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Mucospheres produced by a mixotrophic protist impact ocean carbon cycling

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posted on 2023-05-21, 06:22 authored by Larsson, ME, Bramucci, AR, Collins, S, Gustaaf HallegraeffGustaaf Hallegraeff, Kahlke, T, Raina, J-B, Seymour, JR, Doblin, MA

Mixotrophic protists (unicellular eukaryotes) that engage in both phototrophy (photosynthesis) and phago-heterotrophy (engulfment of particles)—are predicted to contribute substantially to energy fluxes and marine biogeochemical cycles. However, their impact remains largely unquantified. Here we describe the sophisticated foraging strategy of a widespread mixotrophic dinoflagellate, involving the production of carbon-rich ‘mucospheres’ that attract, capture, and immobilise microbial prey facilitating their consumption. We provide a detailed characterisation of this previously undescribed behaviour and reveal that it represents an overlooked, yet quantitatively significant mechanism for oceanic carbon fluxes. Following feeding, the mucospheres laden with surplus prey are discarded and sink, contributing an estimated 0.17–1.24 mg m−2 d−1 of particulate organic carbon, or 0.02–0.15 Gt to the biological pump annually, which represents 0.1–0.7% of the estimated total export from the euphotic zone. These findings demonstrate how the complex foraging behaviour of a single species of mixotrophic protist can disproportionally contribute to the vertical flux of carbon in the ocean.

History

Publication title

Nature Communications

Volume

13

Article number

1301

Number

1301

Pagination

1-15

ISSN

2041-1723

Department/School

Institute for Marine and Antarctic Studies

Publisher

Nature Publishing Group

Place of publication

United Kingdom

Rights statement

Copyright 2022 The Author(s) Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

Repository Status

  • Open

Socio-economic Objectives

Coastal or estuarine biodiversity; Oceanic processes (excl. in the Antarctic and Southern Ocean)

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