FRESH-WATER SPONGE GEMMULES SURVIVE MONTHS OF ANOXIA

Gemmules of Ephydatia muelleri, exposed to anoxic conditions (nitrogen ) in sealed glass ampules, generally showed no differences from oxic c ontrols in hatchability or hatching rate over exposure periods of 1 to 112 days. Unlike controls, hatching was totally inhibited under anoxi a at +20 degrees C. Our results directly demonstrate that this species , and probably many freshwater sponges, can survive seasonal anoxia in the gemmule stage. High gemmule survival under nitrogen also permits them to be stored and transported without regard for external temperat ure. These results are consistent with existence of an ametabolic stat e under anoxia, but much more detailed work is needed to prove this co njecture.