SOUTH CAROLINA
South Carolina's coast is rapidly developing but there are no coastal acidification monitoring programs in the state. Like other estuaries, marsh habitats and tidal creeks can have extremely high carbon dioxide content and low pH as a function of biological activity. Nevertheless, shifts in these extremes could impact South Carolina's culturally and economically important coastal resources.
SOUTH CAROLINA
CHEMISTRY
South Carolina does not have any ongoing acidification monitoring programs. The primary source of carbon chemistry information in South Carolina is from existing water quality programs that collect pH data. Complexities in pH measurement methods can limit the utility of these water quality programs for understanding long-term acidification trends, but this data, along with data from offshore and nearby states, could provide clues into South Carolina's future.
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IS CARBON DIOXIDE INCREASING? The lack of monitoring limits our understanding of acidification trends in the state, particularly in the dynamic estuaries. Water quality data from the National Estuarine Research Reserve System's ACE Basin and North Inlet-Winyah Bay do not show significant declines in average pH from 2002 to 2015. There is evidence that carbon dioxide is increasing on the shelf off the South Carolina coast and throughout the South Atlantic Bight.
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WHY? Scientists have found that this increasing trend in the South Atlantic Bight can be attributed to increased temperatures and increased carbon coming from rivers and marshes. When this organic carbon is broken down by microbes, CO2 is released and oxygen is consumed (just like when humans breathe). The rate of this breakdown increases in warmer temperatures. One important consideration is whether sea level rise will further increase this CO2 export from marshes in the future.
Monitoring Locations:
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ACE BASIN AND NORTH INLET-WINYAH BAY: These two estuarine sites are part of the National Estuarine Research Reserve System (NERRS) with ongoing water quality sampling programs and pH measurements. The NERRS data can be accessed here.
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UNIVERSITY OF GEORGIA/UNIVERSITY OF DELAWARE: Dr. Wei-Jun Cai's laboratory has been engaged in carbonate chemistry sampling in the South Atlantic Bight, including off the South Carolina coast, since the late 1990s. Access Dr. Cai's publications here.
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ECOA: The East Coast Ocean Acidification (ECOA) cruise (formerly the Gulf of Mexico and East Coast Carbon Cruise) passes by once every 3 years with a transect off the South Carolina coast. The research cruise is supported by the National Oceanic and Atmospheric's Ocean Acidification Program.
SOUTH CAROLINA
BIOLOGY
There is little research in South Carolina on the effects of acidification on the state's natural resources. Research from other states suggest some South Carolina resources could be vulnerable.
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OYSTERS AND CLAMS: Extreme natural conditions in South Carolina estuaries could render oysters less vulnerable to acidification but there has been little research to evaluate potential impacts on South Carolina populations. The pH in marsh habitats is frequently well-below the pH documented to have significant effects on female reproduction (pH <7.1). Even though South Carolina estuaries experience large swings in pH, research suggests these fluctuations do not necessarily protect organisms from impacts of acidification. Research evaluating impacts of high CO2 and insecticides on clams and oysters found higher larval clam mortality in high CO2 conditions than with the insecticide alone.
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SHRIMP AND BLUE CRABS: Findings on effects of acidification on crustaceans have been mixed. Studies of blue crabs in other states have shown that acidified conditions do not affect juvenile crab food consumption or growth, but that there may be impacts to larval development. There are no studies of acidification effects on species of shrimp commonly found in South Carolina, but northern shrimp show greater impacts from increased temperature than decreased pH. In the Pacific whiteleg shrimp, scientists found high CO2 conditions disrupted the normal acclimation response of the shrimp to low dissolved oxygen conditions.
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COLD-WATER CORAL: Cold-water corals can be found in deep waters off the coast of South Carolina. Large reefs of Lophelia were recently discovered 160 miles offshore of Charleston. Studies of this species from other regions show mixed effects of acidification, with high variability in how calcification responds to low pH conditions. Though corals may still be able to calcify, there may be risks of acidification to the whole reef framework.
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FISH: Juvenile and adult fish appear to be relatively resilient to acidification, with species such as cobia only showing effects in extreme conditions. Similarly, scup do not show effects of high CO2 conditions on their growth or survivability. There is some evidence from other regions that larval fish could be more susceptible, with research, for example, showing reduced survival and growth in silversides.
SOUTH CAROLINA
SOCIOECONOMICS
Estuaries and the organisms within them are vital cultural and economic resources in South Carolina.
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OYSTER HARVESTING: Oyster landings have increased seven-fold in South Carolina between 2007 and 2016 with the state accounting for a large portion of the oyster production in the South Atlantic Region. Due to a 2014 moratorium on oyster seed imports from states north, nearly all oyster seed for South Carolina oyster mariculture comes from a single hatchery. There is evidence that other species of oysters can be bred to be more resilient to acidification.
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OYSTER RESTORATION: Organized oyster restoration efforts in South Carolina began in 2001. These efforts place bags of oysters shells along shorelines that attract oyster larvae to settle on them. Research in the Chesapeake Bay show these restoration efforts can help buffer against low pH conditions.
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SOCIAL VULNERABILITY: South Carolina's social vulnerability of shellfisheries to acidification is considered medium because of the sensitivity of harvested species, poorly buffered rivers and localized potential for acidification, and low adaptation capacity .
WHO ARE THE SCIENTISTS?
Lou Burnett
College of Charleston
Lou Burnett is a professor emeritus of biology at the College of Charleston. He studies the responses of marine organisms to hypoxia and elevated CO2 and is interested in the effects of these two variables on animal performance and innate immunity. He was the former president of the Southern Association of Marine Laboratories and the Society for Integrative and Comparative Biology.
Photo credit for all images on this page: Travis Nickey, used with permission