Rozprawy doktorskie na temat „Stream fauna”

Previous research has shown that a range of physical and biological drivers can influence the composition of faunal assemblages occupying localities within streams. There is much debate in the literature about which of these is more important. Descriptive and experimental field studies were conducted in two relatively undisturbed, second order rainforest streams in southeast Queensland, Australia. The principal objectives were to describe spatial and temporal patterns in pool fauna and explore relationships between these patterns and physical attributes of habitat, disturbance and biotic interactions. The macroinvertebrate and vertebrate fauna of 12 small stream pools were sampled approximately monthly over a period of 15 months. Samples were collected from all major within-pool habitat types and concurrent measurements of potentially important environmental parameters were made at landscape scales of stream, pool and habitat patch. Faunal assemblages were consistently different between the two streams and between the various within-pool habitat types, although the latter may partially be explained by differences in sampling protocols applied in the different habitat types. However, spatial and temporal variation in faunal assemblages within habitat types was large at the scales of whole pools and within-pool habitats, and this variation occurred apparently independently of variation in physical habitat attributes. These results indicated that very little of the local scale faunal variation could be explained by abiotic drivers and that some other factors must be responsible for the observed faunal patterns. Previous research had indicated that atyid shrimps can play a significant ecological role in rainforest streams, where they act as 'ecosystem engineers' by removing fine sediment from hard surfaces. This subsequently alters algal dynamics and faunal composition in streams. A pool-scale manipulative experiment was conducted to investigate the role of the atyid Paratya australiensis, which is an abundant and conspicuous component of the fauna. Removal of shrimp from pools had no effect on sediment accrual on hard surfaces and consequently did not affect algal biomass or faunal assemblages. The lack of effect on sediment accumulation was attributed to the low rate of deposition in these streams, which was an order of magnitude lower than in streams where atyids have been demonstrated to play a keystone role. The fish Mogurnda adspersa was found to be the primary predator of pool fauna in the study streams, where it preyed on a wide variety of taxa. Dietary analyses revealed that an ontogenetic shift occurred in both diet and the within-pool habitat where fish fed. Within this general framework, individual fish had strong individual prey preferences. Significant correlations were found between the natural abundance of Mogurnda in pools and faunal assemblage patterns in both gravel habitat and pools in general, indicating that predation had an effect on pool fauna. The nature of this effect varied between habitats. A direct density dependent response was observed in gravel habitat. In contrast, the response in pools varied considerably between individual pools, perhaps reflecting the differing prey preferences of individual fish. Despite these correlations, an experimental manipulation of the density of Mogurnda at a whole-pool scale did not conclusively identify a predation effect. This may have been due to problems with fish moving between treatments, despite attempts to constrain them, and low experimental power due to the inherent high variability of pool fauna. Overall, the results of the study indicated that there was considerable spatial and temporal variation in pool fauna despite similarities in the physical attributes of pools and their close proximity. This variation appeared to occur at random and could not be explained by abiotic or biotic factors. Predation had a small effect, but could not explain the overall patterns, whereas disturbance by spates had very little effect at all. Stochastic processes associated with low level random recruitment were identified as a possible and plausible explanation for observed patterns. These conclusions are discussed in terms of their implications for our understanding of the ecology and management of streams.

Previous research has shown that a range of physical and biological drivers can influence the composition of faunal assemblages occupying localities within streams. There is much debate in the literature about which of these is more important. Descriptive and experimental field studies were conducted in two relatively undisturbed, second order rainforest streams in southeast Queensland, Australia. The principal objectives were to describe spatial and temporal patterns in pool fauna and explore relationships between these patterns and physical attributes of habitat, disturbance and biotic interactions. The macroinvertebrate and vertebrate fauna of 12 small stream pools were sampled approximately monthly over a period of 15 months. Samples were collected from all major within-pool habitat types and concurrent measurements of potentially important environmental parameters were made at landscape scales of stream, pool and habitat patch. Faunal assemblages were consistently different between the two streams and between the various within-pool habitat types, although the latter may partially be explained by differences in sampling protocols applied in the different habitat types. However, spatial and temporal variation in faunal assemblages within habitat types was large at the scales of whole pools and within-pool habitats, and this variation occurred apparently independently of variation in physical habitat attributes. These results indicated that very little of the local scale faunal variation could be explained by abiotic drivers and that some other factors must be responsible for the observed faunal patterns. Previous research had indicated that atyid shrimps can play a significant ecological role in rainforest streams, where they act as 'ecosystem engineers' by removing fine sediment from hard surfaces. This subsequently alters algal dynamics and faunal composition in streams. A pool-scale manipulative experiment was conducted to investigate the role of the atyid Paratya australiensis, which is an abundant and conspicuous component of the fauna. Removal of shrimp from pools had no effect on sediment accrual on hard surfaces and consequently did not affect algal biomass or faunal assemblages. The lack of effect on sediment accumulation was attributed to the low rate of deposition in these streams, which was an order of magnitude lower than in streams where atyids have been demonstrated to play a keystone role. The fish Mogurnda adspersa was found to be the primary predator of pool fauna in the study streams, where it preyed on a wide variety of taxa. Dietary analyses revealed that an ontogenetic shift occurred in both diet and the within-pool habitat where fish fed. Within this general framework, individual fish had strong individual prey preferences. Significant correlations were found between the natural abundance of Mogurnda in pools and faunal assemblage patterns in both gravel habitat and pools in general, indicating that predation had an effect on pool fauna. The nature of this effect varied between habitats. A direct density dependent response was observed in gravel habitat. In contrast, the response in pools varied considerably between individual pools, perhaps reflecting the differing prey preferences of individual fish. Despite these correlations, an experimental manipulation of the density of Mogurnda at a whole-pool scale did not conclusively identify a predation effect. This may have been due to problems with fish moving between treatments, despite attempts to constrain them, and low experimental power due to the inherent high variability of pool fauna. Overall, the results of the study indicated that there was considerable spatial and temporal variation in pool fauna despite similarities in the physical attributes of pools and their close proximity. This variation appeared to occur at random and could not be explained by abiotic or biotic factors. Predation had a small effect, but could not explain the overall patterns, whereas disturbance by spates had very little effect at all. Stochastic processes associated with low level random recruitment were identified as a possible and plausible explanation for observed patterns. These conclusions are discussed in terms of their implications for our understanding of the ecology and management of streams.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Full Text

Connectivity in ecological systems is a broad concept that embodies the transmission of ecosystem components throughout landscapes at multiple spatial and temporal scales. Of relevance to the present study are the connections (or lack thereof) among local populations of stream fauna - population connectivity in lotic systems. Dispersal, recolonisation and migration are the demographic forms of population connectivity, and gene flow is the genetic aspect of population connectivity. Both forms of population connectivity have underpinned some of the classic theories and hypotheses in stream ecology, and have implications for pure and applied stream ecology, including ecosystem restoration. Conceptual models in ecology can facilitate understanding and predictability of the ecosystem processes they represent, and have potential applicability as management tools or 'rules of thumb' in conservation and restoration programs. Various theoretical models describe potential patterns of connectivity among local populations and in this thesis these models were used to evaluate population connectivity in a freshwater fish (southern pygmy perch, Nannoperca australis) and two reproductively isolated genetic lineages of freshwater shrimp (Paratya spp.) in small, geomorphically degraded streams in south eastern Australia. These streams (the Granite Creeks) have been the focus of a recent habitat restoration trial and several studies have examined fish and macroinvertebrate community responses to the experiment. It was the purpose of this study to contribute information about population connectivity in the selected species to complement these community ecology studies. Population connectivity was examined in these species using molecular data (mitochondrial and nuclear genetic data) and natural abundance isotopic signatures of nitrogen and carbon. At the landscape scale, results showed that populations of N. australis and the P. australiensis lineages were isolated among the streams and among sites within streams, and that there was no consistent pattern of isolation-by-distance in genetic data for any species. Thus, classic models of population connectivity, such as the Island Model and Stepping-Stone Model, were not supported by this study. Results indicated that population models that incorporated more complex aspects of stream structure may be more appropriate than these classic models for approximating observed patterns of population connectivity in lotic systems. The Stream Hierarchy Model (SHM) predicts that the hierarchical aspect of stream structure (i.e. stream confluences) have a dominant role in shaping patterns of population connectivity in lotic fauna, whereby populations among streams are more isolated than those within them. Although stream confluences were found to have an important role in population subdivision for the species examined in this study, the expectations of the SHM were met for only N. australis. For the P. australiensis lineages, the influence of topography (i.e. the longitudinal aspect of stream structure) was just as important as stream confluences in isolating local populations. Large-scale determinants of population isolation were thus found to be associated with both the hierarchical and longitudinal aspects of stream structure, and were not well represented by any single theoretical model of population connectivity. At within-stream scales, upland populations tended to be extremely isolated from other populations and had temporally stable genetic signatures. In contrast, lowland populations were connected to other lowland populations within the same stream to a greater degree, although the connections were patchy and a slight signature of temporal instability in the genetic data was evident for one of the P. australiensis lineages. Thus, metapopulation or patchy population models were found to represent connections among lowland populations within the same stream, although they were not appropriate for describing connectivity among upland populations. This finding highlights the importance of the longitudinal aspect of stream structure in shaping ecological patterns in lotic systems, and demonstrates that local patterns of population connectivity can vary over relatively small spatial scales. Overall, the results illustrate that both hierarchical and longitudinal aspects of stream structure can have important roles in isolating populations of stream fauna. They therefore also represent constraints for the ability of aquatic fauna to colonise restored habitat in streams. The corollary of this, however, is that such isolated populations of stream fauna represent appropriate population units at which to target habitat restoration. The hierarchical and longitudinal aspects of stream structure may thus represent 'rules of thumb' or 'landscape filters' that stream restoration ecologists could use to predict likely isolated populations of lotic fauna across the landscape. Such a 'rule of thumb' might be the inclusion of multiple isolated population units in restoration programs, as this strategy is likely to generate the greatest biological response to the restoration at the landscape scale, particularly with respect to intra-specific genetic diversity captured by restoration. At small spatial scales, such as for a single stream or tributary, the longitudinal aspect of stream structure can be an important factor to consider when designing stream habitat restoration programs. In this study, lowland sites were unstable and there were patchy connections among local lowland populations within the same stream, whereas upland populations were isolated at this scale. In contrast, other studies have found that upstream populations of some species can be connected in a patchy fashion in other systems. For such unstable sections of stream, where there are patchy patterns of local population connectivity, the inclusion of multiple restored patches, especially refugial habitat, is likely to produce the greatest biotic response at the patch scale, particularly with respect to demographic responses (such as local colonisation). Multiple restored refugial patches will enable species to persist throughout the stream section during adverse environmental conditions, will allow for variation in local movement patterns and distances between species and between years with contrasting environment conditions (e.g. stream flow), and may harbour different species assemblages and intraspecific genotypes due to stochastic processes (i.e. have functional heterogeneity). The hierarchical and longitudinal aspects of stream structure are thus important determinants of population connectivity at both large and small spatial scales, and have implications for how stream biota will respond to restoration at patch and landscape scales.

Connectivity in ecological systems is a broad concept that embodies the transmission of ecosystem components throughout landscapes at multiple spatial and temporal scales. Of relevance to the present study are the connections (or lack thereof) among local populations of stream fauna - population connectivity in lotic systems. Dispersal, recolonisation and migration are the demographic forms of population connectivity, and gene flow is the genetic aspect of population connectivity. Both forms of population connectivity have underpinned some of the classic theories and hypotheses in stream ecology, and have implications for pure and applied stream ecology, including ecosystem restoration. Conceptual models in ecology can facilitate understanding and predictability of the ecosystem processes they represent, and have potential applicability as management tools or 'rules of thumb' in conservation and restoration programs. Various theoretical models describe potential patterns of connectivity among local populations and in this thesis these models were used to evaluate population connectivity in a freshwater fish (southern pygmy perch, Nannoperca australis) and two reproductively isolated genetic lineages of freshwater shrimp (Paratya spp.) in small, geomorphically degraded streams in south eastern Australia. These streams (the Granite Creeks) have been the focus of a recent habitat restoration trial and several studies have examined fish and macroinvertebrate community responses to the experiment. It was the purpose of this study to contribute information about population connectivity in the selected species to complement these community ecology studies. Population connectivity was examined in these species using molecular data (mitochondrial and nuclear genetic data) and natural abundance isotopic signatures of nitrogen and carbon. At the landscape scale, results showed that populations of N. australis and the P. australiensis lineages were isolated among the streams and among sites within streams, and that there was no consistent pattern of isolation-by-distance in genetic data for any species. Thus, classic models of population connectivity, such as the Island Model and Stepping-Stone Model, were not supported by this study. Results indicated that population models that incorporated more complex aspects of stream structure may be more appropriate than these classic models for approximating observed patterns of population connectivity in lotic systems. The Stream Hierarchy Model (SHM) predicts that the hierarchical aspect of stream structure (i.e. stream confluences) have a dominant role in shaping patterns of population connectivity in lotic fauna, whereby populations among streams are more isolated than those within them. Although stream confluences were found to have an important role in population subdivision for the species examined in this study, the expectations of the SHM were met for only N. australis. For the P. australiensis lineages, the influence of topography (i.e. the longitudinal aspect of stream structure) was just as important as stream confluences in isolating local populations. Large-scale determinants of population isolation were thus found to be associated with both the hierarchical and longitudinal aspects of stream structure, and were not well represented by any single theoretical model of population connectivity. At within-stream scales, upland populations tended to be extremely isolated from other populations and had temporally stable genetic signatures. In contrast, lowland populations were connected to other lowland populations within the same stream to a greater degree, although the connections were patchy and a slight signature of temporal instability in the genetic data was evident for one of the P. australiensis lineages. Thus, metapopulation or patchy population models were found to represent connections among lowland populations within the same stream, although they were not appropriate for describing connectivity among upland populations. This finding highlights the importance of the longitudinal aspect of stream structure in shaping ecological patterns in lotic systems, and demonstrates that local patterns of population connectivity can vary over relatively small spatial scales. Overall, the results illustrate that both hierarchical and longitudinal aspects of stream structure can have important roles in isolating populations of stream fauna. They therefore also represent constraints for the ability of aquatic fauna to colonise restored habitat in streams. The corollary of this, however, is that such isolated populations of stream fauna represent appropriate population units at which to target habitat restoration. The hierarchical and longitudinal aspects of stream structure may thus represent 'rules of thumb' or 'landscape filters' that stream restoration ecologists could use to predict likely isolated populations of lotic fauna across the landscape. Such a 'rule of thumb' might be the inclusion of multiple isolated population units in restoration programs, as this strategy is likely to generate the greatest biological response to the restoration at the landscape scale, particularly with respect to intra-specific genetic diversity captured by restoration. At small spatial scales, such as for a single stream or tributary, the longitudinal aspect of stream structure can be an important factor to consider when designing stream habitat restoration programs. In this study, lowland sites were unstable and there were patchy connections among local lowland populations within the same stream, whereas upland populations were isolated at this scale. In contrast, other studies have found that upstream populations of some species can be connected in a patchy fashion in other systems. For such unstable sections of stream, where there are patchy patterns of local population connectivity, the inclusion of multiple restored patches, especially refugial habitat, is likely to produce the greatest biotic response at the patch scale, particularly with respect to demographic responses (such as local colonisation). Multiple restored refugial patches will enable species to persist throughout the stream section during adverse environmental conditions, will allow for variation in local movement patterns and distances between species and between years with contrasting environment conditions (e.g. stream flow), and may harbour different species assemblages and intraspecific genotypes due to stochastic processes (i.e. have functional heterogeneity). The hierarchical and longitudinal aspects of stream structure are thus important determinants of population connectivity at both large and small spatial scales, and have implications for how stream biota will respond to restoration at patch and landscape scales.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Faculty of Environmental Sciences
Full Text

Doctor of Philosophy
Department of Biology
Keith B. Gido
Habitat fragmentation and loss threaten global biodiversity, but organism responses to changing habitat availability are mediated by structural properties of their habitats. In particular, organisms inhabiting dendritic landscapes with hierarchically arranged branches of habitat tend to have limited access to some patches even in the absence of fragmentation. Consequently, organisms inhabiting dendritic landscapes such as streams respond strongly to fragmentation. Using a combination of meta-analysis, field observations, and ecological network modeling I show that stream fishes respond to fragmentation in predictable ways. First, I addressed how dams and stream dewatering have created a mosaic of large river fragments throughout the Great Plains. Using a geographic information system and literature accounts of population status (i.e., stable, declining, extirpated) for eight “pelagic-spawning” fishes, I found stream fragment length predicted population status (ANOVA, F2,21 = 30.14, P < 0.01) and explained 71% of reported extirpations. In a second study, I applied a new measure of habitat connectivity (the Dendritic Connectivity Index; DCI) to 12 stream networks in Kansas to test the DCI as a predictor of fish response to fragmentation by road crossings. Results indicated fish communities in stream segments isolated by road crossings had reduced species richness (alpha diversity) and greater dissimilarity (beta diversity) to segments that maintained connectivity with the network, and the DCI predicted patterns in community similarity among networks (n = 12; F1,10 = 19.05, r2 = 0.66, P < 0.01). Finally, I modeled fish distributions in theoretical riverscapes to test for mechanistic linkages between fragmentation and local extirpations. Results suggested the number of small fragments predicted declines in patch occupancy, and the magnitude of change in occupancy varied with dispersal ability (“high” dispersers responded more strongly than “low” dispersers). Taken together, these works show context-dependencies in fish responses to fragmentation, but a unifying theme is that small fragments contribute to attenuated biodiversity. Moreover, the predictable manner in which stream fish react to fragmentation will aid in biodiversity conservation by revealing potential responses to future scenarios regarding changes to habitat connectivity.

Despite a slow start freshwater meiofauna research is now gathering pace. Evidence is accumulating which indicates the importance of their inclusion in lotic metazoan studies. Here I contribute towards this research effort by conducting an investigation of meiofauna and macrofauna from a chalk stream. I sampled meiofauna for a 19 month period, and macrofauna for a 12 month period between April 2004 and October 2005 from the subsurface, macrophyte stands and gravel beds. The chalk stream community was highly diverse with 57 taxa identified from the subsurface and 186 from the benthos. Meiofauna outnumbered macrofauna in all habitats in terms of density. Both meio- and macroinvertebrates preferred macrophyte stands over gravel beds as habitat, indicated by higher densities, biomass and species richness. Speciesabundance relationships and density-size spectra indicated the invertebrate assemblages of the benthos to be stable over the period of the study as patterns varied little between sampling months and habitats. Production and standing biomass were dominated by the macroinvertebrates which suggests meiofauna had a limited role within functioning of the stream. However, gut content data indicated meiofauna may play an important trophic role, linking basal resources and top consumers. Combined gut content and stable isotope analysis suggested a strong pattern of generalist feeding throughout the whole spectrum of body size in the community, rejecting the concept of functional feeding groups. Predominance of generalist feeding also suggested a large number of weak interactions in food webs. While higher species richness lower in food webs indicated greater functional redundancy of lower trophic levels. Density-body size distributions were shallow with a biased distribution of energy towards larger size classes. Moreover, testing of production, standing biomass and PIB body size allometry was inconclusive with regards to theoretical predictions. The interrelationship ofbiodiversity, stability, and trophic dynamics, with body size determine the structure and dynamics of the chalk stream community, not metabolism.

The aim of this work is to analyze if a change in the benthic community can be detected two years after a restoration of a small stream. The samples were taken in a small stream at Tinnerö Eklandskap just south of Linköping. In addition to the restored area, two reference sites upstream and downstream of the restored area were sampled to compare to the restored site. The method used for sampling of benthic fauna in the stream was kick sampling. ASPT, Berger-Parker and Renkonen-indices were used to find out if there was any difference between the reference areas and the restored area. In addition to indices, rank-abundance curves and species lists were made to see if there was any trend difference between the different areas. The only index that showed a difference between the different areas was Berger-Parker diversity index. The reason why there were no greater differences between the areas may be due to the fact that two years is too short to allow time for the benthos to re-colonize the restored area.

Extensive community-based sampling and single-species genetic analysis were used to study factors driving stream invertebrate community assembly on islands. Macroinvertebrates and physicochemistry were surveyed in forty-two streams on La Palma, La Gomera, Tenerife and Madeira (Macaronesia). Island faunal relationships and the role of the stream and catchment environment in determining community composition were investigated with multivariate analyses; assemblage nestedness and species richness, occupancy and abundance were also examined. The relationship between genetic differentiation and range size was tested using allozyme variation in selected species. Island species pools differed in community composition and species richness (total, and endemic), broadly as predicted by theory of island biogeography. Stream and island species richness were correlated, showing unsaturated, possibly dispersal-limited, communities, and stream faunas were nested, evidence that assemblages were not random (e.g. only generalist/dispersive taxa occur at species-poor sites). Endemics occurred in more streams than non-endemics, suggesting greater habitat availability for the former, but similar niche width, endemic and non-endemics having similar local abundance. Species richness, community composition and the abundances of individual species were correlated with stream physicochemistry, itself reflecting geology, rainfall, altitudinal zonation of vegetation and the intensity of stream exploitation. Allozyme variation was surveyed in Mesophylax aspersus (Trichoptera: Limnephilidae) and Wormaldia tagananana (Trichoptera: Philopotamidae), respectively having widespread and localised distributions. Population structure supported the hypothesis that range size is, at least partly, limited by poor dispersal ability in W tagananana. Genetic variation in Ancylus striatus (Gastropoda: Ancylidae) was typical of polyploidy and selffertilisation/ parthenogenesis. Breeding system has consequences for a species' colonisation ability, and may partially explain the wide distribution of A. striatus within the islands. Variation in community composition reflected patterns at a range of scales. Biogeography detennined the island species pooL whilst local physicochemistry determined richness and community composition within islands. Species characteristics that affect their colonisation and c:\tinction probabilities (e.g. habitat selection at the local- and mesoscaks, dispersal patterns and breeding system). influence hoth the local and regional species pools.

A wide-ranging macroinvertebrate and physico-chemical survey of 230 3rd and 4th order streams throughout the Canterbury region was conducted between November 1999 and March 2000. Kick-net sampling, spot water sampling and habitat surveys were used. Invertebrate community composition appeared to be influenced by two overriding factors; the physical condition of the stream, and the amount of anthropogenic development within the catchment. Faunas dominated by Ephemeroptera and Trichoptera and with some Plecoptera present tended to occur in pristine high altitude streams with low conductivity, well vegetated riparian zones, heterogeneous streambed substrates and periphyton consisting primarily of diatom biofilms. Faunas dominated by Crustacea, Oligochaeta and Chironomidae occurred commonly at degraded lowland sites with high conductivity, little or no riparian vegetation, more homogeneous fine substrates and periphyton dominated by thick mats and filaments. Between these two extremes, gradual change in faunas was found, with Trichoptera dominating intermediately disturbed sites. A striking decrease in the relative abundance of Ephemeroptera along an ecological gradient appeared to be associated with increasing intensity of landuse. A comparative investigation of three biotic indices widely used in New Zealand for assessing stream health, indicated that the MCI, OMCI and SOMCI may not assess the health of all sites, consistently. The inconsistencies were probably brought about by two factors. Firstly, presence-absence data used in calculating the MCI may not detect subtle differences in community structure, whereas the quantitative data used by the OMCI and SOMCI may pick up small differences and therefore group sites into different degradation bands. Secondly, published degradation bands for the MCI, OMCI and SOMCI do not appear to be directly comparable in Canterbury. The utility of a quantitative MCI with low-level (order, class, phylum) identification was also investigated, and found to be a potentially viable alternative to the MCI and its derivatives when a low-cost, rapid assessment technique is needed, but expertise in identification is lacking. The health of streams in the Canterbury region as assessed by the MCI, was investigated. The MCI indicated that streams were generally more healthy if they were further inland, at higher altitudes, and were in forested or unmodified catchments. Stream health was poorest in lowland sites with pastoral and urban/city developed catchments, although 42 pastoral sites with MCI values> 100 and taxonomic richness >25 indicated that healthy streams were attainable in agriculturally developed land. Finally, a multimetric approach for assessing the health of Banks Peninsula streams using macroinvertebrates was developed. Five biological metrics (OMCI, % EPT, % Chironomidae, % Mollusca, No. Ephemeroptera) that best discriminated selected reference sites from sites impaired by habitat disturbance and organic pollution were combined into an index of biological integrity; the Banks Peninsula Macroinvertebrate Index (BPMI). Strong relationships between the BPMI and MCI and OMCI suggested that the extra effort required to produce a multimetric index did not result in improved assessment of stream condition. However, a multimetric index can provide additional information on the source of degradation to a stream and indicate where restoration or mitigation should be focussed.

This dissertation is an analysis of the Quaternary fluvial history of central Northamptonshire. It uses new freshwater ostracod data which are interpreted using information on Quaternary and present day habitats and examines in detail associated patterns of environmental change in coarse sediments from which the ostracods were extracted. Stratigraphic, lithological and sedimentological data, supported by a study of geological maps, borehole logs and papers, are employed to produce a new hypothesis to explain the Quatemary development of the Milton River and the River Nene. The alignment of the Milton Formation Valley is established to have proceeded to the east of, but parallel with, the Nene Valley between Northampton and Higham Ferrers, where it turned to the south-east. It comprises locally derived deposits which are shown to be pre-Anglian Glaciation and, at the time of the deposition of the ostracods studied here, an interglacial environment prevailed. However, during a ‘cooling phase”, Milton Formation sediments were incised and the channel became partially infilled with fossiliferous boreal sediments. Further sedimentation continued to produce a non-fossiliferous, periglacial sand, which is typical of the Milton Formation. It is argued that this period of deposition was followed by two glacial episodes, the latter relating to the Lowestoft Formation. Stratigraphic, sedimentological and lithological evidence from the Nene valley shows vestigial terrace gravels exist between Northampton and Wellingborough. The oldest gravels of these features pre-date the Anglian age, sub-glacial tunnel valley” at Northampton, implying the Nene Valley existed prior to glaciation. Before glaciation it is suggested that the Milton River became confluent with the Nene at Northampton and, concurrently, diverted to the north-east at Higham Ferrers. This is believed to be associated with the simultaneous abandonment of the Milton Valley to the south-east of Higham Ferrers and the upstream stretch at Northampton. Evidence presented of downcutting, lateral migration, gravel reworking and changes in the ostracod assemblages in the Nene Valley confirm a history of several climatic oscillations which took place in the pre-Devensian, Devensian and Holocene. These oscillations are tentatively correlated with stages of deposition in the Nene established downstream at Peterborough. This revised fluvial history elaborates the course and age of the Milton River and establishes a pre-Devensian age for much of the Nene Valley sediment. The significance of this new understanding of the upper Nene Valley has been compared with that of the lower Nene Valley at Peterborough, Cambridgeshire. The combined evidence is used to produce a pattern of river development within the Quaternary which may be used as a model when reconstructing the palaeogeography of other rivers and their floodplains by means of their sedimentary structures and related fossils. This idea is explored to a small extent in the thesis, but is more applicable to future work. The new ostracod data throws new light on previous studies from other sites in England. Ostracod species new to the Pleistocene record are to be added to a worldwide data base

O aporte de sedimento fino é um dos principais agentes causadores de impactos a ecossistemas aquáticos. Este trabalho teve por finalidade avaliar por experimentalmente o efeito do sedimento fino sobre a fauna de macroinvertebrados bentônicos em um riacho subtropical. O local escolhido foi o rio Forqueta no distrito de Barra do Ouro pertencente ao município de Maquiné, RS. Foi adicionado por tratamento cerca 3138 cm3 de sedimento fino, separado em duas frações: areia fina (0 mm a 0,250mm) e areia grossa (0,25 mm a 1mm), em dois níveis, com e sem sedimento. Os dados foram analisados através por meio de uma Análise de Variância (ANOVA) de dois fatores para abundância total, riqueza e riqueza rarefeita, além de uma Análise de Variância Multivariada (MANOVA) para abundância relativa e composição de espécies e de uma Análise de Correspondência Canônica (pCCA), esta última, para avaliar o quanto eventos de perturbações influenciam a fauna aquática. A interação entre a velocidade do fluxo e os fatores envolvendo sedimentos também foram avaliados. O sedimento fino afetou negativamente a abundância total, a riqueza e a composição de espécies, mas não a riqueza rarefeita e a abundância relativa.O fluxo foi um importante fator para a distribuição da fauna avaliada, sendo a abundância, riqueza e a riqueza rarefeita maior em áreas com maior fluxo. Houve interação do fluxo com a areia fina, aumentando seu efeito sobre a abundância total e riqueza rarefeita em locais com maior velocidade de fluxo. A pCCA mostrou que eventos pontuais e de curta duração de acréscimo de sedimento fino não são danosos à fauna aquática. Os resultados obtidos mostram que o sedimento fino afeta de forma negativa a fauna de macroinvertebrados bentônicos em riachos, e este efeito negativo se dá por diversas formas, tais como redução do hábitat, perda da qualidade do alimento, estresse fisiológico e por outros. A relação da fauna com a velocidade pode ser atribuída às preferênciasecológicas dos grupos encontrados. Por alguns resultados divergirem de estudos prévios, o efeito do sedimento fino sobre a fauna aquática deve ser mais bem estudado.
One of the main forms by which aquatic ecosystems are impacted is the input of fine sediment. The objective of our study was to determinate by one experiment the effect of fine sediment on benthic macroinvertebrates in subtropical streams. The study area was the Forqueta River in Barra do Ouro district of Maquiné city, Rio Grande do Sul, Brazil. It’s was added 3138 cm3 of sediment, in two fractions: fine sand (0mm – 0.25mm) and coarse sand (0.25mm – 1mm) into the river with two levels (with or without sediment) . The data were analyzed by Analysis of Variance (ANOVA two-way) for abundance, richness and rarefied richness, the last one intended to compare species richness based on an equivalent number of individuals. Using Multivaried Analysis of Variance (MANOVA) we examined the effect of fine sediment on relative abundance and composition of species. Sediment was used as one factor in four levels. A Partial Canonical Correspondence Analysis (pCCA) was used to examine the effect of the disturbance event on communities. The interaction between the flow and the factors of the sediment was examined. There was a negative effect of fine sediment on abundance, richness and species composition, but the effect was null on relative abundance and rarefaction of species richness. The flow was important for distribution of individuals colleted. The abundance, species richness and rarefied richness were highest on places with fastest flows. The flow increased the effect of fine sand on abundance and rarefied richness. The pCCA showed that disturbance events of small frequency consisting of input of terrestrial sediment have no negative effects on benthic macroinvertebrate. The relationship between flow and benthic macroinvertebrates can be attributed to the ecological preferences of species. These results showed that fine sediment impact is harmful for benthic macroinvertebrates in streams, particularly in termsof abundance. This negative effect may be a consequence of loss of habitat, reduced food quality, physiological stress and others forms. Because some results differ from other studies, the effect of the fine sediment on the benthic macroinvertebrates needs to be better studied.

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Universidade Federal de Minas Gerais
This study aimed at determining whether environmental factors as vegetation, environmental integrity, water flow, water velocity and physical and chemical characteristics of the water (pH, dissolved oxygen, temperature and conductivity) can predict the richness, abundance and faunal composition of predator insects which live in bedrock of Atlantic Rainforest streams. The collecting of fauna has been carried out in streams located in the Núcleos Santa Virgínia and Cunha-Indaiá, both located in the Parque Estadual Serra do Mar, São Paulo state, in October 2006 and October and November 2007. In each stream was selected a stretch of about 50 meters. The fauna associated with 25 cobble type rocks was collected with the aid of a hand net with a mesh of 0.25 millimeters. Were collected 779 individuals in 17 taxa. The most abundant taxa were Anacroneuria, Limnocoris, Neotrephes and Argia. The Detrended Correspondence Analysis (DCA) showed a cluster of sampling points according to the scale of the vegetation cover. The graphic representation of similarity matrix Morisita- Horn by UPGMA revealed the formation of clusters consisting of the fauna collected at sites with different water flows, but with similar vegetation cover. The Mantel Test showed a significant relationship of the predatory insects fauna in the vegetation cover (r = -0.189, p = 0.017 for 5000 permutations) and water velocity (p = 0.05 and r = -0.3 for 5000 permutations). The partial coefficients estimated from multiple linear regression showed that the flow has significant influence on the analyzed entomofauna.
O presente trabalho objetivou verificar se os fatores ambientais como cobertura vegetal, integridade ambiental, vazão, velocidade da água e características físicas e químicas da água (pH, oxigênio dissolvido, temperatura e condutividade) podem predizer a riqueza, a abundância e a composição faunística de insetos predadores que vivem em substrato rochoso de riachos da Mata Atlântica. As coletas de fauna foram realizadas em riachos localizados nos Núcleos Santa Virgínia e Cunha-Indaiá, ambos localizados no Parque Estadual Serra do Mar, Estado de São Paulo, nos meses de outubro de 2006 e outubro e novembro de 2007. Em cada riacho, foi selecionado um trecho de aproximadamente 50 metros. A fauna associada a 25 rochas do tipo calhau foi coletada com o auxílio de um puçá com malha de 0,25 milímetros. Foram coletados 779 indivíduos distribuídos em 17 gêneros. Os táxons mais abundantes foram Anacroneuria, Limnocoris, Neotrephes e Argia. A Análise de Correspondência Destendenciada (DCA) mostrou um agrupamento dos pontos de coleta de acordo com a escala de cobertura vegetal. A representação gráfica da matriz de similaridade de Morisita-Horn, através da UPGMA, revelou a formação de agrupamentos constituídos pela fauna coletada em locais com diferentes vazões, porém com coberturas vegetais similares. O Teste de Mantel mostrou uma relação significativa da fauna de insetos predadores com a cobertura vegetal (r = -0,189; p = 0,017 para 5000 permutações) e a velocidade da água (p = 0,05, r = -0,3 para 5000 permutações). Os coeficientes parciais estimados a partir da regressão linear múltipla demonstraram que a vazão teve influência significativa sobre a entomofauna analisada

Dans un contexte d'effondrement global de la biodiversité, concilier le développement des activités industrielles et agricoles, génératrices de richesses, avec la préservation du patrimoine naturel constitue un enjeu majeur. Les acteurs économiques de nos sociétés sont ainsi légalement astreints à éviter, réduire et compenser leurs impacts sur les espèces protégées. Ils se trouvent cependant démunis lorsque les connaissances mobilisables sur ces espèces sont insuffisantes pour évaluer l'ampleur de ces impacts ou pour mettre en place des mesures d'évitement et de compensation réellement efficaces. C'est notamment le cas sur les cours d'eau, écosystèmes soumis à de nombreuses pressions du fait de leurs usages par les sociétés humaines (i.e. ressource en eau et nourriture, transport, production d'énergie, loisirs). L'objet de ce travail de thèse est donc d'améliorer la connaissance de trois espèces d'Odonates protégées par la Directive Habitats Faune Flore et inféodées aux cours d'eau : la Cordulie à corps fin Oxygastra curtisii (Dale, 1834), le Gomphe de Graslin Gomphus graslinii Rambur, 1842 et la Cordulie splendide Macromia splendens (Pictet, 1843), afin de mieux appréhender les impacts de l'anthropisation des cours d'eau sur leurs populations. Nous avons cherché en particulier à (1) améliorer la prise en compte de ces espèces dans les études d'impacts, la gestion des cours d'eau et au sein des sites Natura 2000 où elles sont présentes via la proposition d'un protocole standardisé de suivi, (2) évaluer les conséquences de l'artificialisation de leurs habitats, notamment le réchauffement de l'eau, sur leur phénologie et leur morphologie, et (3) caractériser et évaluer l'impact des ouvrages hydrauliques présents sur les cours d'eau, considérant d'une part les petits ouvrages que sont les chaussées liées à d'anciennes minoteries ou à d'autres usages et, d'autre part, les ouvrages hydroélectriques de plus grandes dimensions. Ce travail est centré sur la région Midi-Pyrénées, région qui héberge encore des populations de ces trois espèces. Il a été réalisé en partenariat étroit entre le Conservatoire d'Espaces Naturels de Midi-Pyrénées, structure animatrice du Plan régional d'actions en faveur des Odonates, et le laboratoire d'Ecologie fonctionnelle EcoLab afin d'assurer un transfert direct des connaissances scientifiques acquises vers les gestionnaires, les aménageurs et les services de l'état en charge de la préservation de la biodiversité
In a context of global biodiversity crisis, reconciling the development of wealth-generating industry and agriculture with nature conservation is a crucial issue. Economic stakeholders are legally obliged to apply the mitigation hierarchy doctrine and thus "avoid, mitigate, and compensate" for their project's impacts. However, for invertebrate protected species, and particularly dragonfly species, basic knowledge on their ecology and population dynamics is lacking. It is thus difficult to accurately anticipate the impacts and propose efficient avoidance and compensation measures. This is particularly true on rivers, which are ecosystems under high pressure owing to their utility for human beings (e.g. water and food resources, transport, energy production, leisure). The aim of this work is to improve knowledge of three protected riverine species of dragonflies: the Orange-spotted emerald Oxygastra curtisii (Dale, 1834), the Pronged clubtail Gomphus graslinii Rambur, 1842, and the Splendid cruiser Macromia splendens (Pictet, 1843), and to provide better assessment methods to evaluate the impacts of the anthropisation of streams on their populations. We sought in particular (1) to improve environmental impact assessments and management of these species within Natura 2000 sites by proposing a standardised survey protocol, (2) to assess the consequences of habitat change, especially water temperature warming, on their phenology and morphology, and (3) to describe and evaluate the impacts of weirs and hydroelectric dams on their populations. This work took place in the Midi-Pyrénées region in southern France, where populations of these three species are still present. It was carried out in close partnership with the Conservatoire d'Espaces Naturels de Midi-Pyrénées, which coordinates the Regional Action Plan for Odonata, and the Functional Ecology Laboratory EcoLab to ensure direct transfer of the scientific knowledge acquired to the ecosystems managers, economic stakeholders and public authorities responsible for biodiversity conservation

Mise au point d'une methode de surveillance des cours d'eau de montagne fondee sur l'etude la faune macroinvertebree benthique. L'hypothese initiale etait que l'on pouvait prevoir le peuplement originel d'une station donnee grace a la seule connaissance de ces caracteristiques constantes (altitude, pente, surface du bassin versant. . . ). Comparaison detaillee du peuplement des vallees d'aure et d'ossau

Etude des eaux courantes d'un massif prealpin karstique (vercors). Typologie des differents cours d'eau en vue de l'amenagement du parc regional. Etude hydrobiologique du furon et notamment incidence du rejet polluant de lans en vercors. Etude des populations de chironomidae

Pour 3 ruisseaux lents de plaine dans le departement de l'isere, les caracteres du milieu et la composition de la faune sont indiques. Les principaux facteurs qui determinent la repartition des especes sont examines