Meeting Abstract

P1-51   -   Investigating the physiological performance of Asterias sea star larvae Bresnahan, K/A*; McAlister, J/S; College of the Holy Cross; College of the Holy Cross kabres22@g.holycross.edu

Hybridization can occur when closely related marine species live in proximity and the barriers to hybridization are weak. Compared to purebred species, hybrids can have either increased performance (positive heterosis or hybrid vigor), or decreased performance (negative heterosis or hybrid inviability). The biogeographical ranges of two species of sea stars, Asterias forbesi and Asterias rubens, overlap forming a hybrid zone in the Gulf of Maine; the majority of collected adults are putative hybrids, exhibiting physical characteristics of both species. To examine and establish baseline values of the physiological performance of A. forbesi and A. rubens purebred and hybrid larvae, we measured their rates of oxygen consumption (metabolic activity) during early development. We performed two trials using a Loligo Systems microplate respirometry system to measure oxygen consumption of half-sibling larvae up through six- or 10-d post-fertilization, depending on the trial. In the absence of external food, we found that per-individual respiration rates varied based on whether offspring were purebred or hybrid. To gauge size-specific respiration rates, we calculated the average body volume using images of larvae taken at each stage. The results from this calculation indicated that size specific respiration rates started high and decreased before plateauing during development in all sibships we examined. We predict that respiration rate is correlated with the energy provisioned by the mother in the egg; additional analyses to be conducted this fall include measuring the average initial amounts of protein, lipid, and carbohydrate energy per egg per mother, and then correlating these values with respiration rates. We will also report the results of statistical analyses. The results from this study provide a baseline foundation for future studies on the impacts of hybridization on larval performance.