P3.104 Friday, Jan. 6 Plasticity of Anti-microbial Activity in Egg Masses of Melanochlamys diomedea in Response to Habitat Variation in Sediment Size and Microbial Load SMOOT, SC*; PLANTE, CJ; PODOLSKY, RD; College of Charleston, Charleston; College of Charleston, Charleston; College of Charleston, Charleston firstname.lastname@example.org
Several marine invertebrates reproduce by encapsulating embryos until hatching inside gelatinous egg masses. The absence of a hard outer covering makes these egg masses particularly susceptible to microbial infection, biofouling, and predation. The mucus and gel matrix surrounding the egg capsules are therefore predicted to contain compounds that reduce these risks. Previous investigations have demonstrated antimicrobial activity with variation between species and lifestages that raise the possibility of plasticity within a species. Furthermore, if adults can adjust the level of protection in response to risk, then the amount of antimicrobial activity found within an egg mass should reflect the bacterial load of the local environment. We are comparing antimicrobial activity in egg masses of the opisthobranch mollusc Melanochlamys diomedea with the likely bacterial loads of their collection sites, involving measures of bacterial density and sediment grain size. Egg masses were collected from the field, lyophilized, and extracted with non-polar ethyl acetate (EtOAc) and polar methanol (MeOH). The extracts were then tested and quantified for antimicrobial activity against marine type cultures (Bacillus subtilis and Vibrio harveyi) and several environmental bacterial strains isolated from egg masses using a 96-well plate assay. Bacterial density was determined using a general bacterial DNA strain and sediment grain size with a RoTap sediment sorter. We will present the results of comparisons among six sites located on different parts of San Juan Island, WA that vary in sediment size and microbial loads.