THE EFFECTS OF SALINITY, TEMPERATURE, AND PHOTOPERIOD ON EPITOKAL METAMORPHOSIS IN NEANTHES-SUCCINEA (FREY-ET-LEUCKART) FROM SAN-FRANCISCO BAY

The combined effects of salinity, temperature, and photoperiod on the frequency of epitokal metamorphosis in the semelparous polychaete Neanthes succinea (Frey et Leuckart) were examined in laboratory experiments. Worms metamorphosed significantly more often and sooner in salinities of 20 parts per thousand than of 5 parts per thousand. Worms maintained at 5 parts per thousand for 10-12 months, and then gradually exposed to higher salinities up to 20 parts per thousand also metamorphosed more readily than controls kept at 5 parts per thousand. Neither temperature nor photoperiod alone had a significant effect on the frequency of epitokal metamorphosis, but salinity and temperature had an effect on timing and synchronization.