Red Algae of the Genus Prionitis May Provide Environmental Factors that Facilitate the Settling and Growth of the Bryzoan Genus Watersipora

Invasive bryozoans in the genus Watersipora are part of a diverse fouling community on docks, pier pilings and ship hulls in bays and harbors around the world. Determining where and why these bryozoans invade different harbors may in part rely on a careful examination of the complex relationships between these bryozoans and other native and exotic organisms, particularly with regard to where the larvae of these bryozoans initially settle and grow in these communities. Previous sampling lead us to hypothesize that Watersipora sp. may settle and grow specifically on red algae in the genus Prionitis. To test this hypothesis, we surveyed the Eureka (California) Public Marina in Humboldt Bay on three different occasions in early spring, mid-summer, and late fall. We divided this marina into different sampling areas for each survey period so no area was surveyed more than once. A quadrant size of 30.48 X 30.48 cm was randomly placed along the waters edge up against the dock, and the presence or absence of Watersipora and Prionitis in each quadrant area was recorded. Our data does not show a positive correlation between the genus Prionitis and Watersipora in this fouling community; however, but further larval preference studies should be conducted to explore the early life history of Watersipora sp. to determine whether the presence of other species helps facilitate the invasion of this wide-spread bryozoan genus.