We examined growth and egg production rates of Pseudodiaptomus forbesi (Copepoda: Calanoida) in the northern San Francisco Estuary (SFE), California, USA. Data from several earlier studies were combined with new data to assess the responses of these vital rates to environmental factors. We measured 118 growth rates of early copepodites (C1–C3) and 191 egg production rates (EPRs) during spring–autumn of 10 years between 2006 and 2018. Samples were taken from four habitat types: brackish open water, fresh open water, wetland, and tidal channel. Growth rates averaged 0.21 d⁻¹ (range 0–0.53 d⁻¹), while EPR averaged 2.4 eggs ♀⁻¹ d⁻¹ (range 0–11 eggs ♀⁻¹ d⁻¹). Mass-specific EPR of females averaged about 20% of copepodite growth rate, meaning that specific egg production rate is not a suitable proxy for specific growth rate of this species. A rectangular hyperbola predicted 24% of the variation in growth rate from chlorophyll concentration and 19% of the variation in EPR (28% with habitat type as a covariate). Most of the chlorophyll values were below levels where growth rate or EPR approach their maxima. Lipid composition in a subset of samples gave no better prediction of growth rate than chlorophyll and was unrelated to EPR. Growth and reproduction of P. forbesi were food-limited most of the time, particularly in the open-water habitats. Despite high variability, these measurements make clear that the chronically low primary production in the northern SFE imposes limits on the food web supporting declining fish populations.

我们研究了美国加利福尼亚州旧金山河口 (SFE) 北部的Pseudodiaptomus forbesi ( Copepoda : Calanoida ) 的生长和产蛋率。几项早期研究的数据与新数据相结合，以评估这些生命率对环境因素的反应。我们在 2006 年至 2018 年之间的 10 年春秋期间测量了 118 次早期桡足类 (C1-C3) 的生长率和 191 次产蛋率 (EPR)。样本取自四种栖息地类型：微咸开放水域、淡水开放水域、湿地, 潮汐通道。生长率平均为 0.21 d ^-1（范围 0-0.53 d ^-1），而 EPR 平均为 2.4 个鸡蛋 ♀ ^-1 d ^-1（范围 0-11 个鸡蛋 ♀^-1  d ^-1 )。雌性群体特定的 EPR 平均约为桡足类生长速率的 20%，这意味着特定产蛋率不是该物种特定生长速率的合适代表。矩形双曲线预测 24% 的生长速率变化来自叶绿素浓度和 19% 的 EPR 变化（28% 以栖息地类型作为协变量）。大多数叶绿素值低于增长率或 EPR 接近其最大值的水平。样本子集中的脂质成分没有比叶绿素更好地预测生长速率，并且与 EPR 无关。P. forbesi 的生长和繁殖大多数时候食物有限，特别是在开放水域的栖息地。尽管变异性很大，但这些测量结果清楚地表明，北部 SFE 长期低初级生产对支持鱼类种群下降的食物网施加了限制。