SEASONAL DISTRIBUTIONS OF THE PHOTOSYNTHESIZING CILIATES LABOEA STROBILA AND MYRIONECTA-RUBRA (=MESODINIUM-RUBRUM) IN AN ESTUARY OF THE GULF-OF-MAINE

The mixotrophic ciliate Laboea strobila was present year-round in the surface waters of the Damariscotta estuary, Maine, USA. In contrast, t he abundance of the autotrophic ciliate Myrionecta rubra showed a stro ng seasonality and was absent during most of the summer and autumn. No n-loricate species usually dominated ciliate abundance and biomass, bu t tintinnids were occasionally dominant. L. strobila constituted up to 15% of the total ciliate biomass (including M. rubra) while M. rubra biomass exceeded the combined biomass of all other ciliates on several dates. The maximum biomass observed for M. rubra was ca 35 mu g Cl-1. When M. rubra was present, its estimated contribution to primary prod uction was usually greater than that of L. strobila. Up to 23% of tota l community photosynthesis was attributed to these 2 ciliates even tho ugh red water blooms of M. rubra were not observed.