Author: Sheri-Lynn D. McKeePublisher:
ISBN:
Category : Aquatic invertebrates
Languages : en
Pages : 0
Book Description
Structure and Size Distribution of Benthic Macroinvertebrate Communities Along a Eutrophication Gradient in Streams of the Ottawa Valley
Author: Sheri-Lynn D. McKeePublisher:
ISBN:
Category : Aquatic invertebrates
Languages : en
Pages : 0
Book Description
Structure and Size Distribution of Benthic Macroinvertebrate Communities Along a Eutrophication Gradient in Streams of the Ottawa Valley
Author: Current and Selected Bibliographies on Benthic Biology
Author: Macroinvertebrate Community Structure and Function in Seasonal, Low-land, Tropical Streams Across a Pristine-rural-Urban Land-use Gradient
Author: Julie Elizabeth HelsonHierarchical Structure of Stream Benthic Macroinvertebrate Communities Sampled at Varying Spatial Scales
Author: Iwona K. CiesielkaPublisher:
ISBN:
Category : Animal communities
Languages : en
Pages : 248
Book Description
Determining the Association Between the Structure of Stream Benthic Macroinvertebrate Communities and Agricultural Best Management Practices
Author: Roger Holmes (M.Sc.)Publisher:
ISBN:
Category :
Languages : en
Pages : 174
Book Description
Farmers have been encouraged to adopt more sustainable farming practices (BMPs) that mitigate adverse agricultural effects on the natural environment. However, the ability of BMPs to protect or restore riverine systems continues to be questioned due to limited evidence directly linking BMP use with improved ecological conditions. The exclusion of hydrological pathways in previous field studies may explain why a direct link has not yet been established. The goal of this study was to assess the association between benthic macroinvertebrate community structure and the number and location of agricultural BMPs. Macroinvertebrates and water chemistry were sampled in 30 headwater catchments in the Grand River Watershed. Catchments exhibited gradients of BMP use and location as measured by the degree of hydrologic connectedness. Stepwise ordination regressions and variance partitioning were used to determine which environmental variables (i.e., BMP metrics, water chemistry parameters, habitat characteristics, and land use variables) were associated with benthic macroinvertebrate community structure. Water chemistry parameters were negatively associated with BMP metrics suggesting BMPs were mitigating losses of nutrients and sediments. However, BMP abundance and location explained minimal variation in benthic macroinvertebrate structure within the 30 sampled catchments. The absence of a strong association between BMPs and benthic macroinvertebrates may indicate a need for greater numbers and targeted siting of BMPS to improve water quality beyond a threshold point that would allow recolonization of intolerant invertebrate taxa. Focusing of conservation goals on ecological conditions and the promotion of BMPs that enhance in-stream habitat may also be required.
Spatial and Temporal Variability of Stream Benthic Macroinvertebrates
Author: Leonard SandinPublisher:
ISBN:
Category : Benthos
Languages : en
Pages : 180
Book Description
Predictable Changes in Abundance, Composition, and Size Structure of Fish and Macroinvertebrates Along an Urbanization Gradient in the Ottawa-Gatineau Area
Author: Johannie DuhaimePublisher:
ISBN:
Category : Aquatic habitats
Languages : en
Pages :
Book Description
As land use transformations are the main driver of biological diversity loss at the global scale, it is essential to provide predictions and understanding of their impacts in order to improve the mitigation of ecosystem perturbations. The first objective of this project was to describe the response of biological assemblages along a gradient of urbanization and to compare metrics of watershed imperviousness in order to determine, as has been suggested in the literature, whether effective imperviousness, which represents the proportion of impervious area directly connected to the stream by storm sewers, is a better predictor of stream impairement than total imperviousness in the watershed. Decline in sensitive taxa abundance is initiated at 14% total imperviousness and 3% effective imperviousness in the Ottawa-Carleton region and, total and effective imperviousness have equivalent predictive power. The second objective of this project was to describe how the structure of metazoan assemblages in urban streams, as described by size spectra attributes (i.e. slopes, intercepts, number of logarithmic size classes occupied, and residual variance), varies with watershed size, land use and water quality. Streams size spectra of the Ottawa-Gatineau region have relatively shallow slopes, reflecting relatively higher densities of organisms in the larger size classes compared to other ecosystem types (e.g. lakes, oceans, soils, coastal waters). Size spectra slopes, density corrected for size, number of size classes, and residual variance vary predictably along gradients of watershed size, watershed proportion of natural land use and periphyton chlorophyll a. A systematic trend of declining spectra slopes with increasing periphyton biomass suggests that ecological efficiency declines in urban eutrophic streams.
The Diversity and Composition of Benthic Macroinvertebrate Assemblages in Streams in the Mackenzie River System, Northwest Territories
Author: Ryan William ScottPublisher:
ISBN:
Category :
Languages : en
Pages : 138
Book Description
Impending natural resources development and concern about the effects of climate change have spurred increased efforts to study and monitor aquatic habitats in the Mackenzie River system. As part of Environment Canada's attempt to survey the system in advance of the construction of the Mackenzie Gas Pipeline, benthic macroinvertebrates were sampled at 50 streams spanning the geographical range of the Mackenzie system in the Northwest Territories, Canada, to assess spatial patterns in diversity and assemblage structure and the environmental factors driving them. Replicated, quantitative D-net samples were collected during the late summer of 2005 through 2008, mostly at crossings of the proposed pipeline route. 373 macroinvertebrate taxa were recorded, mainly aquatic insects, which were identified to the genus or species levels; other groups were identified to higher taxonomic levels. Ephemeroptera and Plecoptera diversity declined along a latitudinal gradient, while Trichoptera diversity declined in the middle of the latitudinal range and rose towards the far north. Chironomidae (Diptera) increased in diversity and abundance towards the far north, becoming dominant in the northern sub-arctic forest and lowland tundra of the Mackenzie Delta. Diversity, measured as the average generic richness per stream, correlated with a composite environmental variable representing stream size, but not much else; spatial trends in local generic richness were only apparent in the far north of the study area. Regional diversity was assessed using rarefaction curves and showed a clear decrease from south to north across the study area for most taxa; the major exception was the chironomid subfamilies Orthocladiinae and Chironomini, the former being diverse throughout the study area and the latter increasing in diversity on the tundra. Odonata, Hemiptera and Coleoptera were well-represented in the south of the study area, but decreased sharply in diversity and abundance in the north; another common order, Megaloptera, was entirely absent from the study area, as were crayfish. Community composition varied along a latitudinal gradient, with some species restricted to northern latitudes and many more species restricted to the southern areas. Composition varied by region, as did the environmental factors that control it. Streams in the north of the system are connected to hundreds of small lakes and tend to freeze in the winter, which increases habitat stability; assemblages in this region were characterized by relatively large chironomids that are usually associated with lentic habitats and by a lack of taxa that are intolerant to freezing. Substrate was the main factor explaining differences in assemblage composition in this region. Just to the south, alluvial streams are more common and permafrost is continuous with very shallow active layers, iv which likely results in intense discharge peaks and ice scour in the spring and flashy summer hydrographs. Invertebrates in this region were mainly short-lived, small sized orthoclads, baetids and chloroperlids; the annual disturbance regime seems likely to be an important factor shaping community composition in this region. Many streams in this region received input from saline springs, resulting in perennial flow, and these streams harboured several taxa that were absent or rare in other streams at similar latitudes, including several stoneflies (e.g. Pteronarcys, Sweltsa); the presence of flow during the winter was found to be a major factor affecting community composition in this region, which surrounded the town of Norman Wells, NT. Nutrient dynamics appeared to be important in structuring benthic assemblages in the southern portion of the study region, with highnutrient streams supporting a diverse fauna which included many taxa that were absent in the north, while communities in low-nutrient streams were more similar to the northern alluvial stream fauna. There was no spatial distinction between low- and high-nutrient streams in the southern region, and the difference may be due to the local conditions of permafrost, which is patchy and discontinuous in the region. Evidence that winter ice and permafrost conditions are important drivers of benthic invertebrate diversity and community composition in the Mackenzie system, along with the latitudinal gradients which are consistent with a temperature/climate gradient, raises the possibility that benthic assemblages may be useful as indicators of effects of global climate change on freshwater habitats in the Canadian north. More immediately, construction of the Mackenzie Gas Pipeline may affect stream habitat due to sedimentation, and plans for the operation of the pipeline have raised concerns about potential effects on permafrost conditions. Implications for development of a biomonitoring program utilizing benthic invertebrates and their potential as indicators of climate change are discussed.
Macroinvertebrate Community Composition in Stream Networks Across Three Land Cover Types
Author: Raj Kiran ParmarPublisher:
ISBN:
Category : Aquatic invertebrates
Languages : en
Pages : 124
Book Description
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.