[1] Umea Univ, Dept Ecol & Environn Sci, Marine Ecol, SE-90187 Umea, Sweden
[2] Umea Marine Sci Ctr, SE-91020 Hornefors, Sweden
[3] Linkoping Univ, Dept Mol & Clin Med, Div Med Microbiol, SE-58185 Linkoping, Sweden
[4] Univ Copenhagen, Bot Inst, DK-1353 Copenhagen K, Denmark