Meeting Abstract

P3.148  Wednesday, Jan. 6  Effects of delayed hatching on muscle and skeletal development and feeding rates in the California grunion, Lueresthes tenuis TREYBIG, T. A.*; CARRILLO, A.; HOESE, W. J.; DICKSON, K. A.; California State University, Fullerton; California State University, Fullerton; California State University, Fullerton; California State University, Fullerton tracietreybig@gmail.com

The California grunion, Leuresthes tenuis, spawns on sandy beaches during spring high tides. Fertilized eggs incubate in the sand for 9-14 days until wave action reaches them, which stimulates the embryos to hatch. If this does not happen, embryos may remain viable for up to 35 days post-fertilization (dpf) and hatch during subsequent spring high tides (= delayed hatching). We studied effects of delayed hatching on larvae from eggs collected from single females, fertilized with the sperm of a single male, incubated in the lab at 20°C, and hatched at 10 and 28 dpf. We hypothesized that, during extended incubation, additional development and differentiation would occur, and thus 28-dpf larvae would be longer, have more developed skeletal structures and locomotor muscle, and would have greater feeding rates than 10-dpf larvae. We found that the 28-dpf larvae were significantly longer, had significantly more dentary and pharyngeal teeth, and had visible hypural cartilage within the caudal fin anlage. However, the percentage cross-sectional area composed of slow and fast locomotor muscle did not differ significantly between 10- and 28-dpf larvae. In addition, we found that the 28-dpf larvae consumed more rotifers, Brachionus sp., during a 4-h period. Thus, delayed hatching in L. tenuis results in larvae with a more developed skeleton and improved feeding performance. These positive effects of delayed hatching may offset known negative effects (decreased hatching rate and energy reserves) and thus may affect larval survival and recruitment to adult populations.