Cold-water coral reefs are biodiversity hotspots of the deep sea. The most dominant reef-building cold-water coral in the Atlantic is Lophelia pertusa, which builds vast and structurally complex habitats. Studying the behaviours of deep-sea species is challenging due to the technological difficulties in making prolonged observations in situ, so little is known about the behavioural ecology of this important species. Observations in laboratory studies can help to enhance our understanding of the range of behaviours these species exhibit. Here we present video evidence that the cold-water coral Lophelia pertusa is capable of producing mucus nets as part of their feeding strategy. This finding suggests that L. pertusa has a more diverse range of feeding strategies than previously thought.

Research on the biology and ecology of cold-water corals (CWCs) is still in its infancy.The growth patterns of CWCs in their natural environments are poorly known. Growth rateinvestigations on these deep-sea reef builder species are needed to predict recovery timesfollowing damage to their ecosystems. This study investigates a new approach for analysingCWC growth rate, suitable for in situ application. Lopheliapertusa and Madrepora oculata (Scleractinian) were collectedfrom the Lacaze-Duthiers canyon in the northwestern Mediterranean Sea (520 m depth),marked and then either redeployed in situ for 6 months, or maintained inaquaria for growth rate comparison at a constant temperature of 13 °C, corresponding totheir habitat conditions. Two different types of staining (calcein and manganese) andthree different exposure times (30, 60 and 240 min) were tested. The results show thatcalcein offers rapid incorporation and easy detection, making it particularly suitable forskeletal growth rate investigations compared with other chemical staining. In situlinear polyp growth rates of 7.5 ± 1.2 mm y-1 and 3.5 ± 2.1 mmy-1 were measured in new polyps of L. pertusa and M.oculata, respectively. Those values were significantly higher in young polypsthan in older ones, where they decreased to 1.3 ± 1.5 mm y-1 and 1.2 ± 1.2 mmy-1. Beyond the study of coral reef growth processes, this approach offers amethodological basis for habitat quality assessment which could be used in the managementof deep-sea marine protected areas (MPA).

Continuous long-term measurements of temperature, salinity and current velocity, have been recorded over 44 months at the Tisler Reef. The Tisler Reef is a 2 km long cold-water coral reef on the sill of the Kosterfjord, located in the north-eastern Skagerrak, Norway. The reef comprises principally Lophelia pertusa, at depths between 70 and 160 m, and is an important habitat for sponge, crustacean and fish species including a number of species of commercial importance. Analysis of the current velocity data has identified a number of features such as flow reversals. These reversals in flow direction are often associated with significant changes in bottom temperature. During the autumn months of 2006 and 2008, a series of large and rapid increases in bottom temperature were observed, with temperatures seen to rise by approximately 4°C in a 24 hour period on both occasions. The occurrence of the 2006 and 2008 events corresponded with the observation of mass mortality in the long-lived sponge Geodia baretti. Historical temperature records from the region suggest that these temperature shocks are uncharacteristically high. The temperatures observed at the reef exceed the typical short-term physiological limits of L. pertusa thus future temperature shock events may have a swift and negative impact on the cold-water coral reef ecosystems of the Skagerrak.

This study describes species of the genus Hymedesmia from three areas of cold-water coral reef: Mingulay Reef Complex (Scotland, UK) and Rockall and Porcupine Banks (off UK and Irish coasts). Five new species are described: Hymedesmia (Hymedesmia) gibbosa, H. stoneae, H. tendali, H. xavierae and H. valentinae. Records are provided of other poorly known Hymedesmia species: H. bocki, H. cohesibacilla, H. curvichela, H. ebria, H. gustafsoni, H. simillima, H. irregularis, H. proxima, H. hibernica and H. primitiva. Information on distribution of other Hymedesmia species occurring in Britain and Ireland is presented. The sites studied represent a variety of depth-ranges and the data collected suggest that some Hymedesmia species may be restricted to particular bathymetric zones.