A PRELIMINARY STUDY OF RESPIRATION AND EXCRETION RATES IN THE PRAWN MACROBRACHIUM AMAZONICUM HELLER, 1862 WHEN EXPOSED TO VARIED FLOW REGIMES AND SALINITIES

Resumo

Macrobrachium amazonicum was examined as a potential candidate to routinely monitor water quality in the laboratory (bioassay). Both oxygen uptake and ammonia excretion rates were measured at different flow rates and salinities to correlate water flowwith metabolism and establish base line data. Respiration showed a typical flow dependent response that tended to level out above a respiration rate of 0.60 mgO2g-1.h-1. The minimum maintainable respiratory rate was 0.2 mg O2.g-1.h-1 at a flow of 2.5 ml.min-1 and an oxygen concentration of 2.8 mg.l-1. All tested salinities depressed oxygen uptake to about 85% of freshwater values. There was no correlation evident, however, between salininity and degree of oxygen uptake Inhibition. O:N ratios were consistently 16:1 independent offlow in adult specimens.

Keywords: Macrobrachium amazonicum, respiration rate, excretion rate, salinity, waterquality monitoring.

Descritores: Macrobrachium amazonicum, taxa de respiragao, taxa de excregao.salinidade, monitoramento da qualidade da agua.