Burrow morphology of Uca uruguayensis and Uca leptodactylus (Decapoda: Ocypodidae) from a subtropical mangrove forest in the western Atlantic

Abstract

The continuous excavation of burrows by fiddler crabs generates bioturbation in the sediment, which can be estimated from burrow morphology. The aim of the present study was to describe the burrow morphology of Uca uruguayensis and U. leptodactylus and its relationship with demography of resident individuals and to estimate the level of bioturbation in the sediment generated by each species. For all individuals from each of the 2 species, sex was determined and the carapace width (CW; mm) measured. Burrows were characterized according to burrow diameter (BD; mm), maximum burrow depth (MBD; mm) and burrow volume (BV; cm3). The density of each species in the study area was also evaluated. In both species, the males were larger and occupied burrows with higher BV compared to females. Differences between sexes in relation to the burrow characteristics might reflect sexual dimorphism within the group and are probably related to the fact that males use the burrows for mating. BD and BV showed significant positive relationships with the size of resident crabs. The amount of sediment removed per burrow was estimated from mean BV: 10.78 cm3 of sediment/burrow for U. uruguayensis and 12.38 cm3 of sediment/burrow for U. leptodactylus. Despite the density and depth differences between the 2 species, the similarity in burrow volume suggests that U. uruguayensis and U. leptodactylus present the same importance in terms of the bioturbation process. Burrow morphology is highly associated with characteristics of the occupant, although extrinsic factors should also be considered, and its description can provide estimates on the bioturbation generated by Uca species in mangrove forests.

Organic matter affects fiddler crab distribution? Results from field and laboratorial trials

“…established in accordance with the maximum burrow depth for this species (Machado et al, 2013). We used one crab per microcosm to avoid intra-specific competition for territory as an interference factor.…”

Size-Class and Sex Dependent Variations of Burrow Architecture of Fiddler Crab, Uca rosea (Tweedie, 1937) in Sundarbans

“…Being deposit feeders and burrowing in habit into the sediment, fiddler crab burrows are central to predator avoidance, reproduction and protection from the natural forces like wind and tidal activities [2,3].The burrowing activities increase oxidation and proper drainage of the sediment [4], increase the growth of substrate micro-organism and enhance the rate of decomposition of plant debris within the sediments [5].…”

Response of estuarine meiofauna communities to shifts in spatial distribution of keystone species: An experimental approach

“…Besides, as the species expand their distributions into areas of increased climatic suitability a decoupling of species interactions may allow some species to rapidly exploit a wider range of environments (Menéndez et al, 2008). Leptuca leptodactyla and L. uruguayensis are morphologically similar species (Crane, 1975), have the same bioturbation potential (Machado et al, 2013;Natalio et al, 2017) and where they co-occur, often share the similar intertidal area (Ng et al, 2008;Checon and Costa, 2017). Fiddler crabs are conspicuous intertidal keystone species (sensu Power et al, 1996) from tropical and subtropical regions, and play a key role in controlling estuarine meiofauna by predation and changing the physical and chemical environment during their burrowing and feeding activities (e.g., Payton et al, 2002;Kristensen, 2008;Citadin et al, 2016).…”