The Impact of Ocean Acidification on the Calcification of Reef-Building Corals and Coral Reef Communities

EPA Grant Number: FP917446
Title: The Impact of Ocean Acidification on the Calcification of Reef-Building Corals and Coral Reef Communities
Investigators: Crook, Elizabeth D
Institution: University of California - Santa Cruz
EPA Project Officer: Michaud, Jayne
Project Period: September 1, 2012 through August 31, 2015
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2012) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Marine/Environmental Science


This research focuses on how decreasing pH may impact the calcification of coral reef ecosystems using a field site in the Caribbean that experiences natural acidification. The study will assess the impact of low pH water on organismal recruitment and subsequent individual and community development (succession). Additionally, this work aims to determine the calcification rates, lipid analysis and zooxanthellae counts of corals at the sites of low pH water to assess their relative growth rates and overall health when compared to corals at control sites.


To determine how ocean acidification will impact reef community development, experimental recruitment tiles have been deployed in the field (in both low pH and ambient zones) and will be retrieved after a period of approximately 14 months. These tiles then will be analyzed to determine differences in community structure and net calcification between the experimental and control tiles. To assess how ocean acidification will affect coral calcification, coral cores and coral tissue samples obtained from the low pH and control sites will be analyzed. The coral cores will be scanned by computed tomography, and the density, annual linear extension and calcification rates of the cores will be assessed. Additionally, tissue samples will be analyzed to address the overall health of polyps living in low pH seawater.

Expected Results:

It is expected that coral calcification will decrease with decreasing pH, in addition to net community calcification rates. Specifically, the low pH water should negatively impact coral larvae recruitment and growth, as well as the settlement and growth of other calcifying organisms (such as crustose coralline algae and calcifying macroalgae). Moreover, it is likely that corals residing in the low pH seawater will have decreased density, linear extension and calcification rates.

Potential to Further Environmental/Human Health Protection

This research has the potential to aid in the understanding of how reef environments will be impacted by future increases in carbon dioxide. Combined, these projects should be adequate to assess the health of the reef in the proximity of the ojos, and to ascertain whether any ecosystemwide or species-specific adaptations have been made with respect to low pH waters over time. The results will have implications for the long-term changes that could be expected in coral reef ecosystems in response to future ocean acidification and associated pH changes; therefore, they have the potential to impact a much broader framework of mitigation strategies and environmental decision making, public awareness and advanced sustainability of coral reefs in acidified oceans.

Supplemental Keywords:

ocean acidification, coral reefs, pH

Progress and Final Reports:

  • 2013
  • 2014
  • Final