilize these habitats as juveniles, some of which are valuable to fisheries as adults. It has been suggested that due to the lack of exposure at low tide, rock pools do not represent a true intertidal habitat, as organisms are not subject to the full range of environmental fluctuations seen in adjacent habitats. There is unequivocal evidence indicating that, like the surrounding emergent substrata, conditions in rock pools are highly regulated by the tidal cycle and that the degree of environmental fluctuations will vary greatly with intertidal height and degree of exposure of individual pools, much like patterns seen in adjacent habitats. Fishes inhabiting rock pools can be broadly categorised into groups based on their major zoographic provinces, life history traits and their behavioural affinities, on top of basic taxonomic categorizations. Global patterns indicate two main rock pool fish communities, those of Gondwanan origin and those of Laurasian origin. South African rock pools are relatively well studied from a taxonomic perspective compared to elsewhere, however, like the rest of the globe, factors influencing their fish communities are far less understood. The aim of this study was to determine which, if any, physical and biological rock pool characteristics have any significant influence on the Abundance, Diversity and Community of fishes at Goukamma MPA, South Africa. This site was chosen due to a lack of previous surveys of rock pool fishes at this site and because of a need for an inventory of faunal communities in protected areas in South Africa. The shoreline within the reserve is dominated by sandy shores and interspersed with mixed rock-based habitats. Aelonite platforms form mixed shores and are found along areas west of the Goukamma estuary. Hard, predominantly older Table Mountain Sandstone layers are found along the eastern shore near Buffalo Bay. Rock pools are found at both shore types. Aelonite platforms were formed geologically recently from sand dunes formed during the interglacial periods of the Pleistocene and as a result are relatively flat and easily eroded into circular pools by loose rocks. The hard table mountain sandstone pools formed in cracks and faults caused by geological tilting action, and tend to long and thin rather than circular. Fifty-five rock pools were sampled, to investigate the influence of spatial (Location and Headland), temporal (Season), abiotic (Area, Height, Depth, Rugosity) and biological (Rock, Algae,) characteristics of rock pools on the distribution, abundance, diversity and community composition of rock pool fishes. A total of 747 fishes, representing seven families and 16 species were collected, using a non-lethal anesthetic, clove oil. Clinus cottoides, Parablennius cornutus and Caffrogobius caffer were the most dominant species, together making up almost 85% of the fish community. Total fish Abundance was not found to significantly change with any of the variables. The Shannon-Wiener Species Diversity Index for the whole of Goukamma was 1.64, however, it differed significantly among Locations, was greatest in pools of larger Area, lower Heights and higher cover of Rock. Community was found to significantly change with Location and was significantly influenced by Area, Rugosity, Height and Depth. Rock pool fish communities in South Africa show clear biogeographical patterns. These patterns show five distinct bioregions along the South African coastline in that familial distributions tend to be broken by the same oceanographic barriers seen in the distributions of many other marine taxa. The results suggest that rock pool fishes tend to exhibit distinct preferences to pools of certain typology and will seldom move over even small distances in search of new pools. Overall the study followed past findings from studies of similar type, both within South African and elsewhere.

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Burger, Lynton Francois. "The distribution patterns and community structure of the Tsitsikamma rocky littoral ichthyofauna." Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1005104.

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The results of a community survey of the rocky intertidal and subtidal reef ichthyofauna of the Tsitsikamma National Park and adjacent areas are presented. An updated species checklist is given, comprising 116 species of 46 families, including a new genus and species of Tripterygiid. Single species are shown to dominate, in terms of numbers, both the cryptic and subtidal components for all the areas sampled down the vertical profile. Species richness, evenness and diversity are found to increase with depth for both the cryptic and suprabenthic components. A community level feeding study shows an increase in trophic specialisation with depth and food availability is found to be an important factor delimiting littoral fish vertical distribution. The nursery function of the Tsitsikamma rocky littoral area is assessed and it is shown that shallow littoral areas as a whole are more important than intertidal pools alone in functioning as nurseries. The results of the study are found to fit into the existing trend of an increase in species richness and diversity, from west to east, along the South African coast. A significant difference is shown between the observed frequencies of species on exploited reefs outside the Park and unexploited reefs inside the Park. The density of the key reef predator Petrus rupestris is shown to be nine times more abundant on deep reef inside the park compared to deep reef outside the park (0.0045 fish/m² and 0.0005 fish/m² respectively) and a paucity of larger individuals of this species on exploited reefs is noted. Marked differences in the relative abundance of other species between exploited and unexploited reefs are evident and it is hypothesised that community disruption has occurred on exploited reefs, either directly or indirectly because of the removal of P. rupestris. These results are discussed in the context of marine reserves as a conservation strategy and a recommendation is made to extend the 5.6km seaward boundary of the Tsitsikamma National Park westwards to include the large concentration of presently exploited rocky reefs between the Blaaukrans river mouth and Natures Valley.

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Appenzeller, Alfred R. (Alfred Rudolf). "On the application of hydroacoustic methods to analyses of the distribution and abundance of pelagic fishes : behavioral and statistical considerations." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39782.

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This thesis explored the influence of fish behavior and distribution on the accuracy and precision of quantitative estimates of fish biomass and abundance as assessed by hydroacoustic techniques. Rainbow smelt (Osmerus mordax), a pelagic fish known to undertake diel vertical migrations and to exhibit changes in aggregation intensity associated with these movements was used as the model species for this study. The diel vertical migrations of smelt resulted in their potential inaccessibility to the acoustic gear. To obviate this problem a model of the diel migration of smelt based on observations of their behavioral responses to ambient light and water temperatures, was developed and used to time acoustic estimates of fish biomass and abundance to periods when they were unbiased by inaccessibility. Acoustic surveys were then conducted to evaluate the direct influence of fish aggregation on estimates of fish abundance, and to examine the effect of changes in fish distributions on the statistical validity of acoustic analyses. Comparative acoustic surveys, conducted when fish were schooled and dispersed, showed abundance was underestimated by up to 50% when schooling prevailed. The influence of changes in the level of fish patchiness, induced by diel schooling, on the statistical precision of acoustic estimates of abundance and biomass was found to be insignificant. Cluster sampling, a robust approach to the inherent problems of transect sampling created by autocorrelated data series was applied to acoustic data for the first time and its effectiveness was assessed. Cluster sampling yielded estimates of biomass and of abundance that were more precise than were estimates based on the traditional approach of analyzing complete transects.

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Chakona, Albert. "Comparative biogeography and ecology of freshwater fishes in the Breede and associated river systems, South Africa." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1015694.

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Distribution patterns and levels of genetic diversity in extant taxa are a product of complex palaeogeographic processes and climatic oscillations as well as the species’ intrinsic ecological adaptations. The Cape Floristic Region of South Africa presents a unique system for studying the processes that promote species diversification and distribution patterns. This region has a high degree of endemism of both terrestrial and aquatic biota and is clearly isolated from neighbouring areas by the Cape Fold Mountains and the Great Escarpment. The objective of this study was to firstly examine the ecology of freshwater fishes belonging to the genera Galaxias, Pseudobarbus and Sandelia in the south-western CFR. This was followed by an assessment of the genetic diversity of these taxa. Unique lineages were identified and their distribution was mapped. The work aimed to explore the role of the region’s complex palaeogeographic and climatic history as well as the role of the species’ ecological adaptations in driving lineage diversification and shaping contemporary distribution patterns. The four main components of the study can be summarised as follows: 1. Habitat associations of three widely distributed lineages of Galaxias zebratus Pseudobarbus burchelli and Sandelia capensis were evaluated at multiple localities in minimally disturbed mountain tributaries of the Breede, Duiwenhoks and Goukou River systems. The lineages have distinct habitat associations which were related to differences in their morphological traits. The slender-bodied Galaxias ‘nebula’ and the fusiform-shaped Pseudobarbus ‘Breede’ are capable of exploiting upper reaches with faster water velocity. By contrast, the laterally compressed Sandelia ‘eastern’ is restricted to lower reaches, making this lineage more susceptible to a wide array of impacts. 2. A recently discovered lineage of Galaxias zebratus, (Galaxias ‘nebula’), was found to be capable of tolerating emersion for a prolonged period of time. This is the first time that such capabilities have been documented in an African galaxiid. These adaptations have implications for the interpretation of Galaxias ‘nebula’s wide distribution range. 3. The phylogeography of Galaxias ‘nebula’ across its entire distribution range was investigated using two mitochondrial genes (cytochrome c oxidase subunit I (COI) and cytochrome b (cyt b)). This lineage has a complex evolutionary history that was influenced by both intrinsic and extrinsic factors. Rare events such as episodic drainage connections during Pleistocene and Holocene pluvial periods, possibly augmented by river confluences during periods of lower sea-levels and river capture events seem to be the most credible explanation for the extensive contemporary distribution and the relatively shallow genetic divergence between different river systems. 4. Mitochondrial cyt b sequences were used (i) to assess genetic diversity in G. zebratus, P. burchelli and S. capensis from the south-western CFR and (ii) to determine the roles of intrinsic ecological adaptations and extrinsic landscape and climatic changes in promoting genetic diversification and shaping present day distribution patterns of lineages in the three taxa. Marine incursions during periods of major sea-level transgressions are proposed to have isolated populations in upland refugia, thereby driving allopatric divergence in these species. Subsequent connections of rivers during wetter periods and lower sea-levels are proposed to have facilitated post-speciation dispersal of lineages to attain present day distribution patterns. While detailed morphological studies and further genetic analysis are needed to substantiate the taxonomic status of the newly discovered lineages of Galaxias zebratus, Pseudobarbus burchelli and Sandelia capensis, results of the present study indicate that the south-western CFR represents a previously unrecognised centre of freshwater fish diversity and microendemism in the broader Cape Floristic Region. Accurate identification of lineages and comprehensive mapping of their distribution is a fundamental pre-requisite for ecological studies, assessing conservation status and implementation of appropriate conservation measures.

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Hall, Colin Mark. "Some aspects of the ecological structure of a segmented barrier lagoon system with particular reference to the distribution of fishes." Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1004936.

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The Wilderness lakes system represents a segmented barrier lagoon and comprises three interconnected lakes; Rondevlei, Langvlei and Eilandvlei. The latter is further linked by the Serpentine channel to the Touw river and Wilderness lagoon. The role of these channels, as well as a sluice in the Serpentine, in structuring certain aspects of the ecology of the system was investigated. An analysis of the salt budget of the lakes suggests that the Serpentine dampens tidaI processes to such an extent that they play only a minor role in the overall budget. Furthermore, the channel between Eilandvlei and Langvlei prevents any tidal salt input to the upper lakes. Their estuarine environments are however maintained by salt inputs which occur when the mouth is closed. This unusual phenemenon means that the sluice may have a minimal effect on the salt budget of the system because it is only closed when the mouth of the lagoon is open. Environmental conditions in each of the lakes, the Touw river and Wilderness lagoon were compared in terms of their physico-chemical characteristics and submerged macrophyte communities. A principal components analysis suggests that the physico-chemical environment of each lake is similar. The Touw river however has a very different environment, whilst that of Wilderness lagoon has some similarities to both the lakes and the river. During the study macrophyte communities recovered from a major recession which occurred between 1979 and 1981 . Biomasses in excess of 1000g m⁻² were recorded in both Langvlei and Eilandvlei. In the latter however, macrophyte growth was less prolific than in the former, as some areas of the littoral supported no growth at all. Macrophyte encroachment in the channels is a major factor inhibiting water flow between the lakes. This encroachment is most severe in the Eilandvlei/Langvlei channel where macrophytes covered 80% of the channel's area.The dominant fish fauna throughout the system is composed of a marine/estuarine migratory component. In the lakes the Mugilidae and Sparidae are the most common families, whilst in the lagoon and Touw river predators such as Lichia amia and Argyrosomus hololepidotus also commonly occur. Eilandvlei serves as the initial nursery area for most migratory species. An estimated 52000 fish migrated up the Serpentine towards Eilandvlei during February 1984 . Most fish do not penetrate as far as Langvlei, and this can be related to macrophyte encroachment in the Eilandvlei/Langvlei channel. However, it is argued that should this channel be dredged and the macrophytes removed, the nursery potential of the system would not be greatly enhanced . This is because environmental heterogeneity, in association with an abundance of food in Eilandvlei, make this lake the most attractive nursery area to juvenile marine/estuarine fish.

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Sackmann, Brandon S. "Remote Assessment of 4-D Phytoplankton Distributions off the Washington Coast." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/SackmannBS2007.pdf.

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Shiell, Glenn Raymond. "The spatial distribution and temporal shifts in the biology of Holothuria whitmaei Bell [Echinodermata: Holothuroidea], Ningaloo Reef, Western Australia." University of Western Australia. School of Animal Biology, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0081.

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[Truncated abstract] Aspects of the biology of the commercial sea cucumber Holothuria whitmaei were investigated at Coral Bay, Ningaloo Reef, Western Australia. The study was partitioned into several components: i) spatial distribution, ii) temporal changes in behaviour and iii) reproduction biology. The spatial distribution of H. whitmaei at Coral Bay was typical of that reported in the literature. H. whitmaei had distinct preferences for outer reef habitats, including the outer reef flat and reef slope. However, the distribution of H. whitmaei within these habitats was heterogeneous, or, aggregated within certain micro-habitat zones - predominantly at the leading edge of the reef flat, perpendicular to the prevailing current. Two potential biological advantages of this distribution were hypothesised: i), that species aggregation enhances prospects for gamete fertilisation, a process which may be impeded under typical densities, and ii), large deposits of detrital matter, an important food source for holothurians, may accumulate within these zones. ... A striking feature of the reproduction biology of this species was the potential for specimens to mature asynchronously. It was hypothesised that this phenomenon may be a reflection of isolated individuals located too far from conspecifics to receive pheromone signals; cues which are known to entrain synchronous gonad development in some holothurians. Hence, it was proposed that aggregations of H. whitmaei may be important to the maintenance of population recruitment, given that animals at the periphery of species concentrations may have relatively little chance of achieving fertilisation. ... Given that H. whitmaei were observed to maintain highly specific patterns of distribution, this may have significant ramifications for trophic level cascades in the outer reef zone, particularly where this species is present in higher densities (i.e. >100 ind. ha-1). The findings of this study, apart from highlighting the spatial and temporal biological attributes which may facilitate feeding and reproductive success, also emphasised the importance of biological knowledge to the management of sea cucumber fisheries. The study highlighted the need for further research to ascertain both the importance of species aggregations to population recruitment, and of the actual densities required to achieve high rates of gamete fertilisation. Such knowledge may help ultimately to identify suitable habitats for inclusion in marine protected areas.

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Shea, Kwok-ho, and 佘國豪. "Species composition and temporal and spatial patterns in butterflyfishes (chaetodontidae) associated with coral communities insub-tropical Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42841513.

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Popple, Ian D. "Application of ultrasonic telemetry to movement of the graysby Cephalopholis cruentata in a marine reserve in St. Lucia, W.I." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33825.

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Ten individuals of Cephalopholis cruentata, a marine serranid common on Caribbean coral reefs and important to artisanal reef fisheries, were implanted with acoustic transmitters on two reefs within the Soufriere Marine Management Area, St. Lucia. The mean home range area determined was 2120m2. Home range shape was non-circular, with a mean aspect ratio of 0.72. Neither home range size nor home range shape differed between the study sites or as a function of fish size. However, more active fish, as determined by movement per hour and displacement per hour, had larger home ranges.
Use of space within the home range was characterised as activity rates (movement per hour), displacement rates (maximum distance between fish locations per hour), and preferential use of specific areas (% of position fixes in different areas). All fish demonstrated a clear preference for specific areas in their home range. Activity, displacement and % time spent in the preferred reef area were not correlated with fish size. Activity and displacement were higher by night than by day, and consistent with this, fish spent less time in their preferred home range area by night than by day. Given the home range size and movement patterns of C. cruentata determined in the study, the effectiveness of the marine reserve zones in the Soufriere Marine Management Area in protecting C. cruentata is assessed.

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Mesa, Kathryn A. "The influence of temperature, salinity, and dissolved oxygen on juvenile salmon distributions in a nearshore estuarine environment." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24863.

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This study examines the effects of a low oxygen environment, in concert with fluctuating temperature and salinity conditions, on the nearshore depth distributions (0-1 m) and flood tide movements of juvenile chinook (Oncorhynchus tshawytscha) and chum (O. keta) salmon. Comparisons are made between an unpolluted and a sewage polluted estuarine intertidal flat in the Fraser River estuary, British Columbia, the polluted area being characterized by the regular occurrence of low dissolved oxygen levels. Results are based on 380 beach seine samples taken between April and June of 1984. In general, chum and chinook salmon of increasing length were captured in increasing depths, though this pattern was modified by seasonal changes in water temperature. Low dissolved oxygen conditions in deeper waters may have been responsible for the presence of larger, and often sluggishly swimming fish in higher oxygenated surface water layers or in shallow waters near the shore. In both areas, the risk of aerial predation was high. On a flood tide, the likelihood of capturing a chinook salmon was reduced as temperatures increased and oxygen levels decreased. A combination of avoidance behaviour and a regularity in the movement patterns of chinook onto the study area in the later stages of the flood tide may account for their rare occurrence in low oxygen concentrations (<6 mg/1) and high temperatures (>20 °C). Fish mortalities were most likely to occur on the ebb tide when fish were forced into waters of low oxygen content by the drainage patterns characteristic of the polluted study area. Though wide ranges in salinity were recorded on both tidal flats, this factor was not strongly correlated to Chinook distributions. However, significantly higher salinity levels in the unpolluted area may account for the greater numbers of chum salmon captured there. An understanding of the influence of estuarine water quality conditions on the distribution of juvenile salmonids may assist in the identification of significant sources of mortality in their early marine life. This knowledge is particularly important in the evaluation of water quality changes as caused by human activity.
Science, Faculty of
Zoology, Department of
Graduate

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19

Lawson, Gareth L. "Distribution, patchiness, and behavior of Antarctic zooplankton, assessed using multi-frequency acoustic techniques." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39220.

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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2006.
Includes bibliographical references (p. 297-311).
The physical and biological forces that drive zooplankton distribution and patchiness in an antarctic continental shelf region were examined, with particular emphasis on the Antarctic krill, Euphausia superba. This was accomplished by the application of acoustic, video, and environmental sensors during surveys of the region in and around Marguerite Bay, west of the Antarctic Peninsula, in the falls and winters of 2001 and 2002. An important component of the research involved the development and verification of methods for extracting estimates of ecologically-meaningful quantities from measurements of scattered sound. The distribution of acoustic volume backscattering at the single frequency of 120 kHz was first examined as an index of the overall biomass of zooplankton. Distinct spatial and seasonal patterns were observed that coincided with advective features. Improved parameterization was then achieved for a theoretical model of Antarctic krill target strength, the quantity necessary in scaling measurements of scattered sound to estimates of abundance, through direct measurement of all necessary model parameters for krill sampled in the study region and survey period.
(cont.) Methods were developed for identifying and delineating krill aggregations, allowing the distribution of krill to be distinguished from that of the overall zooplankton community. Additional methods were developed and verified for estimating the length, abundance, and biomass of krill in each acoustically-identified aggregation. These methods were applied to multi-frequency acoustic survey data, demonstrating strong seasonal, inter-annual, and spatial variability in the distribution of krill biomass. Highest biomass was consistently associated with regions close to land where temperatures at depth were cool. Finally, the morphology, internal structure, and vertical position of individual krill aggregations were examined. The observed patterns of variability in aggregation characteristics between day and night, regions of high versus low food availability, and in the presence or absence of predators, together reinforced the conclusion that aggregation and diel vertical migration represent strategies to avoid visual predators, while also allowing the krill access to shallowly-distributed food resources. The various findings of this work have important implications to the fields of zooplankton acoustics and Antarctic krill ecology, especially in relation to the interactions of the krill with its predators.
by Gareth L. Lawson.
Ph.D.

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20

Bowen, Katie. "Connectivity of Coastal and Oceanic Ecosystems: Pelagic Habitat Use by Juvenile Reef Fishes in the Gulf of Mexico." NSUWorks, 2015. http://nsuworks.nova.edu/occ_stuetd/394.

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The assemblage structure, abundance, biomass, and vertical distribution of juvenile reef fishes in the offshore pelagic habitat of the northern Gulf of Mexico are described as part of the NOAA-supported Offshore Nekton Sampling and Analysis Program. The results presented here are from a 3-month, continuous sampling series in 2011 in which discrete depth strata from 0 to 1500 m were sampled using a 10-m2 MOCNESS midwater trawl. This is the first study to examine pelagic juvenile reef fish distributions across the entire oceanic northern Gulf of Mexico seaward of the continental shelf break after the Deepwater Horizon Oil Spill. During this series, 87,407 specimens were collected, of which 838 were reef fishes, representing seven orders, 30 families and 119 species. The faunal composition of pelagic juvenile reef fishes was diverse and well mixed, with no discernable spatial structure with respect to water masses and solar cycle. Seventy-nine percent of the pelagic juvenile reef fishes were collected in the epipelagic and the dominant families were Congridae, Carangidae, Tetraodontidae, and Acanthuridae. Species richness, biomass, and frequency of occurrence of pelagic juvenile reef fishes was greatest between 0-200 m and decreased with depth. Data from the assemblage structure, abundance, biomass, and vertical distribution of pelagic juvenile reef fishes collected from this cruise series will contribute to the lack of knowledge regarding the dispersal dynamics and coastal-connectivity of these fishes in the northern Gulf of Mexico.

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21

Torgersen, Christian E. "A geographical framework for assessing longitudinal patterns in stream habitat and fish distribution /." 2002. http://hdl.handle.net/1957/9825.

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22

"Distribution of marine zooplankton in coastal waters of Southern China." 1998. http://library.cuhk.edu.hk/record=b5889620.

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by Tam, Pui Fun.
Thesis (M.Phil.)--Chinese University of Hong Kong, 1998.
Includes bibliographical references (leaves 147-166).
Abstract also in Chinese.
List of Tables --- p.i
List of Figures --- p.ii
List of Plates --- p.v
Acknowledgements --- p.vi
Abstract (in English) --- p.vii
Abstract (in Chinese) --- p.ix
Chapter Chapter 1. --- General introduction --- p.1
Chapter Chapter 2. --- Temporal and spatial distribution of Copepoda in the Zhujiang River estuary --- p.3
Chapter 2.1 --- Literature review --- p.3
Chapter 2.1.1 --- Physical properties of estuaries --- p.3
Chapter 2.1.2 --- Factors affecting the zooplankton community --- p.4
Chapter 2.1.2.1 --- Temperature --- p.4
Chapter 2.1.2.2 --- River discharge and salinity --- p.5
Chapter 2.1.2.3 --- Coastal hydrography --- p.6
Chapter 2.1.2.4 --- Biological factors --- p.6
Chapter 2.1.3 --- Site description of the Zhujiang River estuary --- p.7
Chapter 2.2 --- Introduction --- p.9
Chapter 2.3 --- Materials and methods --- p.10
Chapter 2.4 --- Results --- p.13
Chapter 2.4.1 --- Physical parameters and chlorophyll concentration --- p.13
Chapter 2.4.2 --- Seasonal and spatial variations in the abundance of planktonic copepods --- p.17
Chapter 2.4.3 --- Seasonal variations in the relative abundance of dominant copepods --- p.27
Chapter 2.4.4 --- Relationship between copepod abundance and chlorophyll a concentration --- p.26
Chapter 2.4.5 --- Seasonal and spatial distribution and salinity and temperature preference of dominant copepods --- p.30
Chapter 2.5 --- Discussion --- p.41
Chapter 2.5.1 --- Seasonal variations in copepod abundance --- p.41
Chapter 2.5.2 --- Seasonal and spatial variations in species diversity --- p.43
Chapter 2.5.3 --- Seasonal and spatial distribution of dominant species --- p.45
Chapter 2.5.4 --- Seasonal succession and spatial segregation of dominant copepods --- p.51
Chapter 2.5.5 --- Seasonal and spatial distribution of non-dominant copepods --- p.52
Chapter 2.6 --- Conclusion --- p.60
Chapter Chapter 3. --- "Spatial and temporal distribution of marine cladocerans in Tolo Harbour, Hong Kong" --- p.61
Chapter 3.1 --- Literature review --- p.61
Chapter 3.1.1 --- Geographical and seasonal distribution of marine cladocerans --- p.61
Chapter 3.1.2 --- Vertical distribution --- p.65
Chapter 3.1.2.1 --- Diel vertical migration --- p.65
Chapter 3.1.2.2 --- Marine cladocerans as epiplankters --- p.68
Chapter 3.1.2.3 --- Diel vertical distribution of marine cladocerans --- p.69
Chapter 3.1.3 --- Horizontal distribution --- p.70
Chapter 3.1.4 --- Reproduction --- p.71
Chapter 3.1.5 --- Feeding --- p.72
Chapter 3.1.5.1 --- Food composition --- p.72
Chapter 3.1.5.2 --- Diel feeding behaviour --- p.74
Chapter 3.16 --- Site description of Tolo Harbour --- p.77
Chapter 3.2 --- Introduction --- p.79
Chapter 3.3 --- Materials and methods --- p.80
Chapter 3.3.1 --- Field sampling --- p.80
Chapter 3.3.1.1 --- Physical parameters --- p.80
Chapter 3.3.1.2 --- Ambient chlorophyll concentration --- p.82
Chapter 3.3.1.3 --- Zooplankton sampling --- p.82
Chapter 3.3.1.4 --- Gut pigment content --- p.83
Chapter 3.3.2 --- Measurement of gut evacuation rate --- p.84
Chapter 3.3.2.1 --- Gut evacuation rate --- p.85
Chapter 3.3.2.2 --- Clearance rate --- p.86
Chapter 3.3.3 --- Zooplankton distribution --- p.86
Chapter 3.3.3.1 --- Quantitative analysis --- p.86
Chapter 3.3.4 --- Statistical analysis --- p.92
Chapter 3.3.4.1 --- Overall population --- p.92
Chapter 3.3.4.2 --- Size --- p.93
Chapter 3.3.4.3 --- Reproductive condition --- p.94
Chapter 3.3.4.4 --- Gut pigment content and gut clearance rate --- p.95
Chapter 3.4 --- Results --- p.96
Chapter 3.4.1 --- Physical parameters and chlorophyll concentration --- p.96
Chapter 3.4.2 --- Spatial and temporal distribution of marine cladocerans --- p.102
Chapter 3.4.2.1 --- Species composition and abundance --- p.102
Chapter 3.4.2.2 --- Vertical and horizontal distribution in general population --- p.105
Chapter 3.4.2.3 --- Vertical and horizontal patterns in size distribution --- p.110
Chapter 3.4.2.4 --- Distribution of marine cladocerans at different stages --- p.118
Chapter 3.4.3 --- Feeding ecology of marine cladocerans --- p.125
Chapter 3.4.3.1 --- Did variation in gut pigment content --- p.125
Chapter 3.4.3.2 --- Gut evacuation rate --- p.125
Chapter 3.4.3.3 --- Diel changes in clearance rate of Penilia avirostris --- p.129
Chapter 3.5 --- Discussion --- p.132
Chapter 3.5.1 --- "Diel vertical and horizontal distribution of 3 marine podonids: Pseudevadne tergestina, Podon sp. and Pleopis schmackeri" --- p.135
Chapter 3.5.2 --- Diel vertical and horizontal distribution of Penilia avirostris --- p.138
Chapter 3.5.3 --- Size distribution of marine cladocerans --- p.140
Chapter 3.5.4 --- Feeding behaviour of marine cladocerans --- p.142
Chapter 3.6 --- Conclusion --- p.145
References --- p.147

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23

Toole, C. L. (Christopher L. ). "Settlement, distribution, growth, and mortality of juvenile dover sole (Microstomus pacificus) off northern Oregon." Thesis, 1994. http://hdl.handle.net/1957/35180.

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Demographic characteristics of juvenile Dover sole (Microstomus pacificus) were examined in relation to physical and biotic factors to develop a hypothesis explaining annual variations in recruitment. Surveys were conducted along the Oregon continental shelf at depths between 50-400 m bimonthly during 1989 and annually (in March) between 1990 and 1993. To determine settlement timing, growth, and mortality, daily growth increments were validated, as was position of the first post-settlement annulus. A method of estimating precision of otolith elemental composition with the electron microprobe was developed; otolith microstructure and microchemistry were used to identify a landmark associated with settlement. Mean density of 0-group settlers varied annually, with 1989 and 1990 high, 1991 and 1992 low, and 1993 intermediate. 0-group abundance was correlated with fall offshore divergence one year before settlement and with southward geostrophic velocity during the summer before settlement. These conditions may be related to production of prey available to pelagic larvae. Density of 0-group Dover sole was highest between 100-119 m, but deeper areas were also utilized in years of highest abundance. Density was not correlated with spawning stock biomass or density of older juveniles. It was correlated with rex sole (Glyptocephalus [Errex] zachirus) density. Growth rate was positively correlated with mean April-October upwelling and was not related to density or mortality of Dover sole. First-year mortality was positively correlated with early settlement of 0-group larvae, possibly due to an advantage of settling and migrating to the primary nursery area well in advance of the spring transition. A multiple regression model predicting density of 1-group Dover sole from three physical environmental factors was applied to an independent time series of Dover sole "age-5" recruitment estimates (Turnock and Methot 1992). The model was a poor predictor of annual recruitment to fisheries but a good predictor of trends based on five-year running averages. Results suggest that multi-year trends in Dover sole recruitment to fisheries can be explained by a small set of density-independent physical factors.
Graduation date: 1995

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24

Regueiras, Ana Vanessa Basto. "Symbiotic relationships between cyanobacteria and marine sponges: abundance, geographical distribution, phylogeny and chemdiversity." Tese, 2018. https://repositorio-aberto.up.pt/handle/10216/118129.

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25

Regueiras, Ana Vanessa Basto. "Symbiotic relationships between cyanobacteria and marine sponges: abundance, geographical distribution, phylogeny and chemdiversity." Doctoral thesis, 2018. https://repositorio-aberto.up.pt/handle/10216/118129.

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26

Morris, Robert M. (Robert Michael). "Marine bacterioplankton abundances and distributions." Thesis, 2004. http://hdl.handle.net/1957/29171.

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27

Ambusaidi, Hilal Saud. "Distribution and assemblages of demersal fish in Oman." Thesis, 1994. http://hdl.handle.net/1957/35315.

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The Sultanate of Oman has 1700 km of coastline extending from the Arabian Gulf south to the Arabian Sea. The demersal fish distributions and assemblages have not previously been well defined. In winter, variations in the oceanography of the area are minimal. In summer, however, the Arabian Sea is strongly influenced by the southwest monsoon. For this study the continental shelf off Oman was divided into eight regional areas and research trawl data on the distribution of demersal fish assemblages was studied using two forms of multivariate statistical analysis: two-way indicator species analysis and detrended correspondence analysis. The study was carried out to examine the influence on the species assemblages of geographical zonation, seasonal variation, and factors such as depth, time of day, and distance from untrawlable ground. There was seasonal variation in the fish assemblages and this variation was greatly influenced by the summer monsoon. Within each regional area depth appeared to be the major factor determining species distribution. In addition to the multivariate analyses, univariate techniques were applied to the catch rate data for forty commercial species to study in detail the influence of time of day and distance from untrawlable ground, factors which could potentially influence stock assessment estimates of fish biomass. Because the data were highly unbalanced, they were analyzed using General Linear Model with five factors, two continuous variables, and ten interaction terms to examine variation in the log-transformed catch rates. The factors time of day and distance from untrawlable ground, in combination with other factors, had significant effects on the catch rates for half of the species.
Graduation date: 1995

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28

Fowler-Walker, Meegan J. "Regional and local patterns in kelp morphology and benthic assemblages." 2005. http://hdl.handle.net/2440/37803.

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Most ecologists work at scales where complexity is greatest ( i.e. local ), and it is not surprising, therefore, that we tend to be captivated by the description and explanation of local variation whilst being pessimistic about the existence of broader patterns. Using a character ( kelp morphology ) known for its local and unaccounted variation, the morphology of the canopy - forming algae Ecklonia radiata ( Phaeophyta ) was quantified across > 5000 km of temperate Australian coastline, ( i ) between different configurations of algal stand ( i.e. monospecific vs mixed - species stands ) and ( ii ) across multiple spatial scales. A key result was that despite variation at local scales ( km ), differences between stands became increasingly clear at broad scales ( 1000 ' s km ), which supports the idea that large - scale patterns can emerge from apparent stochasticity at small scales. Within each stand, regional scale differences in morphological characters were evident ( i.e. Western Australia = South Australia ≠ Eastern Australia ). These characters correlated with geographic and environmental variables to indicate that the majority of morphological variation across temperate Australia was accounted for by longitude, wave exposure, water temperature and plant density. Morphological differences associated with environmental factors may reflect a plastic response to the local environment, or alternatively may reflect genetically fixed traits ( i.e. ecotypes ). An independent test of morphological variation associated with wave exposure environments, using a reciprocal transplant experiment, revealed that morphological plasticity was the mechanism enabling E. radiata to adopt different morphologies between exposure environments. The presence of kelp canopies has strong spatial relationships with organisms growing underneath them, and variation in the morphology of these canopies may facilitate distinct assemblages within the understorey habitat. Variation in the morphology of E. radiata was found to be associated with the structure of understorey assemblages, over broad spatial scales. This canopy - understorey association revealed two ' types ' of kelp forest ; one characteristic of Western and Southern Australia and the other of Eastern Australia. Patterns of canopy - benthos association have mostly been done on horizontal surfaces and experimental tests showed that such patterns on horizontal surfaces were not representative of vertical surfaces, which enables us to recognize the conditions for which we can reliably anticipate the structure of benthic organisms, thereby improving the predictive power of models that account for widespread patterns in subtidal heterogeneity. In conclusion, this thesis suggests that there are fundamental differences between the ecology of kelp forests at local scales ( i.e. between types of stand ) and at regional scales ( i.e. between the south and east coast of temperate Australia ), reflecting differences in kelp morphology that may be caused by environmental conditions ( e.g. exposure ) and may influence associated taxa ( e.g. understorey ). Consideration of such local - scale variation ( specificity ) when testing for the existence of broad - scale phenomena ( generality ) not only strengthens our understanding of the ecology of subtidal forests, but will also improve the predictive power of further research in this system.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

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29

Johnson, Angela Michelle. "An investigation of the distribution and abundance of ichthyoplankton and juvenile benthic fishes in relation to nearshore hypoxia within the Northern California Current system." Thesis, 2012. http://hdl.handle.net/1957/34734.

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Nearshore hypoxia within the Northern California Current (NCC) system is a seasonal phenomenon caused by coastal upwelling and occurs mainly during late-summer and early fall. The effects of low oxygen levels on fish and invertebrate communities, particularly during early-life history stages, however, are poorly known for this area. I investigated the effects of hypoxia on the density, community structure, vertical and horizontal distribution of fish larvae and juveniles, as well as body condition of juveniles, along the central Oregon and Washington coasts during the summers of 2008 - 2011. During this sampling period, bottom dissolved oxygen (DO) values ranged from 0.49 to 9.85 ml l��, and the number of hypoxic (e.g., < 1.4 ml l��) stations sampled was low compared to 2002 and 2006 (only 54 sampling stations for the ichthyoplankton study out of 493, and only 12 stations out of 90 for the benthic juvenile study). From the ichthyoplankton study, I found that the overall density of fish larvae increased as bottom-DO values increased; however, the effect on individual species density was limited. Between 44.65 ��N and 46.00 ��N (~Florence, OR �� Astoria, OR), fish larvae altered their vertical distribution when bottom-DO was low by rising in shallower water layers. From the benthic juvenile study, I found that English sole (Parophrys vetulus), butter sole (Isopsetta isolepis), speckled sanddab (Citharichthys stigmaeus) and Pacific sanddab (Citharichthys sordidus) dominated the catch with annual variation in abundances. Species composition, abundance and length had strong relationships with depth. Species abundance for English sole (< 75 mm), speckled sanddab (<100 mm) and Pacific sanddab also increased with increased bottom-DO. However, the body condition of butter sole (< 75 mm) and of large speckled sanddab (��100 mm) increased with decreased bottom-DO. Overall my research elucidates important patterns of larval and juvenile fish distribution within the NCC during summer. In both studies I have found a limited effect of DO on abundance, distribution and community assemblages. Variables other than DO, such as depth, season and location, dominated the explained variance of the intervening multivariate and univariate analysis. However, due to the paucity of samples during hypoxic events, continued monitoring of nearshore larval and juvenile species over varying hypoxic conditions is necessary for understanding the impact of hypoxia on these communities and subsequent adult populations.
Graduation date: 2013

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30

Rivers-Moore, Nicholas Andrew. "Water temperature and fish distribution in the Sabie River system : towards the development of an adaptive management tool." Thesis, 2003. http://hdl.handle.net/10413/3597.

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Water temperatures are a fundamental water quality component, and a key abiotic determinant of fish distribution patterns in rivers. A river 's thermal regime is the product of a multitude of thermal drivers and buffers interacting at different temporal and spatial scales, including, inter alia, air temperatures, flow volumes (including groundwater flows and lateral inputs from tributaries), channel geomorphology and riparian vegetation. "Healthy" river systems are self-sustaining, with adequate thermal variability to maintain biotic diversity. Temporal variability of flow volumes and water temperatures, and how these change along the longitudinal axis of a river, contribute towards a rivers "signature". Rivers that have had their signatures altered through anthropogenic impacts may no longer be sustainable, and require varying levels of management. Successful river management should include a quantification of these signatures , a definition of the "desired" state which management aims to achieve, associated "thresholds" of change or concern, and monitoring programmes. Such an approach requires flexibility and adaptability, as well as appropriate tools being available to natural resource managers. Indices, the utility of which are enhanced when included in predicative modelling systems, are a common means of assessing system variability and change. The degree of confidence placed in such tools depends on the level of fundamental science, and the degree of system understanding, underpinning them. This research contributes to the understanding of the ecological significance . of water temperatures in variable semi-arid river systems, using the Sabie River (Mpumalanga, South Africa) as a case study, and indices derived from biological indicators (Chiloglanis , Pisces: Mochokidae) to quantify the effects of cumulative changes in heat units against a hypothesised critical water temperature threshold. Hourly water temperatures for 20002002 collected at nine sites in the main rivers of the Sabie catchment, together with biannual surveys of relative abundances and community patterns of fish collected using standard electrofishing techniques, were used to provide the basis for a modelling system which aims to provide river managers with a tool for quantifying changes to the thermal regime of the Sabie River. This modelling system consisted of a suite of pragmatic models, including multiple linear regression models for simulating daily maximum water temperatures, and simple cause-and-effect relationships between biological indices (change In condition factor and change in the ratio of relative abundances of two species of Chiloglanis) and annual metrics of time-of-exposure to heat stress. It was concluded that changes in the thermal regimes of the rivers in the Sabie catchment are likely to lead to changes in fish distribution patterns, and a decline in river health. Inherent system variability suggests that management decisions will be made in the face considerable uncertainty. Indirect management of water temperatures may be possible through maintenance of flow volumes and flow variability. However, the most appropriate management approach for maintaining fish diversity within these rivers is to ensure that obstacles to fish migration are minimized, to maximise the ability of river biota to respond to thermal changes, by accessing suitable alternative habitats or refugia. Future research should focus on extending the time series of water temperatures from such river systems, and further understanding the drivers and buffers contributing to the thermal regimes of variable semi-arid river systems in South Africa. Additional testing of the validity of the hypothesized relationships between abiotic processes underpinning biotic patterns should be undertaken.
Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.

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31

HAASOVÁ, Ivana. "Tasemnice čeledi Gryporhynchidae z Afriky." Master's thesis, 2009. http://www.nusl.cz/ntk/nusl-51551.

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Morphological-taxonomical study of gryporhynchid cestodes from Africa is presented. New material from Kenya, Senegal and Sudan was studied and we belong to 17 species in 8 orders - Amirthalingamia macracantha (Joyeux et Baer, 1935) Bray, 1974; Anomotaenia riccii (Fuhrmann et Baer, 1943) Baer et Bona, 1960; Cyclustera magna (Baer, 1959) Bona, 1975; Cyclustera sp.; Dendrouterina macrosphincter (Fuhrmann, 1909) Baer et Bona, 1960; Neogryporhynchus sp.; Paradilepis lloydi (Southwell, 1926) Spasski, 1954; Paradilepis maleki (Khalil, 1961); Paradilepis urceina Bona, 1975; Paradilepis urceus (Wedl, 1855) Joyeux et Baer, 1950; Parvitaenia macrocoleo Bona, 1975; Parvitaenia macropeos (Wedl, 1855) Baer et Bona, 1960; Parvitaenia megascolecina Bona, 1975; Parvitaenia purpurea Johri, 1959; Parvitaenia samfyia Mettrick, 1967; Valipora ardeolae (Singh, 1952) Baer et Bona, 1960 and Valipora mutabilis (Linton, 1927). Known larval stages and adults from Africa are presented in review of species.

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32

Lockett, Daniel Edwin IV. "A Bayesian approach to habitat suitability prediction." Thesis, 2012. http://hdl.handle.net/1957/28788.

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For the west coast of North America, from northern California to southern Washington, a habitat suitability prediction framework was developed to support wave energy device siting. Concern that wave energy devices may impact the seafloor and benthos has renewed research interest in the distribution of marine benthic invertebrates and factors influencing their distribution. A Bayesian belief network approach was employed for learning species-habitat associations for Rhabdus rectius, a tusk-shaped marine infaunal Mollusk. Environmental variables describing surficial geology and water depth were found to be most influential to the distribution of R. rectius. Water property variables, such as temperature and salinity, were less influential as distribution predictors. Species-habitat associations were used to predict habitat suitability probabilities for R. rectius, which were then mapped over an area of interest along the south-central Oregon coast. Habitat suitability prediction models tested well against data withheld for crossvalidation supporting our conclusion that Bayesian learning extracts useful information available in very small, incomplete data sets and identifies which variables drive habitat suitability for R. rectius. Additionally, Bayesian belief networks are easily updated with new information, quantitative or qualitative, which provides a flexible mechanism for multiple scenario analyses. The prediction framework presented here is a practical tool informing marine spatial planning assessment through visualization of habitat suitability.
Graduation date: 2012

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Dissertations / Theses on the topic 'Marine fishes – Geographical distribution'

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