The changeso f the distributionp atternso f somed inoflagellatecso nsidereda s biologicali ndicators showedt he developmenot f the 1982-1983E l Nifio. During El Nifio conditionst he density of dinoflagellatews as diminishedb, ut there was a largern umbero f speciesm, any of which are rarely foundi n thisr egion.P rotoperidiniumo btusuma, n indicatoro f coldc oastalw aters,d isappearedal most completelyd uringE l Nifio 1982-1983b, ut it was very abundantw hen the conditionsr eturnedt o normal. Ceratium breve, an indicator of equatorial surface waters, during normal conditions is restrictedt o the northerna rea up to 5°S;d uringE l Nifio it was distributedu p to 15°S.S everals pecies indicators of warm waters were widely distributed during El Nifio 1982-1983 but are very rare or absent during normal conditions.