Population structure of Macrobrachium amazonicum (Heller, 1862) (Decapoda: Palaemonidae) in Miranda Hydroelectric Plant Reservoir, Araguari river, Minas Gerais, Brazil

Abstract

Aim The present study aimed to analyze a M. amazonicum population structure in a reservoir of the “Triângulo Mineiro”, Brazil. Methods Monthly surveys were carried out from April/2012 to May/2013 at the Miranda Hydroelectric Plant Reservoir located in Araguari river, state of Minas Gerais. A sampling section of 100 m long, 5 m wide and depth not exceeding 1 m was defined on the banks of the reservoir. Sampling consisted on two persons quickly passing a 2 mm sieves in partially submerged marginal vegetation, for one hour. The sampled specimens were identified, sexed and measured. Results A total of 2,584 specimens were analyzed, of which 64.62% were females (3.93% ovigerous, 5.94% non-ovigerous and 54.75% juveniles), 29.16% males (21.41% adults and 7.76% juveniles) and 6.22% juveniles of undetermined sex. The sex ratio (1:2.21) indicated a clear deviation for females, for the whole sampling period, monthly and for each size class. Males had an average carapace length (CL = 4.50 ± 0.71 mm) significantly lower than females (CL = 4.64 ± 1.47 mm) and the size frequency distribution revealed a unimodal pattern, with peaks occurring in 4.0 - 4.9 mm size class for males and in 3.0 - 3.9 mm size class for females. The relation between total and carapace length was significant, indicating a negative allometric growth. No males’ morphotypes were found. The population presented a continuous reproduction with a gradual increase between April and June/2012. Female sexual maturity was determined for 6.3 mm of CL, while for males was estimated for 4.0 mm. Conclusion The Miranda reservoir population had a body size variation similar to the continental populations of Pantanal. The sexual dimorphism observed may be related to the absence of male morphotypes and to the “pure search” reproduction strategy. The deviated sex ratio for females may increase the chance of fertilization and the reproductive success. The presence of juveniles and ovigerous females throughout the year indicates a continuous reproduction pattern of the population.

REPRODUCTIVE ASPECTS OF THE PRAWN <i>Macrobrachium amazonicum</i> IN A CONTINENTAL POPULATION LIVING DOWNSTREAM OF A HYDROELECTRIC DAM

“…According to Costa and Silva et al (2019), females may represent up to 85% of the population. Similarly, our results showed a female-biased sex ratio (F:M = 4.13:1) and females were 80.51% of the population.…”

Does fecundity of Macrobrachium amazonicum (Heller, 1862) change between upstream and downstream a dam? A case study in Água Vermelha Reservoir, Brazil

“…Due to rapid reproduction, this prawn has quickly spread throughout several dams (Paiva & Campos 1995). In the state of Minas Gerais, M. amazonicum has been recorded in dams by Silva et al (2017), Silva et al (2018), Costa e Silva et al (2019), Paschoal et al (2019) and Rodrigues et al (2020).…”

“…In the Hydrographic Basins of Brazil, it has been reported in estuarine and/or freshwater aquatic ecosystems, from the state of Roraima to Paraná (Melo 2003, Peleggi et al 2013. This species has become an important economic resource for artisanal fishing over the last decade, being increasingly used as a food resource by riverine populations (Paschoal et al 2019;Costa e Silva et al 2019). Due to rapid reproduction, this prawn has quickly spread throughout several dams (Paiva & Campos 1995).…”

BIOLOGIA POPULACIONAL E PERÍODO REPRODUTIVO DO CAMARÃO Macrobrachium amazonicum (HELLER, 1862): UMA REVISÃO BIBLIOGRÁFICA ABRANGENDO DIFERENTES REGIÕES DO BRASIL

“…Mais estudos sobre M. amazonicum foram realizados devido ao grande interesse pelo cultivo comercial da espécie (Silva et al, 2007). Acredita-se que futuramente a espécie será comercializada em larga escala devido sua ampla distribuição (Silva et al, 2019) Macrobrachium amazonicum é a espécie de água doce mais encontrada no Brasil (Lima & Odinetz-Collart, 1997)…”