Dun­beg study re­veals mys­tery of the deep

The Oban Times - - NEWS -

AN EX­PER­I­MENT con­ducted in a Scot­tish loch has re­vealed how a mi­cro­scopic an­i­mal – the main food source for many larger marine species – sched­ules its day us­ing its own ge­netic clock.

The ‘body clock’ of the cope­pod Calanus fin­marchi­cus shapes its meta­bolic rhythms and move­ment through the wa­ter col­umn.

This, in turn, has an enor­mous in­flu­ence on the en­tire food web in the North At­lantic and Arc­tic oceans where Calanus fin­marchi­cus is a cen­tral plank­ton species.

As part of the study, which has been pub­lished in the jour­nal Cur­rent Bi­ol­ogy, sci­en­tists from the Dun­beg-based Scot­tish As­so­ci­a­tion for Marine Sci­ence (SAMS) car­ried out re­search on Loch Etive, where one of the only known iso­lated pop­u­la­tions of Calanus fin­marchi­cus is found.

In the world’s oceans, count­less zoo­plank­ton species, such as cope­pods and krill, rise to the sur­face at dusk to gorge them­selves on sin­gle- celled al­gae that can only thrive where there is suf­fi­cient sun­light.

The cover of night of­fers the zoo­plank­ton pro­tec­tion from preda­tors such as fish, which need light to hunt. When dawn ap­proaches how­ever, they sink back into the dark depths where they can hide from their preda­tors through­out the day – com­plet­ing a cy­cle that likely rep­re­sents the largest daily move­ment of biomass on the en­tire planet. Re­searchers are still work­ing to de­ci­pher which sig­nals these marine or­gan­isms use to de­cide when to rise and when to de­scend.

The SAMS team, along­side the Al­fred We­gener In­sti­tute, Helmholtz Cen­tre for Po­lar and Marine Re­search (AWI) and the Univer­sity of Olden­burg in Ger­many, showed that Calanus fin­marchi­cus pos­sesses an in­ter­nal ge­netic clock, also called the cir­ca­dian clock, which pro­duces a 24hour rhythm that func­tions with­out a day/night cy­cle. This could be im­por­tant dur­ing the con­stantly dark po­lar win­ter and in the deep sea.

Co-au­thor Dr Kim Last of SAMS added: ‘We have long looked to un­cover the mys­ter­ies of zoo­plank­ton mi­gra­tions and it ap­pears that the cir­ca­dian clock, much like our own, has a very im­por­tant role to play in help­ing the an­i­mals be in the right place at the right time.

‘Such fun­da­men­tal mech­a­nis­tic un­der­stand­ing is cru­cially im­por­tant if we want to pre­dict how marine ecosys­tems will re­spond to the com­plex­i­ties of fu­ture cli­mate change.’

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