Population biology of the freshwater prawnMacrobrachium brasiliense(Heller, 1862) in the Middle Amazon Region, Brazil

Seasonal variation in the population structure of the freshwater prawn Macrobrachium brasiliense (Decapoda: Palaemonidae) in a neotropical region

“…The seasonal variation in the population structure is the result, at least in part, of the relationship between rainfall and the recruitment of UJ. Recruitment increases at the end of the rainy season, with the period with the highest recruitment intensity observed from March to July, a period similar to that recorded for populations in the states of São Paulo and Mato Grosso do Sul (Mantelatto and Barbosa, 2005;Pereira and Chacur, 2009), but different from the populations of the Amazon regions of Brazil and Peru (García-Davila et al, 2000;Oliveira et al, 2019). This difference between the recruitment periods may be related to local environmental factors, such as seasonal rainfall, food resources and predators (Mantelatto and Barbosa, 2005;Bittencourt and Armadio, 2007;Oliveira et al, 2019).…”

“…The frequency distribution of males and females of M. brasiliense between the size classes followed a pattern, with a greater number of females in the smallest size classes and a greater number of males in the largest classes, which may be a reflection of the reproductive strategy called "temporary female guarding" (Bauer, 2004), with dominant males that court and protect females during copulation. This model of population structure seems to be a pattern in M. brasiliense, considering all the populations studied so far (Mantelatto and Barbosa, 2005;Pereira and Chacur, 2009;Oliveira et al, 2019), as well as for other Macrobrachium species (Mattos and Oshiro, 2009;Gualberto et al, 2012;Nogueira et al, 2019b;Perroca et al, 2021). Therefore, this type of sexual system appears to be common within the genus, since most populations are characterized by males being larger than females, with males showing aggressive behavior during social interactions (Fielder and Lee, 1983;Karplus et al, 1992;Karplus and Barki, 2019).…”

“…The hypothesis that rainfall seasonality should affect population structure and reproduction leading to peak recruitment in the dry season was tested. This hypothesis is supported by the theory of upward (bottom-up) and downward (top-down) regulatory processes of population and community dynamics (Collar et al, 2017;Benke, 2018) and by several empirical studies that found a relationship between the reproductive period/recruitment with periods of greatest rainfall (Mantelatto and Barbosa, 2005;Nogueira et al, 2019b;Oliveira et al, 2019). The hypothesis proposes that: [1] different population structures occur between seasons (dry and rainy), i.e., immature and small individuals predominating in the dry season and a predominance of adult individuals and larger size classes in the rainy season; and [2] a significant relationship will occur between juvenile abundance and rainfall.…”

“…In the studies by Mantelatto and Barbosa (2005), Chacur (2009), andOliveira et al (2019) there is no information on morphotypes. In this sense, considering the density observed in the present study and the density of morphotypes in populations of similar species, it is important to note that the density of morphotypes in M. brasiliense males did not follow the patterns observed in M. amazonicum and M. rosenbergii (Cohen et al, 1981;Santos et al, 2006), since the density of the morphotypes "Açu" (dominant) and "Mirim" (submissive) were similar within the population.…”

Male morphotypes of the freshwater prawn Macrobrachium brasiliense (Decapoda: Caridea: Palaemonidae)

“…The species is distributed in 11 states of the Brazilian territory, and in Colombia, Venezuela, the Guianas, and Peru (Coelho & Ramos‐Porto, ; Holthuis, ; Melo, ; Pileggi, Magalhães, Bond‐Buckup, & Mantelatto, ). Most studies of M. brasiliense addressed its population ecology (García‐Davílla, Alcantara, Vasquez, & Chujandama, ; Mantelatto & Barbosa, ; Oliveira, Sant'anna, & Hattori, ), and there are few published distribution records (García‐Davílla & Magalhães, ; Santos, Castro, & Magalhães, ). Despite the species' wide distribution, there have been few taxonomic reviews (Coelho & Ramos‐Porto, ; Pileggi & Mantelatto, ) and few studies of other aspects of the species' biology such as behavior (Nogueira, Costa, & Almeida, ), feeding behavior (Melo & Nakagaki, ), mass‐length relationships or other measures of physiological condition (Taddei et al, ), reproductive potential (Oliveira, Sant'anna, & Hattori, ), or larval morphology (Pantaleão, Gregatti, Taddei, & Costa, ).…”