Sci­en­tist to study ‘rock snot’ on rise

The Guardian (Charlottetown) - - CANADA -

It is a goopy, gritty mess that looks more like dirty brown dreadlocks or filthy shag car­pet than a marine growth.

Suit­ably dubbed “rock snot” by sci­en­tists who study it, the al­gae is slowly tak­ing over riverbeds around the world and rais­ing con­cerns that it could be a new stres­sor to aquatic life.

Josh Kurek, a bi­ol­o­gist at Mount Al­li­son Univer­sity, has stud­ied Didy­mo­sphe­nia gem­i­nata or Didymo for years but is now try­ing to de­ter­mine why the un­usual al­gae is ac­cel­er­at­ing its spread through parts of eastern Canada.

His team will also try to fig­ure out if the thick, gelati­nous mats that can blan­ket a river­way’s rocky bot­tom are tak­ing a toll on al­ready frag­ile ju­ve­nile At­lantic salmon stocks.

“Some­thing in the en­vi­ron­ment has changed over the past few years and con­di­tions are more favourable to form­ing these blooms,” he said.

“We can re­ally fo­cus on what is the spe­cific mech­a­nism that is pro­mot­ing blooms in these ecosys­tems.”

The Na­tional Sciences and En­gi­neer­ing Re­search Coun­cil of Canada has awarded Kurek $24,000 a year for the next five years to study pris­tine salmon rivers on Van­cou­ver Is­land, river sys­tems in the Gaspe re­gion of Que­bec, and the trib­u­taries of the Res­tigouche River in north­ern New Brunswick.

He plans to col­lect lake sed­i­ment cores from ar­eas where Didymo blooms may have oc­curred in a bid to re­con­struct the eco­log­i­cal con­di­tions present at the time. That may al­low sci­en­tists to un­der­stand the en­vi­ron­men­tal changes in wa­ter­sheds over the last mil­len­nium and help to ex­plain why Didymo is now ad­vanc­ing on cer­tain river sys­tems.

Bi­ol­o­gists sus­pect it may be linked to el­e­vated ni­tro­gen in the en­vi­ron­ment from fer­til­iz­ers, the burn­ing of fos­sil fu­els or cli­mate changes that af­fect the way a river flows.

The pro­ject fol­lows on Kurek’s re­search more than a year ago that found Didymo was not an in­va­sive species that was trans­ferred to rivers by an­glers on their boats and gear as pre­vi­ously be­lieved.

Rather, he found the of­fend­ing or­gan­isms have been around for thou­sands of years but were only be­com­ing pro­lific more re­cently pos­si­bly as a re­sult of eco­log­i­cal changes.

Kurek says the al­gae was de­tected in western Cana­dian sites in the late 1990s and in 2006 in Que­bec. In both ar­eas, it was found in pris­tine rivers with low lev­els of nu­tri­ents and very high wa­ter qual­ity.

What’s wor­ri­some to sci­en­tists is that the per­va­sive species has ended up in the same rivers as ju­ve­nile wild At­lantic salmon, rais­ing the ques­tion of whether it is af­fect­ing the de­pleted stock that feeds on in­ver­te­brates found in the mats of al­gae.

“We think Didymo rep­re­sents a new po­ten­tial stres­sor for some of these salmon pop­u­la­tions,” he said.

“There may be ei­ther a neg­a­tive im­pact or there could be a pos­i­tive im­pact, in that it’s pro­vid­ing more food for the fish.”

Kurek says the find­ings may help fish­eries and en­vi­ron­men­tal man­agers con­trol the spread of the al­gae, and pro­tect valu­able wild salmon pop­u­la­tions that are threat­ened by over­fish­ing and warm­ing wa­ters.

Didymo has been found in New Zealand, South Amer­ica and the United States, but Kurek says there are no re­ports of it in Nova Sco­tia, New­found­land or P.E.I.


Mary Russ, ex­ec­u­tive di­rec­tor of the White River Part­ner­ship, holds a rock cov­ered with the aquatic al­gae Didy­mo­sphe­nia gem­i­nata — known as didymo, or rock snot — in the White River in Stockbridge, Vt., in this 2007 photo.

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