Study: Warmer win­ters mean more blue crabs

More Ch­e­sa­peake Bay blue crabs could have domino ef­fects in ecosys­tem

Baltimore Sun Sunday - - NEWS - By Scott Dance

New re­search sug­gests that Ch­e­sa­peake Bay blue crabs will be more plen­ti­ful amid milder win­ters in the com­ing decades, but sci­en­tists say that’s not a rea­son to wel­come global warm­ing.

They pre­dict that more of the crus­taceans will sur­vive the win­ter in the fu­ture, given fore­casts of less fre­quent and in­tense cold. Win­ter cold can kill off sig­nif­i­cant numbers of crabs, who spend the sea­son bur­rowed in mud for warmth.

“In 100 years, we would ex­pect win­ter for crabs in Solomons to look more like win­ter cur­rently looks in south­ern North Carolina,” said Hil­lary Lane Glan­don, who con­ducted the re­search at the Univer­sity of Mary­land Cen­ter for En­vi­ron­men­tal Sci­ence and is now a post doc­toral re­search as­so­ci­ate at the Univer­sity of North Carolina in Wilm­ing­ton. “No win­ter for the crabs.”

In a study pub­lished Mon­day, UMCES re­searchers sug­gest that could have un­pre­dictable domino ef­fects in the larger Ch­e­sa­peake ecosys­tem and could cre­ate new is­sues for reg­u­la­tors man­ag­ing the com­mer­cial crab har­vest.

Tom Miller, a pro­fes­sor and di­rec­tor of the in­sti­tu­tion’s Ch­e­sa­peake Bi­o­log­i­cal Lab­o­ra­tory in Solomons, said a re­duc­tion in cold con­di­tions could lead to pres­sure to al­low win­ter­time har­vest­ing of crabs. That is cur­rently pro­hib­ited in Mary­land, but is al­lowed on a lim­ited ba­sis in warmer states.

And if crabs spend less of the year in hi­ber­na­tion and more time feed­ing, it could have ef­fects down the food chain.

“If crabs start mov­ing and feed­ing year-round, they rep­re­sent an added pre­da­tion pres­sure on the bay’s ecosys­tem, and we don’t know how the ecosys­tem will re­spond,” Miller said.

The re­search pre­dicts that crabs could spend about half as much time hi­ber­nat­ing in 2100 as they do now. In wa­ters near Solomons, in South­ern Mary­land, it could de­crease from about 117 days, on av­er­age, to about 56 days, the study sug­gests.

That could mean vir­tu­ally all crabs sur­vive the win­ter, an in­crease of about 20% in the species’ sur­vival rate in the Ch­e­sa­peake.

The sci­en­tists noted that it is dif­fi­cult to pre­dict how blue crabs will fare sim­ply based on ris­ing tem­per­a­tures. The bay’s crea­tures are also ex­pected to en­dure in­creas­ingly acidic and salty wa­ters, and those changes are ex­pected to have mixed ef­fects on crabs.

BAL­TI­MORE SUN

Re­searchers pre­dict more of the crabs will sur­vive the win­ter in the fu­ture. Win­ter cold can kill off sig­nif­i­cant numbers of crabs, who spend the sea­son bur­rowed in mud for warmth.

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