Hydrogen peroxide is not the cause of fish kills associated with Chattonella marina: Cytological and physiological evidence

• Published in: Aquatic toxicology Vol. 72; no. 4; pp. 351 - 360
• Main Authors: M. Tang, Janet Y., Anderson, Donald M., T. Au, Doris W.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-05-2005; Elsevier Science
• Subjects: Analysis of Variance; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Chattonella marina; Ecotoxicology, biological effects of pollution; Eukaryota - pathogenicity; Eutrophication; Fish Diseases - microbiology; Fish Diseases - mortality; Fish kill mechanism; Fundamental and applied biological sciences. Psychology; General aspects; Gills - drug effects; Gills - ultrastructure; HAB; Harmful algal bloom; Hydrogen Peroxide - toxicity; Hydrogen-Ion Concentration; Microscopy, Electron; Osmoregulation; Perciformes; Quantitative ultrastructure; Reactive oxygen species; Reactive Oxygen Species - toxicity; Time Factors; Water-Electrolyte Balance - drug effects; Quantitative ultrastructure; Reactive oxygen species; Fish kill mechanism; Chattonella marina; HAB; Osmoregulation; Harmful algal bloom; Oxidative stress; Hydrogen peroxide; Ecotoxicology; Free radical; Harmful algae; Aquatic environment; Vertebrata; Ultrastructure; Pisces; Bloom
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2005.01.007

Chattonella marina, a harmful algal bloom (HAB) causative species, was used to study the mortality, physiology, and pathology of a marine stenohaline fish, goldlined seabream exposed to the toxic alga. The median lethal time (LT
50) was 3
h upon exposure to 8000
cells/ml of
C.
marina. Significant induction of filamental chloride cells (CCs) [i.e. increases in CC fractional area and in the volume density of CCs], concomitant with significant reduction of blood osmolality, were found in
C. marina treated fish. To verify whether the toxicity of
C. marina was mediated through oxidative stress, a hydrogen peroxide exposure experiment was carried out and the toxicity as well as cytological and physiological changes were compared with the
C. marina treatment. Hydrogen peroxide at a concentration of 500
μM H
2O
2, (i.e. 25 times higher than that produced by 8000
cells/ml of
C.
marina (20
μM H
2O
2)) was unable to induce similar CC alterations and osmoregulatory impairment in fish as observed in the
C.
marina treatment. Non-specific membrane damage such as severe loss of microvilli projections on the CC apical opening and rupture of epithelial membranes in the lamellae were observed. The LT
50 was 6
h, two times longer than that with 8000
cells/ml of
C.
marina. Based on the cytological and physiological evidence and toxicity data, the mechanism by which
C.
marina kills fish appears to be very different from that caused by H
2O
2/ROS. Osmoregulatory distress is the major cause of fish death upon exposure to
C.
marina.