Two coastal locations situated inside and outside an upwelling area were investigated to assess the influence of environmental factors on the structure of marine shrimp assemblages. The locations were Macaé in the state of Rio de Janeiro (RJ), influenced by upwelling from Cabo Frio (RJ), and Ubatuba in the state of São Paulo, with no upwelling. Samples were collected monthly with trawl nets, in three sites in each location at depths of 5-20 m. The relationship between species abundance and environmental factors was tested by redundancy analysis. The total of 148,266 shrimp captured (102,832 from Macaé and 45,434 from Ubatuba) included 15 species, 13 genera, and 7 families. The caridean Periclimenes paivai was collected for the first time on the RJ coast, expanding its known geographical distribution. Higher richness and J 0 and H 0 values were obtained in the location under upwelling influence (Macaé). Environmental variables (granulometric composition and organicmatter content of sediment, bottom temperature, and salinity) were associated with the abundance of shrimp. Our results suggest that sediment type and temperature are among the most important variables affecting seasonal distribution of the species. However, other factors such as intraspecific migration might have also influenced the observed patterns.

This study aimed to analyze the carcino-bycatch of seabob shrimp (Xiphopenaeus kroyeri) in Macaé/RJ, a region influenced by the Cabo Frio upwelling. Samples were collected monthly with a shrimp fishing boat, from July/2010 to June/2011. The carcino-group bycatch was represented by 15 families, 24 genera and 30 species. The families with the highest number of species were Portunidae (7) and Penaeidae (5), representing 23.33% and 16.66% of the total catch, respectively. For each seabob shrimp captured, 2.94 bycatch individuals were caught on average, with the largest discrepant values in summer (1: 4.82) and autumn (1: 5.76). The main components of this carcinofauna (Artemesia longinaris and Pleoticus muelleri) are species with increasing importance as a fishery resource in the region due to their abundance, and need to be continuously studied over diverse aspects of population biology, aiming to improve conservation actions.

After being stable for nearly a century, the taxonomic history of the genus Xiphopenaeus has been marked by many changes in the last three decades. The taxonomic status of the Atlantic species has a low resolution, and many species are still undefined and grouped as cryptic species. Here we employed an integrative approach to define the species of Xiphopenaeus and the morphological characters needed to differentiate them. We combined the analyses of two molecular markers (COI and 16 S rDNA), scanning electron microscopy and light microscopy. Based on specimens from 17 localities from the Atlantic and Pacific oceans, we detected five divergent genetic groups, three in the Atlantic (A1, A2, A3) and two in the Pacific (P1, P2). Male secondary sexual characters were able to differentiate four out of the five genetic groups. Group A1 corresponds to X. kroyeri, and A2 and A3 correspond to new species. We redescribed the genus and two new species are described and illustrated: Xiphopenaeus dincao nov. sp. (A2) and Xiphopenaeus baueri nov. sp. (A3). Since the holotype of X. riveti was missing and the specimen analysed from group P2 was a female, the status of the species of Xiphopenaeus from the Pacific remains unresolved.

Macrobrachium amazonicum is a commercially important freshwater prawn with a high degree of reproductive plasticity. The species is classified into two groups: coastal populations, with larger individuals exhibiting high fecundity and needing brackish water for larval development; and continental populations, with smaller specimens exhibiting low fecundities and completing metamorphosis in freshwater. The objective of this study was to investigate the influence of environmental factors in the fecundity, egg size and volume, and reproductive output in females of M. amazonicum from a continental population during a two-year period. We also compared our results with those obtained for other continental and coastal populations. Reproductive parameters differed markedly between continental and coastal populations in most cases. The continental population studied here, however, exhibited reproductive characteristics similar to those of coastal populations. The present study found a correlation between the reproductive parameters and the environmental variables analyzed. This result corroborates the hypothesis that wide variation in reproductive parameters in the geographical distribution of M. amazonicum is related to the environmental characteristics in which populations are inserted. We suggest that further studies could investigate the potential of continental populations for aquaculture, which could significantly reduce production costs.

Upwelling areas are among the most productive ecosystems on the planet, influencing the biology of marine organisms. This study investigated the population dynamics of the shrimp Artemesia longinaris in two regions in southeastern Brazil, one inside (Macaé—Rio de Janeiro State) and one outside (Ubatuba—State of São Paulo) the Cabo Frio upwelling area. The aim was to verify the influence of the upwelling phenomenon on the abundance, growth, longevity, size of sexual maturity, and reproductive period of the species. In total, 188,902 individuals were captured at Macaé and 3,461 at Ubatuba. Individuals captured at Macaé showed larger maximum size, higher longevity, and slower growth rate, besides reaching sexual maturity at larger sizes than at Ubatuba. Continuous reproduction was observed in both regions, with juvenile recruitment peaks in spring and summer. Local conditions observed at Macaé were influenced by the Cabo Frio upwelling zone, characterized by productive and cooler waters that are around 20°C during most of the year. The upwelling phenomenon is probably the main factor influencing the population parameters studied here, changing the geographic patterns previously observed for the variation of these parameters in A. longinaris.

The present study investigated the population dynamics ofExhippolysmata oplophoroidesin an area influenced by upwelling, focusing on reproductive period, sex ratio, growth rate, longevity, mortality, relative growth and size of sex change. We also tested the hypothesis that the appendices internae increased in size with sex change from the male to the simultaneous hermaphrodite phase as possible replacements for the male appendices masculinae, which are reduced or lost at sex change. Population structure was assessed by the distribution of size frequency in three demographic groups: male phase, hermaphrodite phase with, and without embryos. For relative growth analysis, the length of the following structures was measured: carapace, second pleuron, first pereopod, second pereopod, appendices internae of the second to fifth pleopods, and appendix masculina. Smaller size classes were composed only by male-phase individuals. The sex ratio was significantly biased towards the simultaneous hermaphrodite phase. Reproduction was continuous in the population throughout the year. Slower growth rates but higher maximum body sizes than those estimated at other locations in south-eastern Brazil were observed in the population studied. Cooler temperatures and higher nutrient levels associated with upwelling may have produced this pattern of reproduction and growth, similar to that found in more southerly austral latitudes. We also found that sex change influences the relative growth of body structures such as the second pereopods, appendices internae, and appendix masculina, and hypotheses on the adaptive value of such allometric growth are proposed.

The present study analyses the cryptic colouration patterns in mud crabs, Panopeus americanus that live in an impacted intertidal mangrove area. The main objectives were to identify the cryptic/non-cryptic transition sizes (males and females) and their relationships to morphological and functional sexual maturity. Individuals were collected from the remnant mangrove of Araçá, on the coast of São Sebastião, São Paulo, Brazil. They were sexed, measured and classified into three colouration categories: white homogeneous, cryptic heterogeneous or dark homogeneous (non-cryptic). A logistic regression was performed to detect the size at which 50% of the population reached the dark homogeneous colouration and functional sexual maturity in females. Morphological sexual maturity for both sexes was estimated through relative growth. A progressive change from heterogeneous to dark homogeneous colouration following growth was observed. Using both analyses of maturity, we detected (1) that individuals of the white homogeneous colouration can be classified as non-reproductive and (2) that there is an overlap between the size at which 50% of females reached the dark homogeneous colouration and their functional sexual maturity (approximately 14.00 mm CW). These findings are primarily explained by ontogenetic changes in habitat use during the species’ life cycle.

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