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

Michael H. Graham, Brian P. Kinlan, Louis D. Druehl, Lauren E. Garske, and Stuart Banks
Created: 10/18/2018 - Updated: 7/18/2019


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 km2 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.


Sector Addressed: 
Target Climate Changes and Impacts: 
Type of Adaptation Action/Strategy: 
Natural Resource Management / Conservation
Create new refugia / Increase size and amount of protected areas
Habitat/Biome Type: 
Climate Type: 

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