Chemical and ecological health of white sucker (Catostomus commersoni) in Rock Creek Park, Washington, D.C., 2003-04 / by Cherie V. Miller ... [et al.] ; prepared in copoeration with the National Park Service

Several classes of chemicals that are known or suspected contaminants were found in bed sediment in Rock Creek, including polyaromatic hydrocarbons (PAHs), phthalate esters, organochlorine pesticides, dioxins and furans, trace metals and metalloids (mercury, arsenic, cadmium, chromium, cobalt, copper, lead, nickel, silver, and zinc), and polychlorinated biphenyls (total PCBs and selected aroclors). Concentrations of many of these chemicals consistently exceeded thresholdor chronic-effects guidelines for the protection of aquatic life and often exceeded probable effects levels (PELs). Exceedance of PELs was dependent on the amount of total organic carbon in the sediments. Concurrent with the collection of sediment-quality data, white sucker (Catostomus commersoni) were evaluated for gross-external and internal-organ anomalies, whole-body burdens of chemical contaminants, and gut contents to determine prey. The histopathology of internal tissues of white sucker was compared to contaminant levels in fish tissue and bed sediment. Gut contents were examined to determine preferential prey and thus potential pathways for the bioaccumulation of chemicals from bed sediments. Male and female fish were tested separately. Lesions and other necroses were observed in all fish collected during both years of sample collection, indicating that fish in Rock Creek have experienced some form of environmental stress. No direct cause and effect was determined for chemical exposure and compromised fish health, but a substantial weight of evidence indicates that white sucker, which are bottom-eeding fish and low-order consumers in Rock Creek, are experiencing some reduction in vitality, possibly due to immunosuppression. Abnormalities observed in gonads of both sexes of white sucker and observations of abnormal behavior during spawning indicated some interruption in reproductive success

Benthic Algal Biomass in the Etowah Basin and Implications to Establishing Nutrient Criteria in Streams

Proceedings of the 2001 Georgia Water Resources Conference, April 26 and 27, 2001, Athens, Georgia.We determined algal biomass in 30 tributaries to the Etowah River in northern Georgia. Mean chlorophyll a ranged from extremely low to 150 mg/m². Several physical and chemical variables were measured as part of this study including dissolved nutrients, total suspended solids, substrate particle size and stream slope. In a multivariate model of algal biomass, three variables, average particle size (+), dissolved oxygen (+), and soluble reactive phosphorus (SRP) (-), entered into the model, which explained 78% of the variation in algal biomass. We subsequently determined that annual concentrations of SRP were strongly related to measures of sedimentation and fine particles at a site. Thus, higher concentrations of SRP were associated with increases in small particles and any positive effect of increased SRP on algal biomass was out-weighed by the negative effect of sedimentation among sites. In a model that included only dissolved nutrients and TSS as potential independent variables, dissolved inorganic nitrogen was positively related and TSS was negatively related to algal biomass. Our data illustrate that sedimentation strongly impacts availability of algae in these watersheds. In addition, these effects can obscure predictive relationships between nutrients and algal biomass, such that alternative nutrient criteria (e.g., biotic indicators) may be more robust where watersheds receive excess sediment.Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, Natural Resources Conservation Service, The University of Georgia, Georgia State University, Georgia Institute of TechnologyThis book was published by the Institute of Ecology, The University of Georgia, Athens, Georgia 30602-2202. The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of The University of Georgia, the U.S. Geological Survey, the Georgia Water Research Institute as authorized by the Water Resources Research Act of 1990 (P.L. 101-397) or the other conference sponsors