Ecology and energetics of two Antarctic sponges.

Retention efficiencies, pumping and respiration rates of the two Antarctic sponge species Mycale acerata and Isodictya kerguelensis from Potter Cove, King George Island, were measured. None of the species reached a 100% retention efficiency at any given particle size. This is probably due to the sediment-laden environment in which the animals were dwelling. A less efficient retention decreases the risk of the filtering structures being clogged. Both species filter down into the bacterial size range. Pumping rates of the species were 180 ml h(-1) (M. acerata) and 220 ml h(-1) (I. kerguelensis) per g ash free dry mass (T=1 degrees C), being lower than measured in temperate water species. Oxygen consumption was 0.088 ml O(2) h(-1) (M. acerata; T=1.8 degrees C) and 0.035 ml O(2) h(-1) (I. kerguelensis; T=1 degrees C) per g ash free dry mass.