Ecological Interactions on Sandy Beach Ecosystems: A Global Synthesis of Mole Crabs and New Insights into Emerita brasiliensis and Emerita rathbunae (Crustacea, Decapoda, Anomura, Hippidae)

Sandy beaches are dynamic intertidal ecosystems where ecological interactions play a critical yet often overlooked role in shaping community structure and population dynamics. This study presents a global synthesis of ecological interactions involving mole crabs of the genus Emerita (Crustacea: Decapoda: Hippidae), complemented by new field and laboratory findings. Through a literature review and targeted sampling, we documented multiple interaction types, including predation, parasitism, epibiosis, competition, and symbiosis, highlighting their ecological and potential evolutionary implications. Predation and parasitism were the most frequently reported interactions worldwide. Our new empirical observations revealed, for the first time, the association of Eucheilota (Hydrozoa) and Maritrema sp. (Digenea) with E. rathbunae, as well as annual infection patterns by Profilicollis altmani (Acanthocephala) and algal epibiosis in E. brasiliensis. These interactions influence key biological processes such as burrowing, reproduction, and survival, ultimately affecting species distribution and population structure. Overall, our findings reinforce the central role of ecological interactions in the functioning and conservation of sandy beach ecosystems, particularly under growing anthropogenic pressures.