UC San Diego

This thesis investigates the biodiversity and ecological roles of the genus Diopatra in the San Diego subtidal zone, focusing on the epifaunal communities found on their tube-caps in both kelp forest and sandy bottom habitats. Through molecular and morphological analyses, two distinct species of Diopatra were identified: Diopatra californica, a resurrected species that was previously synonymized with Diopatra splendidissima, and Diopatra ornata, with both species demonstrating clear habitat preferences. A comprehensive survey of the epifaunal communities on Diopatra tube-caps revealed at least 103 associated species, with significant differences in community composition based on habitat type – both arthropods and molluscs were significantly more abundant in the kelp forest compared to sandy bottoms. The study argues for the resurrection of Diopatra californica as a distinct species due to insufficient support for its synonymization with Diopatra splendidissima, stemming from subjective historical taxonomic practices based on cosmopolitanism. By highlighting the role of Diopatra as ecosystem engineers and the need for further research on their conservation status amidst threats like climate change and fishing practices, this work underscores the complexity of marine biodiversity and the intertwined fates of species within their ecological niches.