Helford barnacles

Look closely at the Helford VMCA barnacles that encrust rocks, shells, lobster pots, moorings, boats, in fact almost any hard surface, and which are particularly obvious in the intertidal or mid-shore area. By far the commonest barnacle present is one with a cone formed from four plates and a diamondshaped opening, Elminius modestus, a relative newcomer to Britain, commonly known as the Australasian barnacle.

This species was first identified in the UK in Chichester Harbour, Hampshire in 1945 where it is believed to have arrived sometime between 1940 and 1943, possibly in ballast water, on ships’ hulls or even on flying boats. It spread as far north as Scotland within 40 years and is now also found in fairly sheltered situations on the Atlantic coasts of Europe from Germany to Gibraltar although it is absent from exposed parts of the north Cornish coast.

This Australasian barnacle has a free-swimming larval form that matures and settles on to a hard surface where it then remains attached. It grows rapidly, has several broods each year and withstands reduced salinity, muddy waters, and tolerates higher and lower temperatures than some native species.

Its initial growth rate can be 6mm in 40 days and it reaches maturity, up to 10mm diam., in its first season. There are no serious predators although crabs, amphipods, shore-fish such as Shanny Lipophrys pholis and occasionally birds, will sometimes attack them. No wonder the Australasian barnacle is so successful.

Extract from HVMCA newsletter No.40 Spring 2010

© Helford Voluntary Marine Conservation Area