Linking seasonal changes in benthic community structure to seawater chemistry

Ocean acidification (OA) resulting from rising atmospheric CO2 represents a potential threat to marine calcifiers and the ecosystems they inhabit. Numerous studies suggest that decreases in net calcification could compromise coral reef ecosystems within the next few decades to century. The effects of OA, combined with physiological stress from rising temperatures, are global changes thought to cause shifts in community structure that accelerate degradation of coral reefs. The Atlantic OA test-bed (AOAT) in La Parguera, Puerto Rico provides a natural laboratory to autonomously monitor seawater chemistry in situ and understand the unique set of feedbacks and interactions between water column chemistry and benthic habitats. In 2011, seasonal benthic habitat characterizations were conducted at two reefs and one seagrass site at La Parguera to quantify the abundance of major benthic calcifiers and relate changes in benthic community structure to any observed changes in seawater carbonate chemistry. Both reef sites were dominated by fleshy macroalgae, and live coral cover ranged from 8 to 10% in all seasons. Observed seasonal patterns in seawater aragonite saturation state were largely decoupled from subtle changes in both soft coral and calcareous algae abundance. Further investigation of the relationship between algal abundance and overlying water column chemistry is ongoing to improve our understanding of potential feedbacks between reef ecosystems and reef water chemistry.

Moyer R. P., Viehman T. S., Piniak G. A. & Gledhill D. K., 2012. Linking seasonal changes in benthic community structure to seawater chemistry. Proceedings of the 12th International Coral Reef Symposium, Cairns, Australia, 9-13 July 2012. 8D Effects of ocean acidification. 5 pp. Article.

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