Beaching of the tunicate Salpa thompsoni at high levels of suspended particulate matter in the Southern Ocean

A mass death event of the pelagic tunicate Salpa thompsoni, which occurred in April 2002 in the Potter Cove, near the Argentinean/German Antarctic station Jubany (62°14S 58°40W), King George Island, South Shetland Islands, is described. Salps appeared on the beach two days after very strong (> 80 km.h-1) winds were registered, which accumulated particulate material in the inner part of the cove and probably also re-suspended bottom sediments. The sharp increase in particulate matter concentrations in Potter Cove caused clogging (sensu Harbison et al. 1986) of salp mucous filtering nets and likely a combination of clogging, winds and tides caused dying salps to be washed out on the beach. Until further research, it may be postulated that particle concentrations exceeding 20 mgDW.l-1 could be considered as natural threshold concentrations for S. thompsoni in the high Antarctic coastal regions