Acute toxicity of bunker A and C refined oils to the marine harpacticoid copepod Tigriopus japonicus mori

Spilt oil from ships, naval accidents and establishments on shore is probably the most dramatic marine pollution, and is one of catastrophic disasters that happened frequently in aquatic environments. For evaluating the toxic effects of oils on marine ecosystem when a significant amount of oils is spilt in the sea, it is necessary to examine experimentally the degree of toxic impact of oils on marine organisms. A lot of extensive studies have been performed to examine the toxic effects of crude, refined and fuel oils and petroleum products on marine organisms such as commercially important fishes, crabs and shellfishes (e.g. Capuzzo 1987; Koyama et al. 1998). However, there is yet little information on the toxic effects of oils on small marine organisms such as copepods, that are important prey items for various aquatic animals. In the present study, we present here the acute toxicity (LC sub(50): the concentration resulting 50% of the exposed organisms being died) of Banker A and C refined oils on the demersal harpacticoid copepod Tigriopus japonicus, which is widely distributed along the coast of Japan, attaining dense populations in tide pools.