First report of genetic data from two invasive Watersipora (Bryozoa) species in the central California coast rocky intertidal

Abstract

Several taxa forming a species complex within the bryozoan genus Watersipora are successful global marine invaders that are common in marine fouling communities in bays and harbors. This species complex has recently been recorded spreading to natural intertidal and subtidal habitats on the central California outer coast near the San Francisco Bay, suggesting that its invasive potential is greater than previously believed. To determine the species and clades present in these outer coast populations, and their relationship to populations in nearby bays and harbors, we produced COI sequences for a set of new Watersipora specimens sampled from four rocky intertidal sites, for which there is currently no published genetic data. Watersipora subtorquata and Watersipora new species were both identified at rocky intertidal sites. All haplotypes identified in this analysis have previously been reported in California harbors and marinas, suggesting that intertidal populations may be sourced from existing populations in harbors, rather than representing independent invasions. Field observations of intertidal populations support Watersipora ’s year-round persistence at rocky intertidal sites , which has significant implications for invasion dynamics and invasion management strategies. Continued sequencing of outer coast Watersipora samples will be crucial to further characterize the genetic diversity and structure of these coastal populations and describe the dynamics of Watersipora ’s outer coast spread.