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Tracing 13C‐enriched dissolved and particulate organic carbon in the bacteria‐containing coral reef sponge Halisarca caerulea: Evidence for DOM‐feeding
Author(s) -
de Goeij Jasper M.,
Moodley Leon,
Houtekamer Marco,
Carballeira Néstor M.,
van Duyl Fleur C.
Publication year - 2008
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2008.53.4.1376
Subject(s) - sponge , dissolved organic carbon , coral reef , organic matter , reef , biology , coral , environmental chemistry , ecology , botany , chemistry
Here we report on the trophodynamics of the bacteria‐containing coral reef sponge Halisarca caerulea . The assimilation and respiration of the 13 C‐enriched substrates glucose, algal‐derived dissolved and particulate organic matter (diatom‐DOM and ‐POM), and bacteria were followed in 1‐ and 6‐h incubations. Except for glucose, all substrates were readily processed by the sponge, with assimilation being the major fate. 13 C‐Enrichment patterns in fatty acid biomarkers revealed that sponge dissolved organic 13 C assimilation was both direct and bacteria mediated as tracer carbon was recovered both in bacteria‐specific and nonbacterial fatty acid. This is the first direct evidence of DOM incorporation by sponges. The present study demonstrates that the encrusting sponge H. caerulea feeds on both DOM and POM and given their dominant coverage of the largest coral reef habitat (coral cavities) it is proposed that organic matter assimilation by cryptic reef sponges may represent an important, largely overlooked ecological function. Quantitatively significant DOM processing may not be the exclusive function of the microbial world on coral reefs; sponges transform DOM to biomass, and thus retain and store organic matter in the reef system.