TROPICAL ATLANTIC EPIPELAGIC LAYER PLANKT ON IN THE WINTER SPRING PERIOD

Mesozooplankton of two regions with different productivity in the trop ical Atlantic was studied in 1995: oligo-trophic (15 degrees N, 40 deg rees W) in February and mesotrophic (1 degrees S, 10 degrees W) in Apr il. The observation were conducted during the destructive period of th e annual development of planktonic communities. The total biomass was equal to 0.17-0.24 gC/m(2) in the first region and to 0.8-0.9 gC/m(2) in the second one. A comparison with measured optical parameters of wa ter show that they do not always unambiguously reflect the biological situation. For example, high transparency of upper layers of water, ch aracteristic to oligotrophic waters, may be observed in the poor seaso n in mesotrophic waters, but the mesoplankton concentration may bz as high, as in mesotrophic and methylotrophic waters. Unconsumed autochth onous detritus production, calculated on the basis of the structural - functional analysis, was equal to 4% of the primary production in the of oligotrophic region and to 12% in the mesotrophic one.