Author: Emma  Saso,  Support Scientist (Smithsonian Institution, National Museum of Natural History)

Designation: 

Description:
The anthozoan subclass Octocorallia is diverse and globally distributed, populating a wide range of environments from deep to shallow water. In the deep sea, octocorals occur on seamounts, submarine canyons and hard-bottom reefs where they contribute to structural heterogeneity and habitat complexity, and engage in symbiotic relationships with various invertebrate and fish species. Despite the vital roles octocorals play as foundation species in deepwater ecosystems, the factors influencing their distribution and community composition are poorly understood. While technological advances in recent years have improved sampling capacity for deep benthic habitats, questions regarding deep-sea octocoral biogeography are complicated still by the existence of cryptic species and unresolved taxonomy, which have historically led to misinterpretations of species endemicity and population connectivity. While recent studies have suggested depth and water mass structure to influence species distribution more strongly than geographic distance, these patterns have not been comprehensively studied throughout the deep North Atlantic to date. The present study combines environmental and species presence data collected during several recent expeditions with previously published results to analyze biogeographic patterns of phylogenetic species diversity and composition across the North Atlantic. Over the course of 19 ROV and HOV <em>Alvin</em> dives in the area, 11 distinct sites spanning depths from 370 to 2800m were surveyed, and 185 octocoral specimens consisting of at least 45 unique species were collected and preserved. Genetic barcodes of <em>28S</em>, <em> COI</em>, and mt<em>MutS</em>  genes were sequenced for each specimen and used to delimit molecular operational taxonomic units (MOTUs) and species relatedness in phylogenetic diversity analyses. We investigated the roles of specific depth-related abiotic variables (i.e. water mass, temperature) and habitat features on distribution and community composition within a phylogenetic framework. The slow growing and highly adapted nature of octocorals makes them extremely susceptible to changing ocean conditions, oil extraction and bottom-trawling. Awareness of the environmental gradients impacting community composition and connectivity is key to informing successful management strategies to conserve these foundation species across the North Atlantic Ocean basin.

Category: Scientific Program Abstract > Special Sessions > CS24 Biodiversity