ARM REGENERATION FREQUENCY IN 8 SPECIES OF OPHIUROIDEA (ECHINODERMATA) FROM EUROPEAN SEA AREAS

Eight ophiuroid species, six from the northern Kattegat-eastern Skager rak and three from the northern Adriatic Sea, were examined for regene ration of arms. The species were separated into groups based upon mode of feeding and habitat. Comparison between groups collected in the no rthern Kattegat-eastern Skagerrak showed that infaunal suspension- and deposit-feeding species (Amphiura filiformis and A. chiajei) had sign ificantly more scars per arm (mean number 0.78) than epibenthic suspen sion feeders (Ophiothrix fragilis and Ophiocomina nigra, 0.29) or epib enthic carnivores and deposit feeders (Ophiura ophiura and O. albida, 0.13). Spatial variation in arm regeneration incidence was found betwe en sampling sites in the northern Kattegat-eastern Skagerrak for Amphi ura filiformis and in the northern Adriatic Sea for Ophiothrix quinque maculata. The ash-free dry weight (AFDW) and nitrogen (N) contents wer e measured in arms of six species of brittle-stars from the northern K attegat-eastern Skagerrak. Differences between species were found, wit h highest concentrations of AFDW and N in Amphiura filiformis, interme diate in A. chiajei, Ophiocomina nigra and Ophiothrix fragilis, and lo west in Ophiura ophiura and O. albida. As the infaunal suspension- and deposit-feeding brittle-stars (Amphiura spp.) had the highest proport ions of damaged arms and highest AFDW and N contents in their arms in this comparison, it is suggested that selective cropping of arms by de mersal fish is the main cause of arm damage on Amphiura spp. in this a rea.