The effects of feeding Great Lakes fish or fish products (carp, sucker, perch scraps, whitefish racks, and alewife fishmeal) to mink were studied. Growth and furring of mink were normal for all species of fish tested. However, mink fed carp failed to reproduce, and the reproductive performance and/or kit survival in groups fed the perch, whitefish, and sucker were inferior to the control. Only the alewife fishmeal diet supported reproduction and kit survival comparable to the control. PCB residues (as Aroclor 1254) accumulated in mink subcutaneous body fat to as much as 38 times the dietary level, while some individual congeners accumulated up to 200 times. The half-life of PCB in mink adipose tissue was determined to be 98 d. The toxicity of PCBs derived from Great Lakes fish was greater than that observed in previous studies with mink fed comparable levels of technical-grade PCBs.
The acute toxicity of larval lampricide (TFM: 3-trifluoromethyl-4-nitrophenol) to 35 species of benthic macroinvertebrates was determined in 96-h flow-through tests. The 96-h LC50 values range from 2.1 mg/liter for blackfly larvae, Simulium pugetense, to values in excess of 38.0 mg/liter for species with heavy exoskeletons: crayfish (Orconectes propinquus), dobsonfly larvae (Chauloides sp), and dragonfly naiads (Ophiogomphus sp.) Younger individuals of the clam (Ligumia sp.) and the mayfly nymph (Ephemerella cornuta) were 2 to 1.5 times more sensitive than larger individuals of the same species. Early emergence of adults and increased locomotor activity were observed among some organisms exposed to sublethal concentrations.
The present study was designed to determine the availability of radiolabeled 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP) to benthic amphipods from experimentally contaminated natural sediments. Amphipods accumulated HCBP primarily by direct uptake from water as a function of exposure time. However, organisms that were directly exposed to the sediments had consistently higher (2.3 to 10.8×) HCBP concentrations than did organisms exposed only to the sediment-desorbed residues in the water. Experimental results demonstrated that the substrate organic matter content and particle size affected the concentrations of HCBP in the water and, in turn, in the organisms. The removal of sediment organic matter enhanced HCBP accumulation by both substrate-exposed and water-exposed organisms. Amphipods accumulated the least HCBP when exposed to silt-clay particle size fractions which contained organic matter. The substrate particle size was less important than the organic content in determining HCBP availability to the amphipods.
The effects of a toxicant, the lampricide TFM (3-trifluoromethyl-4-nitrophenol), on the metabolism of benthic communities were studied in a series of six indoor model streams resembling typical woodland streams. Each artificially illuminated stream consisted of a 4-m pool section and a 4-m riffle section.A specially developed in situ stream respirometer was used for measurements of net primary production and community respiration in pool and riffle communities. Pretreatment levels of gross primary production ranged during summer, fall, and early winter from 10.7 to 79.0 mg O2∙m−2∙h−1 and were suppressed by 25–50% during exposure to 9.0 mg/liter TFM. Community respiration ranged from 10.5 to 36.2 mg O2∙m−2∙h−1 during the same time period and was increased 3–50% by the 9.0 mg/liter lampricide treatment. Calculated photosynthesis to respiration (P:R) ratios proved to be sensitive indicators of the influence of the toxicant. The stream communities demonstrated a capacity to adjust to the toxicant influence as evidenced by the rapid return of metabolic rates to pretreatment levels following the exposure period.
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