ARM REGENERATION AND SPAWNING IN THE BRITTLE STAR AMPHIURA-FILIFORMIS(MULLER,O.F.) DURING HYPOXIA

Arm regeneration and spawning in the brittle star Amphiura filiformis were studied in normoxic oxygen concentration > 8.5 mg O-2 l(-1) (cont rol) and in two levels of hypoxic oxygen concentrations (treatments), 2.7 mg O-2 l(-1) and 1.8 mg O-2 l(-1) (29 and 19% oxygen saturation) i n 'undisturbed' sediments. The treatments were chosen to simulate shor t term hypoxia (17 days) induced over a 2- month period. This study de monstrated reduced arm growth and disturbance of spawning in both hypo xic treatments compared with normoxia. Slowest regeneration of arms wa s observed at 1.8 mg O-2 l(-1) (65% arm regeneration compared to normo xia control). No difference in brittle star behaviour between treatmen ts was observed by eye or in relation to redox potentials in the sedim ent. The results are discussed in relation to Amphiura filiformis prod uction in Scandinavian waters, where seasonal oxygen depletion occurs in the bottom water in some areas. Estimates of possible biomass losse s are calculated.