Seasonal Increase Of Undescribed Bryozoan Species Genus Watersipora In Marine Fouling Communites In Humboldt Bay

Invasive marine bryozoans in the genus Watersipora are widespread in bays and harbors around the world, having become the dominant bryozoan in many near-shore habitats.  The number of species in this genus, and their life-history characteristics remain relatively unknown. This prevents a complete understanding of the invasion dynamics of this highly successful exotic species.  We hypothesized that there would  be a seasonal increase in Watersipora between late spring and early fall in Humboldt Bay, California, based on previous observations of increased larval release in late summer in this genus.  To test this hypothesis, we surveyed the docks at Eureka Public Marina (Humboldt Bay, CA) where undescribed species of Watersipora have been previously documented. This marina was divided into seven sections, which provided six to eight samples on each dock, one sample taken on each side.  A quadrant size of 1’ x 1’ was used to sample randomly chosen locations just below the waterline on each side of the dock.  Notation was made if Watersipora was present or absent at each location along these docks.  This method was performed in late spring, mid- summer, and early fall.  Our data indicates that Watersipora increased in abundance through early fall, consistent with a potential increase in sexual reproduction with increasing water temperature.  Although we cannot rule out the possibility that further introduction of this species onto these docks in late summer lead to this increase, we plan to use highly variable genetic (microsatellite) markers to further elucidate the causes of this seasonal increase.