Marine conservation does not just apply to headline grabbers such as sharks and dolphins, but the multi-coloured underwater communities which live within metres of Plymouth's bustling Barbican. As part of a our week-long Blue Mile series, Louise Vennells discovered the surprising array of life beneath the waves

PLYMOUTH Sound is deceptive. Gazing down from The Hoe, the ever-present circling seagulls are often the only sign of non-human life.

Yet beneath the blue-grey surface, the waters are teeming with a wide array of weird and wonderful species – although experts fear they may not be around forever.

The multiple pressures facing the seas are jeopardising habitats which keep some of the most fragile marine beings alive. Headlines often circulate around warmer waters, where exotic creatures such as sharks are under threat. But, right at the end of our own piers, delicate coral, fish and habitats create a fascinating submerged world which is facing its own apocalypse.

This summer, hundreds of people will swim, paddle, sail, or even walk their way around Plymouth Sound as part of the Blue Mile, on July 3 and 4, which carries a valuable message about climate change. One of its aims will be to reconnect people to their local waters, and to help them discover the delights of what lies beneath the surface.

A range of events to entertain spectators on the shore will highlight the biodiversity of the Sound and beyond. Paul Cox, head of science and learning at Plymouth's National Marine Aquarium, is part of a team which will include Plymouth University, who will help devise the environment camp to go alongside the event. It will also host the Blue Walk, which will incorporate a stroll with a visit to the aquarium.

"It comes as quite a surprise to most people that there's anything of interest living here," said Mr Cox. "We are constantly bombarded with images of great white sharks, and beautiful and fragile coral reefs off the coasts of South Africa, but we are generally unaware of what's in our own seas – and there's some fantastic stuff. There's some amazing diving off Plymouth, as the popularity of locations like the sunken Scylla wreck attest."

He said the Westcountry's position meant that warm water and colder water species combined.

The stunning pink sea fan and Devonshire cup corals are among a number to be the subject of protection.

The multi-coloured cuckoo wrasse, with its vivid blue and orange scales, rivals the rainbow hues of anything in a tropical fish tank, yet it is right at home in the waters off Plymouth. Even octopuses can be found propelling themselves through the brine within 10 miles of the coastline.

The habitat itself in Plymouth Sound is precious. Rocky outcrops and kelp forests provide invaluable shelter, to allow myriad creatures to thrive – for now.

Mr Cox said the combination of a number of different factors placed the seas under enormous pressure.

Among the threats is over-fishing, and even the move towards fish farms to try to satisfy human desire to eat seafood without trawling the seas. Mr Cox said the feed for such farms still comes from the oceans.

Another destructive element is pollution, which has been widely tackled in the Westcountry through South West Water's multi-million Clean Sweep project – but still poses a serious risk in many areas.

Such pressures combine with the ever-present threat of climate change, which could serve to speed up the detrimental impact to the seas.

Mr Cox said: "It's a difficult situation. We have to try to ensure that the seas can remain in a healthy state, so that they can maintain us in a healthy state."

He said the recently passed Marine and Coastal Access Bill, which has paved the way for protected zones to be set up out at sea, was a "glimmer of hope" which could help avert a crisis beneath the surface.

He said the idea of engaging people with the marine environment through sport was "fantastic".

He said: "We are trying to create an experience which is very immersive and experiential. We don't want to tell people stuff as they walk around – we want them to get involved and have a go."

To register to take part in the Blue Mile visit www.thebluemile.org For Blue Mile images and footage of Conrad Humphreys and other accomplished sportsmen talking about the event, visit www.thiswesternmorningnews.co.uk