Department of Animal Sciences and Aquatic Ecology, Ghent University, Ghent, Belgium.
Marine Biology Research Group, Ghent University, Ghent, Belgium.
PLoS One. 2022 Jul 25;17(7):e0271043. doi: 10.1371/journal.pone.0271043. eCollection 2022.
Video monitoring is a rapidly evolving tool in aquatic ecological research because of its non-destructive ability to assess fish assemblages. Nevertheless, methodological considerations of video monitoring techniques are often overlooked, especially in more complex sampling designs, causing inefficient data collection, processing, and interpretation. In this study, we discuss how video transect sampling designs could be assessed and how the inter-observer variability, design errors and sampling variability should be quantified and accounted for. The study took place in the coastal areas of the Galapagos archipelago and consisted of a hierarchical repeated-observations sampling design with multiple observers. Although observer bias was negligible for the assessment of fish assemblage structure, diversity and counts of individual species, sampling variability caused by simple counting/detection errors, observer effects and instantaneous fish displacement was often important. Especially for the counts of individual species, sampling variability most often exceeded the variability of the transects and sites. An extensive part of the variability in the fish assemblage structure was explained by the different transects (13%), suggesting that a sufficiently high number of transects is required to account for the within-location variability. Longer transect lengths allowed a better representation of the fish assemblages as sampling variability decreased by 33% if transect length was increased from 10 to 50 meters. However, to increase precision, including more repeats was typically more efficient than using longer transect lengths. The results confirm the suitability of the technique to study reef fish assemblages, but also highlight the importance of a sound methodological assessment since different biological responses and sampling designs are associated with different levels of sampling variability, precision and ecological relevance. Therefore, besides the direct usefulness of the results, the procedures to establish them may be just as valuable for researchers aiming to optimize their own sampling technique and design.
视频监测作为一种非破坏性的评估鱼类群落的方法，在水生态研究中得到了迅速发展。然而，视频监测技术的方法学考虑因素往往被忽视，特别是在更复杂的采样设计中，导致数据收集、处理和解释效率低下。在这项研究中，我们讨论了如何评估视频横截采样设计，以及如何量化和考虑观察者间变异性、设计误差和采样变异性。该研究在加拉帕戈斯群岛的沿海地区进行，采用了多层次重复观测采样设计，有多个观察者参与。尽管观察者偏差对鱼类群落结构、多样性和单个物种的计数评估可以忽略不计，但由于简单的计数/检测错误、观察者效应和瞬时鱼类位移引起的采样变异性通常很重要。特别是对于单个物种的计数，采样变异性通常超过了横截区和地点的变异性。鱼类群落结构的很大一部分变异性可以用不同的横截区来解释（13%），这表明需要足够多的横截区来解释位置内的变异性。较长的横截区长度允许更好地代表鱼类群落，因为如果将横截区长度从 10 米增加到 50 米，采样变异性会降低 33%。然而，为了提高精度，增加更多的重复通常比使用更长的横截区长度更有效。结果证实了该技术适用于研究珊瑚鱼群落，但也强调了进行合理方法评估的重要性，因为不同的生物响应和采样设计与不同水平的采样变异性、精度和生态相关性相关。因此，除了结果的直接有用性外，建立这些结果的程序对于旨在优化自己的采样技术和设计的研究人员来说可能同样有价值。
