Gemmules of Anheteromeyenia ryderi and Heteromeyenia tubisperma (Porifera: Spongillidae) from southern New England undergo diapause

SUMMARY. 1. The annual cycle of the freshwater sponge, Anheteromeyenia ryderi , was studied in a seepage pond in Connecticut. The adult form of the sponge persisted throughout the year, although some specimens at the edge of the pond degenerated by late summer. During the middle of the winter, adult sponges had a simplified tissue morphology with reduced numbers of flagellated chambers.
2. Gemmules of A. ryderi were also present during all seasons. Gemmule germination occurred during the spring, and some specimens produced new gemmules by late spring.
3. The gemmules of A. ryderi underwent a protracted diapause which was broken under both natural and laboratory conditions by several months exposure to low temperatures (≤5°C).
4. The gemmules of Heteromeyenia tubisperma were also shown to undergo diapause, but in this case diapause was broken by a relatively short cold treatment (1 month).