A change in coral extension rates and stable isotopes after El Niño-induced coral bleaching and regional stress events.
Coral reefs are biologically diverse ecosystems threatened with effective collapse under rapid climate change, in particular by recent increases in ocean temperatures. Coral bleaching has occurred during major El Niño warming events, at times leading to the die-off of entire coral reefs. Here we present records of stable isotopic composition, Sr/Ca ratios and extension rate (1940-2004) in coral aragonite from a northern Venezuelan site, where reefs were strongly impacted by bleaching following the 1997-98 El Niño. We assess the impact of past warming events on coral extension rates and geochemical proxies. A marked decrease in coral (Pseudodiploria strigosa) extension rates coincides with a baseline shift to more negative values in oxygen and carbon isotopic composition after 1997-98, while a neighboring coral (Siderastrea siderea) recovered to pre-bleaching extension rates simultaneously. However, other stressors, besides high temperature, might also have influenced coral physiology and geochemistry. Coastal Venezuelan reefs were exposed to a series of extreme environmental fluctuations since the mid-1990s, i.e. upwelling, extreme rainfall and sediment input from landslides. This work provides important new data on the potential impacts of multiple regional stress events on coral isotopic compositions and raises questions about the long-term influence on coral-based paleoclimate reconstructions.
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Wischhofstr. 1-3, 24148 Kiel, Germany.
S
S
Hetzinger
Geological Institute, RWTH Aachen University, Wüllnerstrasse 2, D-52056 Aachen, Germany.
M
M
Pfeiffer
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Wischhofstr. 1-3, 24148 Kiel, Germany.
W-Chr
WC
Dullo
Curtin University of Technology, Dept. of Environment and Agriculture, Bentley, Western Australia 6102, Australia.|School of Geography, Archaeology and Environmental Studies, University of Witwatersrand, Johannesburg, South Africa.|Australian Institute of Marine Science, Nedlands, WA 6009, Australia.|Freie Universität Berlin, Institute for Paleontology, Malteserstrasse 74-100, 12249 Berlin, Germany.
J
J
Zinke
Institut für Geowissenschaften, CAU Kiel, Ludewig-Meyn-Strasse 10, D-24118 Kiel, Germany.
D
D
Garbe-Schönberg
D000818:Animals; D037421:Anthozoa / Q000378:metabolism*; D002118:Calcium / Q000032:analysis*; D002119:Calcium Carbonate / Q000032:analysis*; D057231:Climate Change; D057894:Coral Reefs; D059000:El Nino-Southern Oscillation; D006358:Hot Temperature; D009792:Oceans and Seas; D013324:Strontium / Q000032:analysis*; D014687:Venezuela
D002119:Calcium Carbonate; D002118:Calcium; D013324:Strontium