Aquarium observations on the deep-water coral<i>Lophelia pertusa</i>(L., 1758) (scleractinia) and selected associated invertebrates

Abstract

Abstract Growth and behaviour of Lophelia pertusa and selected associated invertebrates were observed in aquaria with running sea-water. The coral polyps captured food particles by means of nematocyst adhesion. Food items up to 2 cm long were ingested. The polyps discriminated between food and sediment particles when presented separately, probably involving chemoreceptors. When presented together with food, sediment was ingested. Linear skeletal extension occurred in pulses of up to 1.2 mm·day-1 in young polyps (mean = 9.4 mm·yr-1). Factors influencing the linear extension were: food availability, water quality, and patterns of water flow. The highest extension rate was recorded in periods with influx of new water masses to the aquarium water intake, and in parts of the aquaria with a slow water movement and a high sedimentation rate. Settlement and reproduction of the parasitic foraminiferan Hyrrokkin sarcophaga was observed, but no clear negative effects on the coral could be observed. The polychaete Eunice norvegica appeared to be a non-obligate mutualist. It frequently "stole" food from Lophelia, cleaned the polyps from sediment particles, and it's tube-building stimulated the production of coral skeleton. The latter probably strengthens both polychaete tube and coral skeleton. Two species of polynoids lived as commensals with Eunice.