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[C-3.3 Effects of Acid Rain on Aquatic Organisms]

[Contact Person]

Teiichi Nishimura
Section Chief
Freshwater Fisheries and Environment Division,National
Research Institute of Fisheries Science,Fisheries Agency,
1088 Komaki, Ueda, Nagano 386 Japan
Phone +81-268-22-0594, Fax +81-268-22-0544

[Total Budget for FY1990-1992]

34,239,000 Yen

[Abstract]

　Aquatic plants rose pH in ponds, but their growth and photosynthesis were inhibited at lower pH. In carp, secondary gill filaments were covered with chloride cells from a day after exposure, while serum osmosis, Na⁺ and Cl^- remarkably decreased with decrease in pH. Additive effects of low pH and aluminium varied with temperature, increased with water hardness and more pronouced in fry than fertilized eggs. Maladjustment of osmoregulation was concluded to be caused by H+ and not SO₄^2-, Cl^- or NO₃^- in masu salmon. Less than 24 hour exposure to acidic water was found to induce no effects on osmoregulation in sea-life of chum salmon. Catadromous salmon group fish were suggested to attain their osmo-regulating ability adaptable to both freshwater and marine lives in seaward migratory season. Additive toxicity of low pH and Cu or Al to sperms was recognized in ayu, charr and goldfish. Higher amounts of aluminium were elluted from finer particles of granite and andesite at lower pH. Acid tolerance of freshwater fish including salmon group and aquatic insects were evaluated. Rainbow trouts exposed to acidic environment produced eggs of lower eying and higher deformity rates. Model ecosystem experiment revealed acid loading to water causes change of species composition of plankton and delay of fish growth even when no remarkable decrease in pH is observed.

[Key Words]

Acid Rain, Freshwater Organisms, Osmotic Pressure, Aluminium, Model Ecosystem