News Fried fish

Port Douglas & Mossman Gazette - - NEWS -

FISH liv­ing near the Equa­tor will not thrive in the warmer oceans of the fu­ture.

Ac­cord­ing to an in­ter­na­tional team of re­searchers, the rapid pace of cli­mate change is threat­en­ing the fu­ture pres­ence of fish near the Equa­tor.

‘‘Our stud­ies found that one species of fish could not even sur­vive in wa­ter just three de­grees Cel­sius warmer than what it lives in now," says the lead au­thor of the study, Dr Jodie Rum­mer, from the ARC Cen­tre of Ex­cel­lence for Co­ral Reef Stud­ies (Co­ral CoE) at James Cook Univer­sity.

Dr Rum­mer and her col­leagues stud­ied six com­mon species of fish liv­ing on co­ral reefs near the Equa­tor. She says many species in this re­gion only ex­pe­ri­ence a very nar­row range of tem­per­a­tures over their en­tire lives, and so are likely adapted to per­form best at those tem­per­a­tures.

This means cli­mate change places equa­to­rial ma­rine species most at risk, as oceans are pro­jected to warm by two to three de­grees Cel­sius by the end of this century.

‘‘Such an in­crease in warm­ing leads to a loss of per­for­mance," Dr Rum­mer ex­plains. ‘‘Al­ready, we found four species of fish are liv­ing at or above the tem­per­a­tures at which they func­tion best."

The team mea­sured the rates at which fish use oxy­gen, the fuel for me­tab­o­lism, across dif­fer­ent tem­per­a­tures - at rest and dur­ing max­i­mal per­for­mance. Ac­cord­ing to the re­sults, at warmer tem­per­a­tures fish lose scope for per­for­mance. In the wild, this would limit ac­tiv­i­ties cru­cial to sur­vival, such as evad­ing preda­tors, find­ing food, and gen­er­at­ing suf­fi­cient en­ergy to breed.

Be­cause many of the Earth’s equa­to­rial pop­u­la­tions are now liv­ing close to their ther­mal lim­its, there are dire con­se­quences ahead if these fish can­not adapt to the pace at which oceans are warm­ing.

Dr Rum­mer sug­gests there will be de­clines in fish pop­u­la­tions as species may move away from the Equa­tor to find refuge in ar­eas with more for­giv­ing tem­per­a­tures. ‘‘This will have a sub­stan­tial im­pact on the hu­man so­ci­eties that de­pend on these fish," she says.

A con­cen­tra­tion of de­vel­op­ing coun­tries lies in the equa­to­rial zone, where fish are cru­cial to the liveli­hoods and sur­vival of mil­lions of people, in­clud­ing those in Pa­pua New Guinea and In­done­sia. In an era of rapid cli­mate change, un­der­stand­ing the link be­tween an or­gan­ism and its en­vi­ron­ment is cru­cial to de­vel­op­ing man­age­ment strate­gies for the con­ser­va­tion of ma­rine bio­di­ver­sity.

Chromis fish swim among co­ral

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