Spatial and Temporal Changes of Macroinvertebrate Community Structure in Two UK Lowland River Systems PDF Download

Author: Yong Cao
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Category :
Languages : en
Pages :

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Author: Julie Elizabeth Helson
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Category :
Languages : en
Pages :

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Author: Kevin O'Gorman
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ISBN:
Category : Stream ecology
Languages : en
Pages : 333

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Patter and processes in macroinvertebrate communities are scale dependent, yet few studies incorporate a series of spatial scales into their research. This thesis focuses on the examination of macroinvertebrate communities at different spatial and temporal scales. Two contrasting catchments, Kilworth and Araglin were studied over a two year period to investigate how different land uses influenced macroinvertebrate communities. Within each catchment, each study stream was examined longitudinally for spatial change and within each site samples were taken seasonally over a two year period to investigate temporal variation. Lower altitudes sites in both catchments were found to be quite similar in water chemistry and in macroinvertebrate community metrics, despite differing land uses. Higher altitude sites at three of the four study streams differed substantially to all other sites in terms of macroinvertebrate community structure, lower pH and lower invertebrate density. The principal factors influencling macroinvertebrate composition were a combination of longitudinal variation, altitude and differences in land use all of which varied along the same gradient. Seasonal differences in macroinvertebrate composition were also found. Macroinvertebrate trophic structure (e.g. functional feeding groups) varied in a predictabel manner longitudinally, largely in accordance with the River Continum Concept. A secondary aim of the study was to examine the effects of disturbance on macroinvertebrate communities. Invertebrate recolonisation was studies at one stream in each catchment following two flood events. Macroinvertebrates recolonised both catchments in a similar manner following flooding at both a community and individual taxa level, although similarity between catchments was strongest at the lower altitude sites. Individual taxa showed a strong preference for particular recolonising strategies (i.e. opportunistic, secondary or late colonisers) irrespective of catchment, longitudinal position or year. The effect of a multiple disturbance on macroinvertebrate communities seen during the 1995 disturbance study where a second flooding event occurred. This reverted the macroinvertebrate communities to their initial disturbed state. Lower altitude sites appeared to be more affected by the multiple disturbance and this may be due to the higher shear stress and the greater unpredicitability of floods at lower altitude sites.

Author: British Library. Document Supply Centre
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Category : Great Britain
Languages : en
Pages : 908

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Issue for Mar. 1981 contains index for Jan.-Mar. 1981 in microfiche form.

Author: Kirby Lynn McCready Wright
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Category : Benthic animals
Languages : en
Pages : 0

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Benthic macroinvertebrate communities in riverine ecosystems are shaped by both local and large-scale influences. Most models of riverine community structure are grouped into either discrete or continuum conceptual models. However, there is much uncertainty in how these two classes of conceptual models apply to macroinvertebrate communities in the physicochemically consistent headwaters of spring-influenced rivers. This thesis examined benthic macroinvertebrate community composition and biomass among local discrete geomorphic mesohabitats (riffles, runs, and pools) and along an upstream to downstream gradient in two spring-fed rivers in central Texas (San Marcos River and Comal River, Hays County). The goal of my thesis was to examine the relative importance of downstream distance from springhead versus smaller-scale habitat conditions (i.e., mesohabitat units) in explaining the variation in macroinvertebrate community structure in these two spring-based subtropical riverine systems. I hypothesized that, because I sample in the upper physicochemically consistent reaches of both rivers that local mesohabitat conditions would explain more variation in community composition than downstream distance from springhead. I expected this change in community composition would be driven by replacement of taxa rather than differences in taxonomic richness. I also predicted that non-native benthic species would be more evenly distributed throughout the study reaches due to the consistency of physicochemical conditions. Finally, I predicted that the distribution of taxa specific biomass contributions will follow patterns seen in community composition change and will reflect taxonomic density estimates. To test these hypotheses, I sampled macroinvertebrates and local habitat parameters from mesohabitat types along three reaches in the first ~4 km of each river. I also determined biomass of each taxon and community-wide patterns of biomass distribution of benthic macroinvertebrates. I found that variation in taxonomic composition in both rivers was driven to a greater or equal amount by upstream to downstream distance from spring-influence, and by mesohabitat type. Taxonomic diversity did not vary with distance from springhead but was consistently lower in pool mesohabitats when compared to runs and riffles in both rivers. Compositional changes and patterns in b-diversity within mesohabitat types among study reaches indicated that replacement (as opposed to richness differences) was the main mechanism leading to patterns of b-diversity. I found that a non-native snail (Tarebia granifera) and an endemic spring snail (Elimia comalensis) appear to be spatially partitioning habitat in an upstream- to downstream manner. Finally, I found that Tarebia granifera constituted the largest proportion of benthic macroinvertebrate biomass in several study reaches downstream from springheads.

Author: Jeff A. Yockey
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Category : Aquatic organisms
Languages : en
Pages : 178

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Author: Eve Elizabeth O'Connor
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Category :
Languages : en
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The structure and composition of benthic macroinvertebrate communities can vary spatially and over time. Spatial and temporal variation along a stream has many implications for population and community dynamics, which may influence bioassessment programs. I examined variability in the benthic community of eight streams within the Polecat Creek, Virginia watershed. These streams vary in size from 1st to 4th order. The streams were sampled once every season for eleven years using standard bioassessment protocols. Macroinvertebrates were sampled from both sediment and submerged wood habitats at each site. The coefficient of variation (CV) was used to quantify among season, among year and among site variability of eight community metrics from both the sediment and wood samples. ANOVAs were calculated using Tukey post-hoc test to determine if there were statistically significant differences in taxonomic richness and mean CV values across seasons, years and sites for both sediment and wood samples. Sorenson's Quotient of Similarity was used to examine the extent of differences in the taxonomic composition of the macroinvertebrate communities among the four seasons over the 11 years of the study and among the 8 sampling sites. A high amount of variability was observed among seasons, sites and years. A wide range of CV values was observed among community metrics, with certain metrics exhibiting low overall mean CV values and others exhibiting very high overall mean CV values. It is important to understand the temporal and spatial variability of macroinvertebrates when planning biomonitoring programs.

Author:
Publisher: Academic Press
ISBN: 0123972930
Category : Science
Languages : en
Pages : 577

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Book Description
Advances in Ecological Research is one of the most successful series in the highly competitive field of ecology. Each volume publishes topical and important reviews, interpreting ecology as widely as in the past, to include all material that contributes to our understanding of the field. Topics in this invaluable series include the physiology, populations, and communities of plants and animals, as well as landscape and ecosystem ecology. - Advances in Ecological Research is one of the most successful series in the highly competitive field of ecology - Each volume publishes topical and important reviews, interpreting ecology as widely as in the past, to include all material that contributes to our understanding of the field

Author: Thibault Datry
Publisher: Academic Press
ISBN: 0128039043
Category : Science
Languages : en
Pages : 624

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Intermittent Rivers and Ephemeral Streams: Ecology and Management takes an internationally broad approach, seeking to compare and contrast findings across multiple continents, climates, flow regimes, and land uses to provide a complete and integrated perspective on the ecology of these ecosystems. Coupled with this, users will find a discussion of management approaches applicable in different regions that are illustrated with relevant case studies. In a readable and technically accurate style, the book utilizes logically framed chapters authored by experts in the field, allowing managers and policymakers to readily grasp ecological concepts and their application to specific situations. - Provides up-to-date reviews of research findings and management strategies using international examples - Explores themes and parallels across diverse sub-disciplines in ecology and water resource management utilizing a multidisciplinary and integrative approach - Reveals the relevance of this scientific understanding to managers and policymakers

Author: Raj Kiran Parmar
Publisher:
ISBN:
Category : Aquatic invertebrates
Languages : en
Pages : 124

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Land cover change strongly affects biodiversity in stream ecosystems, with several studies demonstrating the negative impacts of agricultural and urban expansion on local community richness. However, little is known of the effects of land cover on the variation among sets of local communities in stream networks, as well as the drivers of community variation in these systems. Using the metacommunity framework, this study takes a multi-scale approach to understand how macroinvertebrate communities are assembled across three catchment land cover types; native forest, agricultural and urban. Specifically, the aims of this study are to assess; (1) how stream network land cover influences alpha and beta diversity of macroinvertebrate communities and, (2) the relative role of local environmental conditions and spatial dispersal variables in structuring these communities. Benthic macroinvertebrate samples and local in-stream and riparian environmental variables were collected at 20 sampling sites in each of the six study stream networks in Auckland. Spatial distance proxies of macroinvertebrate dispersal in stream networks were calculated using geospatial techniques. Community alpha and beta diversity, environmental and distance variables were analysed using multivariate statistical techniques. Comparisons showed reference forest and impacted (agricultural and urban) networks supported distinct communities, with lower alpha diversity in the impacted stream networks. Unexpectedly, beta diversity in the impacted networks was greater than, or equal to the reference stream networks, with community dissimilarity almost entirely driven by species turnover. Overall, irrespective of land cover, macroinvertebrate communities were largely structured by local environmental conditions. Benthic substrate and the presence and composition of riparian vegetation were the most significant local environmental variables influencing community composition. Spatial dispersal limitation variables had a small, but significant, effect on inter-site community dissimilarity and overall community structure in each catchment. Network distance between local communities explained the greatest variation in community dissimilarity of the three distance types. This study identified potential drivers of macroinvertebrate community variation in Auckland streams, specifically highlighting the relative role of local environmental and spatial dispersal processes. The results of this study have relevance for biomonitoring and state of environment reporting of Auckland’s freshwater systems, as well as future stream rehabilitation projects.