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| Author | : Julie Elizabeth Helson |
| Publisher | : |
| Total Pages | : |
| Release | : 2012 |
| Genre | : |
| ISBN | : |
| Author | : Kevin O'Gorman |
| Publisher | : |
| Total Pages | : 333 |
| Release | : 1998 |
| Genre | : Stream ecology |
| ISBN | : |
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 | : Raj Kiran Parmar |
| Publisher | : |
| Total Pages | : 124 |
| Release | : 2018 |
| Genre | : Aquatic invertebrates |
| ISBN | : |
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.
| Author | : Robert Clayton Johnson |
| Publisher | : |
| Total Pages | : 274 |
| Release | : 2011 |
| Genre | : Invertebrates |
| ISBN | : |
The future expansion of urban areas is one of the most pervasive threats to the natural environment and the services it provides society. In this dissertation, the dynamics of stream macroinvertebrate community structure, secondary production and carbon-nitrogen-phosphorus stoichiometry along an urban development gradient in Louisville, KY are assessed. Chapter 1 provides a brief review of the effects of urbanization on stream ecosystems with an emphasis on macroinvertebrate communities. In Chapter 2, the effects of urbanization on macroinvertebrate and fish communities are assessed at 24 stream sites that drain catchments with varying degrees of urbanization in Louisville. The analysis revealed strong relationships between urbanization, in-stream disturbances induced by urbanization and both biotic communities. In chapter 3, the temporal variation in macroinvertebrate community structure of six streams in Louisville is assessed. From this analysis, it was apparent that temporal variation in macroinvertebrate taxon abundances throughout the year, which primarily resulted from taxon life history differences, can affect the interpretation of biotic indices used to assess the biological integrity of streams. In chapter 4, macroinvertebrate secondary production (i.e. the rate of macroinvertebrate biomass accumulation over time) we quantified at each of the six sites assessed in Chapter 3, and identifies possible regulatory factors of macroinvertebrate production along the urban gradient. In this analysis, macroinvertebrate secondary production was strongly associated with changes in the quantity and quality of food resources at each site. Finally, in chapter 5, macroinvertebrate production data (Chapter 4) are combined with the carbon-nitrogen-phosphorus body elemental contents of each macroinvertebrate taxon to determine how differences in macroinvertebrate community structure and secondary production at each site affect the flow of these vital elements through macroinvertebrate communities. Strong relationships we observed between phosphorus loading into streams, macroinvertebrate production, and the carbon-nitrogen-phosphorus stoichiometry of macroinvertebrate communities at each site. Overall, these results suggest that stream biodiversity is greatly reduced with increasing urbanization in Louisville. Moreover, in addition to losses of biodiversity, secondary production stoichiometric analyses, which are relatively unstudied phenomena in urban streams, indicate potential changes in the roles of these communities in the fundamental ecosystem processes of energy flow and nutrient cycling.
| Author | : Nicholas Arthur Baer |
| Publisher | : |
| Total Pages | : 166 |
| Release | : 2004 |
| Genre | : Coastal ecology |
| ISBN | : |
| Author | : Molly Marie Wozniak |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2023 |
| Genre | : Freshwater invertebrates |
| ISBN | : |
| Author | : Emily R. Arsenault |
| Publisher | : |
| Total Pages | : 154 |
| Release | : 2014 |
| Genre | : Aquaculture |
| ISBN | : |
Headwater streams have some of the best quality water in the country (Dissmeyer 2000). Because headwaters eventually flow into other downstream water bodies like rivers and lakes, they are important places to focus research and conservation efforts. All streams in this study had good water quality based on several assessments of macroinvertebrate communities. 1. Judging from metrics of abundance, richness, EPT, and HBI, all study streams had very good water quality. Thirty-nine total families were observed among the three streams. Whittier Stream was the least healthy of the three, most likely as a result of human disturbances such as a road crossing, fishpond, and mill remnants. It is probable these habitat alterations are having an effect on downstream benthic communities. 2. The riparian zone of each stream was forested and stable, but there were some eroding banks at some points along the study reaches. The abundance of sensitive macroinvertebrates (measured using representative Orders Ephemeroptera, Plecoptera, and Trichoptera) increased with increasing percent canopy cover and decreased with high percentages of sand characterizing the streambed. 3. Macroinvertebrates can be categorized into functional feeding groups based on feeding behavior. Shredders should hypothetically be in high abundance in headwater streams due to high riparian organic matter inputs. However, observed shredders were limited. This may be due to seasonal changes in functional feeding group ratios. In addition, all study streams had a predator/prey ratio that was higher than the ratio expected for a typical stream, which suggests that there might be an abundance of prey biomass in the study stream headwaters. 4. Based on results from stable isotope analysis of carbon and nitrogen, most macroinvertebrates within the study streams seem to be omnivorous. The most complex food web was observed at Stony Brook. Food webs of Beaver Brook and Stony Brook showed similar trophic clustering, a pattern that might be indicative of streams with excellent water quality.
| Author | : Brandy Sue Bergthold |
| Publisher | : |
| Total Pages | : 236 |
| Release | : 2001 |
| Genre | : Aquatic ecology |
| ISBN | : |
| Author | : Roger Holmes (M.Sc.) |
| Publisher | : |
| Total Pages | : 174 |
| Release | : 2014 |
| Genre | : |
| ISBN | : |
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.
| Author | : Kate Roberts |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2000 |
| Genre | : Invertebrate communities |
| ISBN | : |
Natural stresses such as drought can cause changes in macroinvertebrate community composition over time. This study examines the relationship between low flows, macroinvertebrate habitat and the macroinvertbrate community. The sensitivity of AUSRIVAS biological monitoring methods to impacts associated with low flows are also examined. A flow threshold was used to define low flows and to test for changes in macroinvertebrate habitat and macroinvertebrate communities. Assessments of the biological condition of the macroinvertebrate community were performed using AUSRIVAS predictive models. Low flows reduced the available habitat for macroinvertebrates, thus altering resources for macroinvertebrates. However, macroinvertebrate abundance and community composition showed no significant response to the effects of low. AUSRIVAS assessments detected few reductions in biological condition of macroinvertebrate under low flow conditions. The threshold value used to define drought was useful for determining habitat change, but was appropriate for determinig levels at which changes to the macroinvertebrate community occur. Alternative methods such as a combination of low flow thresholds, low flow duration and channel characteristics may enable observations of biological impacts associated with low flow conditions.
