Meeting Abstract

62.3  Wednesday, Jan. 6  Dispersal limitation and post-settlement survival of an introduced ascidian (Botrylloides violaceus) in San Juan Islands, WA CAHILL, A.E.*; CRICKENBERGER, S.; CRIM, R.N.; SELDEN, R.L.; Stony Brook University; Clemson University; University of British Columbia; University of California, Santa Barbara acahill@life.bio.sunysb.edu

Distributions of introduced species are often patchy; however, the mechanisms regulating these patchy distributions are poorly understood. Sessile organisms with short-lived larvae provide an opportunity to test whether these distributions are dispersal-limited or determined through post-metamorphic survival and growth. Here we used the non-native colonial tunicate Botrylloides violaceus to examine the roles of dispersal and predation in determining its distribution by transplanting recently settled juveniles to locations with and without adult B. violaceus colonies. Survival and growth were not different between caged and uncaged treatments at any site, suggesting that predation is not controlling the distribution of this species. However, survival and growth were different among locations. One site without established colonies had significantly lower growth and survival than all others, suggesting the importance of abiotic factors at this site. The other site where adults were absent had similar growth and survival to sites with established colonies, indicating that dispersal limitation is more important at this site than abiotic factors. Our study suggests that the distribution of B. violaceus is limited by both dispersal and environmental conditions that affect juveniles after settlement.