Inhibitory and Toxic Effects of Blue‐green Algae on <i>Daphnia</i>

この論文をさがす

抄録

<jats:title>Abstract</jats:title><jats:p>The effects of the planktonic blue‐green algae, <jats:italic>Aphanizomenon gracile, Synechococcus elongatus</jats:italic>, and <jats:italic>Microcystis aeruginosa</jats:italic>, on survival, growth, and food uptake of <jats:italic>Daphnia pulicaria</jats:italic> were determined. <jats:italic>Synechococcus</jats:italic> and <jats:italic>Aphanizomenon</jats:italic> were unsuitable food when offered alone, but did not affect the daphnids negatively when mixed with <jats:italic>Scenedesmus. Microcystis</jats:italic> was the only one found to be toxic. In pure suspensions of this blue‐green, the daphnids did not survive more than 48 hours; they lived a little longer if <jats:italic>Scenedesmus</jats:italic> was supplied additionally. Growth was markedly reduced when only 50 μg carbon/l of <jats:italic>Microcystis</jats:italic> was added to the normal <jats:italic>Scenedesmus</jats:italic> food. It ceased at a concentration of 250 μg C/l. This can be explained by the reduction of food uptake. Very small quantities of <jats:italic>Microcystis</jats:italic> (10 μg C/l) present in the normal food caused a significant reduction of the filtering rate. Filtering inhibition was associated with the cells. Filtrate of <jats:italic>Microcystis</jats:italic> suspensions was not effective. Thus, the daphnids must ingest the blue‐green cells in order to become toxified. Dual‐labelling experiments showed that <jats:italic>Microcystis</jats:italic> cells are filtered from the medium by Daphnia with the same efficiency as <jats:italic>Scendesmus</jats:italic> and are not rejected. Toxicity of <jats:italic>Microcystis</jats:italic> is considered to be an effective defence mechanism against grazing pressure.</jats:p>

収録刊行物

被引用文献 (4)*注記

もっと見る

詳細情報 詳細情報について

問題の指摘

ページトップへ