Beach and Dune - Gower - page 134

FIG 71. Whiteford Sands and Burrows, looking north from Cwm Ivy Tor. (David Painter)
the author for Figures
SANDY BEACHES
ThewholeoftheSouthWalescoastisexposedtoAtlanticswellfromthesouthwestwhichhascrossedthe
CelticSea,andtowavesfromthesouthgeneratedintheBristolChannelorwavesfromthewestandnorth
generated in St Georges Channel. The Gower coast is therefore exposed to moderate wave action from
the south, but there is locally some shelter from the southwest, notably at Oxwich. The west-facing beach
at Rhossili is sheltered by Worms Head and offshore shallows in Carmarthen Bay, while Port-Eynon and
Oxwich bays face southeast and receive additional protection from headlands to the west. In general the
more sheltered the beach the more varied the fauna. The degree of exposure is reflected in the substrates
found, with muddier, siltier sediments occurring in more sheltered areas. There are, for example, greater
numbersofbristlewormsinthesiltybeachatOxwichBaythanthereareatRhossili,andthesouthernend
of Rhossili beach has a larger number of species than the more exposed northern end. The fine sands in
theshelteredsoutherncornercontaindensepopulationsofrazorshells,tellins,surfclamsandsandmason
worms. There are also two striking predators, the bulky necklace shell Polinices catenus and the pink-
banded shelled seaslug Actaeon tornatilis .
Hidden under the surface of the wide sandy beaches there are numerous animals, the most obvious of
which, due to the visible casts and tubes on the surface of the sand, are the lugworm Arenicola marina ,
the sand mason and at extreme low water the tubeworm Owenia fusiformis . The latter is a thin, cylindric-
al, segmented worm, up to 10 centimetres long, that lives in a tough flexible tube buried in the sand with
its anterior end just protruding from the surface. The tube is composed of sand grains or shell fragments
glued together in an overlapping fashion.