Picture of an Invasion: Watersipora spp. within Humboldt Bay, California

Bays and harbors worldwide are being invaded by exotic species. To track these invasions it is necessary to determine where these species are located within the environment. We focused on the exotic encrusting bryozoan Watersipora spp. found in Humboldt Bay, California.  The bryozoan genus studied (Watersipora) contains cryptic species which complicates assessment of species distribution. Untangling the identities and distribution of these species allows a picture to be constructed showing where they initially grow as well as where they may invade next.  We hypothesized that the cryptic species in the marine bryozoan genus Watersipora occupies specific regions within Humboldt Bay, California. To test this hypothesis we collected tissue samples from colonies found to be growing in the intertidal regions of the bay and along floating dock systems. At the time of collection GPS coordinates were recorded to construct a map of species composition contained within the bay. Tissue samples were preserved in 70% ethanol until DNA extraction and multiplex PCR to produce cytochrome oxidase I species specific fragments that provided the identities of each colony. Our data indicates that of the three species of Watersipora inhabiting Humboldt Bay Watersipora Clade A is predominately found in the northern area of the bay, while Watersipora Clade B is found to inhabit the southern region. The third species Watersipora “New Species” is found growing in both the southern and northern regions. These patterns suggest differential survival of different cryptic species due to microhabitat conditions within the bay.