The effects of four different oils on the metabolic activities of a euryhaline saltmarsh fish, Cyprinodon variegatus.

Respiration experiments with various temperatures and salinities were conducted on the sheepshead minnow, Cyprinodon variegatus. These experiments indicated that animals collected in February and tested at 2, 5, and 10 ppt and 15 C exhibited the only respiration values that were significantly different from all others (2, 5, 10, 25, and 30 ppt; 15, 22, and 27 C). It was also found that the oxygen consumption of fish collected in June and tested at 22 C and 10 ppt was significantly lower than those collected and tested in February under the same conditions. Bioassays were conducted on the fish to determine the 24, 48, and 96 hour median tolerance limits (TLm). The water-soluble fraction (WSF) of the following oils were used: Southern Louisiana Crude, Venezuelan Bunker C, Kuwait Crude, and #2 Fuel oil. In addition, experiments were conducted with the whole oils, except in the case of Bunker C. Of the whole oils tested, #2 Fuel oil had the greatest toxic effect, while Kuwait appeared to have the least toxic effect. The bioassays with the water-soluble fractions of the four oils indicated that Bunker C and #2 Fuel oil were the most toxic. In one experiment utilizing a closed system, respiration increased with increasing WSF concentrations for all oils except Bunker C, where respiration decreased with increasing concentrations. The respiratory rates of the fish in the second experiment were all depressed well below the control values. Respiration was also measured on the fish under the influence of the WSF of #2 Fuel oil in a flow-through system. In one of the experiments, oxygen consumption dropped significantly when the WSF of #2 Fuel oil was introduced into the system, but as the WSF concentration increased so also did respiration. In both flow-through experiments, there occurred a drop in oxygen consumption with the removal of the WSF and the introduction of clean sea water.