Processing of dissolved organic matter by the green finger sponge, Iotrochota birotulata

Sponges are filter-feeding animals that process vast amounts of water, removing particulate and dissolved nutrients and releasing waste products. On coral reefs, sponge processing of seawater is likely to be an important factor structuring the composition and availability of dissolved organic matter (DOM) yet our understanding of this process and the impact to the reef is acutely limited. Here, we leveraged the low microbial symbiont diversity of the sponge, Iotrochota birotulata, with metagenomic analysis of the sponge to predict how the sponge and the single dominant bacterial symbiont (an uncharacterized gammaproteobacterium) may alter the DOM profile. Field-collected samples of incurrent and excurrent seawater for I. birotulata were used to create a profile of DOM for each sample type. DOM was extracted by solid phase extraction and analyzed by liquid chromatography and high-resolution mass spectrometry. Total organic carbon was lower on average in the excurrent water than the incurrent, although not significantly different. However, preliminary analysis of mass spectrometry data indicates a distinct profile of DOM between incurrent and excurrent samples. The predicted metabolite profile from the bacterial symbiont and the sponge will be compared to the observed DOM profiles to determine potential overlap in compounds. This work will deepen our understanding of factors that influence DOM composition on coral reefs and provide insight into the mechanism of how sponges, which are prominent filter feeders on many reefs, alter DOM composition.

Presentation Preference: Poster

Primary Presenter: Emma Rasco, Appalachian State University (rascoe@appstate.edu)

Authors:

Cole Easson, Middle Tennessee State University  (Cole.Easson@mtsu.edu)

Amy Apprill, Woods Hole Oceanographic Institution  (aapprill@whoi.edu)

Cara Fiore, Appalachian State University  (fiorec@appstate.edu)