Mussel shells along US East Coast have higher porosity

Mussel shells along US East Coast have higher porosity

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Research into mussel shells along the US East Coast has revealed that modern-day specimens have become weaker and more susceptible to damage.

Some of the historic and modern-day mussel shells used in the study

Researchers from the American Museum of Natural History have discovered that the porosity in mussel shells along the East Coast of the United States has increased. The cause is believed to be rising ocean temperatures.  

Porosity can affect the structural integrity of mollusk shells, so this means that the shells are weaker and thus more susceptible to damage. 

The findings was published in the journal PLOS ONE

Lead author Leanne Melbourne, a Kathryn W. Davis postdoctoral fellow in the Museum's Master of Arts in Teaching program, said: “Human-caused environmental changes are threatening the ability of mussels and other mollusks to form their shells, and we need to better understand what risks will come from this in the future.”

Making comparisons with museum specimens

For the study, Melbourne used the Museum’s bivalve collection to trace environmental changes in natural settings. She focused on shells collected in the early 1900s and the 1960s from Nahant Bay in Massachusetts, the southern end of Cape Cod, the tip of the Long Island Sound, western Long Island Sound, and New York Harbor.

She then compared them with modern-day shells taken from the same sites, based on factors like the shells’ thickness, surface area, volume, density and porosity.

Reduced porosity

The team found that modern-day shells were more porous than the shells retrieved from the museum collections. Interestingly, they found that the shells collected in the 1960s were significantly more porous than the ones collected in some of the sites in the early 1900s. 

This suggested that increases in temperatures led to increases in porosity.

Since 1902, the seasonal temperature of the North Atlantic has increased up to 3 degrees Celsius, but the warming has not been uniform, and this may have led to some of the variations in porosity in the historical specimens. 

In addition, the influence of the North Atlantic Oscillation, which brought colder-than-expected water temperatures in the 1960s, may also be a factor.

“We know that mussel and mussel reef ecosystem services are dependent on robust shell formation. If they are forming weaker shells, they will break more easily, and we might lose these important organisms,” said Melbourne. 

She added that more research was needed to find out what went on at a materials science level.