Taxonomic Diversity, Assemblage Structure, and Biotic Integrety of Benthic Macroinvertebrates in the Guadalupe-San Marcos River System PDF Download

Author: C. Lexi Smith
Publisher:
ISBN:
Category : Freshwater biodiversity
Languages : en
Pages : 0

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Book Description
Freshwater ecosystems are historically known to support a wide range of biodiversity at various trophic levels. However, the loss of freshwater biodiversity is related to trends in deteriorating water quality caused by anthropogenic disturbances that negatively impact bioindicator communities (e.g., benthic macroinvertebrates; BMI). I incorporated parameters of the Texas Commission of Environmental Quality (TCEQ) Rapid Bioassessment Protocols (RBP) to assess taxonomic diversity, assemblage structure, and biotic integrity of BMI in the Guadalupe – San Marcos River System (GSMR) in Texas. I sampled 25,512 BMI from 44 sites of the GSMR within various sampling methods, regions, habitats, and substrates. Taxonomic diversity and assemblage structure of BMI appeared to be homogenous across the river system regardless of sampling method, habitat, and substrate. However, regions suggested the San Marcos River of having the highest alpha diversity, lowest beta diversity, and greatest biotic integrity compared to the observed anthropogenic disturbance of the Guadalupe River overall. My study emphasizes the need for improved efforts towards large river management and conservation efforts of biotic communities by identifying the structural relationship of BMI assemblages in the GSMR. My results will help improve bioassessments and continuing research for BMI assemblages found within a large river system.

Author: Larry R. Brown
Publisher:
ISBN:
Category : Benthos
Languages : en
Pages : 34

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Author: Ryan William Scott
Publisher:
ISBN:
Category :
Languages : en
Pages : 138

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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.

Author: Rebecca A. Zawalski
Publisher:
ISBN:
Category : Stream invertebrates
Languages : en
Pages : 86

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Book Description
Benthic macroinvertebrates (BMI) are widely used as bio-indicators for local in-stream quality. However, local community structure can be affected by smaller scale (local) environmental conditions and larger scale processes. I assessed the abundance and diversity of BMI and their relationship with local in-stream conditions, regional patterns of land-use/land cover (LULC), and large scale physiographic gradients across the Guadalupe River System, a large basin (3,256 km2) in Central Texas. Macroinvertebrates, water quality, and habitat conditions across 28 sites in the Guadalupe River and its main tributaries were sampled. Highest species diversity occurred near the headwaters, and decreased downstream. Pollution tolerance levels increased downstream and followed an increasing agriculture gradient. Landscape factors explained a large proportion of variation in macroinvertebrate community structure (38%), but 16% of it was spatially structured (shared with spatial factors latitude and longitude) and 4% was explained by spatial factors alone. Local environmental factors were strongly correlated with landscape factors and explained similar amount of variation as landscape factors. My study highlights the importance of incorporating physiographic gradients when examining local and regional diversity and composition of BMI communities, especially in large complex watersheds. My results will help develop more effective monitoring programs for larger river systems.

Author: Jessica Orlofske
Publisher:
ISBN:
Category : Benthic ecology
Languages : en
Pages : 0

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Benthic macroinvertebrate taxonomic data is the foundation of freshwater biomonitoring programs.around the world. Biological trait information has been proposed as an effective alternative or supplement to taxonomic data for ·biomonitoring purposes. Traits are simply measurable, heritable properties of an organism that interact with the environment. Trait data can expand the geographical scope of assessments as well as describe mechanistic relationships between environmental conditions and the biological community to diagnose impact severity and type of stressor. In riverine ecosystems, a change in the flow regime or hydrological alteration is considered the most significant environmental stressor because of the detrimental effects on biological communities and habitats as well as interactions with other stressors. To maintain ecological integrity, trait data can inform the benthic macroinvertebrate assemblage response to flow properties to support environmental flow management criteria. My objective was to define and evaluate traits and trait metrics that could be linked to hydrological conditions. Specifically, I investigated intra- and inter-tax on trait properties for body size and body shape, which are predicted to respond strongly to hydraulic and hydrologic scale variables. Multiple field sites were sampled several times over a five-year period in the unregulated Miramichi River Basin, New Brunswick, Canada to resolve the relationships between flow and ecology. I was able to demonstrate the importance of intraspecific trait variation and trait properties for characterizing the benthic assemblage. By measuring specimen body sizes and establishing body shape criteria using geometric morphometric analysis, I improved the accuracy of traits-based metrics and demonstrated a sizedependent bias in current taxonomic-based metrics. Using both traditional categorical trait states as well as high-resolution trait data, I was able to characterize relationships among aquatic insects and hydrological properties at nested spatial scales. Then I tested the performance of taxonomic and trait metrics to assess hydrological data over short (two-year) to moderate (five-year) temporal scales. High-resolution trait metrics demonstrated equal or greater association with hydrological factors than taxonomic or other trait metrics at these timescales. Trait information can add value to biomonitoring approaches by accurately describing trait expression, enabling stronger statistical inference, and increasing sensitivity and interpretability, which are essential for evaluating the complex relationship between benthic assemblages and their hydrological environment.

Author: Jeremy Douglas Maikoetter
Publisher:
ISBN:
Category : Aquatic invertebrates
Languages : en
Pages : 116

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Riverine benthic macroinvertebrates (BMI) communities are regulated, in part, by the dynamic character of the river's flow regime. Purpose of this study was to assess the influence of a flow regime component (i.e., large flow pulse) on BMI riffle communities, specifically that large flow pulses shifted structure (i.e., richness and density), and therefore maintain the biotic integrity of riverine riffle BMI communities. Predictions were that BMI richness and density would decrease and recover with large flow pulses, ranging between 1 in 2 year events (340 m3/s) to 1 in 5 year events (331 to 886 m3/s), but that density reductions and recovery would differ among taxa categorized as swift, moderate, and slack forms. BMI communities were monitored at 11 sites located in three river basins and distributed among upper and lower reaches of major rivers and tributary streams. A total of 93,400 aquatic macroinvertebrates were identified to family and used to estimate BMI richness and BMI density among 102 riffles (61 riffles pre-flood and 41 riffles post-flood) between 2014 and 2017. Physical and chemical aspects of riffle habitats were similar between pre-flood and post-flood, except that post-flood riffles had less sand and gravel than pre-flood. BMI communities were similar among river basins and were segregated along environmental gradients related to physical and chemical (16%), season (6%), and flood (2%) effects. Only a few sites differed in BMI richness and density between pre-flood and post-flood, indicating that BMI communities among seven of the 11 sites likely recovered before the post-flood sampling events. Increased densities or relative abundances were detected at four sites for swift BMI, at one site for moderate BMI, and at one site for slack BMI. Decreased densities or relative abundances were detected at one site for moderate BMI and at two sites for slack BMI. Among taxa, relative abundances of seven BMI families, which were categorized as swift or moderate, generally increased among the 11 sites, whereas relative abundances of five BMI families, which were categorized as moderate or slack, generally decreased among the 11 sites. Although increasing or decreasing trends in BMI categories and families between pre-flood and post-flood periods were not consistent among all sites, study results suggest that density and relative abundance of some BMI taxa responded positively (e.g., Baetidae, Hydropsychidae, Isonychiidae) and negatively (e.g., Elmidae, Leptophlebiidae, Chironomidae) to high flow pulses. Therefore, flow-responsive BMI taxa found in this study provide potential indicator species for environmental flow standards assessments, although the ubiquitous use of these indicator species across and within drainages is limited.

Author:
Publisher:
ISBN:
Category : Water quality bioassay
Languages : en
Pages : 192

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Author: Alice Belskis
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Non-perennial streams, those that do not continuously flow, make up 51-60% of the earth's streams by length. Yet, they are understudied relative to their perennial, or continuously flowing, counterparts. We sought to determine how benthic macroinvertebrate (BMIs) community structure and beta diversity patterns were related to abiotic factors in non-perennial streams, as they contribute to fauna in downstream perennial waterways. We sampled 38 sites across a non-perennial prairie stream network for BMIs and measured hydrological, biogeochemical, and other environmental variables. We identified the BMIs using DNA metabarcoding. We calculated local contributions to beta diversity (LCBD) to identify ecologically unique sites and calculated species contributions to beta diversity (SCBD) to determine taxa with the strongest contributions to beta diversity patterns across the stream network. Our results show that while LCBD was not influenced by abiotic factors, the richness and replacement components of LCBD were strongly influenced by a site's distance to an upstream groundwater seep. The top contributor to SCBD was Stenonema femoratum, followed by 7 genera of Chironomidae, Perlesta cinctipes, and Faxonius virilis. Importantly, our DNA metabarcoding approach allowed us to identify Chironomidae to the genus level, revealing their importance in SCBD. When considering BMI community structure, an NMDS (Non-Metric Multidimensional Scaling) analysis revealed that the percent flowing water at each site was driving the differences in species across the sites. Here we show that proximity to groundwater sources is key to BMI beta diversity patterns in non-perennial stream networks, and that Chironomidae taxa are important in producing these patterns. This study allows us to fill in some of the knowledge gaps surrounding non-perennial stream beta diversity patterns and provides us with an understanding of the factors that potentially influence these interactions.

Author: Kirby Lynn McCready Wright
Publisher:
ISBN:
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: David M. Rosenberg
Publisher: Springer
ISBN:
Category : Nature
Languages : en
Pages : 512

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Book Description
North American and European governments have adopted national programs for environmental monitoring and assessment that include the use of aquatic biota. These programs will use a variety of indicators of environmental health; benthic macroinvertebrates are one of the most promising of them. The chapters in this book deal with the many different approaches available for using benthic macroinvertebrates in biological monitoring programs.