Depuration of Domoic Acid in the Great Scallop (Pecten maximus) following a bloom of Pseudo-nitzschia cf seriata in the central Irish Sea

Following a bloom of the diatom Pseudo-nitzschia cf. seriata, a known producer of the Amnesic Shellfish Poisoning compound domoic acid, intoxification of the great Scallop (Pecten maximus) with domoic acid was observed in... [ view full abstract ]

Following a bloom of the diatom Pseudo-nitzschia cf. seriata, a known producer of the Amnesic Shellfish Poisoning compound domoic acid, intoxification of the great Scallop (Pecten maximus) with domoic acid was observed in fishing grounds to the west of the Isle of Man in the Irish Sea. Although the phytoplankton bloom was short lived lasting approximately 4-6 weeks, full depuration of domoic acid in great Scallops took up to 16 months. Environmental factors leading to the development of the bloom are investigated and the potential impact of trace metal deposits into the marine environment prior to and during the initial bloom development are explored as potential triggers for domoic acid production in Pseudo-nitzschia cf. seriata.

Data on the domoic acid concentrations of the great scallop collected as whole animal, combined adductor muscle and gonad and separated gonad tissues is presented in context with current EC and UK consent levels for marketing. The results show that depuration occurs faster in the gonad than in the whole animal or adductor muscle and gonad portions. Data on Domoic acid concentrations in queen scallops (Aequipecten opercularis) from the same fishing grounds showed this species to be relatively unaffected by the Pseudo-nitzschia bloom, suggesting possible differential feeding strategies between the two species.

Measured concentrations of the diatom Pseudo-nitzschia cf seriata in routine seawater monitoring samples during the bloom showed concentrations to be below trigger levels of 150000 cells/liter raising the question of whether such trigger levels are adequate or whether they should they be reduced.