Ovarian development and spawning of Macrobrachium amazonicum (Crustacea, Decapoda)

ABSTRACT Macrobrachium amazonicum (Heller, 1862) is the most important species for aquaculture native to South America. This study evaluates the phenotypic plasticity of females of Macrobrachium amazonicum with respect to the gonadal development, and determines the spawning type. Our study consisted of macro and microscopic analysis of the reproductive tract. Ovaries exhibited the following reproductive cells in developmental sequence: oogonia (OO) - mean diameter and standard deviation of 25.4 ± 6.5 μm; previtellogenic oocyte (PVO) - 61.7 ± 10.7 μm, vitellogenic oocyte (VO) - 113.9 ± 24.5 μm; and mature oocyte (MO) - 308.7 ± 56.3 μm. Ovaries increased in volume due to vitellogenesis and changing of basophilic to acidophilic composition. Follicular cells, atresic oocytes and postovulatory follicles were also analyzed. By combining macro and microscopic analysis, the ovaries of M. amazonicum were classified into six stages: Immature, In maturation, Mature, Spawned in maturation, Spawned and Resting. The ovarian development of M. amazonicum followed a standard pattern even among different populations. Considering our results and the evidence in literature, we conclude that spawning for this species is parceled or multiple, that is, synchronous in more than two groups (clutches of oocytes). Such observations provide basis for further studies addressing sustainable management strategies for species conservation and contribute to elucidate the biology of their specimens.