R.M. Errera
R. Kiesling
B.W. Brooks
J. P. Grover
L. Schwierzke
F. Urena-Boeck
J. Baker
J.L. Pinckney
D. L. Roelke
2007
<p><span>Large fish kills associated with toxic populations of the haptophyte </span><i>Prymnesium parvum</i><span> occur worldwide. In the past 5 yr, incidences of </span><i>P. parvum</i><span> blooms in inland water bodies of Texas (USA) have increased dramatically, where cell densities in excess of 1 × 10</span><sup>7</sup><span> cells l</span><sup>–1</sup><span> are typically observed. We conducted field experiments (Lake Possum Kingdom) during the fall and early spring of 28 d duration using 24 enclosures of 1.57 m</span><sup>3</sup><span> each. The experiments investigated the effect of nutrient enrichment, immigration of </span><i>P. parvum</i><span> and addition of barley straw extract on phytoplankton biomass and assemblage structure, </span><i>P. parvum</i><span> population density, zooplankton biomass and assemblage structure, bacteria, and toxicity. Nutrient enrichment stimulated </span><i>P. parvum</i><span> population growth beyond bloom proportions (>1 × 10</span><sup>7</sup><span> cells l</span><sup>–1</sup><span>). However, </span><i>P. parvum</i><span> did not dominate the assemblage under these conditions, as it does during natural blooms. Instead, euglenophytes and chlorophytes dominated. Toxicity, estimated using fish (</span><i>Pimephales promelas</i><span>) and cladoceran (</span><i>Daphnia magna</i><span>) </span><i></i><span>bioassays and which is linked to </span><i>P. parvum</i><span>’s allelopathic and mixotrophic effectiveness, was greatly reduced (eliminated in many cases) under conditions of nutrient enrichment. The suppression of toxicity by nutrient addition suggested that targeted and time-limited nutrient manipulations might be used to mitigate the effects of </span><i>P. parvum</i><span> blooms. Immigration of </span><i>P. parvum</i><span> into natural assemblages and addition of barley straw extract had no significant effect on plankton dynamics.</span> Inter-Research 2007.</p>
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10.3354/ame046125
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Inter-Research Science Publisher
Effects of nutrient enrichment on Prymnesium parvum population dynamics and toxicity: Results from field experiments, Lake Possum Kingdom, USA
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