El Niño,grazers and fisheries interact to greatly elevate extinction risk for Galapagos marine species |
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| Authors: | GRAHAM J EDGAR STUART A BANKS MARGARITA BRANDT RODRIGO H BUSTAMANTE ANGEL CHIRIBOGA SYLVIA A EARLE LAUREN E GARSKE PETER W GLYNN JACK S GROVE SCOTT HENDERSON CLEVE P HICKMAN KATHY A MILLER FERNANDO RIVERA GERALD M WELLINGTON |
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| Institution: | 1. Charles Darwin Foundation, Puerto Ayora, Galapagos, Ecuador;2. Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, PO Box 252‐49, Hobart, Tasmania 7001, Australia;3. Conservation International, 2011 Crystal Drive Suite 500, Arlington, VA 22202, USA;4. CSIRO Marine and Atmospheric Research, PO Box 120, Cleveland 4163, Qld, Australia;5. National Geographic Society, 1145 17th Street NW, Washington, DC 20036, USA;6. Bodega Marine Lab, University of California at Davis, 2099 Westside Road, Bodega Bay, CA 94923, USA;7. Division of Marine Biology and Fisheries, Rosenstiel School of Marine & Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149‐1098, USA;8. Section of Fishes Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles, CA 90007 USA;9. Conservation International, Puerto Ayora, Galapagos, Ecuador;10. Department of Biology, Washington & Lee University, Lexington, VA 24450, USA;11. University Herbarium, 1001 Valley Life Sciences Building #2465, University of California, Berkeley, CA 94720‐2465, USA;12. Department of Zoology, University of Melbourne, Parkville, Vic. 3010, Australia;13. Department of Biology and Biochemistry, University of Houston, Houston, TX 77204‐5001, USA |
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| Abstract: | Comparisons between historical and recent ecological datasets indicate that shallow reef habitats across the central Galapagos Archipelago underwent major transformation at the time of the severe 1982/1983 El Niño warming event. Heavily grazed reefs with crustose coralline algae (‘urchin barrens’) replaced former macroalgal and coral habitats, resulting in large local and regional declines in biodiversity. Following recent threat assessment workshops, a total of five mammals, six birds, five reptiles, six fishes, one echinoderm, seven corals, six brown algae and nine red algae reported from coastal environments in Galapagos are now recognized as globally threatened. The 2008 International Union for the Conservation of Nature (IUCN) Red List includes 43 of these species, while two additional species (Galapagos damsel Azurina eupalama and 24‐rayed sunstar Heliaster solaris) not seen for > 25 years also fulfil IUCN threatened species criteria. Two endemic species (Galapagos stringweed Bifurcaria galapagensis and the damselfish A. eupalama) are now regarded as probably extinct, while an additional six macroalgal species (Dictyota galapagensis, Spatoglossum schmittii, Desmarestia tropica, Phycodrina elegans, Gracilaria skottsbergii and Galaxaura barbata) and the seastar H. solaris are possibly extinct. The removal of large lobster and fish predators by artisanal fishing probably magnified impacts of the 1982/1983 El Niño through a cascade of indirect effects involving population expansion of grazing sea urchins. Marine protected areas with adequate enforcement are predicted to ameliorate but not eliminate ecosystem impacts caused by increasing thermal anomalies associated with El Niño and global climate change. |
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| Keywords: | climate change effects of fishing marine protected area sea urchin threatened species trophic cascade |
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