As I’ve been wrting a fair amount about Lyme Bay and the Lyme Bay Closed Area protection and its effects recently, I thought I’d post a small selection of images to illustrate why the reefs of Lyme Bay are so important.
Sunset corals are one of the very few species of true corals (i.e. stony, or scleractinian, corals, the sort that are responsible for spectacular reefs in tropical waters). It is a solitary coral, where each polyp attaches to the underlying rock and grows seperately, so does not form colonies or reefs. They do however grow in quite dense clusters and are quite beautiful. Sunset corals are rare in UK waters, known to occur at only a handful of locations. The saw-tooth ledges reefs in Lyme Bay support one of the densest populations found around the UK and also the easternmost population known in UK waters.
Lane’s Ground Reef is a boulder reef known for its rich assemblage of sponge species. In recent years these appear to have undergone a significant decline, attributed to bottom trawling and scallop dredging, however since the establishment of the Closed Area, from which trawlers and scallop dredgers are banned, there are now signs of a recovery.
The boring sponge, Cliona celata, is one of the most distinctive sponges in UK waters, with its brilliant sulphur yellow colouring and large size. In fact much of the sponge is hidden as, through a process still not fully understood, it bores in to limestone and sandstone. Apart from this ‘massive’ form shown here, the sponge also occurs in a purely boring form where only the circular yellow oscules can be seen protruding from the rock surface. It is believed that the sponges ability to bore into hard limestone is due to chemicals released, possibily acids.
Pink seafans, Eunicella verrucosa, are the only seafan (gorgonion) species known to occur in English waters. The East Tennants Reef supports one of densest and most extensive populations of seafans in the English Channel. The seafans found here are notable for their large size in addition to the high density found here.
The nudibranch (seaslug) Tritonia nilsodnheri feeds exclusively (as far as we know) on the polyps of of gorgonions and soft corals. The processes on its back strongly resemble seafan polyps and so it is almost perfectly camouflaged on its host. It has been proposed that its pink coloration comes from feeding on pink E. verrucosa seafans. Like E. verrucosa it comes in two colour morphs, pink and white. In English waters where seafans are mostly pink (a small percentage are white) so most Tritonia are also pink. In this picture the Tritonia can be seen sucking the soft polyp tissue out from within the harder calyx that surrounds each polyp.
For more information about Lyme Bay Closed Area and the work we have been doing there to understand the changes occurring following establishment of statutory protection in 2008, read the blogs on my Marine Bio-images website.
For more background on Lyme Bay reefs. Lyme Bay: what makes it special?
And finally, for a clearer understanding of why scallop dredging is so damaging. Scallop dredging, whay is it considered so damaging to reefs?