The relative growths of Persephona lichtensteinii, P. mediterranea, and P. punctata were investigated on the south-eastern Brazilian coast, focusing on differences in the growth rates between immature and mature phases, the onset of morphological sexual maturity, and the breeding seasons of these species. Crabs were collected every two months from January 1991 through to November 1992, from a shrimp fishing boat equipped with two otter-trawl nets. Significant differences in the patterns of body growth were observed between immature and mature phases of all three species. Changes in the growth rates of the chelipeds (males) and abdomen (females) observed for P. lichtensteinii, P. mediterranea, and P. punctata, seem to be related to the puberty moult for both sexes. Males of P. mediterranea and P. punctata reached larger mean sizes of carapace width than females, whereas no difference was recorded for P. lichtensteinii. The body size at which 50% of males attained sexual maturity was also larger in P. mediterranea and P. punctata, and smaller in P. lichtensteinii. The absence of a pronounced sexual dimorphism and the size at the onset of sexual maturity observed only for P. lichtensteinii might be explained by distinct reproductive strategies of males. The presence of ovigerous females during the entire sampling period suggests that all three species have a continuous reproduction pattern at the Ubatuba region. Future studies on the population structure, functional maturity, and mating system should improve the understanding of factors driving the biology and ecology of these species at a subtropical region.

The aims of this study were to identify spatially and temporally the composition and diversity of decapod crustaceans caught at fisheries of shrimp Xyphopenaeus kroyeri in Ubatuba bay. Samples were obtained monthly with a shrimping boat from September 1995 to August 1996 at 8 permanent transects. In total were collected 233094 individuals belonging to 85 species. The greatest riches were obtained for Brachyura (49 species) and Anomura (16 species). In the transects IV and V, the highest values of diversity and smaller abundance of shrimp X. kroyeri were found. Regarding the similarity, transects IV and V has low similarity in relation to other points due to its characteristics, such as location in the bay and type of substrate. Studies on the diversity of bycatch of commercially important shrimps are essential for management plans and conservation of renewable natural resources.

This investigation provided information on the physiological sexual maturity and relationships of growth and reproduction in Goniopsis cruentata (Latreille, 1803). Collections were made monthly from January 1995 through December 1996, on the northeastern coast of São Paulo State, Brazil. The crabs were grouped into juvenile males; adult males; juvenile females, and adult females, including ovigerous ones. For each specimen the carapace width (CW) was measured, and molt condition and macroscopic developmental stage of the gonad tissue were recorded. CWs of physiologically mature crabs were between 21.4 and 23.7 mm for both sexes. This population showed molt activity in all size groups throughout the study period, which suggests continuous growth and the absence of terminal anecdysis. This may be associated with the ability of these animals to copulate during the intermolt, supplying a high proportion of mature individuals over time and ensuring continuity of reproduction year-round.

This study evaluated the influence of the water and air temperatures, pluviosity and photoperiod on the breeding season of Goniopsis cruentata (Latreille, 1803), in Ubatuba littoral, southeastern Brazilian coast. Monthly collections were conducted out from January/95 to December/96 in an estuarine area from 23º29'10"-23º29'45"S to 45º09'10"-45º10'00"W. Water and air temperature variation showed the highest correlation coefficient with the frequency of ovigerous females, r² = 0.73 and 0.68, respectively. However, an analysis of the set of environmental variables, revealed the photoperiod as the factor of highest association with the ovigerous frequency (r² = 0.68). This degree of association allow us to suggest that the breeding season duration of G. cruentata might have some variations over different latitudes, and such results could be quite diverse in populations from different latitudes

AIM: The population biology of the freshwater shrimp Macrobrachium jelskii was investigated here emphasizing the length-frequency distribution, sex ratio, reproductive period and juvenile recruitment. In addition, the abundance of individuals was correlated with the abiotic factors. METHODS: Samples were collected on a monthly basis from July 2005 to June 2007 along the river margin in shallow water of Grande River, at Planura region, State of Minas Gerais, Brazil (20º 09' S and 48º 40' W), using a trawl net (1.0 mm mesh size, and 2.0 m × 0.5 m wide). The fishing gear was handled by two people along the marginal vegetation of the Grande River in a course of 100 m, covered for one hour. In the laboratory, the specimens were identified, measured and sexed. RESULTS: A total of 2,789 specimens was analyzed, which corresponded to 1,126 males (549 juveniles and 577 adults) and 1,663 females (1,093 juveniles, 423 adults non-ovigerous and 147 ovigerous). The sex ratio differed significantly in favor of the females of M. jelskii (1:1.48; χ² = 103.95; p < 0.0001). The mean size of carapace length (CL) of females (6.32 ± 1.84 mm CL) was statistically higher than of males (5.50 ± 1.07 mm CL) (p < 0.001). The length-frequency distribution of the specimens revealed an unimodal pattern and non-normal distribution for males and females (W = 0.945; p < 0.01). No significant relationship between the abundance of M. jelskii and the environmental variables was observed (p = 0.799). CONCLUSION: The presence of ovigerous females and juveniles in the population suggests a continuous reproduction pattern and recruitment for M. jelskii at Planura region.

No abstract

The main goal of this investigation was to characterize the population structure and shell occupancy of two sympatric hermit-crab species, Pagurus brevidactylus and Paguristes tortugae. The study was undertaken at Couves Island on the southeastern coast of Brazil, from March 2010 through February 2011, on subtidal rocky bottoms. Specimens were collected by SCUBA diving sessions. A total of 195 individuals of P. brevidactylus and 132 of P. tortugae were examined. Both populations showed unimodal size-frequency distributions, which were non-normal for P. brevidactylus and normal for P. tortugae. The median size of P. brevidactylus was significantly smaller than P. tortugae; in both species, males were significantly larger than females. For both, juveniles and ovigerous females were recorded in all size classes and in almost the entire sampling period. No significant departures from the 1:1 sex ratio were detected, although some size classes were skewed. Overlaps in shell occupation were recorded. Pagurus brevidactylus and P. tortugae showed similar population features; they reached sexual maturity at small sizes, and the nearly year-round presence of young and ovigerous females suggests continuous reproduction. These inter-specific interactions involving resource partitioning suggest a regulatory process that is probably part of the equilibrium strategy of these populations.

The population biology of Exhippolysmata oplophoroides (Holthuis, 1948) was studied in Ubatuba Bay (23º26'S, 45º02'W), Ubatuba, São Paulo, Brazil, from September/1995 to August/1996. Each sampling comprised eight transects (14 000 m² each), sampled monthly with three repetitions. The specimens were classified with respect to the presence or absence of eggs in the abdominal appendages. Spine-shrimps occurred only on six transects, being most abundant on transect II, with the highest incidence in late spring and throughout the summer months. Ovigerous and non-ovigerous shrimps were present year-round, in an approximately similar proportion (1:1). Site II in Ubatuba Bay is characterized by high salinity and oxygen values, temperature between 26 and 29ºC, low organic matter content in the sediment, and a bottom composed of very fine sand; these environment and biological features allow the establishment and maintenance of the population of E. oplophoroides.