Bloom of Noctiluca scintillans in the South-West

An algal bloom was identified this week and its persistent in the southwest (Dunmanus, Kenmare and South Clare coast). The organism that causes these blooms which are very typical at this time of the year are called Noctiluca scintillans (dinoflagellate) and It is also notable as one of the species that results in bioluminescence which can be observed when the water is disturbed at night. It is one of a number of organisms that can do this.

These naturally forming blooms are known for their typical orange discoloration of the water, which is due to its feeding habits. They are a natural part of coastal biology and are harmless to humans, however, may occasionally cause mortalities among various marine organisms, particularly as the bloom decays and it uses up oxygen which already may be limited due to the high water temperatures. The bloom has created considerable public interest over the week, and some reports of an unpleasant smell have been received resulting from the breakdown of the bloom, as these species are known to release ammonia. It is a naturally occurring bloom which happens annually around the coast of Ireland. It is particularly strong in the South-West this year. The bloom is expected to breakdown, as the current settled weather changes, in due course.