Abstract Coastal lagoons are often exposed to intense short-term environmental changes and strong anthropogenic pressures influencing zooplanktonic communities and production. However, most works focus on long-term temporal scales using monthly or seasonal sampling strategies. The present study analysed the structure of the mesozooplanktonic assemblages, the production (egg production rates) and physiological condition (RNA:DNA ratio) of the copepod Acartia clausi in a temperate coastal lagoon (Ria Formosa) during the summer, using an intensive sampling approach. Salinity was the main factor affecting the short-term variability of mesozooplankton composition, followed by tidal phase (ebb tides) and semilunar cycle (spring tides). There was a positive relationship between the abundance of Appendicularia and the cladoceran Penilia avirostris with the toxic dinoflagellate Gymnodinium catenatum, suggesting no deleterious effects. The egg production rate of A. clausi was influenced by salinity and ammonia concentration, with a positive correlation between the egg productivity and the macronutrient, showing a possible adaptation of this calanoid species. The RNA:DNA index was positively related to egg production rate, suggesting that it is a good proxy for the reproductive output of copepods, even in short-term periods. This study shows that different timescales need to be included in regular monitoring of planktonic assemblages in coastal lagoons in order to understand the influence of environmental and anthropogenic variables on marine organisms.

中文翻译：

---

温带沿海泻湖中的浮游生物群落和桡足类生产：短期内发生了什么变化？

摘要 沿海泻湖经常暴露于强烈的短期环境变化和影响浮游动物群落和生产的强烈人为压力。但是，大多数工作都使用月度或季节性抽样策略关注长期时间尺度。本研究使用密集采样方法分析了夏季温带沿海泻湖 (Ria Formosa) 中桡足类动物 Acartia clausi 的中型浮游组合结构、产量（产卵率）和生理条件（RNA:DNA 比率） . 盐度是影响中型浮游生物组成短期变化的主要因素，其次是潮位（退潮）和半月周期（大潮）。Appendicularia 和枝角类动物 Penilia avirostris 的丰度与有毒的甲藻 Gymnodinium catenatum 之间存在正相关关系，表明没有有害影响。A. clausi 的产蛋率受盐度和氨浓度的影响，产蛋率与常量营养素之间呈正相关，表明这种海藻类可能具有适应性。RNA:DNA 指数与产蛋率呈正相关，表明它是桡足类繁殖产量的良好代表，即使在短期内也是如此。这项研究表明，需要在沿海泻湖浮游组合的定期监测中包括不同的时间尺度，以了解环境和人为变量对海洋生物的影响。