ALLOMETRIC GROWTH OF UCA RAPAX SMITH, 1870 (CRUSTACEA, OCYPODIDAE) IN A POPULATION FROM A SOUTHEASTREN BRAZILIAN MANGROVE

CASTIGLIONI DANIELA; COLPO KARINE; GUIMARAES FERNANDA; NEGREIROS-FRANSOZO MARIA LUCIA

MAÓ - MENORCA - ESPAÑA

Congreso; 36th European Marine Biology Symposium - a marine science odyssey into the 21st Century.; 2001

Growth patterns and the size of maturity constitute important parameters for the understanding of the fiddler crabs biology. The crab´s growth is discontinuous and during this process, certain body parts increase differently from others. This way, the study of r the relative growth was conducted to determine what are the best relations to represent  the morphologic sexual maturity in U. rapax. Crabs were monthly sampled at the Itamarmbuca mangrove (23°24´43"5 and 45°00´73"W) throughout a year period .Carapace width (CW) and length (CL); abdomen width (AW); chelar propodus length (CPL) and height (CPH) for both sexes, and gonopod length (GW) only for males were taken with a caliper (0.01 mm). The data were plotted and the dispersion points were analyzed. Afterwards, the data were adjusted to a power function (y=axb), being CW considered the independent variable "x" and the other dimensions as dependent variables "y". The "b" is the allometric growth constant that shows the relation existing between two variables. When "b" is lower than 1, the growth is characterized by a negative allometry (b< 1); when b= 1, isometry and when b is higher than 1, positive allometry. The softwares Mature I and Mature II were used to estimate the maturity size. The relations that best evidence the size at onset of sexual maturity were the CW x AW, for females (positive allometry; youngs: b=1.69 and adults: b=1.39) and CW x CPl, for mal´es (Dositive allometry; youngs: b= 1.44 and adults: b= 1.65). The relation CW x Gl showed a greater rate of growth during the juvenile phase (b= 1.52), when it is compared with the adult phase (b=1.03). The present analyses showed that 50% of females rmature with 11.4 mm de CW and males reach the morp-hologic sexual maturity with 9.4 mm CWo The positive allometry found for abdomen Width is related with the fact of the femal´es incubate the eggs at the abdominal appendages. The remarkable growth of the male´s cheliped might be related to the reproductive behavior, including courtship and agonistic interactions with other males.