Sponge exhalent seawater contains a unique chemical profile of dissolved organic matter

Abstract

Sponges are efficient filter feeders, removing significant portions of particulate and dissolved organic matter (POM, DOM) from the water column. While the assimilation and respiration of POM and DOM by sponges and their abundant microbial symbiont communities have received much attention, there is virtually no information on the impact of sponge holobiont metabolism on the composition of DOM at a molecular-level. We applied untargeted and targeted metabolomics techniques to characterize DOM in seawater samples prior to entering the sponge (inhalant reef water), in samples exiting the sponge (exhalent seawater), and in samples collected just outside the reef area (off reef seawater). Samples were collected from two sponge species, Ircinia campana and Spheciospongia vesparium, on a near-shore hard bottom reef in the Florida Keys. Metabolic profiles generated from untargeted metabolomics analysis indicated that many more compounds were enhanced in the exhalent samples than in the inhalant samples. Targeted metabolomics analysis revealed differences in diversity and concentration of metabolites between exhalent and off reef seawater. For example, most of the nucleosides were enriched in the exhalent seawater, while the aromatic amino acids, caffeine and the nucleoside xanthosine were elevated in the off reef water samples. Although the metabolic profile of the exhalent seawater was unique, the impact of sponge metabolism on the overall reef DOM profile was spatially limited in our study. There were also no significant differences in the metabolic profiles of exhalent water between the two sponge species, potentially indicating that there is a characteristic DOM profile in the exhalent seawater of Caribbean sponges. Additional work is needed to determine whether the impact of sponge DOM is greater in habitats with higher sponge cover and diversity. This work provides the first insight into the molecular-level impact of sponge holobiont metabolism on reef DOM and establishes a foundation for future experimental studies addressing the influence of sponge-derived DOM on chemical and ecological processes in coral reef ecosystems.

Trophic niche separation that facilitates co‐existence of high and low microbial abundance sponges is revealed by in situ study of carbon and nitrogen fluxes

“…Pawlik et al () recently suggested that sponges might use the refractory fraction of DOC, but this suggestion is not supported by empirical data. Our understanding of the metabolism of DOC by sponges is in its infancy but see Fiore et al (); the elucidation of DOC composition and transformation by the holobiont still needs to be addressed.…”

Temperature‐ and size‐associated differences in the skeletal structures and osculum cross‐sectional area influence the pumping rate of contractile sponge Cinachyrella cf. cavernosa

“…This technique does not give information on the precise characteristics of the flow, such as the velocity distribution and the fluid flow profile (plug or parabolic). However, proximate estimates of sponge pumping rate can be obtained using this technique (Fiore, Freeman, & Kujawinski, ; Weisz et al, ). In the present study, an underwater video camera was set up directly in front of the sponge osculum, and small amounts (2–3 ml) of a concentrated fluorescein dye solution were released into the ambient water, near the sponge osculum.…”

Using genetics to inform restoration and predict resilience in declining populations of a keystone marine sponge

“…Moreover, sponge endosymbionts are important in creating soundscapes that form an acoustic cue for larval settlement in a variety of taxa (Butler et al 2016). As filter feeders, sponges drive nutrient cycling dynamics in the area (Fiore et al 2017;Hoer et al 2018;Valentine and Butler 2019), and contribute to the maintenance of water quality (Peterson et al 2006;Butler et al 2018).…”