Island Life Magazine Ltd December 2006/January 2007 | Page 46

Meadows beneath the sea ISLE OF WIGHT - WILDLIFE sheltered bays and estuaries. The Isle of Wight plays host to some of our larger common eelgrass beds, particularly around Bembridge, Ryde and Yarmouth. Seagrass meadows have long been recognised as very important habitats. Seagrasses provide a valuable food source for our counties’ wildfowl, who feed on the dwarf and narrow-leaved varieties when the tide is out. Underwater, the often dense cover of leaves provides the perfect nursery ground for juvenile fish and crustaceans like shrimp and crabs, where they can shelter and hide from currents and predators. Many of the juvenile fish, when they reach adulthood, will be targeted by commercial fishing vessels, giving seagrass meadows an important economic role. As well as these economically important species, there are other inhabitants of seagrass meadows. Seahorses favour these areas, anchoring to the plants with their tails. These elusive creatures have been discovered in seagrass beds off Dorset, but not yet in Hampshire or the Isle of Wight. However, several have been found washed up on the shores of the Island, one of which survived, so we believe they are out there, just waiting to be discovered. Seagrasses are not only home for a myriad species; the meadows perform other vital functions in our marine ecosystem. Their roots stabilise our shores, trapping sediment and preventing erosion. By doing so it is thought that this process also traps carbon in the seabed, acting as a “sink”, absorbing excess atmospheric carbon that contributes to global warming. Photograph - Steve Trewhella Grass may not always seem the most interesting of refuges for wildlife, but when it lives in the sea it certainly becomes so. Seagrasses, often known as eelgrasses in the UK, are the only group of flowering plants in the world able to live fully immersed in seawater. 46 There are approximately 60 species of seagrass, but only three are found around the coasts of Hampshire and the Isle of Wight. Dwarf eelgrass (Zostera noltii) and narrow-leaved eelgrass (Zostera angustifolia) live on the shore, where they are uncovered by the water at low tide. Common eelgrass (Zostera marina), which has much longer and broader leaves than the other two species, lives fully submerged at depths of up to 5m, sometimes deeper if the water is very clear and allows light to penetrate further. Like all flowering plants, and unlike the seaweed more normally found around our coasts, seagrasses have roots and so live in sandy or muddy areas where their roots can take hold. Our local coasts have a lot of these habitats, so it makes us comparatively rich in what is thought to be a nationally scarce group of plants. Dwarf and narrow-leaved eelgrass meadows are found on the mudflats in Langstone Harbour as well as other Sea meadows in decline Unfortunately, seagrass habitats have not had it easy and meadows have suffered large declines in size over the last century, with some disappearing entirely. In the 1930s, ‘wasting disease’, which is thought to have been caused by a combination of a rise in sea temperatures and a parasite, decimated seagrass beds. This in turn led to declines in all the wildlife associated with the beds. The meadows have started to Island Life - www.isleofwight.net