The armoured planktonic dinoflagellates present at a site adjacent to a floating fish-farm in Loch Eriboll, North Scotland, were studied by surface net-sampling, mainly at two-weekly intervals, over a period of four years 1990–1993. A total of 62 species was recorded. Some dinoflagellates were present at all times of the year but they reached their lowest numbers in May, during the spring diatom bloom, and their highest numbers in mid-summer. There was usually a seasonal pattern in which the most abundant dinoflagellate during the early summer was the heterotrophic species Protoperidinium ovatum, and this was followed in the later summer by the autotroph Ceratium fusus. In 1993 the pattern was rather different, with Gonyaulax species abundant in June and, later in the year, both Protoperidinium cerasus and P. excentricum having periods of abundance. Potential toxin-producing dinoflagellates, Alexandrium tamarense (PSP) and Dinophysis acuminata (DSP), were found in small numbers.
Transcriptomic and isotopic data reveal central role of ammonium in facilitating the growth of the mixotrophic dinoflagellate, Dinophysis acuminata
