Taxonomia e aspectos biogeográficos da flora planctônica de um sistema costeiro salobro - Lagoa Carapebus, município de Carapebus, RJ

Abstract

A taxonomical and biogeographical survey of planktonic flora from Carapebus lagoon (22°50'S e 41º35'W), a brackish coastal system located in the northern Rio de Janeiro State belonging, in part, to Parque Nacional da Restinga de Jurubatiba werc presented. This is a shallow and oligohaline lagoon with dark and slightly alcaline waters. Taxonomical study was based on 145 samples collected by a plankton net and by passing a ílask along water subsurfce at fur stations in February, March, July and October 1996 (Period I), April, August and September 1997 (Period II), and at monthly intervals from May 2000 to April 2001 (Period III). Altogether 1 84 táxons were identified distributed into Chlorophyceae (23%), Cyanophyceae (18%), Euglenophyceae (17%), Bacillariophyceae (11%), Zygnematophyceae (8%), Coscinodicophyceae (5%), Xanthophyceae (4%), Cryptophyceae (4%), Dinophyceae (3%), Chrysophyceae (4%), Prasinophyceae (2%), Charophyceae (1%) e Ulvophyceae (1%). Nineteen species and four genera were new records fr Brazil. Forty-fve and 70 generic and infrageneric taxa were registered for the frst time fr Rio de Janeiro State and fr Brazilian brackish coastal lagoons, respectively. Seventeen taxa could not be identifed at specifc levei and probably almost them must be new to the Science. Concernig the salinity the populations from Carapebus lagoon werc, in general, represented by typical eurihaline limnobiont organisms (76%), fllowed by typical organisms fom brackish waters (10%) and eurihaline marine (3%). From a geographical point of view, of the total infrageneric taxa in Carapebus lagoon, 43% have a cosmopolitan distribution, 13% are widely distributed, 1 9% show scarce distribution and 4% have a temperate/arctic occurrence. Only 11% of the taxa present restricted distribution in tropics. Descriptions, illustrations, infrmations on geographical distribution by the world and in Brazil, and 1 2 indented keys fr the identifcation of all taxa presently registered were given. Taxonomical comments including phenotypic plasticity of the populations identifed as well as the similarity based on the floristic composition registered in quantitative analysis between Carapebus lagoon and three more brackish systems located in the southeastern and southern part of Brazil were discussed.