Friday, 16 April 2010

Brighton Sustainability Conference "The Evolving Seas" Day 2

The second day of the conference focused mainly on renewable energy such as offshore wind farms and wave energy. This included a presentation about the planned wind farm off East Sussex. There was also a very interesting talk from Bournemouth council about the artificial reef.

The rest of the day was taken up by the ecology tours the Shoreham Beach Local Nature Reserve. The following is an overview of the tour I led.

Much of Shoreham Beach Local Nature Reserve supports rare vegetated shingle habitat. We knew before hand that the vegetated shingle plants would be less established than usual due to a more severe winter.

A view of the vegetated shingle as it will be in the summer

During the winter months many of the plants die back beneath the shingle and reappear in the spring. This is a useful adaptation to avoid the worst of the winter storms. The sea kale was most evident, but we also saw biting stone crop, bittersweet, curled dock, sea beet, tree mallow and a single yellow horned poppy plant.

Sea Kale

Biting stone crop

Bitter sweet

We looked at some of the features that allow these plants to survive in these harsh conditions. Waxy and hairy leaves to protect them against the drying affect of the sun, wind and sea spray. Long tap roots mean shingle pants to reach freshwater below the shingle and surface roots provide access to the small amount of nutrients near the surface.
Common lizard

As the plants develop they will support a wealth of terrestrial birds and invertebrates. We did see a couple of common lizards scuttling across the shingle.

People often think of shingle as boring old pebbles. They are half right, most of the pebbles are flint which were formed at the same time as chalk – during the Cretaceous period when Sussex was covered by a warm shallow sea.
At the end of the last ice age, melt water scoured the softer chalk, created valleys, and flints and other pebbles were washed down to the coast where they now form shingle beaches. Even the pebbles have a story to tell. The brown flint has been coloured by organic matter before being washed down to the shore. The bigger, greyish flints eroded from the chalk in more recent times. Elongated flints formed in the burrows of burrowing marine life (when the chalk was still soft like clay) some formed around the dead remains of other sea creatures and hide a fossil deep inside. Pebbles with holes were created when flint formed around sponge. We also found some lignite (sea coal) created by the vegetation that grew in the channel when we were still attached to Europe.
Demonstrating a piece of lignite

Having looked northwards to the South Downs and westward to the chalk cliffs it’s not too much of a surprise to realise that beneath the top layer of shingle is chalk

The beach here is actually quite new in geological terms. Along the Sussex Coast, the waves transport the smaller shingle ever eastwards, this is called longshore drift. With the help of the river Adur, which now runs parallel to the north side of the beach, before entering the sea at the harbour mouth, the Shoreham Beach we know today was created by longshore drift. In fact the Napoleonic fort remains that sit just to the west of the harbour mouth could only be built when the river mouth was stabilized by the first harbour arm built in 1820. Longshore drift constantly blocked the river mouth causing it to find an alternative entrance. Infact the river Adur has entered the sea as far West as Lancing Beach Green and as far east as the Lagoon in Hove. Shoreham has been important for many centuries for ship building (up until Victorian times) and as a Port which is just as important today.

Another fascinating part of the beach is the strandline, made up of seaweed, sea shells, egg cases and all manner of curious objects cast up by the tide – including marine litter.

We found the egg cases of dogfish, ray and whelk. One of the most common shells, the slipper limpet, came across the seas from America on the shells of live oysters planned to re-populate the overfished local oysters. Slipper limpets often live in chains, all males except for the female at the bottom. If the female dies, the next male in line will change sex.

Whelk egg mass and dogfish egg case

Idetifying egg cases

Slipper limpets

Ray egg case

 Sadly, Shoreham Beach is also a good place to illustrate local and global threats. The vegetated shingle plants can be damaged by trampling, bonfires and by people removing the flowers or seeds. A major problem is over enrichment of the shingle caused by dog fouling and garden rubbish. The latter is a major problem as large areas of the shingle have been taken over by invasive species such as red valerian and silver ragwort. These plants can out compete the true vegetated shingle plants. The beach may also be in danger from global problems. Global warming – may cause sea level rise which could eventually flood the plants as they are unable to retreat inland because of coastal squeeze – the plants are tapped between the sea and the houses. More severe storms could also destabilise the shingle and it and the plants could be washed away.

Shoreham beach has a unusual blend of flora and fauna creating a diverse ecology and together with the coastal geography and maritime history, they entwine to tell a fascinating story of this piece of coast. (Also touching on themes discussed in the conference).

I spoke to the delegates briefly on the coach at the end of the ecology walks and they seemed to have enjoyed the afternoon, some mentioned it was a great end to the conference and many said they would return in the summer to see the beach at its best when the shingle plants will be in full flower. I gave each delegate on the tours a copy of the LNR leaflet.

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