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Proc Natl Acad Sci U S A. 2007 Oct 16;104(42):16576-80. Epub 2007 Oct 3.

Deep-water kelp refugia as potential hotspots of tropical marine diversity and productivity.

Author information

1
Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA. mgraham@mlml.calstate.edu

Abstract

Classic marine ecological paradigms view kelp forests as inherently temperate-boreal phenomena replaced by coral reefs in tropical waters. These paradigms hinge on the notion that tropical surface waters are too warm and nutrient-depleted to support kelp productivity and survival. We present a synthetic oceanographic and ecophysiological model that accurately identifies all known kelp populations and, by using the same criteria, predicts the existence of >23,500 km(2) unexplored submerged (30- to 200-m depth) tropical kelp habitats. Predicted tropical kelp habitats were most probable in regions where bathymetry and upwelling resulted in mixed-layer shoaling above the depth of minimum annual irradiance dose for kelp survival. Using model predictions, we discovered extensive new deep-water Eisenia galapagensis populations in the Galápagos that increased in abundance with increasing depth to >60 m, complete with cold-water flora and fauna of temperate affinities. The predictability of deep-water kelp habitat and the discovery of expansive deep-water Galápagos kelp forests validate the extent of deep-water tropical kelp refugia, with potential implications for regional productivity and biodiversity, tropical food web ecology, and understanding of the resilience of tropical marine systems to climate change.

PMID:
17913882
PMCID:
PMC2034254
DOI:
10.1073/pnas.0704778104
[Indexed for MEDLINE]
Free PMC Article

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