Seawater nutrient/metabolite and flow cytometry metadata - Picoplankton incubation experiment 2020

Sponges are known for their efficient uptake of organic matter, both particulate (POM) and dissolved (DOM), from the water column, but there is also evidence that sponges, and their associated symbionts, produce DOM rich in nucleosides and other unidentified metabolites that is transferred to the surrounding reef via their exhalent seawater. However, little is known about the effect of this sponge metabolome on another vital component of reef ecosystems, picoplankton. If the metabolome impacts the structure of the picoplankton community, then there may be a subsequent alteration to the reef dissolved nutrient pool. To address these questions, we exposed Caribbean reef picoplankton communities to either filtered reef sea water (control) or a sponge exhalent metabolome mixture from two Caribbean sponges, Niphates digitalis and Xestospongia muta, in closed, dark incubations for 24 - 48 hours. Sponge exhalent and reef sea water, for use as media in the incubation experiment, was collected on 13-December-2020 from Looe Key Reef Sanctuary Preservation Area (24.54605, -81.40610) in the Florida Keys National Marine Sanctuary (FKNMS) as permitted via FKNMS-2020-149. We used flow cytometry to identify any changes in picoplankton cell concentrations following exposure to sponge-derived nutrients. We also used a cutting-edge suite of analyses to identify nutrient components contributed by the sponge holobiont to reef water and to monitor changes in the incubation bottles, including: targeted and untargeted metabolomics, fluorescent DOM (fDOM), dissolved combined neutral sugars (DCNS), total organic carbon (TOC), total nitrogen (TN), and inorganic nutrients.