The effect of blooming epiphytic algae on the leaf traits and photosynthetic hnction of the submersed macrophyte Potamogeton crispus was investigated under different epiphytic conditions and nutrition levels. Epiphytic algae growth was promoted at a rate of 0.16 chl a pg.cm".d-' on leaf surface area under eutrophic conditions (N: 1 mg.L-'; P: 0.1 mg-L-') and at a rate of 0.004 chl a pg-~m-~.d-' under mesotrophic conditions (N: 0.1 mgL-'; P: 0.01 mg.~-'). In the presence of the algae eaters Macrobrachiurn nipponense and Radix auricularia, the growth of epiphytic algae was markedly suppressed. In the absence of algae eaters, the growth of epiphytic algae for 42 days under the eutrophic and hypereutrophic conditions resulted in 25.2% of decrease of chl a, more than 50% decrease of the electron transport rate, harmful change in content of leaf nitrogen, photosystem I1 activity and photochemical quenching, and a lower production in the plant.

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Trichlorophenol (2,4,6-trichlorophenol [TCP]), a probable human carcinogen, is widely present in the environment. Employing denaturing high-performance liquid chromatography and DNA sequencing analyses, we demonstrated that 10-d exposure of zebrafish to TCP at 5 microg/L resulted in elevated point mutations of p53 gene in the liver genome. The result suggests that TCP might be involved in carcinogenesis by inducing point mutations in the somatic genome.

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