Brachyuran crabs are an important ecological and economical, yet often unstudied aspect of intertidal mudflats of the Arabian Peninsula. Here we provide baseline density estimates of crabs at the relatively pristine intertidal mudflats of Barr Al Hikman (Sultanate of Oman) and provide information on their life cycle and habitat preference. Across the winters of 2012–2015 crabs were sampled on a grid covering the entire intertidal depth gradient. 29 species were found and average densities varied between 12 and 54 crabs/m2. Deposit-feeding and herbivorous crabs were the most abundant species across all winters. Size frequency data and the presence of ovigerous females show that most crabs species reproduce in the intertidal area. P. segnis, the most important crab for local fisheries, was found to use the intertidal area as a nursery ground. We analysed the relationships between the two most abundant crab species, Macrophthalmus sulcatus and Thalamita poissonii and the environmental variables: seagrass density, tidal elevation, median grain size and sediment depth using Random Forest models. The predictive capacity of the models and the relative importance of the environmental predictors varied between years, but crab densities in general were positively associated with seagrass density, presumably because seagrass offers feeding habitat.

中文翻译：

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阿曼苏丹国 Barr Al Hikman 的潮间带泥滩，作为短尾蟹的饲养、繁殖和育苗场

Brachyuran 螃蟹是阿拉伯半岛潮间带泥滩的重要生态和经济方面，但往往未被研究。在这里，我们提供了 Barr Al Hikman（阿曼苏丹国）相对原始的潮间带泥滩上螃蟹的基线密度估计值，并提供了有关其生命周期和栖息地偏好的信息。在 2012-2015 年的冬天，在覆盖整个潮间带深度梯度的网格上对螃蟹进行采样。发现了 29 个物种，平均密度在 12 到 54 只螃蟹/平方米之间。在整个冬季，以沉积为食的蟹和食草蟹是数量最多的物种。大小频率数据和雌性雌性的存在表明，大多数螃蟹物种在潮间带繁殖。P. segnis 是当地渔业最重要的螃蟹，被发现使用潮间带作为育苗场。我们使用随机森林模型分析了两种最丰富的螃蟹物种 Macrophthalmus sulcatus 和 Thalamita poissonii 以及环境变量之间的关系：海草密度、潮汐高度、中值粒度和沉积物深度。模型的预测能力和环境预测因子的相对重要性因年份而异，但螃蟹密度一般与海草密度呈正相关，大概是因为海草提供了觅食栖息地。