BENTHIC STORMS IN THE ARGENTINE BASIN

The Argentine Basin is a region of large lateral gradients and extreme ly high concentrations and integrated loads of particulate matter (PM) in the abyssal nepheloid layer. The region also has large lateral var iations in currents and surface and abyssal eddy kinetic energy. To in vestigate a suggested link between PM concentrations and eddy kinetic energy, transmissometers were attached to current meters moored at 10 m above the seafloor at five sites from the Argentine continental slop e (1970 m) to the central basin (5045 m) from April 1987 to March 1988 . Benthic storms (periods of high PM concentrations often associated w ith high current velocities) were recorded at all sites. The intensity of benthic storms (based on both frequency and elevated PM concentrat ion) increased with distance from the margin, despite frequent periods where currents exceeded the expected erosion velocity near the margin . A good correlation was found between abyssal eddy kinetic energy (AE KE) and variations in PM concentration, except at the central basin si te. At that site, a three month period of very high PM concentrations occurred with only low to moderate currents. The high PM concentration s may have resulted from the rapid input of low-density, organic-rich phytodetritus from a plankton bloom in surface waters.