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Author: Gabrielle Trottier Publisher: ISBN: Category : Languages : en Pages :
Book Description
"The regulation and management of lake water levels have become a major form of anthropogenic disturbance in temperate and boreal aquatic ecosystems. Drawing the water level down as the winter season progresses can lead to substantial exposure of the littoral zone, rendering it susceptible to desiccation and freezing. Such changes in the hydrological regime of littoral zones can have significant effects on aquatic biota, including macroinvertebrates. These organisms are widely considered as robust bioindicators, but it is also well known that their abundance and distribution is characterized by substantial patchiness. Often, scientists who use macroinvertebrates as bioindicators, focus their sampling on a single habitat type (e.g., stony littoral) to reduce the heterogeneity in macroinvertebrate distributions. However, applying such an approach in the context of an environmental stressor makes it difficult to draw general conclusions about the impact of a potential stressor on the entire littoral zone. Recently, a debate has emerged in the literature over the effects of water level drawdown on macroinvertebrate communities and we think that at least part of this debate may be due to different sampling strategies employed across studies to examine the effects of drawdown on macroinvertebrate communities. In order to evaluate how nearshore macroinvertebrate communities, from a variety of habitats, are affected by drawdown, we sampled 15 reservoirs and quantified macroinvertebrate abundance and composition. To these data, we applied a combination of (generalized) linear mixed effects models and multivariate analyses to answer the following question; what are the effects of drawdown on macroinvertebrate abundance and community composition? To address this question and incorporate the possible effects of heterogeneity in abundance and distribution of macroinvertebrates, we explicitly considered multiple physical environmental variables as additional predictors of macroinvertebrate abundance and community composition. We found that drawdown and thermal regime were significant predictors of macroinvertebrate abundance, but explained negligible amounts of variation in the community composition. Overall, these findings help elucidate how macroinvertebrate communities respond to winter drawdown and strengthen the knowledge on how localized environmental conditions influence macroinvertebrates. Furthermore we think that our sampling and analytical approach provides a useful template for other scientists to adopt when quantifying the effect of a potential stressor on nearshore macroinvertebrate communities." --
Author: Gabrielle Trottier Publisher: ISBN: Category : Languages : en Pages :
Book Description
"The regulation and management of lake water levels have become a major form of anthropogenic disturbance in temperate and boreal aquatic ecosystems. Drawing the water level down as the winter season progresses can lead to substantial exposure of the littoral zone, rendering it susceptible to desiccation and freezing. Such changes in the hydrological regime of littoral zones can have significant effects on aquatic biota, including macroinvertebrates. These organisms are widely considered as robust bioindicators, but it is also well known that their abundance and distribution is characterized by substantial patchiness. Often, scientists who use macroinvertebrates as bioindicators, focus their sampling on a single habitat type (e.g., stony littoral) to reduce the heterogeneity in macroinvertebrate distributions. However, applying such an approach in the context of an environmental stressor makes it difficult to draw general conclusions about the impact of a potential stressor on the entire littoral zone. Recently, a debate has emerged in the literature over the effects of water level drawdown on macroinvertebrate communities and we think that at least part of this debate may be due to different sampling strategies employed across studies to examine the effects of drawdown on macroinvertebrate communities. In order to evaluate how nearshore macroinvertebrate communities, from a variety of habitats, are affected by drawdown, we sampled 15 reservoirs and quantified macroinvertebrate abundance and composition. To these data, we applied a combination of (generalized) linear mixed effects models and multivariate analyses to answer the following question; what are the effects of drawdown on macroinvertebrate abundance and community composition? To address this question and incorporate the possible effects of heterogeneity in abundance and distribution of macroinvertebrates, we explicitly considered multiple physical environmental variables as additional predictors of macroinvertebrate abundance and community composition. We found that drawdown and thermal regime were significant predictors of macroinvertebrate abundance, but explained negligible amounts of variation in the community composition. Overall, these findings help elucidate how macroinvertebrate communities respond to winter drawdown and strengthen the knowledge on how localized environmental conditions influence macroinvertebrates. Furthermore we think that our sampling and analytical approach provides a useful template for other scientists to adopt when quantifying the effect of a potential stressor on nearshore macroinvertebrate communities." --
Author: Karen A. Baumann Publisher: ISBN: Category : Cache River (Ill.) Languages : en Pages : 254
Book Description
Humans have altered flow regimes of river systems worldwide. Restoration efforts are growing in an attempt to rehabilitate these modified systems. The ecological effects of alteration and restoration are not yet well understood due to a scarcity of monitoring over a wide range of environmental conditions. I examined macroinvertebrate community structure across four summers, ranging from record flood conditions to extreme drought, in a heavily altered system that is being considered for a flow restoration project. Due to a diversion channel and leveeing, the Cache River in southern Illinois is currently divided into the upper Cache River (UCR), which suffers from erosion and channel incision, and the lower Cache River (LCR), which is impaired by sedimentation and hypoxia. Resource managers are investigating the possibility of restoration via partial reconnection of the UCR and LCR. The Cache River experienced a large flood in 2011 and extreme drought conditions in 2012. I compared macroinvertebrate abundance, biomass, diversity, and community structure during June, July, and August of 2010-2013. Dissolved oxygen, temperature, chlorophyll, and discharge were also measured to aid in mechanistic interpretation. The UCR community had lower abundance (p = 0.04) and higher individual invertebrate body size (p = 0.03) than the LCR, and total biomass did not differ between the two river segments (p = 0.34). Macroinvertebrate community structure differed between the UCR and LCR (p = 0.001) and among years (p = 0.001). The UCR had higher Shannon diversity (p = 0.02) and lower Hilsenhoff Biotic Index (HBI) scores (p
Author: Karl M. Wantzen Publisher: Springer Science & Business Media ISBN: 1402091923 Category : Technology & Engineering Languages : en Pages : 184
Book Description
Most aquatic ecosystems have variable water levels. These water-level fluctuations (WLF) have multiple effects on the organisms above and below the waterline. Natural WLF patterns in lakes guarantee both productivity and biodiversity, while untimely floods and droughts may have negative effects. Human impacts on WLF have led to a stabilization of the water levels of many lakes by hydraulic regulation, untimely drawdown due to water use, or floods due to water release from hydropower plants in the catchments. This book provides a first review in this field. It presents selected papers on the ecological effects of WLF in lakes, resulting from a workshop at the University of Konstanz in winter 2005. Issues addressed here include the extent of WLF, and analyses of their effects on different groups of biota from microorganisms to vertebrates. Applied issues include recommendations for the hydrological management of regulated lakes to reduce negative impacts, and a conceptual framework is delivered by an extension of the floodpulse concept for lakes. Current impacts on water use, including increasing demands on drinking and irrigation water, hydropower etc., and climate change effects on WLF make this book an essential resource for aquatic ecologists, engineers, and decision-makers dealing with the management of lake ecosystems and their catchments.
Author: Kate Roberts Publisher: ISBN: Category : Invertebrate communities Languages : en Pages : 0
Book Description
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.
Author: Max M. Tilzer Publisher: Springer Science & Business Media ISBN: 3642840779 Category : Science Languages : en Pages : 699
Book Description
The vast majority of the world's lakes are small in size and short lived in geological terms. Only 253 of the thousands of lakes on this planet have surface areas larger than 500 square kilometers. At first sight, this statistic would seem to indicate that large lakes are relatively unimportant on a global scale; in fact, however, large lakes contain the bulk of the liquid surface freshwater of the earth. Just Lake Baikal and the Laurentian Great Lakes alone contain more than 38% of the world's total liquid freshwater. Thus, the large lakes of the world accentuate an important feature of the earth's freshwater reserves-its extremely irregular distribution. The energy crisis of the 1970s and 1980s made us aware of the fact that we live on a spaceship with finite, that is, exhaustible resources. On the other hand, the energy crisis led to an overemphasis on all the issues concerning energy supply and all the problems connected with producing new energy. The energy crisis also led us to ignore strong evidence suggesting that water of appropriate quality to be used as a resouce will be used up more quickly than energy will. Although in principle water is a "renewable resource," the world's water reserves are diminishing in two fashions, the effects of which are multiplicative: enhanced consumption and accelerated degradation of quality.
Author: John Gooderham Publisher: CSIRO PUBLISHING ISBN: 9780643066687 Category : Nature Languages : en Pages : 246
Book Description
Freshwater invertebrates identification guide for both professionals and non-professionals. Contains a key to all the macroinvertebrate groups and photographs of live specimens.
Author: Gabrielle Trottier
Author: Gabrielle Trottier
Author: Terrance Lee Henry
Author: Gavin John Svenson
Author: Karen A. Baumann
Author: Karl M. Wantzen
Author: Kate Roberts
Author: Tanya Sulikowski
Author: American Geophysical Union. Joint Assembly
Author: Max M. Tilzer
Author: John Gooderham