A study about the annual fluctuation of the abundance, size composition, sexual proportion, reproductive period and juvenile recruitment of the fiddler crab Uca maracoani (Latreille, 1802-1803) was carried out in a population living in a tidal flat at Guaratuba Bay, Parana State, Brazil (48º36'W e 25º52'S). Crabs were obtained from February 2005 to January 2006, during low spring tides, in monthly collections, and their carapace width was measured. Air temperature oscillated from 17 to 29ºC, luminosity from 8,740 to 151,300 lux, salinity from 8 to 25 and soil temperature (on surface, 5 cm, 10 cm, 15 cm and 20 cm depth) from 18.3 to 28.9ºC. A total of 7,120 individuals were analyzed, among them, 2,578 were sexually indefinite juveniles, 2,377 males (1,113 juveniles and 1,264 mature males) and 2,165 females (944 juveniles, 1,135 mature and 86 ovigerous females). Population abundance oscillated 341 (April) to 994 individuals (January), but its annual fluctuation was not correlated to the oscillation of the abiotic variables. The sexual proportion was 1:1 and the reproduction of the species is continuous type, with two peaks of intensity in the year: one in April and another in November. Juvenile recruitment is also continuous with two periods of intensity in the year: in July and in December-January. Sexually indefinite juveniles measured from 1.14 to 2.62 mm carapace width, juvenile males from 2.58 to 17.83 mm, juvenile females from 2.60 to 11.72 mm, mature males from 17.85 to 35.81 mm and mature females from 11.75 to 31.76 mm. Males reach larger sizes than females.
Annual fluctuation; abundance; reproductive period; juvenile recruitment
