Towards the end of August 1978 SCUBA divers studying a rocky area in Mounts Bay noticed numbers of dead and dying fish and invertebrates in their study area. Their observations were passed on to Dr G. W. Potts (Griffiths, Dennis & Potts, see below, p. 520). Samples of the sea water, which appeared to be very rich in phytoplankton, were taken but unfortunately were too poorly fixed for the identification of naked dinoflagellates. At the same time a number of reports of‘red tides’ and ‘fish kills’ in Mounts Bay were being passed to Mrs Stella Turk of Camborne.

During the first 2 weeks of September 1978, high mortalities of intertidal populations of several ‘bait’ species, notably lugworms, were reported to the Plymouth Laboratory by anglers along the south coast of Cornwall. In the same period, abnormally high numbers of the red-band fish, Cepola rubescens, were caught in the trawls of the Laboratory's research vessels (Dr A. J. Southward, personal communication). In addition, some 20–30 specimens of another burrowing species, Amalosoma eddystonense, were taken in several trawls on the Looe Grounds; this was rather surprising since this large echiuran was thought to be rare in the Plymouth area (Dr P. E. Gibbs, personal communication).

The author also received reports indicating that the non-photosynthetic but luminescent dinoflagellate Noctiluca scintillans (Macartney) Ehrenb. was abundant in coastal areas of the western English Channel. This organism is well known for forming slicks varying in colour from orange to blood-red (Le Févre & Grail, 1970; Grail, Le FévreLehoerff & Le Févre, 1971).