Data for: Transformation of dissolved organic matter by two Indo-Pacific sponges

Dissolved organic matter (DOM) is the largest organic carbon reservoir in
the ocean and an integral component of biogeochemical cycles. The role of
free-living microbes in DOM transformation has been studied thoroughly,
whereas little attention has been directed towards the influence of
benthic organisms. Sponges are efficient filter feeders and common
inhabitants of many benthic communities circumglobally. In our study, we
investigated how two tropical coral reef sponges shape marine DOM. We
compared bacterial abundance, inorganic and organic nutrients in off reef,
sponge inhalant, and sponge exhalant water of Melophlus sarasinorum and
Rhabdastrella globostellata. DOM and bacterial cells were taken up, and
dissolved inorganic nitrogen was released by the two Indo-Pacific sponges.
Both sponge species utilized a common set of 142 of a total of 3040
compounds detected in DOM on a molecular formula level via
ultrahigh-resolution mass spectrometry. In addition, species-specific
uptake was observed, likely due to differences in their associated
microbial communities. Overall, the sponges removed presumably semi-labile
and semi-refractory compounds from the water column, thereby competing
with pelagic bacteria. Within minutes, sponge holobionts altered the
molecular composition of surface water DOM (inhalant) into a composition
similar to deep-sea DOM (exhalent). The apparent radiocarbon age of DOM
increased consistently from off reef and inhalant to exhalant by about 900
14C years for M. sarasinorum. In the pelagic, similar transformations
require decades to centuries. Our results stress the dependence of DOM
lability definition on the respective environment and illustrate that
sponges are hotspots of DOM transformation in the ocean. Here, we provide
the data from this study. The four tables contain the metadata, bulk
measurements of dissolved organic carbon (DOC), total dissolved nitrogen,
NOx, and radiocarbon dating of DOC, bacterioplankton abundances measured
with a flow cytometer, and relative peak intensities of molecular formulas
obtained through Fourier-transform ion cyclotron resonance mass
spectrometry and the online tool ICBM-OCEAN.