The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Scott S. Knight - One of the best experts on this subject based on the ideXlab platform.
-
assessment of pesticide contamination in three mississippi delta Oxbow Lakes using hyalella azteca
2007Co-Authors: Matthew T Moore, Richard E. Lizotte, Scott S. Knight, S Smith, C M CooperAbstract:Three Oxbow Lakes in northwestern Mississippi, USA, an area of intensive agriculture, were assessed for biological impairment from historic and current-use pesticide contamination using the amphipod, Hyalella azteca. Surface water and sediment samples from three sites in each lake were collected from Deep Hollow, Beasley, and Thighman Lakes from September 2000 to February 2001. Samples were analyzed for 17 historic and current-use pesticides and selected metabolites. Ten-day H. azteca survival and growth (as length and dry weight) were measured to determine the degree of biological impairment. Maximum number of detectable pesticides in surface water from Deep Hollow, Beasley and Thighman Lakes was 10, 11, and 17, respectively. Maximum number of detectable pesticides in lake sediments was 17, 17, and 15, respectively. Bioassay results indicated no observable survival effects on H. azteca exposed to surface water or sediment from any lake examined and no growth impairment in animals exposed to lake sediments. However, growth was significantly impaired in surface water exposures from Deep Hollow Lake (2 sites) and Beasley Lake (1 site). Statistically significant relationships between growth impairment (length) and cyanazine, methyl parathion, lambda-cyhalothrin, chlorfenapyr, and pp'DDE surface water concentrations in Deep Hollow Lake as well as trifluralin, atrazine, and methyl parathion in Beasley Lake were observed. Although pesticide frequency and concentrations were typically greater in sediment than surface water, bioassay results indicated decreased availability of these pesticides in sediment due to the presence of clay and organic carbon. Growth impairment observed in surface water exposures was likely due to complex interaction of pesticide mixtures that were present.
-
assessment of pesticide contamination in three mississippi delta Oxbow Lakes using hyalella azteca
2007Co-Authors: Matthew T Moore, Richard E. Lizotte, Scott S. Knight, S Smith, C M CooperAbstract:Three Oxbow Lakes in northwestern Mississippi, USA, an area of intensive agriculture, were assessed for biological impairment from historic and current-use pesticide contamination using the amphipod, Hyalella azteca. Surface water and sediment samples from three sites in each lake were collected from Deep Hollow, Beasley, and Thighman Lakes from September 2000 to February 2001. Samples were analyzed for 17 historic and current-use pesticides and selected metabolites. Ten-day H. azteca survival and growth (as length and dry weight) were measured to determine the degree of biological impairment. Maximum number of detectable pesticides in surface water from Deep Hollow, Beasley and Thighman Lakes was 10, 11, and 17, respectively. Maximum number of detectable pesticides in lake sediments was 17, 17, and 15, respectively. Bioassay results indicated no observable survival effects on H. azteca exposed to surface water or sediment from any lake examined and no growth impairment in animals exposed to lake sediments. However, growth was significantly impaired in surface water exposures from Deep Hollow Lake (2 sites) and Beasley Lake (1 site). Statistically significant relationships between growth impairment (length) and cyanazine, methyl parathion, k-cyhalothrin, chlorfenapyr, and pp 0 DDE surface water concentrations in Deep Hollow Lake as well as trifluralin, atrazine, and methyl parathion in Beasley Lake were observed. Although pesticide frequency and concentrations were typically greater in sediment than surface water, bioassay results indicated decreased availability of these pesticides in sediment due to the presence of clay and organic carbon. Growth impairment observed in surface water exposures was likely due to complex interaction of pesticide mixtures that were present. Published by Elsevier Ltd.
-
combined effects of best management practices on water quality in Oxbow Lakes from agricultural watersheds
2006Co-Authors: R F Cullum, Scott S. Knight, C M Cooper, S SmithAbstract:Abstract Water quality conditions in three Oxbow Lakes were examined before and after best management practices (BMPs) implementation within the Mississippi Delta. Experimental design called for the development of structural and cultural treatments to reduce sediment and associated pollutants entering watershed Oxbow Lakes. Three watersheds were selected and developed with different levels of BMPs. Changes in lake water quality were used as measures of management success. Analyses of water quality data prior to the implementation of BMPs suggested the Lakes were stressed and ecologically damaged due to excessive sediment inflow. Significant improvements in water quality were observed with the use of cultural and structural BMPs. Sediments decreased 34–59%, while Secchi visibility and chlorophyll generally increased. The most dramatic improvements in water quality occurred in the two watersheds that featured cultural practices and combinations of cultural and structural practices. Reducing suspended sediment concentrations in these Oxbow Lakes favored phytoplankton production resulting in increased chlorophyll concentrations and higher concentrations of dissolved oxygen. Cultural BMPs, more so than structural BMPs, play a vital role in improving lake water quality, and are needed in addition to structural measures to ensure improved water quality in Oxbow Lakes receiving agricultural runoff.
-
Influence of watershed system management on herbicide concentrations in Mississippi Delta Oxbow Lakes.
2006Co-Authors: Robert M Zablotowicz, Martin A. Locke, Robert N. Lerch, Richard E. Lizotte, Scott S. Knight, R. Earl Gordon, R. Wade SteinriedeAbstract:The Mississippi Delta Management Systems Evaluation Area (MD-MSEA) project was established in 1994 in three small watersheds (202 to 1497 ha) that drain into Oxbow Lakes (Beasley, Deep Hollow, and Thighman). The primary research objective was to assess the implications of management practices on water quality. Monthly monitoring of herbicide concentrations in lake water was conducted from 2000 to 2003. Water samples were analyzed for atrazine, cyanazine, fluometuron, metolachlor, and atrazine metabolites. Herbicide concentrations observed in the lake water reflected cropping systems of the watershed, e.g., atrazine and metolachlor concentrations were associated with the level of corn and sorghum production, whereas cyanazine and fluometuron was associated with the level of glyphosate-sensitive cotton production. The dynamics of herbicide appearance and dissipation in lake samples were strongly influenced by herbicide use, lake hydrology, rainfall pattern, and land management practices. The highest maximum concentrations of atrazine (7.1 to 23.4 μ gL �1 ) and metolachlor (0.7 to 14.9 μ gL �1 ) were observed in Thighman Lake where significant quantities of corn were grown. Introduction of s-metolachlor and use of glyphosateresistant cotton coincided with reduced concentration of metolachlor in lake water. Cyanazine was observed in two Lakes with the highest levels (1.6 to 5.5 μ gL �1 ) in 2000 and lower concentrations in 2001 and 2002 (b0.4 μ gL �1 ). Reduced concentrations of fluometuron in Beasley Lake were associated with greater use of glyphosate-resistant cotton and correspondingly less need for soilapplied fluometuron herbicide. In contrast, increased levels of fluometuron were observed in lake water after Deep Hollow was converted from conservation tillage to conventional tillage, presumably due to greater runoff associated with conventional tillage. These studies indicate that herbicide concentrations observed in these three watersheds were related to crop and soil management practices.
-
dynamics of herbicide concentrations in mississippi delta Oxbow Lakes and the role of planktonic microorganisms in herbicide metabolism
2006Co-Authors: Robert M Zablotowicz, Martin A. Locke, Robert N. Lerch, Scott S. KnightAbstract:The small Oxbow Lakes central to the Mississippi Delta MSEA project provided a model system for evaluating the effects of watershed management and cropping practices on the dynamics of herbicide concentrations and planktonic populations. In 1996 and 1997, cotton was planted in about 50% of the area of three watersheds, and maximum fluometuron concentrations of 5.7, 5.0 and 12.4 μg L were observed in Beasley, Deep Hollow and Thighman lake water samples, respectively. The metabolite desmethyl fluometuron was present in all Lakes (2.0 to 4.0 μg L). In 1998, significant areas of Beasley and Thighman watersheds were planted in corn. Maximum concentrations of atrazine and metolachlor observed in Thighman lake water in 1998 were 15.0 and 7.2 μg L, respectively, occurring in May. In Beasley Lake, maximum water concentrations of atrazine and metolachlor were 2.5 and 1.8 μg L, respectively, occurring in late summer. Although differences in herbicide dissipation in the Lakes may be partly explained by hydrology, cropping and management practices, the microbiological characteristics of the lake also need to be considered. Differences in planktonic populations and activity were observed among the Lakes,
C M Cooper - One of the best experts on this subject based on the ideXlab platform.
-
assessment of pesticide contamination in three mississippi delta Oxbow Lakes using hyalella azteca
2007Co-Authors: Matthew T Moore, Richard E. Lizotte, Scott S. Knight, S Smith, C M CooperAbstract:Three Oxbow Lakes in northwestern Mississippi, USA, an area of intensive agriculture, were assessed for biological impairment from historic and current-use pesticide contamination using the amphipod, Hyalella azteca. Surface water and sediment samples from three sites in each lake were collected from Deep Hollow, Beasley, and Thighman Lakes from September 2000 to February 2001. Samples were analyzed for 17 historic and current-use pesticides and selected metabolites. Ten-day H. azteca survival and growth (as length and dry weight) were measured to determine the degree of biological impairment. Maximum number of detectable pesticides in surface water from Deep Hollow, Beasley and Thighman Lakes was 10, 11, and 17, respectively. Maximum number of detectable pesticides in lake sediments was 17, 17, and 15, respectively. Bioassay results indicated no observable survival effects on H. azteca exposed to surface water or sediment from any lake examined and no growth impairment in animals exposed to lake sediments. However, growth was significantly impaired in surface water exposures from Deep Hollow Lake (2 sites) and Beasley Lake (1 site). Statistically significant relationships between growth impairment (length) and cyanazine, methyl parathion, lambda-cyhalothrin, chlorfenapyr, and pp'DDE surface water concentrations in Deep Hollow Lake as well as trifluralin, atrazine, and methyl parathion in Beasley Lake were observed. Although pesticide frequency and concentrations were typically greater in sediment than surface water, bioassay results indicated decreased availability of these pesticides in sediment due to the presence of clay and organic carbon. Growth impairment observed in surface water exposures was likely due to complex interaction of pesticide mixtures that were present.
-
assessment of pesticide contamination in three mississippi delta Oxbow Lakes using hyalella azteca
2007Co-Authors: Matthew T Moore, Richard E. Lizotte, Scott S. Knight, S Smith, C M CooperAbstract:Three Oxbow Lakes in northwestern Mississippi, USA, an area of intensive agriculture, were assessed for biological impairment from historic and current-use pesticide contamination using the amphipod, Hyalella azteca. Surface water and sediment samples from three sites in each lake were collected from Deep Hollow, Beasley, and Thighman Lakes from September 2000 to February 2001. Samples were analyzed for 17 historic and current-use pesticides and selected metabolites. Ten-day H. azteca survival and growth (as length and dry weight) were measured to determine the degree of biological impairment. Maximum number of detectable pesticides in surface water from Deep Hollow, Beasley and Thighman Lakes was 10, 11, and 17, respectively. Maximum number of detectable pesticides in lake sediments was 17, 17, and 15, respectively. Bioassay results indicated no observable survival effects on H. azteca exposed to surface water or sediment from any lake examined and no growth impairment in animals exposed to lake sediments. However, growth was significantly impaired in surface water exposures from Deep Hollow Lake (2 sites) and Beasley Lake (1 site). Statistically significant relationships between growth impairment (length) and cyanazine, methyl parathion, k-cyhalothrin, chlorfenapyr, and pp 0 DDE surface water concentrations in Deep Hollow Lake as well as trifluralin, atrazine, and methyl parathion in Beasley Lake were observed. Although pesticide frequency and concentrations were typically greater in sediment than surface water, bioassay results indicated decreased availability of these pesticides in sediment due to the presence of clay and organic carbon. Growth impairment observed in surface water exposures was likely due to complex interaction of pesticide mixtures that were present. Published by Elsevier Ltd.
-
combined effects of best management practices on water quality in Oxbow Lakes from agricultural watersheds
2006Co-Authors: R F Cullum, Scott S. Knight, C M Cooper, S SmithAbstract:Abstract Water quality conditions in three Oxbow Lakes were examined before and after best management practices (BMPs) implementation within the Mississippi Delta. Experimental design called for the development of structural and cultural treatments to reduce sediment and associated pollutants entering watershed Oxbow Lakes. Three watersheds were selected and developed with different levels of BMPs. Changes in lake water quality were used as measures of management success. Analyses of water quality data prior to the implementation of BMPs suggested the Lakes were stressed and ecologically damaged due to excessive sediment inflow. Significant improvements in water quality were observed with the use of cultural and structural BMPs. Sediments decreased 34–59%, while Secchi visibility and chlorophyll generally increased. The most dramatic improvements in water quality occurred in the two watersheds that featured cultural practices and combinations of cultural and structural practices. Reducing suspended sediment concentrations in these Oxbow Lakes favored phytoplankton production resulting in increased chlorophyll concentrations and higher concentrations of dissolved oxygen. Cultural BMPs, more so than structural BMPs, play a vital role in improving lake water quality, and are needed in addition to structural measures to ensure improved water quality in Oxbow Lakes receiving agricultural runoff.
-
water quality from Oxbow Lakes within the mississippi delta management systems evaluation area
2002Co-Authors: R F Cullum, Richard E. Lizotte, Scott S. Knight, C M CooperAbstract:Objectives of this paper were to examine and document pre-management water quality conditions on three Oxbow Lakes and resulting changes following the implementation of Best Management Practices within the Mississippi Delta Management Systems Evaluation Area (MSEA). Aquatic habitats have declined worldwide over the last decade. This decline can be attributed to the draining and clearing of these habitat areas for other agricultural uses. Non-point source pollution associated with agricultural runoff has also contributed to the decline in aquatic habitats. The Mississippi Delta MSEA is a competitive agricultural systems-based research project designed to address the problems associated with non-point source pollutants. This project is unique among MSEA projects because of its location in the Mississippi River alluvial plain and its strong ecological research component. Experimental design of the Mississippi Delta MSEA called for the development of structural and cultural treatments to reduce sediment and associated pollutants entering watershed Oxbow Lakes. Three watersheds within the project were selected and developed with different levels of best management practices (BMPs). Changes in lake water quality and fisheries characteristics were used as measures of management success. Analyses of water quality prior to the implementation of BMPs indicated Lakes that were stressed and ecologically damaged due to excessive in-flowing sediments. Significant improvements in water quality were realized through the use of cultural and structural BMPs. Sediments were decreased 34 to 59%, while Secchi visibility and chlorophyll generally increased. The most dramatic improvements in water quality occurred in the two watersheds that featured cultural practices and combinations of cultural and structural practices, respectively. Reducing suspended sediment concentrations in these Oxbow Lakes resulted in conditions favorable for phytoplankton production. Increases in phytoplankton production resulted in increased chlorophyll concentrations and higher concentrations of dissolved oxygen, leading to improved secondary productivity. Results further indicated that cultural BMPS may play the more vital role in improving lake water quality and may be needed in addition to structural measures to ensure improved water quality in Oxbow Lakes receiving agricultural runoff.
Krystian Obolewski - One of the best experts on this subject based on the ideXlab platform.
-
does hydrological connectivity determine the benthic macroinvertebrate structure in Oxbow Lakes
2015Co-Authors: Krystian Obolewski, Katarzyna Glinskalewczuk, Agnieszka StrzelczakAbstract:In this study, we analyse the qualitative and quantitative structure of benthic macroinvertebrate communities in three Oxbow Lakes differing in hydrological connectivity, located along the lowland Łyna River (NE Poland). The Lakes differed in the extent of surface contact with the main river channel and represented lotic, semi-lotic, and lentic types of water bodies. Mean benthofauna density ranged from 0.9 · 103 (lentic) to 2.0 · 103 indiv. m−2 (semi-lotic) and mean biomass ranged from 16 (lentic) to 202 gww m−2 (semi-lotic); these differences were not statistically significant (P ≤ 0.05). The diversity (Shannon's index) was highest in the lotic and lowest in the lentic ecosystem. It was predominated by Oligochaeta and Chironomidae larvae. The highest, statistically significant differences were observed between the densities of Ephemeroptera larvae (P ≤ 0.05), Megaloptera larvae (P ≤ 0.05) and Arachnida (P ≤ 0.01). In terms of biomass, gastropods prevailed in the semi-lotic, bivalves in the lotic and Chironomidae larvae in the lentic ecosystems. Amongst gastropods, Viviparus viviparus L. dominated in Oxbows connected with the river. Our results, supported by the canonical correspondence analysis (CCA) and hierarchical cluster analysis showed a significant effect of hydrological connectivity, which in a direct or indirect way influenced the macroinvertebrate structure in Oxbow Lakes. As shown by CCA, a free exchange of water between Oxbows and the river channel promotes favourable conditions for the development of hydrobionts. Copyright © 2015 John Wiley & Sons, Ltd.
-
does hydrological connectivity affect the composition of macroinvertebrates on stratiotes aloides l in Oxbow Lakes
2014Co-Authors: Krystian Obolewski, Agnieszka Strzelczak, Katarzyna GlinskalewczukAbstract:Abstract The role of water soldier ( Stratiotes aloides L.) as a significant habitat for invertebrate fauna was investigated in three Oxbow Lakes differed by lateral connectivity with the lowland river. The study was conducted in two lotic Oxbow Lakes of the Slupia River and one Oxbow of lentic type in the Drweca River floodplain (N Poland) within the period of 2008–2009. Hydrological connectivity is a primary factor affecting both abiotic conditions, mainly water trophy, and the faunal structure associated with S. aloides . Overall abundance of epifauna was found to be the highest in standing water (45.1 indiv. kg −1 ) while the lowest in free water flow conditions (25.3 indiv. kg −1 ). The quantitative effect of hydrological connectivity on the faunal composition dwelling S. aloides is significant for Trichoptera larvae which share amounted from 28% for lotic conditions to 39% lentic conditions. Connectivity of an Oxbow with the river favours also the density of Isopoda (26–30%). Oxbow isolation increases share of Hirudinea both in terms of density (35%) as well as biomass (58%). The share of Trichoptera larvae in overall biomass predominated the lotic reservoirs (47–53%). Water soldier leaves are a significant substrate for mining larvae. In the lentic Oxbow they reached the largest density but the highest biomass was stated in the flow-through Oxbow lake. Despite of differences in zoocenotic indices among the three Oxbows, no statistical significance was stated ( p = 0.05). The highest biodiversity on the leaves of water soldier was recorded for the guild of predators, particularly in the Oxbow lake with controlled water flow. Scrapers were the only persistent guild. Based on canonical correspondence analysis (CCA) the density of epifauna guilds we found to be depended on water quality, hydrological conditions, season and water soldier biomass (WSB). Similarly, the variability of guilds’ biomass was explained primarily by water aeration and nutrients (TP, PO 4 -P) availability. The regulation of abiotic conditions undergoes the processes of water exchange between an Oxbow and the main river channel, and thus it is a main factor which alter the qualitative and quantitative structure of epiphytic fauna inhabiting S. aloides .
-
biodiversity of macroinvertebrates in Oxbow Lakes of early glacial river basins in northern poland
2011Co-Authors: Krystian ObolewskiAbstract:River basins are very complex systems which include both abiotic and biotic elements. Such a high number of components results in a situation that normal functioning of river with adjacent areas depends on a set of hydrological and geological processes. They influence biological diversity observed in river basins (Arscott et al., 2005; Marshall et al., 2006). Proper assessment of a lotic system should include not only the main watercourse but also wetlands flooded in spring and autumn. The diversity of habitats in natural river valleys increases biological diversity of aquatic ecosystems and thus the quality of environment (e.g., Boulton et al., 1992; Clausen & Biggs, 1997; Tockner et al., 1999; Gibbins et al., 2001; Sheldon et al., 2002; Arscott et al., 2003; Robinson et al., 2003, 2004; Arscott et al., 2005; Whiles & Goldowitz, 2005; Gallardo et al., 2008; Reese & Batzer, 2007; Obolewski, 2011a; Obolewski & Glinska-Lewczuk, 2011). Each meandering, lowland River is forming its riverbed constantly. Often after rapid floods it turns out that a river flows in new riverbed and the cut-off fragments transform into Oxbow-Lakes (Amoros & Roux, 1988). They can be filled up during river rises and undergo succession (Junk et al., 1989; Tockner et al., 2000). Due to the diversity of river rise intensity, the connectivity between an Oxbow-lake and a river can vary. Therefore, we distinguish lentic, semi-lotic and lotic Oxbow-Lakes. The first type is supplied by river waters under high water table level or by ground waters while the two remaining types are partly or totally connected to a river. Limited exchange of water in a river valley as well as its agricultural use causes that Oxbow-lake drainage area often undergoes anthropopression which leads to quick eutrophication and massive phytoplankton blooms. As a result, water contains considerable amounts of biogenes, mineral salts but low oxygen content. Additional unfavourable factors are hydromorphological features of Oxbows, i.e. small area (between a few hundreds squared meters and a few hectares) and depth which usually does not exceed 3 meters. As a result Oxbows quickly react to changes in temperature and thanks to that they are perfect objects for the research on climate changes even in the global depiction (Klimaszyk, 2004). The structure and functioning of wetland ecosystems, including Oxbow-Lakes, are directly and indirectly connected with the fluctuations in water table level of rivers during floods or flow pulsations (Junk et al., 1989; Tockner et al., 2000). According to Amoros & Roux (1988),
-
macrozoobenthos patterns along environmental gradients and hydrological connectivity of Oxbow Lakes
2011Co-Authors: Krystian ObolewskiAbstract:Abstract Hydrological connectivity and the frequency and intensity of floods are the key factors determining the structure of macroinvertebrates inhabiting wetland ecosystems in river valleys. In 2007, water and macroinvertebrate samples were collected on four occasions in the middle course of the Slupia River and in five Oxbow Lakes (Northern Poland) to determine the hydrological relations in a regulated lowland river environment marked by a moderate climate. The water bodies selected for the study featured different types of connections with the main river valley: two of them were completely cut off from the valley, one was connected via a single branch, one featured a forced-flow connection through drainage pipes, and one was connected by a system of drainage channels. Macroinvertebrates, mostly Chironomidae larvae, were predominant in the eutrophic waters of the river. The prevalent macroinvertebrates found in the eutrophicated Oxbow Lakes isolated from the river were Chironomidae larvae and Crustacea (mainly Asellus aquaticus ). In unobstructed Oxbow Lakes, the main component of benthic fauna was Crustacea, while Ephemeroptera were found mostly in the water body connected to the river via a drainage channel. A canonical correspondence analysis (CCA) showed that hydrological connectivity was the main factor responsible for the structure of invertebrate populations, followed by the physical and chemical parameters of the local environment. A non-conformance analysis revealed that hydrological connectivity enhanced invertebrate abundance and biological diversity, while the overall abundance was marked by unimodal distribution. The developed general model indicates that in the group of measured environmental variables, nitrite concentrations were highly correlated with Shannon diversity and invertebrate composition, while sulphate levels were closely associated with invertebrate abundance in the waters of the analyzed ecosystems.
-
mr ct analysis of the qualitative and quantitative structure of macrozoobenthos in selected Oxbow Lakes of northern poland
2008Co-Authors: Krystian Obolewski, Agnieszka StrzelczakAbstract:Macrozoobenthos inhabiting six Oxbow Lakes in the basins of the Slupia, Łyna, and Vistula rivers was investigated during spring, summer, and fall 2002-2006. The researched reservoirs – re-opened, dredged, with a sluice, natural open, natural semi-open, and natural closed – differed in degree of succession and type of connection with the relevant river. In order to determine the dependency of macrozoobenthos structure on type of Oxbow lake and season, multivariate regression and classification tree method (MR&CT), and indicator species analysis were applied.
Xuejun Shao - One of the best experts on this subject based on the ideXlab platform.
-
responses of macroinvertebrate assemblages to environmental variations in the river Oxbow lake system of the zoige wetland bai river qinghai tibet plateau
2019Co-Authors: Xiongdong Zhou, Zhaoyin Wang, Xuejun ShaoAbstract:The biodiversity value of river-Oxbow lake systems in high plateau peatland has been little recognized, and there are many gaps in our understanding of their ecology. In this study, we investigated the river-Oxbow lake system of the Bai River basin, the main tributary of the Yellow River Source in the Zoige wetland from 2015 to 2016, in attempt to show how the environmental variations, especially hydrological connectivity and macrophyte biomass in the river-Oxbow lake system influenced macroinvertebrates. Habitat patches were investigated in 11 river cross-sections and 18 Oxbow Lakes in the Bai River basin. Through hierarchical clustering and non-metric multidimensional scaling, four main types of habitats were identified in the river-Oxbow lake system in the plateau: sand-bed river, cobble-bed river, sparse-macrophyte Oxbow lake, and luxuriant-macrophyte Oxbow lake. The luxuriant-macrophyte Oxbows were characterized by high dissolved oxygen concentrations, alkalinity, and higher macroinvertebrate richness, density, biomass, and the Improved Shannon-Wiener Index in comparison to the other habitat types. Additionally, influential patterns of environmental variables on macroinvertebrates were analyzed using redundancy analysis. Lasso regression models were established to describe how macroinvertebrate density responded to macrophyte biomass and other variables, and how macrophyte biomass responded to hydrological connectivity and Oxbow size. It was revealed that reduced hydrological connectivity and reduced Oxbow size played important roles in increasing the biomass of submerged macrophyte, and dense macrophyte was directly responsible for the high biodiversity of macroinvertebrates. Different from the commonly believed unimodal influential pattern that medium hydrological connectivity supports the highest biodiversity in Oxbow Lakes reported in previous studies, macroinvertebrates in the high plateau river-Oxbow lake systems benefited from low connectivity and reduced size. Oxbow Lakes, especially those covered with luxuriant macrophytes, diversified the macroinvertebrate assemblages and enhanced primary consumer biomass at the regional scale.
Andrea Farsang - One of the best experts on this subject based on the ideXlab platform.
-
assessing the impacts of the main river and anthropogenic use on the degree of metal contamination of Oxbow lake sediments tisza river valley hungary
2020Co-Authors: Izabella Babcsanyi, Margit Tamas, Jozsef Szatmari, Beata Hambekolah, Andrea FarsangAbstract:Oxbow Lakes, reaches that were cut off from a river during river straightening works, can accumulate during flooding metal-rich suspended sediments transported by a river from mining-impacted source areas and other anthropogenic sources. Additionally, the anthropogenic use of Oxbow Lakes may significantly impact the sediment-bound metal concentrations. The aim was to determine the dominating effect in the sediments’ enrichment in heavy metals. We collected surface sediments (< 10-cm depth) from seven Oxbow Lakes once connected to the Tisza River (a transboundary river in Central and Eastern Europe). Four of the Oxbows were located on the active floodplain, while three Oxbows were at the reclaimed side (i.e., outside the flood defense levee). The sediment samples were subjected to total metal analyses (Cd, Co, Cr, Cu, Ni, Pb, and Zn) and sequential chemical extractions. Contamination indices (geoaccumulation index (Igeo) and pollution load index (PLI)) show a moderate but significant metal pollution of Oxbow Lakes situated on the active floodplain (Igeo (Pb) 0.95–1.25, PLI 2.1–2.8) and an overall unpolluted to slightly polluted status of those at the reclaimed side (Igeo (Pb) − 0.36–0.51, PLI 1.3–1.7). Additionally, the geochemical fractionation of the target metals showed that Cd and Zn were the most labile (Cd 29–48%, Zn 18–37% of non-residual proportions), indicating their environmental significance. Canonical discriminant analysis of the sediment-bound metal concentrations revealed the prevalent role of the river connection over the anthropogenic use in controlling the metal enrichment of Oxbow sediments.
-
evaluation of environmental condition water and sediment examination of Oxbow Lakes
2011Co-Authors: Margit Tamas, Andrea FarsangAbstract:As a result of the river regulation a number of Oxbow Lakes have arisen in the floodplain of the Lower-Tisza. The floodplain Lakes represent natural values and major recreation areas of the lowland region. Due to the human activity the Oxbow Lakes' condition declined. It can be shown by the water quality, the channel discharge by deposit, the high eutrophication of the Lakes and the heavy metal elevation of the sediment. Discovering these processes, analysing the condition and recultivation of the Oxbow Lakes came into prominence only in the past few years. Our research aims to conclude the current environmental pollution of the Oxbow Lakes from statistical analyses of the heavy metal content of the sediment and from the water quality data. The Oxbow Lakes have been classified by chemistry instead of chemical. Results of the research show differences between the floodplain Oxbows and the Lakes outside the dam in terms of the quality of the sediment and the nutrient content of the water.
