Pulling power of Jersey's tides

The expanse of sand at St Ouen's bay shows how far the tide recedes

Jersey has some of the largest tides in the world due to a see-sawing effect of the water in the English Channel.

When it recedes, the immense body of water melts into the horizon, only to rapidly surge back to shore.

These huge shifts have caught out many unsuspecting people who have suddenly found themselves cut off from dry land.

"You have a huge see-saw of water, with high tide at one end and low tide at the other," said Andrew Syvret, marine biologist.

"This massive bulge of water moves backwards and forwards twice each day. When it arrives in our corner of the English Channel this bulge of water really hasn't got anywhere to go.

"We then find ourselves in a giant anti clockwise tidal gyre - a great whirlpool."

North V South

You've got snakelocks anemones, squat lobsters, a gang of shore crabs, pipefish tucked away and, of course, the molluscs that incrust the rocks. Andrew Syvret, marine biologist

Jersey's north and south coast could not be more different. On the north, the sea sweeps up and crashes dramatically into the high cliffs.

There are no such histrionics in the south, as the sea retreats over a gentle slope to reveal vast areas of rock and rock pools.

One such place is La Rocque, on the south-east coast. Here the pools which form at low tide give sanctuary to small fish and sea creatures.

"These very shallow pools with a sandy bottom are incredibly important. You can think of these as incubators or nursery areas," said Mr Syvret.

In the summer, they are three to four degrees warmer than the surrounding ocean, so a lot of small animals will begin their life here. They will use the sanctuary of these pools to grow as fast as they can."

The pools provide the perfect hideaway for sea bass, sole and small turbot, as well as a plethora of crustaceans.

Japweed

Rock pools are teaming with marine life hidden underneath the seaweed

"Although an invasive species, the rafts of Japweed which are strewn across the island's beaches has both a positive and negative effect on indigenous marine life.

"This stuff in particular is a negative in some respects, because it is shading out other species. But it does provide an incredible canopy at low tide for prawns, small fish and molluscs," Mr Syvret said.

The rocks, too, disguise an abundance of life not apparent at first glance and the creatures which live beneath are important to the whole region.

"You've got snakelocks anemones, squat lobsters, a gang of shore crabs, pipefish tucked away and, of course, the molluscs that incrust the rocks.

"I have described the Violet Bank, the Minkies and the offshore reefs around Jersey as the engine room of the English channel," Mr Syvret said.

Vitally important

Mr Syvret uses the Chancre, also known the Brown crab, as an example.

"Historically, we would refer to them as Guernsey crabs, because to get a large chancre you would have to buy it from Guernsey.

"What tends to happen is they start their life here, grow to a certain size, and then go off in search of deeper water.

"We are regularly broadcasting animals to the wider English Channel. We find ourselves in a corner which is absolutely vital to the functioning of the whole English Channel," he said.