Dr. Christopher J. Freeman


Project Title:  Establishing Baselines for Symbiotic Interactions in Marine Sponges Across Naturally Occurring and Anthropogenic Gradients

Advisors:  Valerie Paul, Rachel Collin, Co-Advisor: Nancy Knowlton

In the marine environment, symbiotic interactions are exemplified by the mutualisms between benthic invertebrates and microbial and algal symbionts that allow these organisms to survive and compete for space in nutrient-poor waters. Although these symbioses are crucial for the maintenance of functional diversity in productive and diverse reef systems, our understanding of these interactions and factors structuring them or leading to their disruption is largely restricted to reef-building corals. By forming an ancient symbiosis with diverse and productive microbial communities, marine sponges represent a significant portion of the biomass on reef, seagrass, and hardbottom habitats throughout the world. Moreover, their nutritional diversity and flexibility makes them crucial to biogeochemical cycles and productivity in these distinct systems. However, as disease outbreaks and bleaching events increasingly lead to mass mortality of sponges, it becomes clear that there is a substantial gap in our knowledge of how sponges interact with their environment and how these interactions vary across large geographic regions and local habitats.

This proposal aims to 1) provide an initial evaluation of how these interactions vary across naturally occurring and anthropogenic gradients and 2) conduct experiments to assess whether land-based anthropogenic inputs impact holobiont productivity and the efficiency of nutrient assimilation and transfer to the host.