Evaluation of the rheotaxis behavior of juveniles of the prawn Macrobrachium tenellum Smith, 1871 (Decapoda: Palaemonidae) under laboratory conditions

Abstract Understanding the upstream migration of amphidromous prawns is important to address the impact of anthropomorphic activities in natural freshwater ecosystems. The ability of Macrobrachium tenellum (Smith, 1871) juveniles to overcome an artificial barrier was evaluated, simulating an obstacle in their upstream migration, under an experimental laboratory system. The prawns were collected from a stream located in Puerto Vallarta, Mexico (N = 1000). An experimental recirculation system was used, which consisted of a tank with a capacity of 600 L, a sheet of galvanized steel that acted as an anthropogenic barrier and two submersible electric pumps with flows of 0.12 L/s and 0.40 L/s. In this system, two inclinations of the barrier were tested, 45° and 90° in combination with the two flows. The results show that there are significant differences between the treatments with different inclinations, where a higher stimulation response was observed at the 90° angle. Within this inclination, the flow of 0.40 L/s produced the highest stimulation to climb the barrier in prawns between 30 and 60 mm in length. This study demonstrates the direct relationship between the slope and the effect of water flow of the anthropogenic barriers that hinder the migration process of M. tenellum.