Acute Toxicity Testing of Crude Oil Using Piaractus brachypomus, and Pimephales promelas

Evelyn G. Reátegui-Zirena; Alicia Whatley; Fred Chu-Koo; Paul M. Stewart
Oil industry activities such as exploration, transportation, storage, use and disposal, and oil spills are sources of major contamination problems in Peru with deleterious effects on aquatic organisms. The objectives of this study were to: 1) examine reference contaminant acute toxicity in red pacu Piaractus brachypomus, and 2) assess the acute median lethal toxicity of crude oil in red pacu Piaractus brachypomus and fathead minnow Pimephales promelas. Results showed that median lethal concentration (LC50) values for two reference toxicants in Piaractus brachypomus were: zinc sulfate = 5.74 mg/l, sodium dodecyl sulfate = 11.29 mg/l. Peruvian crude oil was tested on Piaractus brachypomus; the LC50 was found to be > 4.00 mg TPH/l and the median lethal loading (LL50) was found to be > 50000 mg/l; in comparison, the LC50 of the Peruvian crude oil in Pimephales promelas was 1.83 mg TPH/l, and the LL50 was 22875 mg/l. Piaractus brachypomus was also exposed to Louisiana sweet crude oil and the LL50 was 17678 mg/l. Results suggested that the acute toxicity of the three reference toxicants on Piaractus brachypomus was within the range of other published studies on fish, and that this species was more tolerant to the Peruvian crude oil than Pimephales promelas. Based on the acute toxicity tests in Piaractus brachypomus, the Louisiana sweet crude oil was more toxic than the Peruvian crude oil. This study is one of the few toxicity studies using Peruvian crude oil and the first using Piaractus brachypomus as the test species. Further research on additional species and other toxicants related to oil contamination is necessary to assess the effects of this growing industry on the aquatic environment.
Acute Toxicity; Piaractus brachypomus; Crude Oil; Reference Toxicant
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