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.
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Original data is available at : https://doi.org/10.25850/nioz/7b.b.cb.
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All the work was done under the permission of the Ministry of Environment and Climate Affairs (MECA), Sultanate of Oman. We are very grateful to its Director-General Mr Sulieman Al Akhzami, the assistant Director-General Dr. Thuraya Said Al-Sairiri and its former Director-General, Mr Ali Al-Kiyumi, for making all the necessary arrangements. Without the sampling effort of Thomas Lameris, Bram Fey and Brecht De Meulenaer, the data presented in this paper would not have been generated. Marc Lavalye helped to identify the crabs and Emiel van Loon and Allert Bijleveld gave advise on statistical analysis. This study was financed by NWO in the Netherlands (ALW Open Programme Grant 821.01.001 awarded to JAvG) and by The Research Council in the Sultanate of Oman (ORG/EBR/12/002 grant awarded to AK).
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Bom, R.A., van Gils, J.A., Molenaar, K. et al. The intertidal mudflats of Barr Al Hikman, Sultanate of Oman, as feeding, reproduction and nursery grounds for brachyuran crabs. Hydrobiologia 847, 4295–4309 (2020). https://doi.org/10.1007/s10750-020-04418-4
- Barr Al Hikman
- Brachyuran crabs
- Nursery ground
- Portunus segnis
- Sultanate of Oman