The surface of the concrete-faced embankment on the north Wirral coast, Cheshire, England, has no features which retain moisture or provide shelter from Irish Sea waves loaded with abrasive sand. The neighbouring River Dee and River Mersey (Liverpool is in the background of the image) reduce the salinity and deposit large amounts of sediment which coat most hard surfaces. The sea temperatures here are the lowest in winter and highest in summer of any region in Britain except south-east England which is similar. Very few marine species can tolerate these conditions, but A. modestus can, and it occupies more of the surface than any other macro fauna.