On the paradox of thriving cold-water coral reefs in the food-limited deep sea |
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Authors: | Sandra R Maier Sandra Brooke Laurence H De Clippele Evert de Froe Anna-Selma van der Kaaden Tina Kutti Furu Mienis Dick van Oevelen |
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Institution: | 1. Greenland Climate Research Centre, Greenland Institute of Natural Resources, Kivioq 2, PO Box 570, Nuuk, 3900 Greenland;2. Coastal & Marine Laboratory, Florida State University, 3618 Coastal Highway 98, St. Teresa, FL, 32327 USA;3. Changing Oceans Research Group, School of GeoSciences, University of Edinburgh, Grant Institute, King's Buildings, Edinburgh, EH9 3FE UK;4. Centre for Fisheries Ecosystem Research, Fisheries and Marine Institute at Memorial University of Newfoundland, 155 Ridge Rd, St. John's, NL A1C 5R3 Newfoundland and Labrador, Canada;5. Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research (NIOZ), Korringaweg 7, Yerseke, 4401 NT The Netherlands;6. Institute of Marine Research (IMR), PO box 1870 Nordnes, Bergen, NO-5817 Norway;7. Department of Ocean Systems, Royal Netherlands Institute for Sea Research (NIOZ), PO Box 59, Den Burg (Texel), 1790 AB The Netherlands |
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Abstract: | The deep sea is amongst the most food-limited habitats on Earth, as only a small fraction (<4%) of the surface primary production is exported below 200 m water depth. Here, cold-water coral (CWC) reefs form oases of life: their biodiversity compares with tropical coral reefs, their biomass and metabolic activity exceed other deep-sea ecosystems by far. We critically assess the paradox of thriving CWC reefs in the food-limited deep sea, by reviewing the literature and open-access data on CWC habitats. This review shows firstly that CWCs typically occur in areas where the food supply is not constantly low, but undergoes pronounced temporal variation. High currents, downwelling and/or vertically migrating zooplankton temporally boost the export of surface organic matter to the seabed, creating ‘feast’ conditions, interspersed with ‘famine’ periods during the non-productive season. Secondly, CWCs, particularly the most common reef-builder Desmophyllum pertusum (formerly known as Lophelia pertusa), are well adapted to these fluctuations in food availability. Laboratory and in situ measurements revealed their dietary flexibility, tissue reserves, and temporal variation in growth and energy allocation. Thirdly, the high structural and functional diversity of CWC reefs increases resource retention: acting as giant filters and sustaining complex food webs with diverse recycling pathways, the reefs optimise resource gains over losses. Anthropogenic pressures, including climate change and ocean acidification, threaten this fragile equilibrium through decreased resource supply, increased energy costs, and dissolution of the calcium-carbonate reef framework. Based on this review, we suggest additional criteria to judge the health of CWC reefs and their chance to persist in the future. |
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Keywords: | trophic interaction carbon nitrogen respiration recycling loop ecosystem engineer organic matter cold-water coral reef climate change food web |
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