“…Studies comprising differentia1 fi1tration of suspended particu1ate organic matter into different sizes is a way to contribute for the understanding of the re1ative importance of parts of a p1anktonic community. In the Cananeia estuary water samp1e fractionation have been carried out in previous studies, most of them concerned to phytop1ankton and primary production (Teixeira, 1963;Teixeira, Tundisi & Santoro Ycaza, 1967;Tundisi & Texeira, 1968;Tundisi, 1969Tundisi, , 1971). The present report constitutes the first investigation undertaken in this environrnent, concerning to POC, heterotrophic parti-c1es and bacteria size fractionation, and is an integrant part of an investigation into the re1ationships between POC and some biotic environmenta1 varia-b1és.…”