Habi­tat loss is chang­ing po­lar bear health

BBC Wildlife Magazine - - Wild News - Catherine Smal­ley FIND OUT MORE ISME Jour­nal: bit.ly/po­largut

Re­treat­ing sea-ice is al­ter­ing the gut bac­te­ria of po­lar bears, ac­cord­ing to a study by Cardiff Univer­sity and the United States Ge­o­log­i­cal Sur­vey.

Since the beginning of the 21st cen­tury, habi­tat loss has driven a di­vide in the south­ern Beau­fort Sea po­lar bear sub­pop­u­la­tion. While ‘off­shore’ bears re­main on the ice, ‘on­shore’ bears mi­grate to coastal open-water re­gions.

Re­searchers an­a­lysed over 100 fae­cal sam­ples to un­der­stand how this change in be­hav­iour has im­pacted the bac­te­rial com­po­si­tion of the dif­fer­ent bears’ guts.

“We dis­cov­ered that di­ver­sity and com­po­si­tion are sig­nif­i­cantly dif­fer­ent in on­shore bears com­pared to those that re­main on the sea-ice year-round, show­ing for the first time that global change-driven al­ter­ations in habi­tat use are as­so­ci­ated with changes in the gut,” ex­plains So­phie Wat­son, from Cardiff Univer­sity’s School of Bio­sciences.

The ef­fect of this bac­te­rial shift on the long-term health of the on­shore bears is still un­clear, but it could be a cause for concern.

“The bears that have on­shore be­hav­iour are ex­posed to a greater di­ver­sity of par­a­sites (be­cause of their much more var­ied diet) than the off­shore bears, and a change in mi­cro­biota could leave them vul­ner­a­ble to ac­quir­ing those par­a­sites,” says co-au­thor Sarah Perkins.

How­ever, she warns that even a shift in pre­ex­ist­ing mi­crobes could be detri­men­tal to the bears’ health. “Some mi­crobes within the gut mi­cro­biota, if they are able to pro­lif­er­ate, can switch from be­ing com­men­sal to path­o­genic.”

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