RESUMO

Chlorophyll a concentration, ash-free dry weight (AFDW) and accumulation rate of organic matter (net productivity) were determined for periphyton assemblages developed on artificial substrate (glass slide). Periphyton samples were obtained by exposing glass slides on periphyton samplers, which were placed at 12 sampling stations with different levels of pollution around the Pinang River basin. Biomass and chlorophyll a concentration were highly variable, and the highest values were recorded at relatively polluted stations, where biomass peaked at 10.48 mg Chl. a/m² and 8.24 g/m² AFDW. Maximum biomass at clean sites was 4.1 mg Chl. a/m² and 2.45 g/m² AFDW, with maximum net production 85.71 mg AFDW/day. The accumulation of chlorophyll a and AFDW was characteristically higher during the drier months and relatively lower during the wet season at all sampling stations. AFDW positively correlated with chlorophyll a and net productivity.