ARE PROTOZOA RESPONSIBLE FOR CONTROLLING PICOCYANOBACTERIAL ABUNDANCE IN EUTROPHIC WATERS?
Katie Harper, Jackie Parry, John Smith, Lancaster University, Lancaster, LA1 4YQ, and John Day, CCAP, Windermere Laboratory, Far Sawrey, Ambleside, Cumbria, LA22 OLP. Picocyanobacteria (<3 mm) are known to be limited by nutrients in oligotrophic waters but the controlling factors in eutrophic waters are far less clear. The community structure and abundance of picocyanobacteria in Esthwaite Water, a eutrophic lake, were analysed during the summer of 2001 using HIP1 PCR and epifluorescence microscopy, respectively. Results from this study, and whole water enrichment experiments, showed no significant correlation between the abundance of picocyanobacteria and either heterotrophic flagellates or ciliates. It was the dinoflagellates which increased in abundance when whole water was enriched with various picocyanobacterial 'HIP 1 types'. The interaction between these picocyanobacteria and representative dinoflagellate isolates (from the CCAP) has thus been examined under controlled laborator
