Relative growth in the fiddler crab Uca uruguayensis Nobili, 1901 (Brachyura, Ocypodidae) from Garças River mangrove, Guaratuba Bay, southern Brazil

Abstract

-A study on the relative growth was carried out in a population of the fiddler crab Uca uruguayensis from the mangrove of Garças River, Guaratuba Bay, Paraná State, southern Brazil. The dimensions analyzed were the length of the major chela (LMC) of males and width of the abdomen (AW) of females, because they are related to reproductive activities of waving (males) and egg incubation (females). The cheliped handedness in males was also analyzed. The LMC was measured in 480 males, the AW in 566 females, and all crabs had the carapace width (CW) measured that was considered as the reference dimension for both sexes. The inflection point in the graphs between each the dimensions and CW was calculated with the aid of the software REGRANS. The CW ranged from 2.33 to 8.33 mm in males and from 1.65 to 7.79 mm in females. The relationship between CW and LMC showed an inflection point at 4.14 mm CW among males, and between CW and AW at 3.52 mm CW among females. The allometric growth was positive for both dimensions throughout the entire ontogeny of both sexes, before and after the puberty. The equations describing the relationship between CW and LMC in males were: logLMC = -0.695960 + 1.72.logCW for juveniles and logLMC = -1.212513 + 2.5.logCW for adults. In females, the equations were logAW = -0.519071 + 1.02.logCW and logAW = -0.902874 + 1.73.logCW, respectively for juveniles and adults. The population of U. uruguayensis from Guaratuba Bay is composed of the smallest crabs, and it also attains morphological sexual maturity at smallest CW. The frequency of occurrence of right and left handed males was statistically the same (1:1) as in most population of fiddler crabs.Key words: Fiddler crab, major chela length, REGRANS, width of the abdomen at which a species attains its morphological sexual maturity. Crustaceans are particularly appropriate for this study due to their hard exoskeleton that allows precise measurements, and to abrupt changes in the proportions of the body dimensions by the pubertal moulting (Hartnoll, 1978). The two dimensions that are

Temporal distribution in the abundance of the fiddler crab Uca (Leptuca) uruguayensis Nobili, 1901 (Decapoda: Ocypodidae) from Garças River mangrove, Guaratuba Bay, southern Brazil

“…The area is dominated by relatively well preserved mangrove and it belongs to the Boguaçú State Park. For further details of the study area see Martins and Masunari (2013).…”

“…Crabs SUI and those with less than 4.14 mm CW for males and less than 3.52 mm CW for females were collectively called juveniles, based on the study of relative growth of U. (L.) uruguayensis from the same collection site (Martins and Masunari, 2013).…”

“…Another difference in the population parameter was the density: while in the population of Argentina, it varied from 0-42 ind.m -2 , in the present study, it ranged from 12-71 ind.m -2 . This difference may be connected to the contrasting size of these crabs: the male crabs of Argentina population measure up to 14.47 mm CW (Spivak et al, 1991), while those of the Guaratuba Bay, 8.33 mm CW (Martins and Masunari, 2013).…”

“…It has euryhaline habit and occurred in almost all collection sites in this bay (Masunari, 2006). In the Garças River mangrove (Guaratuba Bay), these crabs occur mainly in sunny banks along streams that run inside it (Martins and Masunari, 2013).…”

Morphological variability in populations of the fiddler crab Leptuca uruguayensis (Nobili, 1901) (Crustacea, Decapoda, Ocypodidae) from South America

“…Actually, there is a contrasting size difference between the population from Guaratuba Bay, Brazil (MARTINS; MASUNARI, 2013a) and that from Province of Maldonado, Uruguay (type locality). In Guaratuba Bay, the largest male showed 8.33 mm of carapace width (CW) and the largest female 7.79 mm, and the onset of morphological sexual maturity is 4.14 mm CW for males and 3.52 mm CW for females MASUNARI, 2013a). In contrast, maximum CW value is 16.5 mm for both sexes in the population from Province of Maldonado, Uruguay (CRANE, 1975), a value about twice the largest males from Guaratuba Bay.…”