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Water Quality Management (water + quality_management)
Selected AbstractsThe Role of Fish Communities in Water Quality Management of a Large Shallow LakeINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 5 2003István Tátrai Abstract Management measures of Lake Balaton such as wetland reconstruction at the main inflow to the lake along with the "unplanned" commercial fishery led to great changes in the density and biomass of fish populations. There was no significant difference in CPUE data between the two, eastern and western, basins. Biomass of total fish stock in Lake Balaton has decreased substantially, 2,3 times between 1991,1999, and ranges between 120,194 kg ha,1. Bottom-up effects are more important than the top-down effects due to the impact of internal nutrient load. Changes in the biomass and thus the activity of omnivorous fish in the lake lowered the intensity of various indirect effects and feedback mechanisms causing changes in the nutrient metabolism of the lake. Intensified fishery effort in Lake Balaton did not result in an increased stock of piscivores. The ratio of piscivores and omnivores remained at 5% during the whole study period. Despite this low piscivores to omnivores ratio, the water quality has improved in all basins. [source] River Enhancement in the Upper Mississippi River Basin: Approaches Based on River Uses, Alterations, and Management AgenciesRESTORATION ECOLOGY, Issue 3 2007T. Kevin O'Donnell Abstract The Upper Mississippi River is characterized by a series of locks and dams, shallow impoundments, and thousands of river channelization structures that facilitate commercial navigation between Minneapolis, Minnesota, and Cairo, Illinois. Agriculture and urban development over the past 200 years have degraded water quality and increased the rate of sediment and nutrient delivery to surface waters. River enhancement has become an important management tool employed to address causes and effects of surface water degradation and river modification in the Upper Mississippi River Basin. We report information on individual river enhancement projects and contrast project densities, goals, activities, monitoring, and cost between commercially non-navigated and navigated rivers (Non-navigated and Navigated Rivers, respectively). The total number of river enhancement projects collected during this effort was 62,108. Cost of all projects reporting spending between 1972 and 2006 was about US$1.6 billion. Water quality management was the most cited project goal within the basin. Other important goals in Navigated Rivers included in-stream habitat improvement and flow modification. Most projects collected for Non-navigated Rivers and their watersheds originated from the U.S. Department of Agriculture (USDA). The U.S. Army Corps of Engineers and the USDA were important sources for projects in Navigated Rivers. Collaborative efforts between agencies that implement projects in Non-navigated and Navigated Rivers may be needed to more effectively address river impairment. However, the current state of data sources tracking river enhancement projects deters efficient and broad-scale integration. [source] Refilling, ageing and water quality management of Brucher ReservoirLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 1 2002Wilfried Scharf Abstract Refilling of the formerly oligo-mesotrophic, softwater Brucher Reservoir commenced in April 1993 and took 11 months to completely fill. A severe ,trophic upsurge' in the sense of nutrient enrichment (phosphorus, dissolved organic material) as a result of the decomposition of the inundated vegetation occurred. However, algal crop and phosphorus utilization efficiency, expressed as chlorophyll concentrations per unit of total phosphorus, remained very low. In the absence of any fish stock, a single species, Daphnia galeata, monopolized the resources. Sustained by the detritus food chain, daphnids exerted a severe,,top-down' control upon phytoplankton, thereby preventing any net algal growth. In 1994, artificial mixing prevented the occurrence of anoxic water conditions and internal nutrient enrichment of the lake. Although the decay of the inundated vegetation was still of importance, phosphorus concentrations in the water column approached equilibrium with the external input while dissolved organic material concentrations clearly declined. That year, the reservoir became stocked with minnows, sun bleak (Leucaspius delineatus) and trout. As food limitation, as a result of reduced heterotrophic production, became more severe in the face of an increasing predation pressure, the daphnid population density declined, resulting in a decreasing but still adequate community filtering rate providing pronounced ,clear-water phases' of up to 10 m that were features of the period 1995,1997. Although D. galeata defended its key position in the food web, its life-history traits (e.g. body size) changed. Submerged macrophytes, which since 1995 gradually colonized suitable areas of the reservoir, provided a favourable refuge for minnows from trout predation that resulted in reduced predation pressure upon pelagic daphnids. However, in 1998, ungrazeable algae became prominent, adversely affecting transparency. That year, the significant inverse relationship between chlorophyll : total phosphorus ratios and daphnids became uncoupled during the summer (July,August) by indigestible chlorococcalean algae. Nevertheless, the fishery management that was implemented was successful in sustaining not only the lowest yield of algae at the given nutrient concentration but also the most favourable species composition with respect to water quality. [source] Framework for surface water quality management on a river basin scale: Case study of Lake Iseo, Northern ItalyLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2001D. H. A. Al-Khudhairy Abstract River (DESERT) and lake (EVOLA) water quality models are used to simulate the influences of alternative water quality management scenarios on the quality of receiving surface waters in the Lake Iseo basin, Northern Italy. The scenarios are representative of the European Union Directive on Urban Waste Water Treatment (91/271/EEC) and of the regional authority's objective to reduce the total phosphorus loads from point sources entering Lake Iseo and to restore the lake as close as it is practically possible to its former natural qualitative state. Application of DESERT shows that the regional ,Water Clean Up Plan' can achieve similar reductions in total phosphorus concentrations in the basin's main river system, Oglio River, to the 91/271/EEC directive, but at notably lower economic costs. Application of EVOLA to Lake Iseo shows that it is not practical to achieve the regional authority's objective of a specific total phosphorus concentration in the lake by 2016. Instead, the results show that a more realistic, but higher, total phosphorus concentration can be achieved by 2016. The results of both modelling exercises indicate the usefulness of DESERT and EVOLA for comparing and assessing water quality management scenarios and for revising the regional authority's final objectives with regards to total phosphorus concentration in Lake Iseo, as well as the regional ,Water Clean Up Plan' for restoring and safeguarding the quality of the basin's surface waters. [source] Ammonia reduction in seawater by Yucca schidigera extract: efficacy analysis and empirical modellingAQUACULTURE RESEARCH, Issue 8 2010Roberto A Santacruz-Reyes Abstract Yucca schidigera is a plant native to southwestern USA and Mexico. Its extract has been used in the livestock industry to control ammonia accumulation in animal holding facilities, and to reduce ammonia concentration in animal excreta. This study investigated the potential and effectiveness of Y. schidigera extract (YUPE) for ammonia reduction in seawater. A dose,response experiment was conducted to determine the effect of different concentrations of YUPE at 0, 18, 36, 72 and 108 mg L,1 on total ammonia nitrogen (TAN) at 1, 3 and 9 mg L,1. At a higher YUPE dosage rate, higher TAN reduction was observed, and TAN reduction was highest during the first 12 h, and decreased thereafter. A stepwise multiple linear regression that included the initial TAN, YUPE concentration and time was developed, which accurately predicted empirical TAN concentrations. Applications of this model for ammonia management strategies were formulated for hypothetical tiger prawn (Penaeus monodon) rearing conditions. YUPE's efficacy for ammonia reduction, natural origin and safety make YUPE a potentially suitable compound for water quality management in mariculture. [source] Coastal wetlands of the northern Gulf of California: inventory and conservation statusAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2006Edward P. Glenn Abstract 1.Above 28°N, the coastline of the northern Gulf of California is indented at frequent intervals by negative or inverse estuaries that are saltier at their backs than at their mouths due to the lack of freshwater inflow. These ,esteros' total over 215 000 ha in area and encompass mangrove marshes below 29°N and saltgrass (Distichlis palmeri) marshes north of 29°N. An additional 6000 ha of freshwater and brackish wetlands are found in the Colorado River delta where fresh water enters the intertidal zone. 2.The mangrove marshes in the Gulf of California have been afforded some degree of protected status in Mexico, but the northern saltgrass esteros do not have priority conservation status and are increasingly becoming development targets for resorts, vacation homes and aquaculture sites. 3.We conducted an inventory of the marshes using aerial photography and satellite images, and evaluated the extent and type of development on each marsh. We reviewed the available literature on the marshes to document their vegetation types and ecological functions in the adjacent marine and terrestrial ecosystems. 4.Over 95% of the mangrove marshes have been developed for shrimp farming. However, the farms are built adjacent to, rather than in, the marshes, and the mangrove stands are still mostly intact. 5.The majority of saltgrass marshes above the mangrove line are still relatively unspoiled. However, resort and vacation home development is taking place on land surrounding them. 6.We recommend a system of protected reserves incorporating the pristine wetlands, along with water quality management and buffer zones for the more developed esteros. The saltgrass marshes should be considered for conservation protection, similar to the protection given to the southern mangrove marshes whose value has already been recognized. Copyright © 2006 John Wiley & Sons, Ltd. [source] |