Study examines how the Atlantic surfclam is successfully adapting to climate change – Mongabay.com

Study examines how the Atlantic surfclam is successfully adapting to climate change – Mongabay.com

  • Global climate change poses a severe threat to marine life, but scientists have found at least one species that appears to be successfully adapting to warmer ocean waters.
  • A recent study published in the Proceedings of the National Academy of Sciences found that, even without factoring in the impacts of fishing, global animal biomass in Earth’s oceans is expected to decrease by as much as 17 percent by 2100 under a “high emissions” scenario that leads to 3-4 degrees Celsius of warming.
  • However, a new study published in the journal Marine Ecology Progress Series, shows that, as ocean temperatures rise, Atlantic surfclams, a large saltwater clam found mostly in the western Atlantic Ocean, are capably shifting their range into waters that would have previously been inhospitable to their survival.

Global climate change poses a severe threat to marine life, but scientists have found at least one species that appears to be successfully adapting to warmer ocean waters.

A recent study published in the Proceedings of the National Academy of Sciences found that, even without factoring in the impacts of fishing, global animal biomass in Earth’s oceans is expected to decrease by as much as 17 percent by 2100 under a “high emissions” scenario that leads to 3-4 degrees Celsius of warming. Even under a “low emissions” scenario, in which global warming is limited to just 2 degrees Celsius (the goal of the Paris Climate Agreement), the study found that marine life biomass would drop by 5 percent by 2100.

In addition to warmer waters, ocean acidification and oxygen depletion will take a toll on the wildlife that call Earth’s oceans home. On average, the research determined, we can expect a 5 percent decline in ocean life for every 1 degree Celsius increase in Earth’s average surface temperature.

However, a new study published in the journal Marine Ecology Progress Series shows that, as ocean temperatures rise, Atlantic surfclams, a large saltwater clam found mostly in the western Atlantic Ocean, are capably shifting their range into waters that would have previously been inhospitable to their survival.

According to the study’s authors, Jeremy Timbs and Eric Powell of the University of Southern Mississippi and Roger Mann of the Virginia Institute of Marine Science, the number of larvae produced by Atlantic surfclams is the key to the species’ adaptability. The clams employ a strategy of producing a massive amount of larvae that are widely distributed throughout the ocean, allowing them to reproduce despite the deleterious effects of predators, lack of food, and inhospitable temperatures on surfclam larvae numbers.

The researchers, who examined 30-years’-worth of data from surfclam stock surveys, found that this same reproductive strategy allows Atlantic surfclam larvae to adapt to the impacts of global warming. As ocean temperatures shift and the range of acceptable Atlantic surfclam habitat shifts with it, the clams are gradually moving into the new locations with the most hospitable temperatures for their species.

“For a sedentary species, surfclams are remarkably adaptable to ocean changes that would cause problems for other shellfish,” Powell said in a statement. “This is especially important for fishermen who depend on surfclams, and who are trying to adapt with the rest of the industry to the challenges posed by climate change.”

Atlantic surfclams, a commercially prized species known for its sweet flavor, are distributed along much of the Atlantic coast of North America, from Canada’s Gulf of St. Lawrence to the state of North Carolina in the US. The US National Marine Fisheries Service, known as NOAA Fisheries because it is a division of the National Oceanic and Atmospheric Administration (NOAA), last performed a stock assessment for the species in 2016 and found that the clams have not been over-exploited and are not currently subjected to overfishing. There were nearly 46.4 million metric tons of surfclam spawning stock biomass as of 2015, the assessment determined.

If Earth were to lose 17 percent of ocean life, that could threaten the food security for millions of people around the world. Thus, understanding species’ response to climate change and the range shifts they might undergo is crucial for the seafood industry.

“Studies like this confirm what we have been seeing since the 1990s, and help us predict the industry’s future,” Guy Simmons of SeaWatch International, one of the largest harvesters of clams in the US, said in a statement. “We need to work with our partners in the scientific community as we continue to adapt to a changing ocean.”

Atlantic surfclams. Photo Credit: NOAA.

CITATIONS

• Lotze, H. K., Tittensor, D. P., Bryndum-Buchholz, A., Eddy, T. D., Cheung, W. W., Galbraith, E. D., … & Bopp, L. (2019). Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change. Proceedings of the National Academy of Sciences, 116(26), 12907-12912. doi:10.1073/pnas.1900194116

• Timbs, J. R., Powell, E. N., & Mann, R. (2019). Changes in the spatial distribution and anatomy of a range shift for the Atlantic surfclam Spisula solidissima in the Mid-Atlantic Bight and on Georges Bank. Marine Ecology Progress Series, 620, 77-97. doi:10.3354/meps12964

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