Energy allocation trade-off in Macrobrachium amazonicum, with no resting stage

In this study, we investigated which strategy Macrobrachium amazonicum populations use to survive in river and estuary environments. In each environment, abiotic factors were analyzed in situ, and ovigerous females and males of M. amazonicum specimens were captured. To determine ovarian maturity and morphotypes, gonads were removed and processed histologically, and the gonadosomatic index and condition factor (K) were determined. Ovigerous females were analyzed to determine the relationship between ovarian maturation and the embryonic phases of eggs in the brood pouch. Precipitation, turbidity and dissolved oxygen showed differences between the estuary and river. The population of ovigerous females showed that ovarian maturation was simultaneous with embryonic development. However, the freshwater prawn populations in the river were smaller and consisted of a greater number of ovigerous females with maturing and mature ovaries. In the estuary, ovigerous females with spawned and reorganized ovaries were observed more frequently. In males, the GC morphotype was absent in the river, where the TC morphotype predominated and showed similar reproductive conditions as the GC morphotype in the estuary. M. amazonicum has strategies for allocating energy for reproduction or growth in different environments. This description established the trade-off as a strategy used by M. amazonicum to maintain the population in adverse environments. (C) 2021 Elsevier GmbH. All rights reserved.

Automated summary

The study investigated the survival strategies of Macrobrachium amazonicum populations in river and estuary environments, revealing differences in reproductive conditions and energy allocation between the two environments. The findings suggest that a trade-off strategy is employed by M. amazonicum to maintain populations in adverse environments.