Dinoflagellates as indicators of water masses during El Niño, 1982–1983

Abstract

The changes of the distribution patterns of some dinoflagellates considered as biological indicators showed the development of the 1982–1983 El Niño. During El Niño conditions the density of dinoflagellates was diminished, but there was a larger number of species, many of which are rarely found in this region. Protoperidinium obtusum, an indicator of cold coastal waters, disappeared almost completely during El Niño 1982–1983, but it was very abundant when the conditions returned to normal. Ceratium breve, an indicator of equatorial surface waters, during normal conditions is restricted to the northern area up to 5°S; during El Niño it was distributed up to 15°S. Several species indicators of warm waters were widely distributed during El Niño 1982–1983 but are very rare or absent during normal conditions.