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1.
Understanding effects of flow alteration on stream biota is essential to developing ecologically sustainable water supply strategies. We evaluated effects of altering flows via surface water withdrawals and instream reservoirs on stream fish assemblages, and compared effects with other hypothesized drivers of species richness and assemblage composition. We sampled fishes during three years in 28 streams used for municipal water supply in the Piedmont region of Georgia, U.S.A. Study sites had permitted average withdrawal rates that ranged from < 0.05 to > 13 times the stream’s seven-day, ten-year recurrence low flow (7Q10), and were located directly downstream either from a water supply reservoir or from a withdrawal taken from an unimpounded stream. Ordination analysis of catch data showed a shift in assemblage composition at reservoir sites corresponding to dominance by habitat generalist species. Richness of fluvial specialists averaged about 3 fewer species downstream from reservoirs, and also declined as permitted withdrawal rate increased above about 0.5 to one 7Q10-equivalent of water. Reservoir presence and withdrawal rate, along with drainage area, accounted for 70% of the among-site variance in fluvial specialist richness and were better predictor variables than percent of the catchment in urban land use or average streambed sediment size. Increasing withdrawal rate also increased the odds that a site’s Index of Biotic Integrity score fell below a regulatory threshold indicating biological impairment. Estimates of reservoir and withdrawal effects on stream biota could be used in predictive landscape models to support adaptive water supply planning intended to meet societal needs while conserving biological resources.  相似文献   

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Multimetric indices based on fish and benthic macroinvertebrate assemblages are commonly used to assess the biological integrity of aquatic ecosystems. However, their response to specific stressors is rarely known. We quantified the response of a fish-based index (Mid-Atlantic Highlands Index of Biotic Integrity, MAH-IBI) and a benthic invertebrate-based index (West Virginia Stream Condition Index, WV-SCI) to acid mine drainage (AMD)-related stressors in 46 stream sites within the Cheat River watershed, West Virginia. We also identified specific stressor concentrations at which biological impairment was always or never observed. Water chemistry was extremely variable among tributaries of the Cheat River, and the WV-SCI was highly responsive across a range of AMD stressor levels. Furthermore, impairment to macroinvertebrate communities was observed at relatively low stressor concentrations, especially when compared to state water quality standards. In contrast to the WV-SCI, we found that the MAH-IBI was significantly less responsive to local water quality conditions. Low fish diversity was observed in several streams that possessed relatively good water quality. This pattern was especially pronounced in highly degraded subwatersheds, suggesting that regional conditions may have a strong influence on fish assemblages in this system. Our results indicate that biomonitoring programs in mined watersheds should include both benthic invertebrates, which are consistent indicators of local conditions, and fishes, which may be indicators of regional conditions. In addition, remediation programs must address the full suite of chemical constituents in AMD and focus on improving linkages among streams within drainage networks to ensure recovery of invertebrate and fish assemblages. Future research should identify the precise chemical conditions necessary to maintain biological integrity in mined Appalachian watersheds.  相似文献   

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The effect of market effluent from the Oja-titun market in Ile-Ife, Nigeria on the chemical quality of the Opa Reservoir located 3.5 km downstream was investigated between February and November 2000. Water samples were collected in February, May, August and November from 16 sites, four along each of the market drainage channels (MDC), market stream, tributary stream and the Opa River and Reservoir. The peak level of each variable-biochemical oxygen demand, temperature, total alkalinity, Na(+), K(+), Ca(2+), Mg(2+), PO(4)(3+), SO(4)(2+), Cl(-), NO(3)(-), Pb and Zn-occurred at the MDC, and decreased significantly downstream, except pH, conductivity and dissolved oxygen, which increased. Seasonal fluctuation in most variables was pronounced. Generally, there were high values in the early dry and dry seasons and low values in the rainy and early rainy seasons. Comparison of the reservoir water with international limitation standards for drinking water supply showed that the quality of the reservoir water was very low and that treatment required to achieve minimum limitation standards for drinking water would be both intensive and expensive. The study concluded that the stream borne effluent from the market impacts significantly on the chemical quality of the reservoir water although other tributaries within the Reservoir's catchment are other possible sources of pollutants in the reservoir.  相似文献   

6.
Effects of changing environments of riverside mangroves, coastal land uses, and water quality on fish communities were studied in Bangphra and Thaprik creeks, Trat Bay, Thailand. Regression analysis revealed that fish species richness in the wet season had a negative relationship with water transparency, nitrate, and phosphate and a positive relationship with zooplankton. In the dry season, species richness had a negative relationship with nitrate and phosphate and a positive relationship with salinity, pH, and zooplankton. Abundances and species richness of fish declined over distance from downstream to upstream in both creeks. Riparian mangroves and water quality also declined with distance upstream in both creeks. Results from one-way analysis of variance and Tukey’s HSD test revealed that the highest zooplankton volume with the lowest amounts of nitrate and phosphate were observed at the downstream station in both creeks in each season. Low zooplankton volume with high amounts of nitrate and phosphate were found at the midstream and upstream stations of the creeks. The midstream and upstream stations of Bangphra Creek had low to moderate abundance of mangroves along the riversides, whereas shrimp farms were mainly found along the riversides at the midstream and upstream stations of Thaprik Creek. Correlation analysis results of land-use types and the significant habitat factors were discussed. This study found that mangrove degradation, shrimp farming, and residential and agricultural areas altered water quality and the health of fish habitats, causing the decreases in fish abundance and species richness.  相似文献   

7.
ABSTRACT: The decline of many fish populations within the mid-Appalachian region has been attributed to stream acidification as a result of acid precipitation. Many previous attempts to examine relationships between fish occurrence and acidification have been hindered by a lack of data on water quality and fish distributions. To assess relationships between water quality and bedrock type in the upper Cheat River drainage, we used EPA STORET water quality data (1969–1993) and calculated mean pH and mean alkalinity of streams associated with four bedrock types (Hampshire, Chemung, Mauch Chunk, and Pottsville). We examined the relationship between fish occurrence and bedrock type for 53 headwater streams. We found that acidity in headwater streams associated with Pottsville and Mauch Chunk groups often exceeded biological thresholds for acid-sensitive fish species (pH < 5.5). Streams associated with the Pottsville group typically had fewer cyprinid species and fewer total species than those associated with Mauch Chunk, Chemung, and Hampshire bedrock types. The congruent occurrence of streams with low buffering capacity, streams with pH > 5.5, and streams with low fish species richness indicate that acidification has influenced fish distributions in the upper Cheat River drainage.  相似文献   

8.
Biological assessment of aquatic ecosystems is widely employed as an alternative or complement to chemical and toxicity testing due to numerous advantages of using biota to determine ecosystem condition. These advantages, especially to developing countries, include the relatively low cost and technical requirements. This study was conducted to determine the biological impacts of aquaculture operations on effluent-receiving streams in the Ashanti Region of Ghana. We collected water, fish and benthic macroinvertebrate samples from 12 aquaculture effluent-receiving streams upstream and downstream of fish farms and 12 reference streams between May and August of 2009, and then calculated structural and functional metrics for biotic assemblages. Fish species with non-guarding mode of reproduction were more abundant in reference streams than downstream (P?=?0.0214) and upstream (P?=?0.0251), and sand-detritus spawning fish were less predominant in reference stream than upstream (P?=?0.0222) and marginally less in downstream locations (P?=?0.0539). A possible subsidy-stress response of macroinvertebrate family richness and abundance was also observed, with nutrient (nitrogen) augmentation from aquaculture and other farming activities likely. Generally, there were no, or only marginal differences among locations downstream and upstream of fish farms and in reference streams in terms of several other biotic metrics considered. Therefore, the scale of impact in the future will depend not only on the management of nutrient augmentation from pond effluents, but also on the consideration of nutrient discharges from other industries like fruit and vegetable farming within the study area.  相似文献   

9.
A Water Quality Index (WQI) is a numeric expression used to evaluate the quality of a given water body and to be easily understood by managers. In this study, a modified nine-parameter Scottish WQI was used to assess the monthly water quality of the Douro River during a 10-year period (1992–2001), scaled from zero (lowest) to 100% (highest). The 98,000 km2 of the Douro River international watershed is the largest in the Iberian Peninsula, split between upstream Spain (80%) and downstream Portugal (20%). Three locations were surveyed: at the Portuguese–Spanish border, 350 km from the river mouth; 180 km from the mouth, where the river becomes exclusively Portuguese; and 21 km from the mouth. The water received by Portugal from Spain showed the poorest quality (WQI 47.3 ± 0.7%); quality increased steadily downstream, up to 61.7 ± 0.7%. In general, the water quality at all three sites was medium to poor. Seasonally, water quality decreased from winter to summer, but no statistical relationship between quality and discharge rate could be established. Depending on the location, different parameters were responsible for the episodic decline of quality: high conductivity and low oxygen content in the uppermost reservoir, and fecal coliform contamination downstream. This study shows the need to enforce the existing international bilateral agreements and to implement the European Water Quality Directive in order to improve the water quantity and quality received by the downstream country of a shared watershed, especially because two million inhabitants use the water from the last river location as their only source of drinking water.  相似文献   

10.
The objectives of this study were to assess the biological water of the Iranian Tajan River using different metrics, i.e., a Multimetric Macroinvertebrate Index (MMI) and a traits-based method. Twenty-eight physico-chemical parameters, 10 habitat factors, and abundance of macroinvertebrates were obtained for 17 sites. The Shahid-Rajaie dam divides the Tajan River into an up- and downstream part, with different land uses. Eighteen metrics were used to represent four components of ecosystem quality, including tolerance (Hilsenhoff, SIGNAL), diversity (Margalef, Shannon–Wiener, Simpson, and Evenness), abundance (total number of taxa, individuals, Ephemeroptera, Plecoptera, Trichoptera, EPT, and Insects), and composition of assemblages (% Ephemeroptera, % Plecoptera, % Trichoptera, and % EPT Taxa). The integrated MMI was calculated by averaging the obtained scores of all indices. In the next step, we gathered information on 22 biological traits of macroinvertebrates to evaluate whether (group of) traits could be identified that are indicative for specific or general stress. Result showed a decrease in MMI from upstream (very good water quality) to downstream (bad) due to human activities. Industrial activities like pulping and papermaking operations or sand mining in the downstream part had more effects than agriculture and fish ponds in the upstream part. A redundancy analysis biplot showed the variation between the modalities of trait of macroinvertebrates and their correlation with physico-chemical parameters in Tajan River. The findings show that traits can be indicative for different kind of stress but that more effort has to be put in gathering data sets to disentangle the effect of habitat quality, pollution, and the physico-chemical properties of high- versus lowland rivers.  相似文献   

11.
Abstract: Recent studies have detected estrogenic compounds in surface waters in North America and Europe. Furthermore, the presence of estrogenic compounds in surface waters has been attributed, in some cases, to the discharge of wastewater treatment plant (WWTP) effluent. The primary objective of the current study was to determine if WWTP effluent contributes estrogens to the surface waters of Nebraska. A second objective of this study was to determine if estrogens were found in concentrations sufficient enough to manifest feminizing effects on fish. These objectives were satisfied by deploying polar organic chemical integrative samplers (POCIS) and caged fathead minnows at eight field sites. Deployment sites included: three reference sites (Pawnee Creek, the Little Blue River, and the Middle Loup River), two sites upstream of the WWTPs at Grand Island and Columbus, and three sites downstream of the WWTPs at Grand Island, Columbus, and Hastings. Following the seven day deployments, POCIS extracts were analyzed for estrone, 17β‐estradiol, estriol and 17α‐ethinylestradiol using liquid chromatography tandem mass spectrometry (LC/MS/MS). 17β‐estradiol was detected in POCIS from six of the eight field sites with the greatest quantities recovered in POCIS deployed downstream from the Grand Island and Hastings WWTPs. Estrone was detected only in the POCIS deployed downstream from the Grand Island and Hastings WWTPs. Estrogenic effects were detected in caged minnows analyzed for the hepatic mRNA expression of two estrogen‐responsive genes, vitellogenin (vg1) and estrogen receptor α (ERα). Fish deployed at the site where the greatest quantities of estrogens were recovered (Hastings) had significantly higher expression of both vg1 and ERα than fish deployed at any of the other sites. These results confirm that WWTP effluent contributes biologically significant levels of estrogens to Nebraska surface waters.  相似文献   

12.
ABSTRACT: A selenium budget for Lake Powell, Utah-Arizona was determined based on selenium loads at the principal stream input sites to and the output site from the lake. Based on data collected during 1985-1994, 83 percent of the selenium entering Lake Powell is accounted for at the output site. The rest of the selenium may be incorporated by lake sediment or used by the biota. Considerably more selenium per unit area is produced from the Colorado River Basin above the Colorado River-Green River confluence than from the Green River Basin and the San Juan River Basin combined. The Gunnison River Basin and the Grand Valley in Colorado produce an estimated 31 and 30 percent of the selenium that reaches Lake Powell, respectively. Irrigation-related activities are thought to be responsible for mobilizing 71 percent of the selenium that reaches Lake Powell. Selenium concentrations in water at Imperial Dam on the Colorado River upstream of the United States-Mexico international border are similar to those at the output site of Lake Powell. Therefore, most selenium observed in downstream areas of the Colorado River therefore probably is derived mostly from the Colorado River Basin above Lake Powell.  相似文献   

13.
Water extraction from dryland rivers is often associated with declines in the health of river and floodplain ecosystems due to reduced flooding frequency and extent of floodplain inundation. Following moderate flooding in early 2008 in the Narran River, Murray-Darling Basin, Australia, 10,423 ML of water was purchased from agricultural water users and delivered to the river to prolong inundation of its terminal lake system to improve the recruitment success of colonial waterbirds that had started breeding in response to the initial flooding. This study examined the spatial and temporal patterns of fish assemblages in river and floodplain habitats over eight months following flooding to assess the possible ecological benefits of flood extension. Although the abundances of most fish species were greater in river channel habitats, the fish assemblage used floodplain habitats when inundated. Young-of-the-year (4–12 months age) golden perch (Macquaria ambigua) and bony bream (Nematalosa erebi) were consistently sampled in floodplain sites when inundated, suggesting that the floodplain provides rearing habitat for these species. Significant differences in the abundances of fish populations between reaches upstream and downstream of a weir in the main river channel indicates that the effectiveness of the environmental water release was limited by restricted connectivity within the broader catchment. Although the seasonal timing of flood extension may have coincided with sub-optimal primary production, the use of the environmental water purchase is likely to have promoted recruitment of fish populations by providing greater access to floodplain nursery habitats, thereby improving the ability to persist during years of little or no flow.  相似文献   

14.
ABSTRACT: The applicability of the U.S Environmental Protection Agency's (USEPA) water temperature criteria in evaluating the impact of a thermal discharge from the P. H. Glatfelter Paper Company, Spring Grove, Pennsylvania, is analyzed. A review of the literature relative to 11 temperature Criteria was conducted for six fish species designated by the USEPA as “representative important species” (RIS) of the West Branch Codorus Creek, Susquehanna River drainage. The species were: Notemigonus crysolcucas (golden shiner), Notropis analostanus (satinfin shiner), Rhinichthys atratulus (blacknose dace), Catostomus comme-soni (white sucker), Lepomis gibbosus (pumpkinseed). and Micropterous salmoides (largemouth bass). It was found that by applying only USEPA suggested criteria that a complete evaluation was not satisfactory. Temperature behavior data, specifically preference and avoidance information, coupled with field sampliug was needed to properly assess the effects of the thermal effluent. The final analysis indicated that the thermal discharge of the paper company should have minimal effect on the fish community of Codorus Creek.  相似文献   

15.
The long-term recovery process for fish communities in a warm water stream in East Tennessee was studied using quantitative measurements over 20 years. The stream receives effluents from a U. S. Department of Energy (DOE) facility, but since 1985 these effluents have been greatly reduced, eliminated, or diluted as part of a substantial long-term pollution abatement program. The resulting changes in water quantity and quality led to a recovery of the fish communities, evidenced by significant changes in species richness, abundance (density and biomass), and community composition (e.g., number of fish species sensitive to stress). The fish community changes occurred over a spatial gradient (downstream from the headwater release zone nearest the DOE facility) and temporally, at multiple sampling locations in the stream. Changes in measured parameters were associated with specific remedial actions and the intervening steps within the recovery process are discussed with regard to changes in treatment processes.  相似文献   

16.
ABSTRACT: In 1983, the City of Indianapolis, Indiana, completed construction of advanced wastewater treatment (AWT) systems to enlarge and upgrade its existing Belmont Road and South port Road secondary treatment plants. A nonparametric statistical procedure, a modified form of the Wilcoxon-Mann-Whitney rank-sum test, was used to test for trends in water quality at two upstream and two downstream sites on White River and at the two treatment plants. Results comparing the pre- (1978–1980) and post- (1983–1986) AWT periods show statistically significant improvements in the quality of the treated effluent and of the White River downstream from the plants. Water quality at sites upstream from the city was relatively constant during the period of study. Total ammonia (as N) decreased 14.6 mg/L and BOD5 (five-day biochemical oxygen demand) decreased 10 to 19 mg/L in the two effluents. Total ammonia in the river downstream from the plants decreased 0.8 to 1.9 mg/L and BOD5 decreased 2.3 to 2.5 mg/L. Nitrate (as N) increased 14.5 mg/L in the plant effluents and 2.0 to 2.4 mg/L in the river because of in-plant nitrification. Dissolved oxygen concentration in the river increased about 3 mg/L because of reduced oxygen demand for nitrification and biochemical oxidation processes.  相似文献   

17.
A wastewater model was applied to the Potomac River watershed to provide (i) a means to identify streams with a high likelihood of carrying elevated effluent-derived contaminants and (ii) risk assessments to aquatic life and drinking water. The model linked effluent discharges along stream networks, accumulated wastewater, and predicted contaminant loads of municipal wastewater constituents while accounting for instream dilution and attenuation. Simulations using 2016 data suggested that nearly 30% (8281 km) of streams were wastewater impacted. Low- to medium-order streams had the largest range of accumulated wastewater (ACCWW%) values. ACCWW% exceeded a 1% threshold at >39% of drinking-water intakes (varied by temporal condition). Risk assessments of municipal wastewater-contaminant mixtures indicated that 22% (1479 km) of streams impacted by municipal wastewater (5.5% of all reaches modeled) may pose high risk to aquatic organisms under mean-annual conditions, with fish more susceptible to chronic-exposure effects relative to other taxa. Risk varied temporally and by stream order, with the greatest risk occurring in the summer in small streams. These findings suggest that wastewater may be an important factor contributing to environmental degradation in the Potomac River watershed.  相似文献   

18.
Recovery dynamics in a previously disturbed stream were investigated to determine the influence of a series of remedial actions on stream recovery and to evaluate the potential application of bioindicators as an environmental management tool. A suite of bioindicators, representing five different functional response groups, were measured annually for a sentinel fish species over a 15 year period during which a variety of remedial and pollution abatement actions were implemented. Trends in biochemical, physiological, condition, growth, bioenergetic, and nutritional responses demonstrated that the health status of a sentinel fish species in the disturbed stream approached that of fish in the reference stream by the end of the study. Two major remedial actions, dechlorination and water flow management, had large effects on stream recovery resulting in an improvement in the bioenergetic, disease, nutritional, and organ condition status of the sentinel fish species. A subset of bioindicators responded rather dramatically to temporal trends affecting all sites, but some indicators showed little response to disturbance or to restoration activities. In assessing recovery of aquatic systems, application of appropriate integrative structural indices along with a variety of sensitive functional bioindicators should be used to understand the mechanistic basis of stress and recovery and to reduce the risk of false positives. Understanding the mechanistic processes involved between stressors, stress responses of biota, and the recovery dynamics of aquatic systems reduces the uncertainty involved in environmental management and regulatory decisions resulting in an increased ability to predict the consequences of restoration and remedial actions for aquatic systems.  相似文献   

19.
ABSTRACT: Stream water during fair weather (base flow) is largely ground water discharge, which has been in contact with minerals of the underlying aquifer. Base flow water quality should therefore reflect aquifer mineralogy as well as upstream land use. Three upstream mining categories (unmined lands, abandoned coal mines, and reclaimed coal mines) differed in pH, specific conductance, sulfate, iron, aluminum, and alkalinity for 122 streams in eastern Ohio. Aquifer rock type influenced pH, specific conductance, sulfate, iron, and alkalinity. Reclamation returned many components of acid mine drainage to near unmined levels, although sulfate and specific conductance were not improved. Acid mine drainage problems were less severe in watersheds underlain by the calcareous Monogahela Formation. These results should ayply to other Appalachian coal regions having similar rock units. The water quality data distributions were neither consistently normal nor lognormal. Statistical tests utilizing ranks of the water quality data, instead of the data themselves, proved useful in analyzing the influences of mining category and rock type.  相似文献   

20.
Eutrophication is a serious water quality problem in estuaries receiving increasing anthropogenic nutrient loads. Managers undertaking nutrient-reduction strategies aimed at controlling estuarine eutrophication are faced with the challenge that upstream freshwater segments often are phosphorus (P)-limited, whereas more saline downstream segments are nitrogen (N)-limited. Management also must consider climatic (hydrologic) variability, which affects nutrient delivery and processing. The interactive effects of selective nutrient input reductions and climatic perturbations were examined in the Neuse River Estuary (NRE), North Carolina, a shallow estuary with more than a 30-year history of accelerated nutrient loading and water quality decline. The NRE also has experienced a recent increase in Atlantic hurricanes and record flooding, which has affected hydrology and nutrient loadings. The authors examined the water quality consequences of selective nutrient (P but not N) reductions in the 1980s, followed by N reductions in the 1990s and an increase in hurricane frequency since the mid-1990s. Selective P reductions decreased upstream phytoplankton blooms, but increased downstream phytoplankton biomass. Storms modified these trends. In particular, upstream annual N and P concentrations have decreased during the elevated hurricane period. Increased flushing and scouring from storms and flooding appear to have enhanced nutrient retention capabilities of the NRE watershed. From a management perspective, one cannot rely on largely unpredictable changes in storm frequency and intensity to negate anthropogenic nutrient enrichment and eutrophication. To control eutrophication along the hydrologically variable freshwater–marine continuum, N and P reductions should be applied adaptively to reflect point-source–dominated drought and non–point-source–dominated flood conditions.  相似文献   

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