INTRA- AND INTERSPECIFIC DIFFERENCES IN RATE OF OXYGEN CONSUMPTION IN GOBIID FISHES OF THE GENUS GILLICHTHYS

Abstract

Oxygen consumption was determined for moist fish in a Warburg apparatus. Fish acclimated to 10[degree]C. were tested at 10[degree]C. and 17[degree]C; those acclimated to 24[degree]C. were tested at 24[degree] and 31[degree]C. Five populations of G. mirabilis from California, the Salton Sea, and the Gulf of California were investigated, as was one population of Q, seta (24[degree]C. acclimation only) from the Gulf of California. The regression coefficient of oxygen consumption on weight for G. mirabilis was low at 10[degree]C. and 17CC. (-0.14 and -0.35), and high at 24[degree]C. and 31[degree]C. (-0.45 and -0.63). The values at 24[degree]C. and 31[degree]C. (-0.29 and -0.26) were much lower in G. seta Mean rates were different between all groups, except at 24[degree]C. where only interspecific differences were found. Q10''s [degree]f Gulf fish were usually lower than in other groups of G. mirabilis. For all groups, QlO''s were highest when cold-acclimated (2.2 to 2.8), and lowest when warm-acclimated (1.4 to 1.6). But G. seta had a high Q10 (2.0) at 24[degree]C. There was no effect of size on Q10 during acute changes in temperature, but for chronic changes the smaller fish manifested appreciably higher Q10''s. The degree of intra- and interspecific differences in the nature of the oxygen consumption was roughly of the same order of magnitude as the morphological differences reported in another article.