With 02 _gures and 2 tablesKey words] Phytoplankton\ chlorophyll a\ environmental variables\ sea! sonal variability\ ecology\ bivalve growth\ Chile[ Abstract[ Phytoplankton and its relationships with physical and chemical variables were analysed over a 1!year period in Hueihue and Linao Bays "southern Chile#[ Samples were collected on a monthly basis from May 0880 to May 0882[ The growth rate of a single stock of hatchery!produced oysters "Ostrea chilensis# dis! tributed between these two bays was also monitored monthly[ The growth rate of oysters maintained at Linao Bay "site associated with a _sh farm# was signi_cantly higher\ at every depth\ compared with the oysters maintained at Hueihue Bay[ Temperature and salinity values and their annual~uctuations were similar at both locations\ presenting higher variations at the surface "0 m# due to the in~uence of air temperature and local precipitation than at depth[ However\ signi_cant di}er! ences in phytoplankton abundance and composition were found between the two locations[ The phytoplankton community was characterized by high biomass values during spring and summer\ the dominance of diatoms and an inverse relationship between temperature and species diversity[ However\ phytoplankton cell abundance\ biovolume and chlorophyll a concentration were signi_cantly higher at Linao at every depth sampled[ Cell abundance ranged between 3[38 × 09 3 and 6[34 × 09 5 cells = l Ð0 in Hueihue and between 5[37 × 09 3 and 7[60 × 09 5 cells = l Ð0 in Linao[ The in~uence of temperature on chlorophyll a concentration was signi_cant except at 7 m at both locations[ The instantaneous oyster growth rate was found to be positively correlated with temperature\ chlorophyll a concentration and particulate organic matter at both locations[ A signi_cant negative relationship between oyster growth and amount of particulate inorganic matter was found^this con_rms the important role played by seston composition in oyster growth[ The U[ S[ Copyright Clearance Center Code Statement] 9062!8454:88:1990!9952,03[99:9 Toro\ Paredes\ Villagra + Senn

The phytoplankton community of the Putemun Channel (southern Chile) and its correlation with some environmental variables is analysed in this paper. Samples were collected on a monthly basis from May 1991 to May 1993. A total of 121 phytoplanktonic species were identified. The phytoplankton cell abundance ranged between 3.5 × 10 4 cells/litre and 11.2 × 10 6 cells/litre. The phytoplankton community was characterised by the dominance of diatoms. An inverse relationship between temperature and species diversity was observed. A significant correlation, after excluding tychoplanktonic benthic forms, was found between chlorophyll a, cell abundances, and temperature. The influence of biotic and abiotic variables on oyster (Ostrea chilensis (Philippi 1845)) growth was analysed. The instantaneous growth rate was found to be positively correlated with both temperature and phytoplankton abundance, whereas significant negative correlation between growth and amount of particulate inorganic matter was found.