Research in aquatic ecology requires adequate sampling designs if the underlying processes that govern population and community dynamics are to be understood. Adequate sampling design is particularly important for organisms inhabiting environments such as mangroves. Thus, collecting quantitative ecological data remains a major challenge. Here, we analysed the structural and temporal dynamics of a tidal cycle and mangrove fish assemblages at 15 sites along the Brazilian central coast. Specifically, we used two non‐extractive sampling techniques, which included stationary underwater visual census (s‐UVC) and stationary underwater wide‐camera census (s‐UWC). Our results showed that by reducing potential observer effects, the s‐UWC protocol maximized fish counts, yielding more accurate and precise estimates. In contrast, although the s‐UVC technique was a useful approach, this technique did not yield precise density and richness estimates. Furthermore, the negative effect associated with the presence of an observer (i.e., diver) was a significant constraint to the observer‐based technique. Furthermore, the methods were more similar for the high tide samples and more divergent for the flood tide and ebb tide samples. These pronounced divergences among tidal periods allowed the application of a temporal mixed‐sampling protocol (i.e., unbalanced temporal samples) based on s‐UWC without the loss of statistical power. Methodological gains also were felt with a reduction in the costs associated with the presence of a trained observer in water and overcoming of constraints positively related to depth limitations. Overall, the s‐UWC protocol adequately captures species using different stages of the tide to enter the mangroves.

中文翻译：

---

固定式水下摄像机可更有效地评估清水红树林鱼群：非提取性技术的比较

如果要了解控制人口和社区动态的基本过程，则水生生态研究需要适当的抽样设计。适当的采样设计对于居住在红树林等环境中的生物尤其重要。因此，收集定量的生态数据仍然是一个重大挑战。在这里，我们分析了沿巴西中部沿海15个站点的潮汐周期和红树林鱼群的结构和时间动态。具体来说，我们使用了两种非抽取式采样技术，包括静态水下视觉普查（s‐ UVC）和静态水下广角照相机普查（s ‐ UWC）。我们的研究结果表明，减少潜在的观察者效应，小号‐UWC协议最大程度地提高了鱼类数量，从而得出更准确的估计值。相比之下，尽管s- UVC技术是一种有用的方法，但该技术无法得出精确的密度和丰富度估计值。此外，与观察者（即潜水员）的存在相关的负面影响是对基于观察者的技术的重大制约。此外，对于高潮样本，这些方法更为相似，而对于潮汐和退潮样本，这些方法则更为不同。潮汐期之间的这些明显差异允许基于s的时间混合采样协议（即，不平衡的时间采样）的应用‐UWC不会失去统计能力。还减少了与训练有素的观察员在水中有关的费用，并克服了与深度限制成正比的制约因素，从而获得了方法学上的收获。总体而言，s- UWC协议使用潮汐的不同阶段进入红树林来充分捕获物种。