The main organisms that cause toxic proliferations that affect humans in the Galician estuaries are:
Species: Dinophysis spp.
They are the cause of presence of diarrheal toxin in the Galician estuaries.
They are responsible for the largest closures for the exploitation of seafood. In Galicia, the presence of Dinophysis does not produce red tides; although the coloration of their cells is typically reddish.
Species: Gymnodinium catenatum
Color: Reddish brown
They cause poisoning of paralyzing type (PSP).
Its presence is not usually abundant in the Galician estuaries, but was responsible for toxic proliferations mainly in the 70s and 80s.
Species: Alexandrium spp.
They cause poisoning of paralyzing type (PSP).
In this genus there is a complex of toxic and non-toxic species. In Galicia the main responsible for toxic proliferations is Alexandrium minutum, generally in the Rías Altas (Ares-Betanzos).
Species: Pseudonitzschia australis
Cause of amnesic poisoning (ASP).
It is part of a complex of toxic and non-toxic species. In Galicia it is the only diatom identified as a producer of domoic acid, a potent neurotoxin. Brownish-green color. Their proliferations, although they can be very abundant, do not form distinguishable spots like red tides.