Data_Sheet_1_Detecting Rare Species With Passive Sampling Tools: Optimizing the Duration and Frequency of Sampling for Benthic Taxa.docx

The choice of the duration and frequency of sampling to detect relevant patterns in field experiments or for environmental monitoring is always challenging since time and material resources are limited. In practice, duration and frequency of sampling are often chosen based on logistical constraints, experience, or practices described in published works but are rarely justified and almost never optimized before initiating sampling. Settlement plates are commonly used as a passive sampling tool to study recruitment patterns of fouling organisms (including non-indigenous species) and their deployment is amenable to experimentation with respect to manipulating duration and frequency of sampling. This study aimed to determine the optimal sampling strategy to detect rare species (e.g., a non-indigenous species early in the invasion process when its population size is still small). To do so, we deployed a series of settlement plates of various durations (1–32 days) and sampling frequencies (daily to biweekly) during the seasonal onset of recruitment, when larval supply was low, a situation that mimics the low propagule pressure of the early stages of the invasion process. We demonstrated that a combination of longer sampling duration and higher sampling frequency was the best strategy to maximize taxonomic richness. However, we found that an intermediate sampling duration of 1–2 weeks was optimal for detecting most species. These results can guide species-specific and assemblage-level sampling strategies using settlement plates. Additionally, this study can serve as a practical template for optimizing sampling of other taxonomic groups that were not examined in the present study as well as for the use of other methods.

在田间实验或环境监测中，针对检测相关模式所选择的采样时长与频率往往颇具挑战性，因为时间和物质资源均受限。在实际操作中，采样时长与频率的选择通常基于物流限制、经验或已发表的文献中描述的实践，但很少在采样开始前进行合理的论证和优化。沉降板作为一种被动采样工具，常被用于研究附着生物（包括非本地物种）的招募模式，其在采样时长与频率的操控方面易于进行实验。本研究旨在确定检测稀有物种（例如，在入侵过程中早期阶段，其种群规模仍较小时的非本地物种）的最佳采样策略。为此，我们在招募季节初期、幼虫供应量较低的情况下，部署了一系列不同时长（1-32天）和采样频率（每日至两周一次）的沉降板，以模拟入侵过程早期阶段的低传播压力。我们证明了较长的采样时长与较高的采样频率组合是最大化物种多样性的最佳策略。然而，我们发现，1-2周的中间采样时长对检测大多数物种而言是最优选择。这些结果可为使用沉降板进行物种特异性和群落水平的采样策略提供指导。此外，本研究还可以作为优化其他未在本研究中考察的分类群采样以及使用其他方法的实用模板。