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

Abstract

The present study aims to describe the population structure of the freshwater prawn Macrobrachium brasiliense and to analyze whether it varies seasonally, with emphasis on abundance variation by demographic category, sex ratio, size, and morphotypes, in addition to analyzing the recruitment period and its relationship with rainfall. The collections of M. brasiliense were carried out in a Cerrado region, in the southeastern region of Brazil. The population structure was analyzed according to the size, sex, and life stage. The density of morphotypes was calculated by the proportion of each morphotype in the population. Male and female prawns were more abundant in the largest and smallest size classes, respectively. The juvenile morphotype was the most abundant among males (45.9 %), while the "Mirim" and "Açu" morphotypes occurred in a similar proportion (27.87 % and 26.23 %, respectively). The population structure varied significantly between seasons (dry and rainy). A relationship of juvenile abundance with rainfall was recorded. The recruitment period was observed between the end of the rainy season and the beginning of the dry season, while adults were more abundant at the end of the dry season and the beginning of the rainy season. The information in this study contributes to the knowledge of the influence of seasonality and

Evaluation of population dynamics of Macrobrachium olfersii (Palaemonidae) along ~150 km extension of the Lower Ribeira de Iguape River, São Paulo, Brazil

“…In this pattern, females and males have similar growth until reaching sexual maturity; then, females begin to direct most of their energy towards reproduction (egg production and arranging the incubator chamber), while males invest in somatic growth, becoming the most prominent individuals in the population (Ammar et al 2001, Mossolin & Bueno 2003, Nwosu & Wolfi 2006. Sexual dimorphism related to the larger of males in the population is very common among prawns of the genus Macrobrachium (Fransozo et al 2004, Mantelatto & Barbosa 2005, Mattos & Oshiro 2009, Iketani et al 2016, as well as in other M. olfersii populations studies by Barros (1995), Ammar et al (2001), and Mossolin & Bueno (2002, 2003.…”

Relative growth and morphological sexual maturity of the caridean prawn Macrobrachium villosimanus (Tiwari, 1949) (Decapoda: Palaemonidae)

“…The present study, however, used secondary sexual characters (e.g. appendix masculina length for males; hatchery chamber width for females), noting some researchers (Ahamed & Ohtomi, 2014;Ghizelli-Fraga et al, 2021;Nogueira & Almeida, 2023;Pescinelli et al, 2018) indicate these two variables can be used as good indicators to estimate morphological sexual maturity.…”

Presence of the Neotropical Otter in the Cubatão do Sul River, Santa Catarina, Brazil

“…Nogueira et al, 2021). A diminuição da presença de peixes nos excrementos das lontras a partir de novembro de 2006, coincide com o aumento do número de crustáceos, com um pico em julho de 2007, quando a precipitação é maior.…”