Sunday, 30 May 2010

SWIMMING through clear water, I can see a seabed literally jumping with life.
Long-legged spider crabs encrusted with bright yellow sponges scuttle along, tiny red and white shrimps dart around and from time to time a scallop leaps into action, chattering like a pair of false teeth up into the water column.

In my field of view are dozens of species of multi-coloured sponges, sea anemones, corals and strange plant-like animals. You may think I am describing a dive trip to the Indian Ocean but this is actually a glimpse into the underwater life of the Isle of Man.

It is a completely different world to the land-based one we are familiar with: beautiful, exotic and covering more Manx territory than the Island itself!
Speak to any diver or fishermen and they will tell you what a wealth of marine life we have in Manx waters. But for the majority of land-dwellers, the 87 per cent of Manx territory which is permanently submerged remains a mystery.

What we have underwater is just as diverse as what we can see so easily on land. The seabed has peaks and valleys, plains and undulating hills, just like the Island landscape. The underwater equivalents of forests, meadows and heathland are kelp forests, eelgrass meadows and rocky reefs encrusted with soft corals and sea anemones.This wealth of tiny creatures that keep the marine system running remain out of view.

A recent survey of the Manx seabed by scientists from Bangor University in Gwynedd, North Wales, on behalf of the Department of Environment has highlighted just how diverse our waters really are.

Local divers carrying out Seasearch dives with the Marine Conservation Society are also increasing our knowledge of marine habitats and species, taking spectacular photographs and producing long lists of species from all around the Island.

There is a common misconception that the waters of the Irish Sea are flat, muddy and featureless but this couldn't be further from the truth. Let's have a look at just a few of our special seabed features:

Horse mussel reefs: Horse mussels are large long-lived mussels which look like bigger versions of the better known edible mussel.

Amazingly, these shells can live as long as 100 years but rarely grow more than 20cm in length. Over their long lives they accumulate toxic heavy metals in their tissues so are not suitable for us to eat. Horse mussels are quite a common species on the seabed but what makes them interesting are the huge reef-like structures they create on the seabed. The mussels bind together with the same sort of threads that you see attaching edible mussels to rocks.

Horse mussels are also often partially buried in sediment and they bind together with many other animals and plants, forming a fascinating mass of marine life. This habitat is the Manx equivalent of a coral reef – brimming over with animals and plants and extremely important for biodiversity.

Mussels are filter feeders, which play an important role in keeping our seas clean and clear, sieving small particles out of the seawater. Horse mussel reefs also play the same role as forests on land in storing carbon that would otherwise be in the atmosphere as carbon dioxide, contributing to reducing climate change.

Eelgrass beds: Our underwater meadows bear a remarkable resemblance to pastures on dry land. Eelgrass is a unique flowering plant which, unlike seaweed, has roots and flowers and is more closely related to land plants.

Eelgrass meadows are green and lush and provide shelter for schools of tiny, transparent fish fry, snake-like pipefish and bright pink-painted topshells – a kind of marine snail which grazes on the blades of eelgrass. Eelgrass is known for its importance as a nursery ground for fish and shellfish and also plays a role in stabilising the seabed and reducing coastal erosion.

Eelgrass is a protected species in the Isle of Man and is quite rare.
Much of the eelgrass in north-west Europe died off as a result of disease in the 1930s, so there was probably a lot more around the Isle of Man before that.

There are records of eelgrass in Port Erin Bay and it is thought to occur in a number of other locations. It is now confined to a few small sheltered sites around the coast.

Maerl beds: Maerl beds are another spectacular Manx marine habitat. A special type of red seaweed, maerl forms small nodules of bone-like calcium carbonate with a thin layer of pink living seaweed on their surface. The coral-like branches of maerl interlink to form a complex habitat which provides a home for more than 600 species of animals and plants.

Research in Scotland has revealed that maerl beds provide a nursery area for baby queenies – a place where they can settle and grow before moving onto the queenie beds where they can be caught. Animals living among the delicate pink fingers of maerl include bright dahlia anemones, small sea urchins and vivid red sunstars.

This has just been a quick glimpse below the surface of Manx seas.

Once you start to look it is amazing what you can find. We have nearly 9,000 species of plants and animals in the waters around the British Isles so marine life is a very important part of our biodiversity. This diversity will keep us and our oceans healthy and help us respond to climate change.

Our marine environment is an essential part of our global survival system and it is also incredibly beautiful. During 2010, International Year of Biodiversity, let's make sure that we celebrate the diversity of Manx marine life too.

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