Premium
Toxicities of Crude Oils and Oil‐dispersant Mixtures to Juvenile Rabbitfish, Siganus rivulatus
Author(s) -
Eisler Ronald,
Kissil George Wm.
Publication year - 1975
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1975)104<571:tocoao>2.0.co;2
Subject(s) - salinity , seawater , dispersant , zoology , fractionation , biology , fishery , crude oil , chemistry , chromatography , ecology , geology , physics , optics , dispersion (optics) , petroleum engineering
Toxicities were determined for two crude oils, one from the Persian Gulf (Iran) and one from the Sinai Peninsula (Gulf of Suez), to rabbitfish, Siganus rivulatus, an economically important species of teleost from the Red Sea. Also tested for toxicity were ST 5, a chemical oil dispersant, and oil‐ST 5 mixtures in the ratio 10:1 vol/vol. Static tests conducted in small (3‐liter) jars at 41‰ salinity and 23 C produced LC 50 (168 h) values of 0.74 ml/liter for Iranian crude, 14.5 ml/liter for Sinai crude, and 0.010 ml/liter for ST‐5; LC 50 values for oil‐ST 5 mixtures reflected biocidal properties of ST 5 alone. Iranian oil became less toxic with increasing time in seawater over a period of 168 hours; the reverse was observed for Sinai crude. ST 5 exhibited a dramatic reduction in lethality after 2 hours in the assay medium. The most toxic component tested of Iranian crude was the lowest‐boiling fraction; with Sinai crude it was the highest‐boiling fraction; with ST 5 the volatile surfactant component accounted for almost all deaths. Liver enlargement in rabbitfish was linked with exposure to comparatively high concentrations of crude oil. High sublethal levels of ST 5 caused reductions in blood hematocrit. Rabbitfish survival at a given petrochemical concentration was highest at intermediate salinities of 30‐50‰ in the salinity range tested of 20 to 60‰. Rabbitfish were more resistant to crudes and oil‐dispersant mixtures in continuous flow bioassays conducted in large tanks than in static jar bioassays. Tank tests also suggested that mortalities were higher among toxicant‐stressed fish confined 0.2 to 1.0 meters from the surface than among fish held 1.0 to 1.8 m from the surface.