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Mote Marine Laboratory research programs represented on this page: Chemical & Physical Ecology Program • Ocean Acidification Research Program
Stories on this page: CAOS for corals in a changing climate • First big-picture view of acidification in the U.S. Southeast
CAOS FOR CORALS IN A CHANGING CLIMATE
Coral reefs are threatened by climate change impacts—ocean acidification and warming temperatures driven by excess carbon dioxide—around the world. Fortunately, scientists from far and wide are able to study and address climate impacts using Mote’s state-of-the-art Climate and Acidification Ocean Simulator (CAOS) in the Florida Keys, which was abuzz with new studies this year despite the challenges of COVID-19.
Mote’s CAOS system was filled to capacity with research projects in August and September 2020 and was otherwise busy during the past fiscal year, supporting the work of six Mote programs along with University of Virginia, Pennsylvania State University, Oregon State University, San Francisco State University, Utrecht University (Netherlands), University of Glasgow (Scotland), Louisiana State University, and College of the Florida Keys.
FIRST BIG-PICTURE VIEW OF ACIDIFICATION IN THE U.S. SOUTHEAST
Ocean acidification is not only a concern for corals, but is clearly damaging other marine resources that support livelihoods in parts of the world—such as oyster farms in the Pacific Northwest. In some regions and species, however, its impacts are far less clear. This year, Mote scientists and partners published the first-ever scientific review of acidification in the U.S. Southeast—a place with less acidification research historically but with valuable marine resources that are likely to struggle as this ocean chemistry shift continues.
The article “Acidification in the U.S. Southeast: Causes, Potential Consequences and the Role of the Southeast Ocean and Coastal Acidification Network,” was published in the peer-reviewed journal Frontiers in Marine Science by researchers from Mote and 20 other institutions. Its authors examine a diverse array of studies published to date, teasing out themes and trends that natural resource managers, scientists, marine industry leaders and communities should heed regarding global ocean acidification (driven by carbon dioxide from human activity) and local, coastal acidification driven by multiple processes both natural (such as decomposing organic matter) and human-driven (such as polluted stormwater runoff).
Writing on behalf of the Southeast Ocean and Coastal Acidification Network (SOCAN), the authors highlighted these and other key points:
- Shellfish aren’t just under threat in the Pacific Northwest.
The larvae of hard clams (Mercenaria mercenaria), a major part of ocean-driven economies in the U.S. Southeast, can be negatively influenced by acidification—with experiments showing survival declines and physical harm even at moderate levels of carbon dioxide, along with reduced toughness in juvenile clams’ shells. Eastern oysters (Crassostrea virginica) also show vulnerabilities in lab studies.
It is important to determine if acidification impacts on shellfish in the lab are occurring, or will occur, in U.S. Southeast marine environments. There, shellfish producers have anecdotally noted occasional issues with larval or shell development without obvious causes—a mystery in need of more scientific attention and support.
- Acidification can chip away at coral reefs’ foundations.
Hard corals build calcium-carbonate skeletons that form the foundations of coral reefs and allow them to provide habitat for countless marine species while also buffering storm waves and protecting coastlines. Acidification can impede coral skeleton formation and even erode reef structure. While most of Florida’s Coral Reef still produces more calcium carbonate than it loses, reef calcification is just 10% of its historical rate and on the northernmost reefs in the system are losing calcium carbonate faster than they replace it each year. In general, Florida’s Coral Reef is now in deeper water—depths not predicted until close to year 2100—due to reef erosion and sea level rise (another component of climate change). If reef growth can’t keep pace with rising seas, the reefs will be less able to protect coastal communities against storm waves. Research by Mote and others also suggest that coral wound recovery, reproduction and recruitment (having new offspring settle on the reef) are also affected by acidification. In addition to the relatively shallow system of Florida’s Coral Reef, southeastern U.S. reefs in deeper, colder water are also likely to face risks as acidification increases.
- Acidification combined with low oxygen can have surprising effects—such increasing the toxicity of certain mosquito-control pesticides to clams and oysters.
- There are significant knowledge gaps about acidification impacts on fish, harmful algal blooms and other microscopic algae dynamics. More studies are also needed to identify “refugia” (where features of the local environment help protect against acidification), and understand how natural communities of multiple species respond to acidification collectively. The southeastern U.S. also has significant geographic gaps in detecting and monitoring acidification.
- Based on these and other findings, the organization SOCAN—whose leadership includes Mote scientists—recommends multiple research priorities for acidification in the U.S. southeast:
- Multiple and/or compounding drivers of acidification
- Single organism and community investigation on impacts of acidification
- Life-stage analyses of “important” organisms
- Effects of acidification on harmful algae species
- Buffering capacity of coastal areas to acidification
- Monitoring of estuarine and riverine acidification
- Social and economic impacts from acidification
- Partnering with local management and industry to understand local impacts of acidification