Biologia Populacional de Macrobrachium jelskii (MIERS, 1778) (Crustacea, Decapoda, Palaemonidae) em uma Planície Inundável na Amazônia Oriental, Brasil

Abstract

RESUMO. A biologia populacional de M. jelskii foi investigada com ênfase na distribuição de frequência de comprimento, razão sexual, período reprodutivo e relação peso comprimento. A amostragem foi realizada durante o período de abril/2008 a maio/2009 junto às macrófitas, em um transecto de 50 m. As coletas foram obtidas com peneiras de 55 cm de diâmetro e malha de 2 mm, a cada 2 m, totalizando 25 amostras em todo o período de estudo. No laboratório, os exemplares de M. jelskii foram medidos, pesados, sexados e as fêmeas classificadas macroscopicamente quanto ao grau de maturação. Foram encontrados 910 exemplares, 505 machos e 405 fêmeas. O comprimento total variou de 9,7 a 50,3 mm e a maior frequência relativa de indivíduos ocorreu entre as classes de 19,7 a 21,7 mm e 37,7 a 39,7 mm. Os machos apresentaram tamanhos superiores e a proporção sexual foi instável entre os meses. A reprodução incidiu no período mais chuvoso. As fêmeas obtiveram crescimento isométrico e os machos alométrico negativo, demonstrando dimorfismo nas relações peso total/comprimento total de ambos os sexos.Palavras-chave: área inundável, área de ressaca, camarão.ABSTRACT: Aspects of the population biology of Macrobrachium jelskii (MIERS, 1778) (Crustacea, Decapoda, Palaemonidae) in a flood plain in eastern Amazonia, Brazil.The population biology of M. jelskii was investigated with emphasis on the length frequency distribution, sex ratio, breeding season and length and weight ratio. Sampling was conducted during the April/2008 May/2009 along with macrophytes in a transect of 50 m. The samples were obtained using sieves of 55 cm diameter and a 2 mm mesh, on a 2 m space interval, totaling 25 samples throughout the study period. In the laboratory, specimens of M. jelskii were measured, weighed, sexed and females classified macroscopically as to the degree of maturation. There were found 910 specimens, 505 males and 405 females. The total length ranged from 9.7 to 50.3 mm, and a higher frequency of subjects on the classes occurred between 19.7 to 21.7 mm and from 37.7 to 39.7 mm. The males showed greater sizes and sex ratio was stable between months. Reproduction occurred in the rainy season. Females had isometric growth and male allometric negative, showing dimorphism in relations total weight/total length of both sexes.

Population biology of Macrobrachium jelskii (Miers, 1877) (Decapoda, Palaemonidae) from an artificial pond in Bahia, Brazil

“…Gamba (1997) and Barros-Alves et al (2012) found female biased sex ratios in populations from Venezuela, and from state of Minas Gerais, Brazil, respectively. On the other hand, Lima et al (2013) and Mossolin et al (2013) found no statistical difference in the sex ratio of populations from eastern Amazonia and from São Paulo State, respectively. Finally, Soares et al (2015), studying a population from the São Francisco River, found a female biased sex ratio in lentic environments and the opposite condition in lotic ones.…”

“…Specifically in the case of M. jelskii, rainfall and water temperature play key roles in establishing the reproductive period, as several authors have noted the intensification of the reproductive activity during the warmer and humid months (Gamba, 1997;Lima et al, 2013;Mossolin et al, 2013;Soares et al, 2015;present study).…”

“…Populations of M. jelskii from the states of São Paulo (Mossolin et al, 2013) and Minas Gerais (Barros-Alves et al, 2012;Soares et al, 2015) also showed continuous-seasonal reproductive pattern. On the other hand, populations from Ceará (Paiva and Barreto, 1960), Venezuela (Gamba, 1997) and Amapá (Lima et al, 2013) showed a seasonal reproductive period. Therefore, the reproductive pattern of M. jelskii populations do not support the paradigm that the reproductive activity of decapod crustaceans varies with latitude (Tab.…”

“…In Brazil, studies on the reproductive biology of M. jelskii populations were carried out in the Southeast (Barros-Alves et al, 2012;Mossolin et al, 2013;Soares et al, 2015), North (Magalhães, 2000;Lima et al, 2013) and Northeast (Paiva and Barreto, 1960;Nery et al, 2015). However, no studies have investigated the biology of M. jelskii populations in the state of Bahia and in an urban artificial environment.…”

Aspectos ecológicos de decápodos del río Guayuriba (Meta, Colombia)

“…Sin embargo, esto no concuerda con lo señalado por Pereira (1986) en corrientes venezolanas, quien registró machos con 38,6 mm (LT) y 10,3 mm (LCF), y hembras con 35 mm (LT) y 9 mm (LCF). En otras especies como Palaemon pandaliformis, P. northropi Rankin, 1898, M. amazonicum, M. potiuna y M. jelskii Miers, 1877 las hembras son más pequeñas que los machos (Anger y Moreira 1998, Maciel y Valenti 2009, Lima et al 2013, De Melo y Masurani 2017. Se han planteado algunas hipótesis que explican la variación del tamaño entre sexos en Palaemonidae; una explica que los machos son mucho más grandes porque compiten por aparearse con las hembras e invierten mucha energía para el crecimiento corporal y la adquisición de quelípedos robustos (Correa y Thiel 2003, Bauer 2004, y otra afirma que los machos pequeños y ágiles tienen mayor oportunidad de aparearse varias veces con diferentes hembras y no gastan energía protegiendo territorios (Bauer 2004) pero sí en la producción de esperma (Paschoal et al 2013).…”