Calvin Lee Cheryl Patel Toni Ignoffo Brian A. Bergamaschi Wim Kimmerer Michelle J. Jungbluth 2020 <p><span>In 2016, a massive bloom of the chain-forming diatom&nbsp;</span><i>Aulacoseira granulata</i><span>&nbsp;occurred in the upper San Francisco Estuary, California, with chlorophyll concentrations up to 75 μg Chl L</span>⁻¹<span>. In this study, quantitative PCR was used to investigate consumption of the bloom organism by the numerically dominant zooplankter&nbsp;</span><i>Pseudodiaptomus forbesi</i><span>&nbsp;(Copepoda: Calanoida) and to estimate the contribution of the bloom to egg production. Copepods were collected on four transects during May and June 2016; egg production rates were somewhat elevated above previous rates measured in the estuary. Ingestion of&nbsp;</span><i>A. granulata</i><span>&nbsp;was highest on the first sampling day, just after the peak of the bloom, ranging from 175 to 945 cells copepod</span>⁻¹<span>&nbsp;day</span>⁻¹<span>. One month later ingestion rates dropped to 0–130 cells copepod</span>⁻¹<span>&nbsp;day</span>⁻¹<span>, despite continued dominance of&nbsp;</span><i>A. granulata</i><span>&nbsp;in the plankton. Ingestion of&nbsp;</span><i>A. granulata</i><span>&nbsp;provided from 0 to 21% (median 1%) of the estimated daily carbon required for growth and reproduction of&nbsp;</span><i>P. forbesi</i><span>. Although the copepods probably obtained nutrition from a microbial food web stimulated by the bloom, monitoring data showed little demographic response to this bloom. Thus, a massive diatom bloom in an unproductive estuary provided only a minor stimulus through an abundant consumer to the pelagic food web.</span></p> application/pdf 10.1007/s12237-020-00843-9 en Springer Nature Production of the copepod Pseudodiaptomus forbesi is not enhanced by ingestion of the diatom Aulacoseira granulata during a bloom article