Nascimento do L. R. auteur aut IRD Sifeddine Abdelfettah auteur aut IRD Torgan L. C. auteur aut IRD Albuquerque A. L. S. auteur aut IRD text journalArticle eng text/pdf reformatted digital access The composition and spatial variation of diatom assemblage in surface sediments of Caco Lake (shallow, mesotrophic and weakly acid lake - Maranhao State, Brazil) were analyzed in order to know the distribution pattern of the species along the lake during rainy season (April 1999). Four zones were established in the lake based on 21 diatoms species and habitat affinities. The first three zones (prime three meters deep to six meters deep) were marked by the occurrence of Pinnularia gigas, Frustulia rhomboides, Encyonopsis krasskei, Eunotia camelus, E. femoriformis and E. monodon. Zone IV (seven to nine meters deep) was inhabited mainly by Surirella biseriata and Fragilariforma floridana. During the beginning of the rainy season, the diatom assemblage in Caco Lake was composed mainly by benthic and epiphytic forms that reflected the low lake levels and the abundance of littoral vegetation present in this lake. specialized diatoms shallow lake surface sediments Caco Lake Brazil 036 53 1 241-248 2010 1516-8913 https://www.documentation.ird.fr/hor/fdi:010049377 10.1590/S1516-89132010000100030 1516-8913 [F B010049377] https://www.documentation.ird.fr/hor/fdi:010049377 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers16-08/010049377.pdf IRD - Base Horizon / Pleins textes 2010-04-06 2017-08-23 fdi:010049377 fre