Effects of salinity, stocking density and feeding in Macrobrachium pantanalense larviculture

Macrobrachium pantanalense is a recently described endemic shrimp from Pantanal. The species completes its life cycle in freshwater and is used as an ornamental species for freshwater aquaria, as well as a model organism in risk assessment trials of anthropic impacts. However, all risk assessment trials performed to date have used wild specimens. As such, it is paramount to standardize the laboratory culture of M. pantanalense to allow the use of cultured specimens that safeguard the reliability and replicability of trials being performed. The present work evaluated the use of freshwater and different salinity levels (2, 4 and 6) for the larviculture of M. pantanalense, as well as larval stocking densities of 20, 40 and 60 larvae L−1. Six different larval feeding regimes were also evaluated: 100 % newly hatched Artemia nauplii (AN), 100 % wild zooplankton (WZ), 100 % inert diet (ID), 50 % AN + 50 % WZ, 50 % AN + 50 % ID and 50 % WZ + 50 % ID. Larvae of M. pantanalense were able to successfully metamorphose to post larvae (PL) when cultured in freshwater, although a higher % of PL was achieved under a salinity of 4 (25.6 ± 15.0 %). No significant differences were recorded in survival under different stocking densities. The best larval feeding regime tested was 100AN, promoting a higher production of PL (44.3 ± 18.3 %) when compared with other diets. Overall, the larviculture of M. pantanalense can be enhanced by using brackish water instead of freshwater. By employing a moderate larval stocking density (up to 60 larvae L−1) and an easy to use “of-the-shelf” larval live feed (Artemia nauplii) PL of M. pantanalense can be produced in the laboratory. The present findings are a first step towards the development of a production protocol for M. pantanalense in the laboratory to perform risk assessment trials of growing anthropic stressors impacting Pantanal