Search

The direction of bottom currents and their extent from the seaward margin of the continental shelf (300 m) to the Hatteras Abyssal Plain (5335 m) off North Carolina have been determined on the basis of 150 multishot bottom camera lowerings representing approximately 3000 compass-oriented photographs. Correlative data were obtained from sediment samples, submarine topography studies, and 55 hydrographic samples from the bottom water. There are three major currents on the deep-sea floor : the Gulf Stream with a marked seasonal variation in location, the Western Boundary Undercurrent which may split into sections,and one derived from Antarctic Bottom Water. Zones of no motion are identified between each of the three.

Quantitative analyses of biomass, density, and taxonomic composition of the benthic fauna from 9 Campbell Grab stations off Peru are presented. The results are generally similar to those reported for fauna from other regions at similar depths and distances from shore. The quantitative similarity between the fauna of this and other regions is discussed.

A coupling of sonic pinger bottom reflections with a wire tension recorder has enabled the writers to precisely determine bottom contact and trawl “on bottom” times during deep trawls at depths of 5000 m. Use of this technique removes the uncertainties involved in wire angle calculations for bottom contact determinations and should significantly reduce the amount of wire used in deep-trawlings, as well as the amount of wire lost due to kinks.

The finding of a considerable amount of turtle grass at abyssal depths off North Carolina and at bathyal depth off Florida suggests a continuing fall-out of sea grass as a source of organic enrichment for deep-sea floor. Turtle grass does not grow in the Carolinas but is abundant in Southern Florida, Bermuda, and the Bahamas; which indicate that the grass is distributed by the Gulf Stream rather than simple shore-to-depth transport.