The ecological importance of seagrass as a habitat and keystone species is widely known and it is protected by law in several countries. They can spread across large areas, forming expansive underwater meadows which contain a huge biodiversity, sometimes 30 times more species can be found in seagrass compared to the neighbouring sandy habitats. Seagrass habitats also play a huge role in carbon capture and coastal protection.
However, as a species seagrass is very fragile, easily disturbed and damaged by human activity. Both boat anchors and traditional mooring systems can have detrimental impacts on seagrass meadows. Anchors pull up seagrass by the roots releasing trapped carbon in the seabed and mooring chains move across the seabed with the changing tides and currents scouring the seabed of life. As a result, massive damage can occur within seagrass meadows where anchor or mooring lines are present.
So, what can we do? The obvious answer would be to stop people anchoring on seagrass meadows, and in Tor Bay their seagrass beds are voluntary no-anchoring zones with the Wild Planet Trust encouraging water users not to anchor at known seagrass sites and to use new permitted mooring. However, seagrass meadows are often located in beautiful locations that are very popular with both water enthusiasts and boat users alike. So, what else can we do to help protect seagrass while also providing safe access to those who want to visit the area?
Solution 1: Helix Screw Anchor and Elastic mooring rope
Consisting of a helix screw and an elastic mooring line this method has proved to have virtually zero impact on the surrounding marine environment while still having substantial holding power. Having under gone many different tests this method has registered an excess of 20,000ibs of holding power. The helix screw is screwed deep into the seabed with the elastic mooring line secured to the head of the screw at one end and a buoy at the other. With the screw fixed in place there is no scouring from an anchor and due to the elastic nature of the mooring rope no matter the tide the buoy will keep the line of the seabed preventing drag damage.
Solution 2: Hanging Buoys
Similar to the Helix Screw and Elastic rope the aim of this anchor system is to keep the line off the seabed to prevent scouring damage. However, instead of using an elastic mooring line this method uses several buoys of varying buoyance to hold the line above the seabed. Once again using a Helix screw the mooring line is attached between the head and a buoy on the surface. Only this time at equal intervals along the line from the surface to seabed the line is connected to several smaller buoys which hold it above the seabed in the water column. As the tides go in and out the buoys keep the line above the seabed preventing it from damaging the seagrass.
While both these methods have been proven to work, they work better in areas of moderate wave depth and lessor tidal range. So, there’s no one size fits all when it comes to these alternative “green” mooring methods and designs need to designed to fit with specific conditions for the meadow in question.
These methods can also be very expensive both to make and through regular maintenance, the synthetic materials do not weather well and many organisms are prone to grow in between the fibres and can weaken the elastic. With this in mind what do you think the best method might be to use in the Trust’s upcoming seagrass project? While we are unlikely to have boats mooring on our site, we still require marker buoys to mark out the perimeter of our plots. Have you got any alternative ideas that might work? Let us know!