October 1, 2017.
The colonial ascidian Didemnum vexillum is an invasive species with detrimental economic and ecological impacts on ecosystems where it is newly introduced. Populations of this recent marine pest are rapidly expanding along the North American coasts and provide the opportunity to assess whether population proximity and shared environmental factors influence genetic relatedness. The population in Tomales Bay, CA is the most diverse measured to date on the Northeast Pacific coast with the population composed of six different haplotypes; other locations are composed of three or four haplotypes. The diversity in Tomales Bay suggests it be an anomaly or possibly a matter associated to areas of limited diversity. D. vexillum populations in isolated areas such as Drakes Estero and Bodega Bay, CA are of close geographic range to Tomales. Drakes’ population is associated with aquaculture structures of the past and Bodega with fishing and recreational boat traffic. This study involved the genetic examination of these populations by barcoding the mitochondrial locus COI to determine haplotype distributions of Drakes Estero and Bodega Bay. From the ten Bodega and five Drakes sequences, there are at least two haplotypes represented. However, the results are preliminary; phylogenetic analysis of all sequences in comparison to the known haplotypes of D. vexillum is necessary before concluding which haplotypes are present in the populations.
Romberg Tiburon Center for Environmental Studies (RTC)
The 2017 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (www.chevron.com), the National Marine Sanctuary Foundation (www.marinesanctuary.org), the California State University Office of the Chancellor, and California Polytechnic State University, in partnership with Romberg Tiburon Center.