||Emersion in the Mangrove Forest Fish 'Rivulus marmoratus': A Unique Response to Hydrogen Sulfide.
Abel, D. C. ;
Koenig, C. C. ;
Davis, W. P. ;
||Charleston Coll., SC. Grice Marine Biological Lab. ;Scripps Institution of Oceanography, La Jolla, CA.;Environmental Research Lab., Gulf Breeze, FL.
||CONTRIB-68; EPA-R-805469; EPA/600/J-87/061;
Water pollution ;
Hydrogen sulfide ;
Mangrove forests ;
Rivulus marmoratus ;
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The mangrove forest fish Rivulus marmoratus (Cyprinodontidae) has frequently been observed out of water, a phenomenon generally attributed to habitat drying. The authors tested the hypothesis that hydrogen sulfide, a substance characteristically found in their environment, can serve as a stimulus for emersion. In the field the authors found R. marmoratus in water with low to moderate levels (<250 ppb) of H2S. In the laboratory, R. marmoratus leaped from water contaminated with H2S at ecologically relevant concentrations (median response at 123 ppb). Aquatic hypoxia did not induce emersion, but prey capture did. Oxygen consumption by both juveniles and adults decreased significantly in air (27 and 25%, respectively). The results suggest that avoidance of H2S and the ability to survive terrestrial conditions enable this species to permanently occupy an area of the forest unavailable to other fishes.