Effects of sea bloom, chattonella antiqua, on gill primary lamellae of the young yellowtail, seriola quinqueradiata.

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Abstract
Histological and histochemical alterations on gill primary lamellae of the teleost, young yellowtail (S. quinqueradiata), affected by the sea bloom (C. antiqua) were studied and causative factors responsible for fish death were considered. A significant loss of mucous goblet cells on the afferent ridges occurred within .apprx. 1 h. Among the remainder, mucous cells located on the afferent ridge of the basal part of the gill primary lamellae were markedly impaired (64% decrease in number). In TEM [transmission electron microscopy] preparations, hyaline degenerations of the mucous cell membrane were observed. Histochemically, these mucous goblet cells contained neutral and acid glycoproteins. The cell layer on both ridges exposed to sea bloom appeared to be thinner than that of controls. The cell body of the internal multilayered mass had shrunk and intercellular spaces were markedly expanded. These edematous gill lamellae might have been caused by the disappearance of the mucous coat, leading to locally impaired osmoregulations. Gas exchange on the gill lamellae might have been disturbed.