Single-cell visualization indicates direct role of sponge host in uptake of dissolved organic matter

Michelle Achlatis, Mathieu Pernice, Kathryn Green, Jasper M. de Goeij, Paul Guagliardo, Matthew R. Kilburn, Ove Hoegh-Guldberg, Sophie Dove

Research output: Contribution to journalArticlepeer-review

21 Citations (Web of Science)

Abstract

Marine sponges are set to become more abundant in many near-future oligotrophic environments, where they play crucial roles in nutrient cycling. Of high importance is their mass turnover of dissolved organic matter (DOM), a heterogeneous mixture that constitutes the largest fraction of organic matter in the ocean and is recycled primarily by bacterial mediation. Little is known, however, about the mechanism that enables sponges to incorporate large quantities of DOM in their nutrition, unlike most other invertebrates. Here, we examine the cellular capacity for direct processing of DOM, and the fate of the processed matter, inside a dinoflagellate-hosting bioeroding sponge that is prominent on Indo-Pacific coral reefs. Integrating transmission electron microscopy with nanoscale secondary ion mass spectrometry, we track 15N- and 13C-enriched DOM over time at the individual cell level of an intact sponge holobiont. We show initial high enrichment in the filter-feeding cells of the sponge, providing visual evidence of their capacity to process DOM through pinocytosis without mediation of resident bacteria. Subsequent enrichment of the endosymbiotic dinoflagellates also suggests sharing of host nitrogenous wastes. Our results shed light on the physiological mechanism behind the ecologically important ability of sponges to cycle DOM via the recently described sponge loop.

Original languageEnglish
Article number20192153
Number of pages1
JournalProceedings. Biological sciences
Volume286
Issue number1916
DOIs
Publication statusPublished - 4 Dec 2019

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