Annual variation in biomass and the community structure of crustacean zooplankton over 5 years in Lake Toya, Japan

Syuhei Ban, Wataru Makino, Hiroyuki Sakano, Hiroyuki Haruna, Hiroshi Ueda

    研究成果: Article査読

    10 被引用数 (Scopus)

    抄録

    The biomass and population dynamics of crustacean zooplankton were determined in oligotrophic Lake Toya in Japan over 5 years from May 1992 to May 1997. In 1992 and 1993, zooplankton biomass was up to 4. 3 g dry weight m-2, whereas it decreased to <1 g dry weight m-2 after 1994. This extreme change in biomass was associated with the succession of dominant species from larger ones, such as Daphnia longispina and Cyclops strenuus (s. lat.), to smaller ones, such as Eubosmina tanakai and Bosmina longirostris. Consequently, this biomass change seemed to cause an increase in the chlorophyll a concentration in the euphotic zone and a decline in lake transparency. Because the birth rates of the dominant species were somewhat higher after 1994, the decline in the populations of larger crustaceans seemed to depend more on their rate of death rather than rate of birth, and this higher death rate is not considered to be attributed to food shortage. Although these results strongly suggest a top-down cascading effect of fish predation upon crustaceans, annual catches of two commercially important planktivorous fish species have also decreased in the lake, coincidentally with decreases in zooplankton biomass. This may be attributable to fishing regulations that prohibit catching smaller fish, implying that such smaller fish affect zooplankton and phytoplankton, as well as lake transparency.

    本文言語English
    ページ(範囲)59-70
    ページ数12
    ジャーナルLimnology
    14
    1
    DOI
    出版ステータスPublished - 2013 1月

    ASJC Scopus subject areas

    • 生態学
    • 水圏科学
    • 水の科学と技術

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