3) What measures are the Broads Authority (BA) taking to prevent an increase in Prymnesium Parvum, and if there is an outbreak/increase what actions will the BA be taking to reduce/prevent fish mortalities?

An out come from the meeting was that Dan Hoare a conservation officer from the Broads Authority would attend the Broads Angling Stratagy Group Meeting in December 2009 to give a full presentation to the group as to the extent of the proposals and any measures that would be taken regarding the concerns over Prymnesium.

NACA officers attended the BASAG meeting and posed many questions regarding the concerns that another devestating Prymnesium outbreak would have on the area.

The proposal of works are to dredge the main channel of Heigham Sounds, the dredgings are to be placed in Gabion type containers to recreate a old reed bed therefore isolating Duck broad from the main channel, access to duck broad would be by a shallow opening at the north end of the broad.
Assurances were given by the broads authority that the measures being proposed would offer suitatble protection against a Prymnesium outbreak, and some weeks following the meeting formal answers were given to the questions above:
A response from the Broads Authority

1)     Can the Broads Authority (BA) advise of all the proposed dredging works for the future, say for the next three years, and include what, where and approximately when?

The Sediment Management Strategy (SMS) outlines the prioritization process used to determine dredging sites and dredge specifications.  The Action Plan gives a five year dredging programme, with the current years programme (2009/10) given, as well as the next two years outline programmes.  Please follow the link below for the Strategy document and the current Action Plan 2009/10.

http://www.broads-authority.gov.uk/managing/rivers-and-broads/sediment-management/sediment-management-strategy.html

2)     Can the BA provide a copy of the Appropriate Assessment? I am aware of Strategic Environment Assessments being carried out by the BESL team regarding their works in the Broads. Is the BA making a SEA for the proposed dredging/construction works?

Please find the Appropriate Assessment submitted to Natural England, as part of the Planning process, attached.  At the time of development of the SMS, the BA were advised that an SEA was not required for a project of this scale.  The BA were however required to make an assessment of the strategy against Regulation 48 of the Habitats Regulations.  Please follow the link below and see to Appendix 5 for this Habitats Regulations assessment.

http://www.broads-authority.gov.uk/broads/live/managing/rivers-and-broads/sediment-management/sediment-management-strategy/Appendices.pdf

3)     What measures is the BA taking when 'aiming to minimize disturbance and any potential negative impact' regarding probable increased levels of prymnesium?

Please see the Appropriate Assessment for details, in particular Section 3, on the monitoring we shall put in place to determine during the 20m x 20m trial, whether any effects on water quality or Prymnesium levels are observable.  The very process of conducting the works in a step-by step manner, and using the monitoring to aid decision-making in choosing to scale up to the final full restoration phase, reflects our caution in what is a sensitive conservation and angling interest site.

4)     If there is an outbreak of prymnesium following the works that achieves a level dangerous to the fish in the area, what measures will the BA have in place to prevent/reduce fish mortalities?

Should levels of monitored Prymnesium during the dredging works reach levels considered to be at a level dangerous to fish stocks, the continuation of works would be rapidly reviewed, with halting of works an accepted option.

In the event of a Prymnesium outbreak, at any time, we are currently working closely with the area EA Fisheries team, to develop an updated Action Plan.  This dredging project has highlighted the urgent requirement for such a plan, as the Prymnesium issue is ever present.  The closure of the Catfield borehole and freshwater refuge previously operated in times of fish stress due to Prymnesium toxicity is no longer available.  The refuge options currently available are being explored, and close working with local landowners and the Broads IDB is expected.  Potential areas where such refuge/s can be effective, require finding appropriate sources of fresh, or Prymnesium free, water supplies, and suitable dykes/areas of water where fish are prepared to access in times of need.  As this piece of work develops, updates will be given to the various liaison and stakeholder groups.

Since writing this piece the planning for the Island creation scheme has been approved by the Broads Planning committee, Since this decision many meetings have taken place discussing anglers options the Norwich Pike anglers Club has been at the forefront of these discussions with input from NACA the PAC and the Angling Trust,the following is the latest plan of action to monitor the Prmnesium levels during the works and actions to be taken should levels increase.

Monitoring of Phase 2 trial – 20m x 20m Island Re-Creation

Water Quality

Any detrimental impacts to the water quality could have a direct impact on fish populations and an indirect impact on the wildlife that relies on fish for food. There are concerns that the disturbance of sediment could lead to a release of nutrients which could adversely affect fish populations, and could increase the likelihood of a Prymnesium parvum outbreak. Therefore it is critical that water quality is monitored before, during and after the works to afford us early warning of potential problems.

It is proposed that water quality and Prymnesium cell density will be monitored on a weekly basis for a month prior to the start of works to obtain information on background water quality conditions. Longer term background data has been provided by the Environment Agency.  Prymnesium cell density will be sampled at three sites, the works site within Heigham Sound/Duck Broad; the entrance to Hickling Broad from Deep Go Dyke; and on Meadow Dke adjacent to the Stubb Mill outflow.

During the works, temperature, dissolved oxygen, conductivity, pH and secchi depth will be monitored by Broads Authority staff on hand held meters on a daily basis at the works site.  Following cessation of the works water quality and Prymnesium cell density will continue to be monitored on a weekly basis for a month after the sediment moving operation ends.

Dissolved oxygen content of water is critical to aquatic health. The amount of dissolved oxygen in the water is dependent on temperature, water depth and pH. Dissolved oxygen levels in the water will vary throughout the diurnal cycle, therefore it is crucial to take the readings consistently at the same time of the day. This is recommended as in the morning before works commence. Following consultation with the Environment Agency dissolved oxygen readings below certain critical thresholds will cause a halt to all works, as set out in the decision tree below.