Meeting Abstract

75.5  Friday, Jan. 7  Does delayed hatching in the California grunion, Leuresthes tenuis, affect larval development, swimming activity and survival? ARYAFAR, H.*; DICKSON, K.A.; California State University Fullerton; California State University Fullerton HelenaAryafar@gmail.com

The California grunion spawns terrestrially and is able to extend embryonic incubation in the sand beyond the initial incubation period of 9-14 days post-fertilization (dpf), to up to 30 dpf at 20°C. We tested the hypotheses that extended incubation in the California grunion results in larvae with less yolk and reduced post-hatching survival when not fed (disadvantages), but that are longer and have increased swimming activity (advantages of delayed hatching). We measured notochord length (NL), swimming activity, and yolk area of larvae hatched after initial incubation (10 dpf) and extended incubation (28 dpf) at 20°C from nine batches of embryos, each from one female and one male. In one batch, we measured the time to 50% mortality in 10-dpf and 28-dpf larvae when starved versus fed. NL was significantly lower in 28-dpf larvae than in 10-dpf larvae from two batches, significantly greater in four, and did not differ significantly in the other three. Volitional swimming activity did not differ significantly between 28-dpf larvae and 10-dpf larvae in all but one batch. Yolk content was significantly lower in 28-dpf larvae from all batches studied. Survival time was lower in 28-dpf larvae than in 10-dpf larvae, paralleling the decrease in yolk content. The effect of delayed hatching varied among batches for NL and yolk area, which suggests parental effects. Reduced energy reserves that result in greater mortality when starved, and decreased swimming activity, suggest that larvae that must delay hatching are at a disadvantage when competing with those that do not.