Research Technical Report

Growth and Distribution of the Invasive Bryozoan Watersipora in Monterey Harbor, California

Lonhart, S.I. (September 2012)

In: D.L. Steller and L.K. Lobel (editors), Diving for Science 2012. Proceedings of the American Academy of Underwater Sciences 31st Scientific Symposium. American Academy of Underwater Sciences, Dauphin Island, Alabama. p. 89-98.

ABSTRACT

Invasive species are common inhabitants of harbors along the coast of California. Tunicates, sponges, and bryozoans are among the more common invertebrates found in fouling communities on floating docks and pilings. An invasive bryozoan, tentatively identified as Watersipora subtorquata, has been in Monterey Harbor since the early 1990s, but only recently has it been detected outside of the harbor. Since relatively little is known about Watersipora and its interactions with other sessile species in California, sanctuary staff studied the growth and distribution of Watersipora in Monterey Harbor beginning in 2010. Sanctuary science divers used monthly fixed photo quadrats to collect percent cover data from cement pier piling surfaces in four orientations and at two depths. Colony growth of the invasive bryozoan was rapid (up to 0.33 mm/d) and exhibited differences by piling, orientation, and depth. Percent cover of several native invertebrate species was correlated with the presence/absence of Watersipora, and the invader has the potential to form monocultures, smothering all other species. Sanctuary staff will continue to characterize the spread of this invader within the harbor and collaborate with academic researchers to determine its ecological impact in nearby kelp forests.

Suggested Citation:

Lonhart, S.I. 2012. Growth and Distribution of the Invasive Bryozoan Watersipora in Monterey Harbor, California. In: D.L. Steller and L.K. Lobel (editors), Diving for Science 2012. Proceedings of the American Academy of Underwater Sciences 31st Scientific Symposium. American Academy of Underwater Sciences, Dauphin Island, Alabama. p. 89-98.