Pollution — Session Summary
The pollution session comprised only two contributions, a talk by Torbjørn Dale on “Effects from oil, dispersed oil and fertilized oil on planktonic ciliates” and a poster by Juan Miguel Gonzáles with J Iriberri, L Egea and I Barcina on the “Role of protozoa in the regulation of enteric bacteria populations in seawater”. The oil effects study during spring and summer 1980 and summer 1981 at Lindåspollene, western Norway, used enclosures to which oil, oil/dispersant and oil/nutrients were added at the surface. The experiments with added oil alone showed that the upper 1–2 m layers were depopulated within 1–2 weeks when the oil concentrations exceeded 0.2–1 mg 1-1. The disappearance of the ciliates was probably due to downward migration, revealed as temporary density peaks of the ciliates. The effects were stronger in summer than in spring. Within the total assemblage of heterotrophic ciliates (including mixotrophic species), Tontonia spp. appeared to be among the most sensitive, whereas the tintinnids Parafavella dentlculata and Acanthostomella norvegica appeared to be among the least sensitive.