Deep Sea Sponge Aggregations
Deep sea sponge aggregations are found on both hard and soft substrates at depths of between 250 and 1300m; ancient iceberg plough marks are an ideal habitat as the stable boulders and cobbles provide numerous attachment points for the sponges. They are composed principally of glass sponges and the giant sponges ( Desmospongia). The spicules from dead sponges that cover the seabed inhibit the colonisation of the sediments by burrowing animals but the sponges provide an ideal attachment point for brittlestars lifting them above the sea bed where they can catch passing food particles. At present these aggregations are known from the Faroe-Shetland channel at around 500m deep and also occur in the Porcupine Seabight in the north-west Atlantic.
Physical disturbance to the seabed from demersal trawling may cause direct damage to these communities along with the associated increase in turbidity and subsequent sedimentation. They are also potentially vulnerable to pollution from oil and gas operations and from bio-prospecting.