DOM cycling on coral reefs: Assessing the impacts of macroalgae and emergent sponges on DOM composition

Sponges now dominate Caribbean reefs after decades of declines of reef-building corals. Unlike most benthic reef organisms, sponges are ecosystem engineers that filter huge volumes of seawater, turning-over the water-column and transforming seawater chemistry. Interestingly, the most common species of emergent (large, non-cryptic) sponges on Caribbean reefs range from those having a high abundance of microbial symbionts in their tissues (HMA) to those with low microbial abundance (LMA) and we have demonstrated that these two categories of emergent sponges had variable effects on DOM composition.  While the quantity of DOM in seawater commonly assessed, little is known about the finer-scale composition of the DOM that is processed by sponges.  In tandem, abundances of macroalgae and cyanobacteria are increasing on coral reefs and many species have been shown to generate large amounts DOM.  Using a suite of complimentary approaches, including new derivatization techniques, targeted analyses, untargeted metabolomics, and both on-reef and controlled laboratory experiments, we are beginning to generate a more detailed characterization of ambient and algal-derived DOM components in seawater and the effect of sponge processing. Results highlighting specific changes between algal species on DOM production and between HMA and LMA sponges on DOM composition will be presented.

Presentation Preference: Oral

Primary Presenter: Wendy Strangman, UNC Wilmington (strangmanw@uncw.edu)

Authors:

Lydia Davis, UNC Wilmington  (davisla@uncw.edui)

Zane Ritter, UNC Wilmington  (zgr7619@uncw.edu)

Courtney Clevenger, UNC Wilmington  (ctk6717@uncw.edu)

Kyler Sloan, UNC Wilmington  (kms1532@uncw.edu)

Megan Laufer, UNC Wilmington  (mcl8732@uncw.edu)

Christian Richter, UNC Wilmington  (cr5868@uncw.edu)

Cody Wilson, UNC Wilmington  (ctw7213@uncw.edu)

Ralph Mead, UNC Wilmington  (meadr@uncw.edu)

Joe Pawlik, UNC Wilmington  (pawlikj@uncw.edu)

Winn Johnson, UNC Wilmington  (johnsonw@uncw.edu)

Wendy Strangman, UNC Wilmington  (strangmanw@uncw.edu)