Smaller Bay ‘dead zone’ likely, ac­cord­ing to ex­perts


Spe­cial to the Star Demo­crat

— This sum­mer’s “dead zone” in the Ch­e­sa­peake Bay is ex­pected to be about av­er­age or slightly smaller, ac­cord­ing to or­ga­ni­za­tions that re­leased the find­ings on June 13.

A dead zone is an area of the wa­ter with lit­tle or no oxy­gen that can kill fish and aquatic life.

Sci­en­tists pre­dict the dead zone to be about 1.58 cu­bic miles, or about the vol­ume of 2.3 mil­lion Olympic-size swim­ming pools, which is close to the long-term av­er­age as mea­sured since 1950.

The anoxic por­tion of the zone, which con­tains no oxy­gen at all, is pre­dicted to be about 0.28 cu­bic miles in early sum­mer and grow to 0.31 cu­bic miles by late sum­mer. Both are smaller than the av­er­age, due to low river flow and low nu­tri­ent load­ing from the Susque­hanna and Po­tomac rivers this spring, sci­en­tists re­ported.

Jeremy Testa, as­sis­tant pro­fes­sor at the Uni­ver­sity of Mary­land Cen­ter for En­vi­ron­men­tal Sci­ence’s Ch­e­sa­peake Bi­o­log­i­cal Lab­o­ra­tory in Solomons who was in­volved in putting to­gether the fore­cast, said nu­mer­ous field and lab­o­ra­tory stud­ies show that even mod­est hy­poxia (low oxy­gen) can im­pact fish be­hav­ior, growth and over­all health.


“Dead zones over the past 30 years have been higher than in the 1950s to 1970s,” Testa said. “The most se­vere dead zones in re­cent years have been in the sum­mers of 2003 and 2011.”

Dead zones are caused by ex­cess nu­tri­ent pol­lu­tion, pri­mar­ily from hu­man ac­tiv­ity like agri­cul­ture and waste­water, ac­cord­ing to the Na­tional Oceanic and At­mo­spheric Ad­min­is­tra­tion.

Oxy­gen lev­els in dead zones are not high enough to sup­port most marine life and habi­tats in wa­ters near the bot­tom, and dead zones can threaten the Bay’s pro­duc­tion of crabs, oys­ters and other fish­eries, ac­cord­ing to NOAA.

The model to estimate the dead zone is based on nu­tri­ent load­ing es­ti­mated from the U.S. Ge­o­log­i­cal Sur­vey, and de­vel­oped by NOAAspon­sored re­searchers at the Uni­ver­sity of Mary­land Cen­ter for En­vi­ron­men­tal Sci­ence and the Uni­ver­sity of Michi­gan.

USGS es­ti­mated that the Susque­hanna River, which runs from New York, through Penn­syl­va­nia and into the Ch­e­sa­peake Bay, de­liv­ered 66.2 mil­lion pounds of ni­tro­gen to the Bay from Jan­uary through May 2016, which is 17 per­cent be­low av­er­age con­di­tions, ac­cord­ing to NOAA.

Testa said the re­cent rains, which struck the mid-At­lan- tic area through­out most of May, will re­sult in ad­di­tional new nu­tri­ent in­puts to parts of the Ch­e­sa­peake Bay. The dead zones es­ti­mates in­clude the river flow and nu­tri­ent loads from May, “so we are ac­count­ing for some of the re­cent rain ef­fects,” he said.

“There has been a re­cent trend to­ward less hy­poxia later in the sum­mer that may sig­nal an emerg­ing re­sponse to actual re­duc­tions in nu­tri­ent pol­lu­tion,” said Don­ald Boesch, pres­i­dent of the Uni­ver­sity of Mary­land Cen­ter for En­vi­ron­men­tal Sci­ence. “But it’s no rea­son to be com­pla­cent — we have a long way to go to fin­ish the job.”

Ch­e­sa­peake Bay Foun­da­tion Se­nior Sci­en­tist Beth McGee said in a state­ment re­leased Mon­day that the link be­tween the Susque­hanna River pol­lu­tion and the dead zone un­der­scores the im­por­tance of re­duc­ing ni­tro­gen pol­lu­tion from Penn­syl­va­nia.

“The Com­mon­wealth’s (Penn­syl­va­nia’s) ef­forts to re­duce ni­tro­gen pol­lu­tion re­main off track by mil­lions of pounds.” McGee said. “CBF be­lieves that an av­er­age sized dead zone is still un­ac­cept­able, and that Penn­syl­va­nia and the other Bay states must im­ple­ment the plans they de­vel­oped to re­duce pol­lu­tion and re­store wa­ter qual­ity in lo­cal rivers, streams and the Ch­e­sa­peake Bay.”


The nu­tri­ent load­ing, from the mouth of Susque­hanna River in Havre de Grace, ac­counts for the 10 per­cent smaller pre­dicted size of hy­poxic ar­eas in the Bay this sum­mer.

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