Clams Provide Record of Ocean Temperature Rise

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by Becky Wink Cooper

clamThe quahog clam is the world’s longest-living animal. Found in great quantities in the oceans off the coast of northern Europe and the eastern US, quahogs can live up to 500 years or more.

Like tree trunks, the shells of quahog clams are marked with a growth ring for every year. Eco Magazine reports that these growth rings are now being used as a record of ocean temperature rise.

David Reynolds is the lead author on this study. He explains, “These growth rings allow us to accurately age and measure the annual growth in each of the shells that we studied. In a similar way to trees, all shells that were alive at the same time will respond to the environment in the same way. If conditions are particularly good for growth one year, all the shells experiencing those conditions will respond by laying down a wider growth ring and vice versa.”

Reynolds and the team analyzed data over a 1000-year period and analyzed it with other historical records about air temperature, oceanographic data, and information from tree rings, to name a few. The result?

“The analysis of the isotope record found that 20th century changes in seawater temperature and salinity on the North Icelandic shelf, especially from 1950-2000, are unprecedented relative to the last millennium,” says Reynolds.

What does this mean for our future? Reynolds and his team are using this information to build better climate models. Ocean temperature is known to drive weather and climate extremes. Better understanding of the changing ocean temperature can help communities prepare for extreme weather that it can cause.

And, it helps bring an important focus to what is happening in our world in the modern era.


This article appeared in OTE’s January 2016 newsletter. Go here to read the full newsletter.