TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 60 (No. 4), pp. 731-741, 2004


Effects of CO2 on Marine Fish: Larvae and Adults

Atsushi Ishimatsu1*, Takashi Kikkawa1,2, Masahiro Hayashi1, Kyoung-Seon Lee1 and Jun Kita3

1Marine Research Institute, Nagasaki University, Taira-machi, Nagasaki 851-2213, Japan
2Central Laboratory, Marine Ecology Research Institute, Onjuku, Chiba 299-5105, Japan
3Research Institute of Innovative Technology for the Earth (RITE), Kizugawadai, Kizu-cho, Kyoto 619-0292, Japan

(Received 13 October 2003; in revised form 30 March 2004; accepted 6 April 2004)

Abstract: CO2-enriched seawater was far more toxic to eggs and larvae of a marine fish, silver seabream, Pagrus major, than HCl-acidified seawater when tested at the same seawater pH. Data on the effects of acidified seawater can therefore not be used to estimate the toxicity of CO2, as has been done in earlier studies. Ontogenetic changes in CO2 tolerance of two marine bony fishes (Pag. major and Japanese sillago, Sillago japonica) showed a similar, characteristic pattern: the cleavage and juvenile stages were most susceptible, whereas the preflexion and flexion stages were much more tolerant to CO2. Adult Japanese amberjack, Seriola quinqueradiata, and bastard halibut, Paralichthys olivaceus, died within 8 and 48 h, respectively, during exposure to seawater equilibrated with 5% CO2. Only 20% of a cartilaginous fish, starspotted smooth-hound, Mustelus manazo, died at 7% CO2 within 72 h. Arterial pH initially decreased but completely recovered within 1-24 h for Ser. quinqueradiata and Par. olivaceus at 1 and 3% CO2, but the recovery was slower and complete only at 1% for M. manazo. During exposure to 5% CO2, Par. olivaceus died after arterial pH had been completely restored. Exposure to 5% CO2 rapidly depressed the cardiac output of Ser. quinqueradiata, while 1% CO2 had no effect. Both levels of ambient CO2 had no effect on blood O2 levels. We tentatively conclude that cardiac failure is important in the mechanisms by which CO2 kills fish. High CO2 levels near injection points during CO2 ocean sequestration are likely to have acute deleterious effects on both larvae and adults of marine fishes.

*Corresponding author E-mail: a-ishima@net.nagasaki-u.ac.jp

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