THE FIDDLER CRAB, UCA BENGALI CRANE, 1975: POPULATION BIOLOGY AND BURROW CHARACTERISTICS ON A RIVERBANK IN SOUTHERN THAILAND.

We studied the population structure of Uca bengali Crane, 1975 (crab density, sex ratio, and body size (i.e., carapace length and width, major claw length and width)), along with burrow characteristics (diameter, length, depth, and volume) as well as sediment characteristics (percent moisture content and organic matter) along a bank gradient at three distances (2, 4 and 6 m) from the edge of a tidal river. The results showed no differences in crab density, sex ratio, and body size among the three distances. The percent moisture content at 2 m distance was higher than at 4 and 6 m, and the percentage organic matter at 2 m distance was higher than at 6 m distance. Burrows were shorter in length, shallower in depth, and smaller in volume at 2 m distance, but these measures increased with increasing distance from the river edge. Both males and females made three distinct burrow shapes: I, J and U; the J-shaped burrows were the most numerous at all distances. [ABSTRACT FROM AUTHOR]