Sources of variation in the response of embryonic Membranipora sp. to prolonged UVA radiation exposure

Abstract

Phenotypic plasticity in larval organisms plays a large role in individual survival and populationwide recruitment. Intrapopulation variation that occur at the adult stage in response to different habitats and adaptive mechanisms are often passed on to progeny. In this study, we looked at the response of embryos of Membranipora sp. to prolonged UVA radiation exposure. We compared embryos of eggs from colonies collected in different light environments as a means of assessing embryonic variability in response to environmental stress. Colonies of Membranipora sp. were collected from two depths (0-0.5m and 1.8-2m) off of the dock at Friday Harbor Laboratories on San Juan Islands, Washington. Stimulation of zygote release was achieved using Ethylenediaminetetraacetic acid (EDTA) at 0.1μM concentrations, and embryos were irradiated with UVA light from a lamp continuously for 61 hours. We measured rate of development by counting hatched blastulae at semi-regular intervals over the course of this time period. Our results show that embryos from colonies at greater depth in the ocean are more susceptible to developmental delays caused by UV radiation than those from shallower depths. We believe this variation in response reflects the impact that local conditions have on parental colonies of Membranipora. These results suggest that there may be an acclimation response in parent colonies that can be conferred to their offspring.