Ecology of Sponges in Hatteras Harbor, North Carolina

Patterns of settling, growth, gemmule formation, and disappearance of sponges in Hatteras Harbor are presented for a one—year period and related to water temperature. Ten species are represented in the harbor, of which eight were recorded settling on submerged clam shells. Certain water temperatures, critical for some sponges, are realized two months earlier than in Milford Harbor, Long Island Sound. In response to these temperatures, certain events in the life cycles of Microciona prolifera and Haliclona loosanoffi occur two months earlier in Hatteras Harbor. In Hatteras Harbor, the latter species persists throughout the winter, exhibits two periods of settling, and relies on gemmules to survive adverse summer conditions, whereas in Long Island Sound it exhibits a single period of settling and relies on gemmules to survive adverse winter conditions. Observations are also made on competition for space by sponges and by the compound ascidian, Botryllus schlosseri, and on other aspects of the ecology of sponges in Hatteras Harbor.