Chaetognatha from the Florida Current and Coastal Water of the Southeastern Atlantic States

This paper reports the Chaetognatha in plankton samples collected in the waters off the coast of the southeastern Atlantic States during nine cruises of the U. S. Fish and Wildlife Service's M/V Theodore N. Gill. From a total of 590 samples examined 12 species representing 3 genera are identified. The results show the distribution of chaetognaths to be very uniform paralleling the coast in a north-south direction. There are no apparent seasonal changes in the distribution of the species. Across the continental shelf and Florida Current they decreased noticeably in abundance. The inshore stations usually have two to five times as many individuals per cubic meter as do the stations in the Florida Current.

Three kinds of water are identifiable in the area, Carolinian Coastal, Florida Current and Sargasso Sea water. Sagitta hispida has its highest percentage of incidence in Carolinian Coastal water. S. hexaptera, S. lyra, and Krohnitta subtilis occur in more than 90 per cent of the samples from the Florida Current; their presence in Coastal water probably indicates recent incursions of Florida Current water. Of the remaining eight species S. helenae and S. tenuis are characteristically coastal forms that appear frequently in the edge of the Florida Current. The other six species live principally in the Florida Current in this area but often appear in Coastal water. Over a long period of time development of tolerance to varied conditions probably explains the lack of sharply defined distributional limits of most species in the area.