Influence of habitat types on the burrowing behaviour and other behaviours of Tubuca arcuata (De Haan, 1835) (Decapoda: Brachyura: Ocypodoidea): a case study of the north shore of Hangzhou Bay, China

Abstract Fiddler crabs are common intertidal crustaceans with significant ecological and research value. In recent years, human activities have increasingly impacted intertidal zones. Habitat elements such as sediment particle size and vegetation cover may influence fiddler crab burrowing behaviour. Crab burrows are crucial for survival and closely linked to fiddler crab distribution. Therefore, the changes in these habitat elements may have altered the distribution of fiddler crabs. To better understand the mechanisms of habitat effects on fiddler crab distribution, further research is essential. This study focuses on Tubuca arcuata along the northern coast of Hangzhou Bay, China, employing field experiments and observations to examine the effects of three habitat types (bare mudflat, bare sandflat, and vegetated mudflat) on burrowing and other behaviours of T. arcuata . The results show that burrow density in vegetated mudflats is significantly higher than in the other two habitats, likely due to favourable soil compactness, cohesive particles, and root support for burrowing. In contrast, bare sandflats exhibit extremely low burrow density, requiring prolonged burrowing efforts and triggering distinct “chimney” building behaviour. These results are possibly due to poor sediment cohesiveness, low plasticity, and excessive soil compactness. Additionally, observations of other behaviour show that waving behaviour occurs more frequently on bare mudflats but are suppressed in vegetated mudflats, potentially due to visual signal obstruction. Aggregations of T. arcuata in vegetated mudflats may intensify intraspecific competition, leading to more frequent aggressive and defensive behaviours. This study can provide a reference for habitat research on other intertidal burrowing crab species.