Biologia do caranguejo-uçá capturado na reserva extrativista marinha de Soure, Ilha do Marajó, Pará, Brasil

Abstract

Mangroves are important ecosystems, sources of life and energy of extensive regions, typically estuarine or marine. These areas are rich in nutrients and presents high bioproductivity. In Brazilian mangrove ecosystems, the land crab is the most important resource in economic and social terms. The main areas of occurrence of the land crab are concentrated in Brazilian North and Northeast regions. The Soure Marine Extractive Reserve was established in November 2001, with the objective of ensuring the sustainable use and conservation of renewable natural resources, protecting the livelihoods and culture of the local extractive population. The objective of this work was to study the reproductive biology and the relationship between the main linear body measurements and weight of the land crab Ucides cordatus in Soure Marine Extractive Reserve, in order to provide information for the sustainable management of this resource in this Extractive Reserve. Sampling occurred from August 2007 to October 2009. The specimens were identified, sexed, measured and weighed; only females were evaluated for reproductive maturation stage. We collected 2,635 specimens, 1,075 females and 1,560 males. Females in stage IV were found mainly in the fourth and first quarter of the year, females in stage V (ovigerous) occurred more frequently in the first and second quarter of the year. The length and width of the shell at which 50% of the U. cordatus females were considered mature were respectively 2.30cm and 3,31cm. The sex ratio was 0.69:1; in percentage terms, females accounted for 40.80% and males for 59.20%, resulting in a value of χ 2 = 89.27. Males present size and average weight different from females; males are larger and heavier than females. The length-width carapace relation showed no significant difference in carapace length between males and females for the same carapace width. Length-weight and width-weight relations of the carapace were determined for males and females separately, which showed significant difference between weight gain and carapace length and between weight and carapace width for males and females. The land crab reproduction is seasonal, occurring in a period of the year. Females, in Soure, reach sexual maturity at smaller sizes than that described for species in other regions of Brazil. Among the average size relations, males were longer, wider and heavier than females. The length-width carapace relation for males and females showed the same slope, with no sexual dimorphism and presented a positive allometric growth. For length-weight carapace and width-weight carapace relations, determined to separate sex, we found significant difference between weight gain and carapace length and between weight and carapace width for males and females; there is an allometric negative growth for both relations. The results of this work are organized in scientific articles and divided into three chapters.