Description of [Ascophyllum nodosum] and epiphytic sponges and ascidians on variable salinity infralittoral rock
Dense subtidal stands of Ascophyllum nodosum, heavily epiphytised by sponges and ascidians in lagoon-like habitats. The wracks Fucus vesiculosus and Fucus serratus can be present along with the brown seaweed Chorda filum and the red seaweed Polyides rotundus. The crab Carcinus maenas can be present between the A. nodosum holdfasts along with the shrimps Mysidae. Situation: Nearby rock often supports similar biotopes of submerged fucoids and green seaweeds (unit A3.341). Slightly deeper rock often supports Laminaria saccharina (unit A3.3132), usually surrounded by more extensive areas of sediment. Seagrass beds thrive well in the muddy sand of these lagoons and often cover large areas. They include both Ruppia maritima and Zostera marina (units A5.5343 and A5.5331).