Développement juvénile de Menippe nodifrons Stimpson, 1859 (Crustacea, Decapoda, Xanthidae) en laboratoire

Les huit premiers stades juvéniles de #M. nodifrons étudiés en laboratoire, ont été obtenus à partir d'élevage de larves provenant de femelles oeuvées collectées à Ubatuba, S.P., Brésil. Les expériences d'élevage ont été réalisées à une température de 24 (+ ou -) 1°C en eau de mer de salinité 34,5°/oo, utilisant comme alimentation des nauplii d'#Artemia salina et de petites portions de muscles de poisson. Dans ce travail sont présentées les descriptions morphologiques détaillées du premier stade juvénile, les caractères diagnostiques pour les autres stades obtenus, la durée de chaque stade et une analyse comparative avec des espèces semblables étudiées antérieurement, appartenant à la région sud-est du Brésil. (Résumé d'auteur

Ecology of the Rock Shrimp Sicyonia dorsalis Kingsley, 1878 (Crustacea: Sicyoniidae) in a Subtropical Region of Brazil

The present study analyzes the abundance and distribution of the rock shrimp Sicyonia dorsalis, in relation to water temperature, salinity, depth, organic matter content, and sediment texture in Mar Virado (MV), Ubatuba (UBA) and Ubatumirim (UBM), 3 distinct bays along the northern coast of São Paulo State (23°S, 45°W), Brazil. Six transects were taken in each bay, 4 being parallel to the coastline and 2 next to the rocky shores. Monthly samples were taken over a 2-year period (1998 and 1999) with a shrimp fishing boat equipped with double-rig nets. A total of 2,498 specimens was obtained with 804 from MV, 922 from UBA, and 772 from UBM. The spatial distribution of S. dorsalis did not differ among bays. Higher abundance values were recorded in areas where silt+clay comprised more than 60% of the sediment. Abundance also followed a seasonal trend, being highest during spring when intrusions of the cold South Atlantic Coastal Waters are most common, promoting the migration of this shrimp species to more sheltered areas. In short, sediment type and water temperature appear to be the most important environmental variables analyzed which affect the spatial and seasonal distribution of S. dorsalis

Reproductive Biology and Recruitment of Xiphopenaeus kroyeri in a Marine Protected Area in the Western Atlantic: Implications for Resource Management

The potential of a recently established marine protected area (MPA) in the Western Atlantic, Brazil, as a \u27seed production\u27 and nursery ground for Xiphopenaeus kroyeri, an intensively exploited penaeid shrimp, was investigated in an attempt to reveal any future benefit of this new MPA to adjacent populations experiencing heavy exploitation. Overall, we observed that males and females \u3e12 and 20 mm carapace length, respectively, contributed the most to reproduction in the studied population. Reproductive activity of X. kroyeri was continuous at the MPA; 2 annual reproductive peaks were recorded from March to April and from November to December, which were followed by recruitment events occurring from March to April 2009 and November 2009. Sediment, temperature, and algae and plant biomass floating near the bottom were relevant in driving reproductive activity and recruitment in X. kroyeri. The high reproductive potential of the studied population and the occurrence of abundant juveniles throughout the sampling area, indicating the existence of a nursery ground within the region, suggest that this MPA might provide important benefits in the near future. We argue in favor of future long-term studies on the larval dispersion, reproductive biology and ecology of X. kroyeri in MPAs and non-MPAs to construct a base for future management of this species and to aid stock recovery in fishing areas that are heavily exploited

Morphology of the First Zoeal Stage of Platypodiella spectabilis (Herbst, 1794) (Decapoda, Brachyura, Xanthidae) Obtained in the Laboratory

Ovigerous females of the xanthid crab Platypodiella spectabilis (Herbst, 1794) were obtained from 2 widely separated localities: the Ubatuba coast (Félix Beach, São Paulo) of Brazil and Guana Island in the British Virgin Islands (BVI). First stage zoea larvae were obtained from females at both locations. Those from Brazil are described and illustrated. The first zoea bears dorsal, rostral, and lateral carapace spines, plus a well-developed and spinose antennal protopod that bears a greatly reduced exopod with 2 minute setae. This antennal morphology, along with other characters, places the species among the “Group I” xanthid zoeas of Rice (1980) and Martin (1984, 1988). Differences between larvae from Brazil and those from the BVI are minor and are attributed to within-species variation. Characters that serve to separate these larvae from those of cooccuring xanthids are presented. Comments on the distribution and size of Platypodiella spectabilis are included

Structure of the population of the red mangrove crab Goniopsis cruentata (Latreille, 1803) (Crustacea, Decapoda, Brachyura), on a Brazilian sub- tropical estuarine mangrove.

G. cruentata is one of the most abundant crabs in South Western Atlantic mangroves, and fill most of the niches provided by these ecosystems. The trophic role of this crab in the ecosystem is wider than reported to sesarmid and ocypodid crabs and plays important role on propagule predation, affecting the mangrove recruitment and community composition. This paper reports some population parameters as size classes frequency distribution, breeding period, sex ratio, molt cycle and recruitment of the G. cruentata in southeastern Brazilian coast. A total of 1,150 crabs was obtained, without mean size meaning difference between sexes. Frequency distribution were bell-shaped and adult crabs were dominant. Ovigerous females were recorded in almost all months. The sex ratio shows no meaning difference from 1:1 ratio. Molt activity was recorded over all sampled period. The frequency of molt on the size classes reveals a larger activity regarded to smallest body sizes. The population of G. cruentata seems to follow the expected standards of the tropical marine crabs. Moreover, some population attributes, as recruitment and breeding period did not match exactly within these standards, suggesting that population regulation is constrained for the local conditions

Sampling technique affects the population structure assessments of fiddler crab Minuca vocator (Herbst, 1804) (Ocypodidae: Gelasiminae)

We examined how the sampling technique can affect the evaluation of Minuca vocator (Herbst, 1804) population structure. We used two sampling procedures: catch-per-unit-effort (CPUE) and quadrat technique (QT). Body size, size?frequency distribution, population density, juvenile recruitment rates, proportion of ovigerous females and sex ratio were compared between the sampling procedures. QT allowed us to estimate and compare crab and burrow densities. CPUE sampled both adult crabs and the largest crabs more frequently, whereas QT recorded a greater proportion of smaller crabs. CPUE underestimated the size of M. vocator populations, while density estimates obtained with QT were accurate. The proportion of juveniles was higher with QT than with CPUE, suggesting that recruitment rates estimated by QT were more suitable. The sampling effort provided by CPUE was more efficient for obtaining ovigerous-dependent information than QT. Both sampling techniques showed a predominance of males in all three M. vocator populations. The population density estimation based on burrows overestimated the natural density of M. vocator in all mangroves. Our results suggest that neither CPUE nor QT individually were accurate sampling techniques, but together provided reliable assessments of fiddler crab populations.Instituto de Limnología "Dr. Raúl A. Ringuelet

Growth Phases and Differential Growth Between Sexes of Uca maracoani Latreille, 1802-1803 (Crustacea, Brachyura, Ocypodidae)

Among crustacean decapods, fiddler crabs of the genus Uca are the most characteristic of the intertidal zones of tropical and subtropical estuaries. The present study determined the growth phases and the beginning of differential growth between the sexes, based on analyses of relative growth of Uca maracoani. Collections were made in the Jabaquara mangrove, located in Paraty, Rio de Janeiro, Brazil. Specimens were collected manually during low tide periods. In the laboratory, crabs were sexed and measured. We measured carapace width (CW), carapace length (CL), propodus length (PL; the right one for females and the major one for males), propodus height (PH), abdomen width (AW), and gonopod length (GL; for males). The beginning of differential growth between the sexes could be identified by the allometric technique. Males and females showed 3 distinct growth phases. Differential growth between sexes began when males reached 7 mm and females 9.2 mm CW. The growth pattern among different phases and the beginning of differential growth seemed to maintain a strict relationship with the ontogenetic changes, mainly those related to behavioral and reproductive aspects. This information is important for general biological knowledge of this species, mainly concerning aspects of its growth

Sampling technique affects the population structure assessments of fiddler crab Minuca vocator (Herbst, 1804) (Ocypodidae: Gelasiminae)

We examined how the sampling technique can affect the evaluation of Minuca vocator (Herbst, 1804) population structure. We used two sampling procedures: catch-per-unit-effort (CPUE) and quadrat technique (QT). Body size, size?frequency distribution, population density, juvenile recruitment rates, proportion of ovigerous females and sex ratio were compared between the sampling procedures. QT allowed us to estimate and compare crab and burrow densities. CPUE sampled both adult crabs and the largest crabs more frequently, whereas QT recorded a greater proportion of smaller crabs. CPUE underestimated the size of M. vocator populations, while density estimates obtained with QT were accurate. The proportion of juveniles was higher with QT than with CPUE, suggesting that recruitment rates estimated by QT were more suitable. The sampling effort provided by CPUE was more efficient for obtaining ovigerous-dependent information than QT. Both sampling techniques showed a predominance of males in all three M. vocator populations. The population density estimation based on burrows overestimated the natural density of M. vocator in all mangroves. Our results suggest that neither CPUE nor QT individually were accurate sampling techniques, but together provided reliable assessments of fiddler crab populations.Instituto de Limnología "Dr. Raúl A. Ringuelet