Evaluation of suspended solids as an ecological risk factor for centrarchid fishes in warmwater streams
Abstract
Suspended solids is one of the most important and pervasive nonpoint water pollution problems affecting aquatic communities in warmwater agricultural streams. Despite the importance of suspended solids, numerical water quality criteria have not been established for the protection of stream fishes because of a lack of agreement on appropriate concentration-response testing methods with fish. This study provides a new approach to quantify the effects of total suspended solids (TSS) on survival and growth of centrarchid fishes in standardized laboratory exposures, and to determine the probability of occurrence of these same effect levels in streams as part of an ecological risk assessment for TSS. Survival and growth of young centrarchids were measured after 7 or 14 d exposures to bentonite clay suspensions (particle size 0.0010-0.0005 mm) in recirculating tanks. Live nauplii of Artemia salina were fed in excess to all treatments. The clay concentration causing a 25% reduction in total biomass (IC25) of juvenile smallmouth bass Micropterus dolomieui after 7 days was 35 mg/L. This TSS value was equaled or exceed in a small Indiana stream 100% of the time at an upstream site and 45% of the time at a downstream site during the months of May and June in 1991 and 1992. Frequencies of exceedence in larger streams were 77% for the Eel River, (1970-1980), 39% for Raccoon Creek (1960-1976), and 68% for the Yellow River (1980-1981). The 14 day IC25 for juvenile bluegill Lepomis macrochirus was 76 mg/L, a level equaled or exceeded 31% of the time in the Eel River. The results show that survival and growth as determined in early life-stage tests are appropriate endpoints for establishing TSS water quality criteria for TSS and that TSS recurrence intervals (probability of exceedence) are applicable for in-stream exposure assessment.
Degree
Ph.D.
Advisors
Spacie, Purdue University.
Subject Area
Freshwater ecology|Ecology|Environmental science|Aquaculture|Fish production
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