BAD BAC­TE­RIA THREAT­ENS WHALES

Trek Magazine - - Editor’s Note -

Droplets and ex­haled breath caught from the blow­holes of killer whales along the Pa­cific coast are pro­vid­ing scientists with in­sights into whale health and re­veal­ing bac­te­ria and fungi that may be a threat to the mam­mals.

“We wanted to find out what sort of bac­te­ria and fungi are present in healthy whales and the po­ten­tial pathogens they are be­ing ex­posed to in their en­vi­ron­ment,” said Stephen Raverty, the lead au­thor on the study and an ad­junct pro­fes­sor at UBC’s In­sti­tute for the Oceans and Fish­eries. “In some cir­cum­stances, these path­o­genic mi­crobes could pose a threat to the an­i­mals and con­trib­ute to clin­i­cal dis­ease.”

A group of fish-eat­ing killer whales, known as south­ern res­i­dent killer whales, are an en­dan­gered species that live in the Pa­cific Ocean off the coast of Cal­i­for­nia and north to the Sal­ish Sea off the western coast of Bri­tish Columbia. Over the course of one decade in the 1990s, their num­bers dropped from about 108 an­i­mals to about 70. Some of the threats to whales in­clude changes to their habi­tat, such as in­creased ship­ping traf­fic, noise, con­tam­i­nants, and less prey. But these fac­tors alone do not ex­plain why the whale pop­u­la­tion hasn’t re­cov­ered.

This lat­est ef­fort gives scientists a look at the mi­cro­biome of the large mam­mals. The find­ings can be used as a base­line to com­pare how the health of whales change over time, es­pe­cially when there is ev­i­dence of dis­ease.

Raverty and his col­leagues found bac­te­ria and fungi in the whales that cause dis­ease in hu­mans and land-based an­i­mals, in­clud­ing sal­mo­nella, Sta­phy­lo­coc­cus au­reus and fungi such as Peni­cil­lium, and Phoma, among oth­ers. These re­sults were com­pared to the mi­cro­bial pathogens that Raverty and his col­leagues are find­ing in whale au­top­sies, also known as necrop­sies, of stranded killer whales in the re­gion.

“We’re not sure if these mi­crobes nat­u­rally oc­cur in the marine en­vi­ron­ment or if they may be ter­res­tri­ally sourced,” said Raverty. “These an­i­mals are long rang­ing and as they mi­grate along the coast, they are ex­posed to agri­cul­tural run-off and ur­ban dis­charge, which may in­tro­duce a va­ri­ety of mi­crobes into the wa­ter.”

Re­searchers also found ev­i­dence of an­tibi­otic re­sis­tance in some of the bac­te­ria, pos­si­bly re­lated to hu­man ac­tiv­i­ties in coastal re­gions and in the marine habi­tat.

“As­sess­ing whether an­i­mals are healthy or sick is vir­tu­ally im­pos­si­ble to do for live an­i­mals as big as whales,” said An­drew Trites, di­rec­tor of the Marine Mam­mal Re­search Unit at UBC, who was not in­volved in the study. “Raverty and his col­leagues found a way to as­sess health by col­lect­ing mi­cro­biota and pathogens when the whales ex­haled be­tween dives. It is an in­ge­nious way to give whales a checkup.”

Raverty and col­leagues col­lected breath sam­ples from whales. Photo: Pete Schroeder

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