In the Mediterranean Sea, shallow rocky reefs and the associated three-dimensional (3D) structure support rich and abundant communities; they are therefore of functional importance, in particular for the renewal of fish stocks. However, these habitats and their functions are likely to be altered by anthropogenic pressures inducing habitat transformations. It is therefore necessary to assess their 3D structure, their transformations and relationship to communities, especially for management and conservation purposes. In this article we aimed i) to compare two methods that quantify the metrics of the 3D structure (rugosity) of shallow rocky reefs (chain-and-tape method and photogrammetry), and ii) to quantify the possible links between this habitat structure and the fish assemblages. We found that photogrammetry and the chain-and-tape method yielded a similar estimate of rugosity, but photogrammetry was the most efficient method in terms of measurement quality and time (when considering in-water acquisition). This method also displayed the best repeatability. The 3D habitat descriptors (mean surface rugosity, variation of surface rugosity and depth) differed significantly between the studied sites and were therefore included as covariables. Total fish abundance and species richness increased with higher mean surface rugosity. In addition, the composition of fish assemblages was significantly influenced by surface rugosity, although this effect was modulated by depth. When focusing on specific taxa, neither density patterns nor size class distributions displayed clear patterns in relation to rugosity metrics. However, this study demonstrated that spatial variability of teleost fish assemblages can be explained by habitat rugosity which probably increases the number of shelters and food resources, and therefore improves chances of survival. In addition, our study has shown that photogrammetry is an appropriate method to assess 3D structure metrics in a temperate rocky reef.

中文翻译：

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地中海浅岩礁的三维结构：使用摄影测量出生的描述符来评估其对相关硬骨鱼组合的影响

在地中海，浅层岩礁和相关的三维 (3D) 结构支撑着丰富而丰富的群落；因此，它们具有重要的功能，特别是对于鱼类种群的更新。然而，这些栖息地及其功能可能会因人为压力导致栖息地转变而改变。因此，有必要评估它们的 3D 结构、它们的转换以及与社区的关系，尤其是出于管理和保护目的。在本文中，我们的目标是 i) 比较两种量化浅层岩礁 3D 结构（粗糙度）指标的方法（链带法和摄影测量法），以及 ii) 量化该栖息地结构与鱼组合。我们发现摄影测量和链带法产生了类似的粗糙度估计，但摄影测量是测量质量和时间（考虑水中采集时）最有效的方法。该方法还显示出最佳的重复性。3D 栖息地描述符（平均表面粗糙度、表面粗糙度和深度的变化）在研究地点之间存在显着差异，因此被列为协变量。总鱼类丰度和物种丰富度随着平均表面粗糙度的增加而增加。此外，鱼类组合的组成受表面粗糙度的显着影响，尽管这种影响受深度调节。当关注特定分类群时，密度模式和大小类别分布都没有显示出与粗糙度指标相关的清晰模式。然而，这项研究表明，硬骨鱼类组合的空间变异性可以用栖息地的凹凸不平来解释，这可能会增加庇护所和食物资源的数量，从而提高生存机会。此外，我们的研究表明，摄影测量是评估温带岩礁 3D 结构指标的合适方法。