Changes in coral reef metabolism during the 2015 El Niño in the eastern Pacific

Wade R McGillis, Lamont Doherty Earth Observatory, Geochemistry, Palisades, NY, United States, Derek Manzello, Atlantic Oceanographic and Meteorological Laboratory, NOAA, Miami, FL, United States, Tyler B Smith, University of the Virgin Islands, Center for Marine and Environmental Studies, St. Thomas, United States, Andrew Baker, University of Miami, RSMAS, Miami, FL, United States, Peggy Fong, University of California, Los Angeles, Ecology and Evolutionary Biology, Los Angeles, CA, United States, Peter Glynn, University of Miami, Key Biscayne, FL, United States, Jennifer Smith, Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, United States, Yuichiro Takeshita, Carnegie Institution for Science, Department of Global Ecology, Stanford, CA, United States, Todd R Martz, University of California San Diego, La Jolla, CA, United States, Diana Hsueh, Columbia University, Palisades, NY, United States, Chris Langdon, Rosenstiel School of Marine and Atmospheric Science, Miami, FL, Nichole Price, Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States and Juan Mate, Smithsonian Tropical Research Institute, Panama City, Panama
Abstract:
The likely strong 2015-2016 El Niño event offers an opportunity to assess coral reef benthic metabolism under stressful high temperatures, coral bleaching, and mortality. During a period of increasing ocean temperatures caused by the 2015-2016 El Niño-Southern Oscillation (ENSO), we assessed the metabolism, at hourly intervals, of eastern Pacific coral reefs using the Benthic Ecosystem and Acidification Measurement System (BEAMS). We measured coral reef net ecosystem productivity (NEP) and net ecosystem calcification (NEC) in 2014 before the start of the El Niño event and in 2015 during the first anomalously high sea surface temperatures of the 2015 El Niño. Increases in ocean temperatures of 1-2°C between 2014 and 2015 caused over 30% decline in calcification at Uva Is. (Panama) and Darwin Is. (Galapagos), along with significant coral bleaching at Uva and coral paling at Darwin. Warming at Saboga Island, in the seasonally upwelling Gulf of Panama, was only ~0.3oC, did not result in significant bleaching, and was accompanied by a significant increase in coral reef metabolism. Additional key findings include an increase in nighttime dissolution of calcium carbonate during ENSO heating. Light-NEP and light-NEC relationships were generated for each location, and showed that variations in metabolism were strongly correlated with the incident bottom solar intensity, with strong daily cycles and patterns of light-enhanced calcification also identified. The response of different coral species also provides in situ data on the varying metabolism. The metabolism of the 2015-2016 El Niño shows the possible reef function under future warming and acidified conditions. These emerging results may be harbingers of significant further decreases in metabolism, and other detrimental impacts, if this region experiences additional warming during the current ENSO event.
Back to: Coral Reef Calcification in a Changing Ocean: From Microscale Mechanisms to Macroscale Responses III