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February 05, 2016

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Motorboat noise may literally scare fish to their deaths

Feb. 5, 2016
Courtesy of the University of Exeter
and World Science staff

The rate at which some fish fall prey to oth­ers can dou­ble when boats are mo­tor­ing near­by, new re­search sug­gests.

Ma­rine bi­ol­o­gist Ste­phen Simp­son at the Un­ivers­ity of Ex­e­ter in the U.K. and col­leagues found that noise from pass­ing mo­tor­boats in­creases stress lev­els in young cor­al reef fish and re­duces their abil­ity to flee from preda­tors. This halves their sur­viv­al chances.

A pred­a­tory dusky dotty­back eyes a young Am­bon dam­sel­fish. (Cre­dit: Chris Mir­bach)


The re­search­ers hope the find­ings will in­spire bet­ter en­vi­ron­men­tal noise man­age­ment in coast­al ar­eas.

“We found that when real boats were mo­tor­ing near to young dam­sel­fish in open wa­ter, they be­came stressed and were six times less likely to star­tle to sim­u­lat­ed pred­a­tor at­tacks com­pared to fish tested with­out boats near­by,” said Simp­son.

“The com­bina­t­ion of stress and poor re­sponses to strikes by preda­tors is why these fish be­came such easy prey,” added col­la­bo­ra­tor An­dy Rad­ford of the Un­ivers­ity of Bris­tol in the U.K.

The sci­en­tists com­bined lab­o­r­a­to­ry and field ex­pe­ri­ments, us­ing play­backs and real boat noise, to test the im­pact of mo­tor­boat noise on sur­viv­al of young Am­bon dam­sel­fish dur­ing en­coun­ters with their nat­u­ral pred­a­tor the dusky dot­ty­back.

The re­search­ers, how­ev­er, are op­ti­mis­tic that the situa­t­ion can im­prove.

“If you go to the Great Bar­ri­er Reef, there is a lot of noise from mo­tor­boats in some places. But un­like many pol­lu­tants we can more easily con­trol noise. We can choose when and where we make it, and with new tech­nolo­gies, we can make less noise. For ex­am­ple, we could cre­ate ma­rine qui­et zones or buff­er zones, and avoid known sen­si­tive ar­eas or times of year when ju­ve­niles are abun­dan­t,” said Simp­son.

“You might ar­gue that cli­mate change is a big­ger threat to reef life, but if we can re­duce the ef­fect of lo­cal noise pol­lu­tion we build great­er re­sil­ience in reef com­mun­i­ties to loom­ing threats such as glob­al warm­ing and ocean acidifica­t­ion,” added col­la­bo­ra­tor Mark Meekan of the Aus­tral­ian In­sti­tute of Ma­rine Sci­ence.

The study is pub­lished in the jour­nal Na­ture Com­mu­nica­t­ions.


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The rate at which some fish fall prey to others can double when boats are motoring nearby, new research suggests. Marine biologist Stephen Simpson at the University of Exeter in the U.K. and colleagues found that noise from passing motorboats increases stress levels in young coral reef fish and reduces their ability to flee from predators. This halves their survival chances. The team hope the findings will inspire better environmental noise management in coastal areas. “We found that when real boats were motoring near to young damselfish in open water, they became stressed and were six times less likely to startle to simulated predator attacks compared to fish tested without boats nearby,” said Simpson. “The combination of stress and poor responses to strikes by predators is why these fish became such easy prey,” added collaborator Andy Radford of the University of Bristol in the U.K. The scientists combined laboratory and field experiments, using playbacks and real boat noise, to test the impact of motorboat noise on survival of young Ambon damselfish during encounters with their natural predator the dusky dottyback. The researchers, however, are optimistic that the situation can improve. “If you go to the Great Barrier Reef, there is a lot of noise from motorboats in some places. But unlike many pollutants we can more easily control noise. We can choose when and where we make it, and with new technologies, we can make less noise. For example, we could create marine quiet zones or buffer zones, and avoid known sensitive areas or times of year when juveniles are abundant,” said Simpson. “You might argue that climate change is a bigger threat to reef life, but if we can reduce the effect of local noise pollution we build greater resilience in reef communities to looming threats such as global warming and ocean acidification,” added collaborator Mark Meekan of the Australian Institute of Marine Science. The study is published in the journal Nature Communications.