The effects of ocean acidification on benthic reef communities

Atmospheric C02 has been increasing since the pre-industrial era, reducing the ocean pH and causing a shift in the carbonate chemistry by ocean acidification (OA). As a result of increasing partial pressures of carbon dioxide in the marine environment, previous studies have shown that coral reef species experience decreases in growth, reproduction, and survival. In this mesocosm study, terra cotta tiles maintained at Little Conch Reef for two years were relocated to experimental tanks, including four control tanks and four tanks with elevated pC02 to assess the effects of OA on non-calcifying & calcifying organisms, and the reef community structure. There was a significant decrease in crustose coralline algae on the bottom community of the tiles under OA conditions and a significant increase in turf algae on the side community in the treatment tanks. Therefore, these results indicate that ocean acidification not only affects individual organisms, but the associations among various reef community organisms, and may cause detrimental shifts in community structure. The mesocosm methodology allows for controlled and simultaneous investigation of species-specific and multi-taxa responses to increases in exposure to pC02