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Toxic algae fish fears raised as Broads Authority prepares to begin dredging in Hickling

PUBLISHED: 16:35 25 October 2018 | UPDATED: 15:41 26 October 2018

Dead fish on the Broads killed by Prymnesium parvum in 2015. Picture: John Innes Centre

Dead fish on the Broads killed by Prymnesium parvum in 2015. Picture: John Innes Centre

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Fears for the welfare of fish living in Broads water have been raised ahead of a project to dredge a section of Hickling Broad.

Rob Field of the John Innes Centre  Picture: James BassRob Field of the John Innes Centre Picture: James Bass

Work is to begin soon to clear a section of reedswamp at the edge of the largest body of water the park has to offer.

However, scientists and anglers have raised concerns that the Broads Authority (BA) is not doing enough to monitor whether the works could put the lives of fish at danger, courtesy of a deadly algae virus.

Their fears are that the dredging could potentially bring a toxic breed of algae called Prymnesium parvum into bloom, and that the BA is not doing enough to monitor this danger.

The Prymnesium levels are currently being monitored on a twice weekly basis. However, scientists at the John Innes Centre have argued this is not regularly enough.

General secretary of the Pike Anglers Club of Great Britain, John Currie. Picture: Elixir MediaGeneral secretary of the Pike Anglers Club of Great Britain, John Currie. Picture: Elixir Media

Rob Field, a professor at the centre, said: “Based on our recent work on the Broads, our view is that it would be appropriate to measure levels every couple of days before, during and after dredging.

“Weekly monitoring is probably too infrequent to be informative in terms of enabling a timely response to an emergency bloom issue.”

The BA though, has insisted it would never dredge to begin with if testing indicated a risk.

Prof Field has carried out extensive research into the algae virus, which has been held responsible for the deaths of thousands of fish in the past. In this research it was found hydrogen peroxide could provide an antidote to the blooms.

He added: “It is also important to point out there is little merit on monitoring without immediate mitigation strategy in place.

“Given the potential bloom risk around dredging, it would be prudent to have hydrogen peroxide supplies on site during dredging activities, so they can be deployed quickly.”

A BA spokesman, however, said: “The suggestion that a stock of hydrogen peroxide should be kept on site during dredging is not valid.

“The introduction of hydrogen peroxide on a large scale into a water system has not yet been established as a safe way of dealing with algal blooms.”

The BA currently has access to a rapid response team trained to carry out any treatment - should it be necessary - but a spokesman said this should not be required as a result of dredging.

The added: “If a distressed fish were spotted, officers would immediately contact the environment agency for assistance.”

John Currie, chairman of the Pike Anglers’ Club of Great Britain, also expressed fears.

He said: “The Broads Authority should be approaching this with much greater caution.

“If it were to bloom there will be thousands of fish dead, which would be devastating - particularly for angling which is worth millions to tourism on the Broads.”

Broads Authority response

Despite the concerns, the Broads Authority has insisted it is doing all it can to monitor the situation.

A spokesman insisted specific checks were carried out on more than a weekly basis - as has been claimed - and that telltale signs could also be spotted through routine tests already conducted.

A spokesman said: “Broads Authority environment officers are currently testing specifically for prymnesium algae on a twice-a-week basis in areas most at risk of developing the algal bloom.

“In addition to this, they take weekly samples of a range of environmental conditions within the broad.

“Furthermore, during dredging projects key environmental conditions such as temperature and water levels are monitored daily.

“If the results of the general check suggests conditions are more likely to cause prymnesium algae to bloom, dredging is suspended until further investigations can take place.

“If the unfavourable conditions persist, dredging will cease until conditions are favourable once again.

“The BA also works in partnership with Natural England and the EA to ensure that they are dredging during periods when the environmental conditions are at their lowest likelihood of developing.”

The prymnesium parvum algae tends to bloom in shallow water during warm weather and with the work being carried out across the autumn and winter, the BA says a bloom would therefore be very unlikely.

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