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Studies focusing on the natural history of species are essential for developing effective conservation measures and evaluating ecological hypotheses. To this end, we describe natural history data of the Cotinga River toadhead turtle, Phrynops tuberosus, in the Banabuiú River in Ceará, Brazil, and evaluated sexual dimorphism, epibionts, and mutilation effects. We hand-captured 134 individuals by snorkeling, over a period of one year, resulting in the capture of 94 males, 24 females, and 16 juveniles. Females had larger head width and body mass than males, while males had longer tail length. One quarter of the turtles captured had some sort of injury or deformation, most common injuries being missing claws, mutilations, and shell deformations. We found no difference in body condition index between mutilated and non-mutilated animals. Mollusks, insects, and leeches were found as epibionts on P. tuberosus and most of the captured turtles had extensive algal cover. Future studies should focus on understanding the effect of mutilations on animal fitness and reproductive success. [ABSTRACT FROM AUTHOR]

We studied two key traits in the life of organisms, body size and sexual maturity, and a population attribute, density, of the crab Goniopsis cruentata. Also, we evaluated the role of environmental factors on population density. We caught crabs in two mangrove sites that are under different influence of tidal fluctuation, and obtained pH and salinity of mangrove soil from each site as well as rainfall data for the period of study. Both body size and sexual maturity differed between sites, in which individuals from the small-bodied population matured at smaller sizes than their counterparts from the large-bodied population, which matured at larger sizes. In addition, density of the small-bodied population was lower than that of the large-bodied one. We did not detect any influence of the environmental factors on population density. Our finding indicate that key life history traits and population characteristics can vary on a very small spatial scale which may help to further elucidate the biology of natural populations. [ABSTRACT FROM AUTHOR]

The relationship between weight and size of individuals can be used to evaluate the status of a pop-ulation, which is particularly useful for natural populations that are being exploited. Ucides cordatus occurs on the Atlantic coast of the American continent, from Florida (USA) to Santa Catarina (Brazil). This species is economically very important, most of all in the Northeastern area of Brazil, as well as in the Dominican Republic and Suriname. The objective of this study was to analyze life phases ('fattening', 'matumba', 'milk-crab', 'maturation' and 'walking') by use of the weight-length rela-tionships, as well as temporal variations in this condition factor for each sex of U. cordatus. For this purpose, individuals were sampled monthly for twenty-four months at the Jaguaribe River estuary, Ceará State, Northeastern Brazil. The relationship between total weight and céphalothorax width was established using regression analysis, adjusted by a power equation. The dynamics of the condition factor were analyzed for each sex using the variation of its averages related to annual life cycle; this was done for each of the previously-mentioned phases. The relationship between total weight and céphalothorax width showed an isometric growth in males and negative allometric growth in females suggesting that, for the same reference size, males are heavier than females. When considering the average of the female condition factors, these were greater than those for males during the annual life cycle, except during the 'maturation' phase, which is the phase with a higher demand of ener-getic reserves for males. Annual variation of the condition factor in females presented no significant difference. [ABSTRACT FROM AUTHOR]