No abstract

This study records, for the first time, the occurrence of all four male morphotypes in a population of Macrobrachium amazonicum from a continental environment, with an entirely freshwater life cycle. The specimens studied came from the Tietê River, state of São Paulo, Brazil, and were collected in a lotic environment downstream from Ibitinga Dam. This population was compared with other continental populations, including a population from the dam itself, collected in a previous study. Four samples of 30 minutes were taken monthly, using a trap, from January to April 2011. Each male specimen was measured with respect to seven body dimensions as follows: carapace length (CL), right cheliped length (RCL), dactyl length (DCL), propodus length (PPL), carpus length (CRL), merus length (ML) and ischium length (IL). The relative growth was analyzed based on the change in growth patterns of certain body parts in relation to the independent variable CL. The four male morphotypes proposed for the species were found using morphological and morphometric analyses. Different biological characteristics were found between the populations studied. The male population of the lake of Ibitinga and from Pantanal presented mean sizes and number of morphotypes lower than the population studied here. These differences seem to be closely related to ecological characteristics of the environments inhabited by these populations. Our results supported the hypothesis that coastal and continental populations of M. amazonicum belong to the same species.Keywords: freshwater prawn, allometry, Tietê River, Amazon River Prawn, morphotype characterization. Ocorrência de morfotipos em machos de Macrobrachium amazonicum(Caridea, Palaemonidae) em uma população com ciclo de vida completamente dulcícola ResumoEste estudo registra, pela primeira vez, a ocorrência dos quatro morfotipos de Macrobrachium amazonicum em uma população continental com ciclo de vida totalmente dulcícola. Os camarões são provenientes do Rio Tietê, estado de São Paulo, Brasil, e foram coletados em um ambiente lótico abaixo da Barragem de Ibitinga. Essa população foi comparada com outras populações provenientes de ambientes continentais, incluindo a de um estudo anterior na represa da barragem de Ibitinga. Quatro amostras de 30 minutos foram realizadas mensalmente, utilizando armadilhas, de janeiro a abril de 2011. Cada indivíduo macho foi mensurado em relação a sete dimensões corporais, sendo elas: comprimento da carapaça (CL), comprimento total do quelípodo direito (RCL), comprimento do dáctilo (DCL), comprimento do própodo (PPL), comprimento do carpo (CRL), comprimento do mero (ML) e comprimento do ísquio (IL). O crescimento relativo foi analisado de acordo com as mudanças nas taxas de crescimento de determinadas partes do corpo em relação à variável independente CL. Os quatro morfotipos descritos para a espécie foram encontrados, utilizando análises morfológicas e morfométricas. Diferentes características biológicas foram encontradas entre a população estudada e as demais...

This study evaluated the starvation resistance of the shrimp Neocaridina davidi during the first and the third juvenile stages (named here as JI and JIII) by means of the estimation of point-of-no-return (PNR 50 ). Two experiments were conducted with increasing numbers of days without food and two controls (one with continuous feeding, CF; the other, with continuous starvation, CS). Time to the first molt and number of molts did not differ among the treatments beginning at JI or JIII. Nevertheless, longer periods of starvation influenced growth and survival of juveniles beginning the starvation as JI, but these effects were not observed in JIII. The estimated values of PNR 50 for JI and JIII were 16.15 ± 0.31 and 9.44 ± 0.26 days, respectively. The early stages of the life cycle are more tolerant to starvation than other decapods previously studied. Such ability indicates a great potential of this species for aquaculture.

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.

The aims of this study were to describe and illustrate the early larval stages of the snapping shrimp Alpheus brasileiro Anker, 2012 and to review the larval morphology (Zoea I) of the genus Alpheus Fabricius, 1798. Larvae were obtained from two females with embryos collected in an intertidal estuary in Cananéia, São Paulo state, Brazil. The published descriptions of all available Alpheus zoea I (only 14 spp., 4.7%) were used for a comparison of larval morphology. The zoeae I of Alpheus species are very similar, but A. brasileiro can be separated from the other studied species by the following set of characteristics: antennal scale 5-segmented with 11 plumose setae and 2 simple setae; coxal endite of maxillule with 3 simple setae and 2 sparsely plumose setae; and coxal endite of maxilla with 1 simple seta and 1 sparsely plumose seta. The description of early larval development of A. brasileiro indicates consistent characteristics, which, when analyzed along with other morphological, molecular, and biogeographical aspects, can help to elucidate the complex phylogenetic relationships between the species in the group. However, this is the first zoeal description of a member of Alpheus       armillatus species complex and it therefore does not permit a comparison. Only with new additional descriptions we will be able to generate a clearer scenario in this field due the high similarity among the species.