Resumen En el presente estudio se analizaron los parámetros de crecimiento y longevidad de machos y hembras de Macrobrachium brasiliense. Las muestras se obtuvieron mensualmente desde julio/2012 hasta junio/2013 en la región de Triângulo Mineiro, Minas Gerais, Brasil. Un total de 199 camarones adultos (97 machos, 102 hembras) fueron analizados y medidos según la longitud del caparazón (CL, mm). Los machos (9.64 ± 4.17 mm, CL) fueron más grandes que las hembras (7.7 ± 3.39 mm, CL). Las curvas de crecimiento para CL por el modelo de von Bertalanffy se describen mediante las ecuaciones: CL = 21.0 [1 - e -0.00446 (t)] para los machos y CL = 20.0 [1 - e -0.00454 (t)] para las hembras. Al comparar las curvas de crecimiento con la prueba tipo F, no hubo diferencias entre los coeficientes de crecimiento (K) de machos y hembras (GL22; F3.16 = 2.476; p = 0.088). La longevidad se estimó en 2.83 años para los machos y 2.78 años para las hembras. En general, la longevidad observada es similar a la de las especies de Macrobrachium.

Abstract Growth and longevity parameters of males and females of Macrobrachium brasiliense were analyzed. Sampling was carried out monthly from July 2012 to June 2013 in Triângulo Mineiro region, Minas Gerais, Brazil. A total of 199 adult prawns (97 males and 102 females) were analyzed and measured according to the carapace length (CL, mm). Males (9.64 ± 4.17 mm, CL) were larger than females (7.7 ± 3.39 mm, CL). CL growth curves by the von Bertalanffy model are described by the equations CL = 21.0 [1 - e -0.00446 (t)] for males and CL = 20.0 [1 - e -0.00454 (t)] for females. Comparison of the growth curves by performing the F-type test, showed that there was no difference between the growth coefficients (K) of males and females (GL22; F3.16 = 2.476; p = 0.088). Longevity was estimated as 2.83 years for males and 2.78 years for females. In general, the observed longevity is similar to that of other Macrobrachium species.

RESUMO O conhecimento acerca da dieta de uma determinada espécie é essencial para fornecer informações sobre o crescimento e manutenção das populações em ambiente natural. Macrobrachium brasiliense (Heller, 1862) é uma espécie de camarão de água doce com ampla distribuição no Brasil, ocorrendo frequentemente em ambientes aquáticos inseridos no bioma Cerrado. O objetivo deste estudo foi avaliar a dieta natural de uma população de M. brasiliense, comparando os itens alimentares consumidos em função do sexo, sazonalidade e tamanho corporal dos indivíduos. Foram realizadas coletas mensais entre setembro de 2018 a agosto de 2019. Os indivíduos coletados tiveram seu sexo identificado e o comprimento do cefalotórax mensurado. O conteúdo estomacal foi avaliado a partir do grau de repleção, método de pontos e de frequência de ocorrência. Verificou-se elevada frequência de detrito vegetal no conteúdo estomacal e uma frequência menor de insetos aquáticos, porém significativa. Não houve diferenças significativas quanto à dieta de machos e fêmeas e entre as estações seca e chuvosa. Foi observado um aumento do consumo total de insetos com aumento de tamanho de machos e fêmeas de M. brasiliense. Uma preferência de dieta por Trichoptera foi registrada em ambos os períodos de amostragem para machos e fêmeas.Os resultados obtidos confirmam uma dieta onívora para a espécie e sugerem que a composição e a proporção de itens podem variar em função do tamanho dos indivíduos e da disponibilidade dos itens no ambiente.

ABSTRACT Knowledge about the diet of a given species is essential to provide information on the growth and maintenance of populations in a natural environment. Macrobrachium brasiliense (Heller, 1862) is a species of freshwater prawn widely distributed in Brazil, being frequent in aquatic environments inserted in the Cerrado biome. The aim of this study was to evaluate the natural diet of a population of M. brasiliense, comparing the consumed food items according to sex, seasonality and body size of individuals. Monthly collections were carried out between September 2018 and August 2019. The individuals collected had their sex identified and the length of the cephalothorax measured. Stomach content was assessed based on the degree of repletion, the method of points and the frequency of occurrence. There was a high frequency of plant material in the stomach contents and a smaller but significant frequency of aquatic insects. There were no significant differences regarding the diet of males and females and between the dry and rainy seasons. It was observed an increase in total insect consumption with the increase in size of males and females of M. brasiliense. A diet preference for Trichoptera was recorded in both sampling periods for males and females. The results obtained confirm an omnivorous diet for the species and suggest that the composition and proportion of items may vary depending on the size of the individuals and the availability of the items in the environment.

Abstract Caprellid amphipods are common crustaceans at Sargassum beds of southeastern Brazil and constitute an important link between primary producers and marine consumers. The goal of this study is to evaluate population and reproductive biology of two caprellid species: Paracaprella tenuis Mayer, 1903 and Pseudaeginella montoucheti Quitete, 1971. Sargassum cymosum Agardh, 1820 samples were collected monthly between October 2010 and September 2011 in a rock shore in southeastern Brazil. The caprellids were identified, counted, measured and classified as males, immature females, sexually mature females, ovigerous females and juveniles. Eggs were counted and measured. Higher densities of P. tenuis and P. montoucheti were found mainly in winter and lower densities in fall and summer. Density variation is probably related to organic matter supply and substrate availability. Both species showed continuous reproduction with reproductive peaks. Pseudaeginella montoucheti larger egg volume indicates a longer incubation period. The egg volume was directly related to female size. The number of eggs was weakly related to female size, indicating that fecundity may be driven by other factors, such as the physiological conditions. Sex ratio deviated for males suggests a higher longevity of males. The present study highlighted important data of two caprellids species that occur in algal beds of different regions.

ABSTRACT The palaemonid shrimp Macrobrachium amazonicum is widely distributed in coastal rivers, estuaries and inland waters of South America. Despite this, little is known regarding its biology in the natural environment. Furthermore, this species is economically important because it is the main freshwater shrimp commercially exploited by artisanal fisheries in northern and northeastern Brazil, besides showing great potential for aquaculture. Considering this, the present study aimed to analyze aspects of the reproductive biology of M. amazonicum. A total of 251 females were analyzed, 102 of these being ovigerous. The carapace length ranged from 6.03 to 10.06 mm (average ± standard deviation: 7.52 ± 0.84 mm). Reproduction was continuous with a gradual increase from April to June 2012. No significant relationship between frequency of ovigerous females and environmental variables was observed. The fecundity showed a positive linear relation with the carapace length and the number of eggs varied from 33 to 389 (average ± standard deviation: 203 ± 78.06 eggs/female). A dominance of eggs at an early stage was observed in most months. There was an increase in the size/volume of eggs from early to late embryonic stage. Ovigerous females produced eggs at the same development stage, with the same size and volume regardless of their body size. The results demonstrated higher similarity of this population to other continental M. amazonicum populations than from estuarine ones, showing the environment influence in the life-history of individuals.

A biologia populacional de três espécies de anfípodes da família Ampithoidae (Ampithoe ramondi, Cymadusa filosa e Sunampithoe pelagica) associadas a Sargassum filipendula da Praia da Fortaleza, litoral norte do Estado de São Paulo foi estudada entre junho de 2000 e maio de 2001. Os anfípodes foram identificados, contados e separados em classes de tamanho através de um conjunto de peneiras agrupadas. Foram obtidos histogramas mensais de jovens, machos e fêmeas. A razão sexual dos ampitoídeos foi avaliada mensalmente. A biologia reprodutiva das espécies foi avaliada através freqüência relativa mensal de fêmeas ovígeras, de sua fecundidade, volume médio dos ovos e correlação do tamanho da cabeça com o número de ovos contidos em seus marsúpios. Ampithoe ramondi foi a espécie mais abundante. As maiores densidades para as três espécies ocorreram na primavera e no verão. A razão sexual apresentou diferença significativa de 1:1 apenas para A. ramondi (1:1,2; x² = 4,37; g.l. = 1; p < 0,05). Fêmeas ovígeras foram registradas em quase todos os períodos de amostragem. Correlação positiva baixa entre o tamanho da cabeça da fêmea e o número de ovos contidos na bolsa incubadora foi registrada somente para A. ramondi (r² = 0,27; p < 0,05; n = 33). Cymadusa filosa apresentou a maior fecundidade e o maior volume dos ovos.

The population biology of three species of the family Ampithoidae (Ampithoe ramondi, Cymadusa filosa e Sunampithoe pelagica) associated with Sargassum filipendula at Fortaleza beach, northern coast of São Paulo state was investigated from June 2000 to May 2001. The amphipods were identified, counted and separated in size classes through a nested sieve set. Month hystograms were obtained for juveniles, males and females. The ampithoid sex ratio was determined monthly. The reproductive biology of the species was evaluated by the relative frequency of ovigerous females, fecundity, average egg volume and correlation analysis between head lengh of ovigerous females and number of eggs in its brood pouch. Ampithoe ramondi was the most abundant species. The higher densities of the three species occurred in spring and summer. The sex ratio presented a significant difference from 1:1 only for A. ramondi (1:1.2; x² = 4.37; g.l. = 1; p < 0.05). Ovigerous females were registered for almost all the sampling periods. A positive correlation between the female head lengh and the number of eggs were only registered for A. ramondi (r² = 0.27; p < 0.05; n = 33). Cymadusa filosa showed the greatest fecundity and egg volume.