Ocean news alarm­ing for At­lantic re­gion

Annapolis Valley Register - - NEWS - Rus­sell Wanger­sky’s col­umn ap­pears in 36 SaltWire news­pa­pers and web­sites in At­lantic Canada. He can be reached at rus­sell.wanger­sky@thetele­gram.com — Twit­ter: @wanger­sky.

Here’s to get­ting used to the un­usual.

Since it’s Oc­to­ber, a sum­mer that was warmer than usual for many parts of the At­lantic prov­inces is now in the rearview mir­ror.

Also prob­a­bly slid­ing into me­mory, for ev­ery­one ex­cept maybe fish­eries sci­en­tists, are this year’s re­mark­ably warmerthan-usual ocean tem­per­a­tures, not only off Nova Sco­tia and Prince Ed­ward Is­land, but off parts of New­found­land as well.

Ris­ing ocean tem­per­a­tures along the At­lantic coast of North Amer­ica are, of course, old news: as I’ve writ­ten be­fore, the rise in coastal tem­per­a­tures is not only mea­sured in de­grees, but in the move­ment of fish stocks: fish that used to be off North Carolina have made their way to New Jer­sey. In other places, there are fears that species that can’t move quickly enough — like lob­ster — may die off in the south­ern parts of their tra­di­tional range.

But there’s a new bit of ocean news that should be ev­ery bit as alarm­ing for peo­ple in the At­lantic re­gion.

For years, sci­en­tists have been pre­dict­ing — rel­a­tively suc­cess­fully — the an­nual size of a hy­poxic patch of wa­ter in the Gulf of Mex­ico. The Gulf of Mex­ico dead zone is an area of ocean bot­tom where the amount of dis­solved oxy­gen in the wa­ter is so low that it can’t sup­port marine life. This year, it’s about 14,760 square kilo­me­tres in size — sci­en­tists cal­cu­late how big it will be ev­ery year by look­ing at things like rain­fall, be­cause, in that gulf, the dead zone is caused pri­mar­ily by agri­cul­tural fer­til­iz­ers swept down the Mis­sis­sippi River from its broad wa­ter­shed. The dead zone kills fish, dam­ages their abil­ity to re­pro­duce, and also drives them away.

But now there are con­cerns that a dif­fer­ent North Amer­i­can gulf is also los­ing oxy­gen.

And it’s closer to home.

The Gulf of St. Lawrence is warm­ing — and los­ing oxy­gen faster — than al­most any re­gion in the world’s oceans, clos­ing in on be­com­ing hy­poxic in some ar­eas as well. That’s the find­ings of a new study by sci­en­tists based at the Univer­sity of Wash­ing­ton.

But in this case, the prob­lem isn’t agri­cul­tural runoff. In its own way, it’s a much big­ger prob­lem; the way two sets of ma­jor ocean cur­rents are be­hav- ing is chang­ing, and that change is driv­ing warmer, saltier wa­ter into the gulf. ( That warmer wa­ter is ca­pa­ble of car­ry­ing less oxy­gen.)

The study found that, as a re­sult of cli­mate change and the change in ocean tem­per­a­tures, warm Gulf Stream wa­ters are mov­ing fur­ther north, and the cold wa­ters of the Labrador Cur­rent are slow­ing — the Gulf Stream wa­ters are mov­ing into deep- wa­ter ar­eas of the Gulf of St. Lawrence that used to be re­plen­ished with more oxy­gen­rich Labrador Cur­rent wa­ter. ( There’s also be­lieved to be some ex­tra hy­poxic ef­fect from the growth of new, warm-wa­ter bi­o­log­i­cal crit­ters in the warmer wa­ter.)

The risks of lower oxy­gen lev­els in­clude threats to species like cod, Green­land hal­ibut and snow crab.

The other in­ter­est­ing thing is, of course, that a lot of the At­lantic re­gion’s weather is also strongly af­fected by the both Gulf Stream and Labrador Cur­rent.

More trou­bling than any­thing else? When it comes to the dead zone in the Gulf of Mex­ico, there are ways to con­trol farm­ing op­er­a­tions to try and limit agri­cul­tural runoff — at least by help­ing farm­ers limit field fer­til­iza­tion to pe­ri­ods when there’s likely to be less runoff.

There’s no way to change the way that ocean cur­rents op­er­ate — and re­searchers say there’s no real way to know ex­actly what hap­pens next.

I guess we’ll find out the hard way

Rus­sell Wanger­sky East­ern Pas­sages

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