Meeting Abstract

P3.128  Wednesday, Jan. 6  Effects of delayed hatching on energy reserves and survival of the California grunion, Leuresthes tenuis ARYAFAR, H.*; DICKSON, K.A.; Cal State Univ Fullerton; Cal State Univ Fullerton haryafar@fullerton.edu

The California grunion has the unique ability to both spawn terrestrially and extend embryonic incubation in the sand beyond the initial hatching period of 9-14 days post-fertilization (dpf). Maternally supplied proteins and lipids provide energy for embryonic development and may play a role in larval survival. Previous studies showed a linear decline in oil droplet size with time post-fertilization in grunion embryos, but how energy reserves change during extended incubation is not known. We quantified changes in both yolk and lipid as a result of delayed hatching in L. tenuis, and tested if delayed hatching results in reduced post-hatching survival. We measured yolk surface area, larval lipid content, and time to 50% mortality when starved, in larvae hatched after initial incubation (10 dpf) and extended incubation (28 dpf) at 20°C. We also measured notochord lengths (NL) of larvae from 8 batches of eggs, each from an individual female fertilized by sperm from one male. NL was significantly higher in 28-dpf larvae than in 10-dpf larvae from 3 of 8 batches, significantly lower in 2 of 8, and did not differ significantly in the other 3. This suggests maternal effects, which we plan to investigate in future studies. Yolk and lipid content were significantly lower in the 28-dpf larvae from all but one batch studied, and survival time was significantly reduced in 28-dpf larvae. Thus, because of reduced energy reserves and increased mortality when starved, larvae that must delay hatching are at a disadvantage when competing with those that do not. Future experiments will test if additional development during extended incubation results in increased swimming performance that may offset these negative effects.