Corals that host endosymbiotic dinoflagellates maintain the majority of their metabolisms through photoautotrophy, and the coral host can additionally feed heterotrophically. These feeding modes can be regulated by some corals, and an increase of heterotrophic feeding during thermal stress can increase resilience of the coral holobiont. This two part laboratory-based study examines the degree of heterotrophic plasticity of two scleractinian corals, Acropora azurea and Pocillopora damicornis, at normal water temperatures and elevated temperatures. A. azurea has a higher predicted bleaching susceptibility compared to P. damicornis, and the two species may regulate their heterotrophic capacities to differing degrees with increased water temperatures. The heterotrophic capacities for A. azurea are not currently known, while P. damicornis is recognized to rely on heterotrophy to maintain metabolic functions. One controlled experiment examines the clearance rates that each coral species removes natural planktonic assemblages in water from Pago Bay, Guam. This research provides the opportunity to assess the size-fractionated planktonic community structure in a nearshore reef environment, which is poorly understood throughout Micronesia. In an additional controlled experiment, each coral species will be fed with isotopically enriched Artemia nauplii and assessed for the contribution of photoautotrophy and heterotrophy to the holobiont through carbon-13 and nitrogen-15 stable isotope analysis of coral tissue and endosymbionts.

Primary Presenter: Star Dressler, University of Guam (dresslerc@gotritons.uog.edu)

Authors:

Atsushi Fujimura,   ()

Heloise Rouze,   ()

Christine Ferrier-Pages,   ()