PLANS for a revolutionary scientific trial to monitor the environmental impact of dredging in Falmouth Harbour have been revealed.

The tests, which are awaiting approval from the Marine Management Organisation (MMO), will study the impact of dredging on the maerl beds that inhabit the seafloor in the area.

If the trial results are favourable, it could lead to the all-important green light being granted for a £25 million capital dredging project for the port to begin next year.

The trial will be conducted independently by marine experts from the Plymouth University Marine Institute.

Falmouth Harbour Master, Captain Mark Sansom, met with top executives at the MMO in Newcastle on Monday to obtain important re-assurances on several matters relating to the small scale dredging trial.

Proposals to dredge a deep water channel into the docks have been held back by concerns around the impact of moving maerl, a calcified seaweed that covers the seabed in parts of the Fal, and the effect this could have on the aquatic species living among it.

Less than two per cent of dead maerl within the special area of conservation (SAC) in Falmouth Harbour will be affected by the dredging proposals together with a small area of live maerl.

The approach channel into the inner harbour currently has a minimum depth of 5.1 metres, which is shallow by the standards of modern ports, making it unsuitable for larger vessels, particularly the ever-increasing demand for visiting cruise ships.

Harbour bosses claim that without dredging, Falmouth’s future as a thriving working port would be threatened.

Dredging a channel will safeguard existing port functions and open up new opportunities by accommodating larger vessels, including those that can support the growing marine energy industry.

David Ellis, chairman of Falmouth Harbour Commissioners, said: “We take our environmental responsibilities very seriously and understand that there are concerns about dredging.

“FHC is responding to these concerns in order to ascertain what the potential impact will be on the maerl communities.”

The trial will see dredging at six different sites located within the planned deep water channel from the Carrick Roads into the docks, to the north east of the eastern breakwater in an area known as the Falmouth Bank.

A video survey conducted in November 2011 using state-of-the-art towed video equipment confirmed that the proposed dredge site is predominantly dead maerl, with one small area containing live maerl present.

Six trial sites in the proposed dredge channel have therefore been proposed; five of which will extract dead maerl and one of which will include the live maerl covering.

Plymouth University Marine Institute has overseen the design of the trial, which will involve the careful extraction of a limited amount of the surface maerl habitat, storing it at the surface and relaying it in the same location. Samples taken before and after, and from adjacent sites, will determine the impact on the translocation.

Professor Martin Attrill, director of Plymouth University Marine Institute, said: “We will be providing independent scientific analysis of the seabed communities in the planned dredge area. We have been using underwater high definition video cameras to map the area and establish the coverage of both dead and live maerl beds.

“Most importantly, we will also be undertaking a trial in which we will remove the top layer of maerl at several sites, store it under suitable conditions, and then return it to the seabed.

“We will then assess the impact of this procedure on the maerl and the organisms that live within it.

“Together, these results will provide the MMO with information on whether this can be a suitable mitigating method to reduce the impact of the planned channel dredging.”

Partial funding for the trial will come from Cornwall Council who have agreed in principle to contribute towards the cost.

Councillor Chris Ridgers, Cornwall Council’s portfolio holder for economy and regeneration, said: “We trust that with the evidence it will provide that we can then move swiftly to secure the licence and permissions required to allow the dredging to take place so that the benefits that Falmouth Docks can provide to the Cornish economy can be maximised.”

Peter Child, managing director of A&P Falmouth, said: “We all have an interest in the environment and supporting sustainable development but there needs to be a balance between both to sustain a vibrant economy and community.”

During the 1980s scores of eastern European fishing vessels anchored all over the Falmouth Bank every winter as ships do today.

Yet the maerl appears to be unaffected by ships anchoring and stirring up the seabed with their engines.

The harbour was extensively dredged for calcified seaweed (maerl) for decades when 30,000 tonnes were dredged annually for fertiliser.

Video surveys of the harbour have also revealed extensive live maerl beds in an area which was dredged 30 years ago.