Life history and population dynamics of the chaetognath Sagitta elegans in central Long Island Sound

One chaetognath species is found in Long Island Sound. Sagittaelegans. Individuals ranging in length from 1.5 to 22 mm werefound from March through August. Length at maturity ranged from13 to 22 mm. Maximum abundances. 67 ind m^–3 in 1982 and106 md m in 1983. occurred in early summer Two cohorts wereseen during both years, beginning as eggs produced in April-May.and in late June. The population is not endemic to Long IslandSound because temperatures during summer exceed 19C, whichseems to be lethal. The appearance of the first cohort in springis due to advection of animals from shelf waters. The secondcohort, however, is produced locally. The S. elegans populationin Long Island Sound is unique in two ways. First, the adultsare considerably longer than predicted by McLaren's (1963) Belhrdekfunction, and second, the total abundance of eggs, juvenilesand adults is at least two times higher than anywhere else.