Water column ecology: In situ observations of marine zooplankton from a manned submersible

Techniques and tools have been developed to observe, photograph, and collect zooplankton and detritus in the uppermost 600 m from the JOHNSON-SEA-LINK submersibles. Since 1977, investigations in tropical Bahamian and Gulf Stream waters have provided new information about the distribution patterns of many pelagic animals. For example, the giant larvacean Bathochordaeus charon, was common and frequently numerous (3-9 larvaceans/m³) from 45-65 m where relatively high concentrations of phytoplankton occurred. Foraminiferans (Hastigerina pelagica), salps (Salpa cylindrical, S.maxima), and amphipods were often very abundant within the deep chlorophyll maximum layer (75-90m) where 80% of the active chlorophyll was in the < 20 m fraction. Near 600 m, the ctenophore Thalassocalyceinconstans, appeared to feed on particulate matter that fell onto its flattened oral surfaces.