Fiddler crab burrow morphology: how do burrow dimensions and bioturbative activities compare in sympatric populations of Uca vocans (Linnaeus, 1758) and U. annulipes (H. Milne Edwards, 1837)?

Abstract

Dimensions of crab burrows were compared in two sympatric populations of fiddler crabs, Uca vocans and U. annulipes, to determine interspecies variation. Nine dimensions of burrow architecture were defined from 62 complete burrow casts of U. vocans: burrow diameter, BD; burrow volume, BV; total burrow depth, TBD; burrow neck height, BNH; curved burrow length, CBL; horizontal length, HL; chamber diameter, CD; angle between descending neck of burrow and the substrate surface, β; angle between the bend in the burrow and the perpendicular, θ . None of the nine dimensions of burrow architecture showed any difference between sexes. Six out of seven linear burrow dimensions differed significantly among crabs in the three size classes recognized; BNH did not differ among small, medium, and large-sized crabs. Regardless of species, larger-sized crabs dug larger entrances and resided in more voluminous burrows. The architecture of the burrows in the two sympatric populations is rather similar: the only significant difference is that Uca vocans had wider BDs than U. annulipes. This could be due to the difference in carapace proportions of the two species: adult specimens of U. vocans have significantly larger carapace length to width ratios than those of U. annulipes. Comparisons of β between the two species showed that the descent slopes of the burrows were similar, indicating that there is no evidence to suggest that burrows of fiddler crabs in sandy habitats have steeper descent slopes than those in muddy habitats. The mean volume of sediment excavated by U. vocans per m 2 , though not significantly greater than that of U. annulipes, suggests that U. vocans is potentially a more active agent of sediment re-working than its sympatric species in this lagoon. RÉSUMÉLes dimensions des terriers de crabes ont été comparées chez deux populations sympatriques de crabes violonistes, Uca vocans et U. annulipes, afin de déterminer la variation interspécifique. Neuf mesures de l'architecture du terrier ont été définies à partir de 62 moulages de terriers complets de 1 ) e-mail: slim@nie.edu.sg © Koninklijke Brill NV, Leiden, 2006 Crustaceana 79 (5): 525-540 Also available online: www.brill.nl 526 SHIRLEY S. L. LIM U. vocans : diamètre du terrier, BD ; volume du terrier, BV ; profondeur totale du terrier, TBD ; hauteur du conduit d'entrée du terrier, BNH ; longueur de la partie courbe du terrier, CBL ; longueur horizontale, HL ; diamètre de la chambre, CD ; angle entre la partie descendante du terrier et la surface du substrat, β; angle entre la courbure du terrier et la perpendiculaire, θ. Aucune de ces neuf mesures de l'architecture du terrier n'a montré de différences entre les sexes. Six des sept dimensions linéaires du terrier différaient significativement parmi les crabes, dans les trois classes de taille reconnues ; BNH ne différait pas, que les crabes soient de petite, moyenne ou grande taille. Par rapport à l'espèce, les grands crabes creusaient des entrées plus grandes et demeuraient dans des terriers de plus grand volume...

Groundwater‐derived dissolved inorganic and organic carbon exports from a mangrove tidal creek: The missing mangrove carbon sink?

“…The dominant mangrove species are Avicennia marina, Aegiceras corniculatum, Bruguiera gymnorrhiza, and Rhizophora stylosa, with smaller isolated populations of Ceriops australis, Excoecaria agallocha, and Lumnitzera racemosa. Crab burrows are the predominant feature of the sediments, and the fiddler crabs species that are dominant in the area (Uca vocans and Uca bellator minima; Meziane et al 2006) are known to create new burrows after each tidal cycle (Lim 2006). Sampling campaigns were conducted in winter (July 2011) and summer (January 2012) during spring tides (maximum tidal amplitude , 2 m).…”

Selective geochemistry of iron in mangrove soils in a semiarid tropical climate: effects of the burrowing activity of the crabs Ucides cordatus and Uca maracoani

“…2). Thus, in Brazilian mangroves, Ucides cordatus reaches larger maximum carapace sizes (male carapace width >90 mm, females >70 mm; Diele and Koch 2010), and also makes wider and deeper burrows (depth >210 cm; Schories et al 2003) than Uca maracoani (depth ∼40 cm; Lim 2006). The burrowing characteristics of U. cordatus imply the removal of a larger amount of sediment, which probably results in greater aeration at depth.…”

“…The fiddler crab Uca maracoani makes simple, unbranched and relatively shallow burrows (approx. 40 cm deep) that may be shared (Lim 2006;Kristensen 2008). Ucides cordatus, in contrast, builds more complex burrows, often with multiple entrances (Bright and Hogue 1972) and with depths between 20 cm and 2 m, which are relatively straight and uniform in aspect (Castilho-Westphal et al 2008).…”

Plant effects on burrowing crab morphology in a Chinese salt marsh: Native vs. exotic plants

“…For example, fiddler crabs usually excavate simple J-shaped burrows with single openings (Wolfrath, 1992;Mouton and Felder, 1996), whereas the burrows of sesarmid crabs range from simple unbranched burrows to complex burrow systems with multiple openings (Lee and Koh, 1994;Stieglitz et al, 2000). Crab sex (Eshky et al, 1995;Lim and Diong, 2003), body size (Lim, 2006), and burrow age (Rudnick et al, 2005;Kristensen, 2008) are also all correlated with burrow morphology.…”