Heterotrophic protists are essential components of the marine ecosystem, yet they are often excluded from monitoring programmes. With limited resources, monitoring strategies need to be optimised considering both scientific knowledge and available resources. In doing so, it is crucial to understand how sampling frequency affects the value of the data. We analysed 11 years of weekly heterotrophic protist time-series data from Station L4 in the Western English Channel to explore how different sampling intervals impact data quality. In the L4 dataset, comprising 55 protist taxa, the reduction of sampling frequency from weekly to four times a year at specific seasons decreased the number of taxa encountered by 38% for ciliates and 29% for heterotrophic dinoflagellates while the mean annual biomass or its mean variation were not affected. Furthermore, when samples were taken only four times a year, biomass peaks of the ten most important taxa were often missed. The primary motivator for this study was furthering the development of the heterotrophic protist monitoring in temperate and subarctic marine areas, e.g. the Baltic Sea. Based on our findings, we give recommendations on sampling frequency to optimise the value of heterotrophic protist monitoring.

中文翻译：

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优化采样频率以监测海洋生态系统中的异养原生生物

异养原生生物是海洋生态系统的重要组成部分，但它们通常被排除在监测计划之外。在资源有限的情况下，需要同时考虑科学知识和可用资源来优化监测策略。在此过程中，了解采样频率如何影响数据值至关重要。我们分析了来自西英吉利海峡 L4 站的 11 年每周异养原生生物时间序列数据，以探索不同的采样间隔如何影响数据质量。在包含 55 个原生生物分类群的 L4 数据集中，在特定季节将采样频率从每周减少到每年四次，使纤毛虫遇到的分类群数量减少了 38%，异养甲藻减少了 29%，而年平均生物量或其平均值变化不受影响。此外，当样品一年只采集四次时，十个最重要的类群的生物量峰值经常被遗漏。这项研究的主要动机是进一步发展温带和亚北极海洋区域（例如波罗的海）的异养原生生物监测。根据我们的发现，我们就采样频率提出建议，以优化异养原生生物监测的价值。