Multi-trophic markers illuminate the understanding of the functioning of a remote, low coral cover Marquesan coral reef food web

• Published in: Scientific reports Vol. 11; no. 1; pp. 20950 - 14
• Main Authors: Fey, Pauline, Parravicini, Valeriano, Bănaru, Daniela, Dierking, Jan, Galzin, René, Lebreton, Benoit, Meziane, Tarik, Polunin, Nicholas V. C., Zubia, Mayalen, Letourneur, Yves
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.10.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 704/158; 704/829; Algae; Animals; Biodiversity and Ecology; Coral reef ecosystems; Coral Reefs; Ecological function; Ecosystem; Ecosystems; Environmental Sciences; Eutrophic environments; Eutrophic waters; Eutrophication; Fatty acids; Fatty Acids - analysis; Fishes - physiology; Food; Food Chain; Food chains; Food sources; Food webs; Herbivorous fish; Herbivory; Hot Temperature; Humanities and Social Sciences; Isotope Labeling; Isotopes; multidisciplinary; Organic matter; Phytoplankton; Phytoplankton - chemistry; Polynesia; Science; Science (multidisciplinary); Sciences of the Universe; Sea surface temperature; Seasonal variations; Seaweed - chemistry; Seaweeds; Stable isotopes; Trophic levels; Zooplankton; Zooplankton - physiology; Polynesia
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-00348-w

We studied the food web structure and functioning of a coral reef ecosystem in the Marquesas Islands, French Polynesia, characterized by low coral cover, high sea surface temperature and meso- to eutrophic waters. The Marquesas constitute a relevant ecosystem to understand the functioning of low diversity reefs that are also subject to global change. A multi-tracer assessment of organic matter pathways was run to delineate ecosystem functioning, using analysis of fatty acids, bulk and compound specific stable isotope analysis and stable isotopes mixing models. Macroalgae and phytoplankton were the two major food sources fueling this food web with, however, some marked seasonal variations. Specifically, zooplankton relied on phytoplankton-derived organic matter and herbivorous fishes on macroalgae-derived organic matter to a much higher extent in summer than in winter (~ 75% vs.  ~ 15%, and ~ 70 to 75% vs.  ~ 5 to 15%, respectively) . Despite remarkably high δ 15 N values for all trophic compartments, likely due to local dynamics in the nitrogen stock, trophic levels of consumers were similar to those of other coral reef ecosystems. These findings shed light on the functioning of low coral cover systems, which are expected to expand worldwide under global change.