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Effects of chronic exposure to coal‐derived oil on freshwater ecosystems: II. Experimental ponds
Author(s) -
Giddings Jeffrey M.,
Franco Paul J.,
Cushman Robert M.,
Hook Leslie A.,
Southworth George R.,
Stewart Arthur J.
Publication year - 1984
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620030310
Subject(s) - microcosm , ecosystem , daphnia magna , zooplankton , ecology , biology , gambusia , freshwater ecosystem , aquatic ecosystem , cladocera , environmental science , zoology , fishery , chemistry , toxicity , fish <actinopterygii> , organic chemistry
Ten 15‐m 3 outdoor ponds were treated daily for 8 weeks with a synthetic coal‐derived crude oil; ecological effects were monitored for an additional 52 weeks. The experimental design included two replicate ponds at each of five oil input rates (from 1 to 16 ml/m 3 /d) plus two untreated controls. A gradient of responses was observed across the gradient of treatment levels. Cladoceran zooplankton populations and ecosystem metabolism (production/respiration) were affected at the lowest input rate, but the effects disappeared before the end of the oiling period and this exposure level (approximately 3% of the 48‐h LC 50 for Daphnia magna ) was considered safe for this ecosystem. At the next higher treatment level, effects on zooplankton and ecosystem metabolism were greater and persisted until the oiling ended; reproduction of mosquitofish ( Gambusia affmis ) was also impaired. Major changes occurred throughout the ecosystem at higher treatment levels. The two highest treatment levels completely disrupted the pond community: The ponds recovered from the next‐to‐highest treatment but the effects of the highest treatment persisted for more than a year. Indirect effects occurred at all treatment levels and included changes in water quality, replacement of sensitive taxa by more tolerant competitors and changes in abundance of some species because of increases or decreases in their predators. The results of this experiment were qualitatively and quantitatively similar to those of a parallel experiment in pond‐derived microcosms, and thus substantiated the ability of the microcosms to simulate larger, more natural ecosystems.