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|Title:||The assessment of Black Rock Harbor dredged material impacts on laboratory population responses|
|Authors:||Environmental Research Laboratory (Narragansett, R.I.)|
United States. Environmental Protection Agency.
Field Verification Program (Aquatic Disposal)
Gentile, J. H. (John H.)
Scott, K. John.
Lussier, Suzanne M.
Redmond, Michele S.
Black Rock Harbor
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: Studies were conducted to determine the applicability of using population responses to assess the impact of dredged material. Laboratory methods were successfully developed to continuously expose Ampelisca abdita and Mysidopsis bahia to bedded and suspended sediments throughout their life cycle. Biological effects, including survival, individual growth, reproduction, and intrinsic rate of population growth, were measured over a range of exposures to Black Rock Harbor dredged material (BRH). Short-term effects (96-hr LC50) were observed at BRH suspended sediment concentrations of 262 mg/l and 80 mg/l for M. bahia and A. abdita, respectively, while the 10-day LC50 for A. abdita was 10.5 mg BRH/1. Thus, A. abdita was three times more sensitive to the acute effects of BRH sediment than M. bahia. Acute toxicity in A. abdita was strongly time dependent with 10-day exposures showing an eightfold increase in toxicity compared to the 4-day toxicity data. This may be the result of A. abdita's more intimate contact with the contaminated sediments. The concentrations of BRH suspended sediments causing effects on growth, reproduction, and population growth to M. bahia were 25, 18, and 8 mg/1, respectively. Ampelisca abdita growth and reproduction were impaired at 2.2 mg/1, and population growth was affected at 1.1 mg/1. This study demonstrates that chronic responses are the best predictors of environmental impacts. The use of population responses is of particular value since populations are the level of biological organization of concern. The application of demographic techniques to life cycle toxicity tests provides an ecological framework for interpreting the significance of chronic toxicity data.
|Appears in Collections:||Technical Report|