Accute toxicity of nitrite on Pleoticus muelleri at different salinity

FENUCCI, J.L.; ESPINO, M.L.; DÍAZ, A.C.; VELURTAS, S.M.

New Orleans

Congreso; Aquaculture America; 2015

wORLD AQUACULTURE SOCIETY

The red shrimp Pleoticus muelleri is a commercially important species in Argentina and presents a great potential for aquaculture, so it is important to determine optimal culture conditions in order to have healthy individuals. In culture systems, nitrite is the most important pollutant; and it may be accumulated as a result of imbalances in the activity of nitrifying bacteria. Salinity is a key environmental factor, its variations affects nitrite toxicity and health of shrimps. Both stressors are considered disruptors of multiple physiological functions in aquatic animals, including production of reactive oxygen species; so the measurement of total antioxidant capacity (AT) can be used to estimate their effects. The objectives of this study were to evaluate the salinity influence on the acute toxicity of nitrite; and its effects on AT on the shrimp P. muelleri. Shrimp (8.64±0.17g) were acclimated for 48hs at 33; 30 and 25ups of salinity. Short-term LC50 (median lethal concentration) toxicity tests were carried out at 0; 50; 100 and 200mg/l of nitrite. At the end of the trial, hepatopancreas were isolated for analysis of AT, which was estimated on the basis of the scavenging activity on the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). Table 1 shows the values of LC50 at different salinities and times. LC50 decreases with decreasing salinity and increase exposure time, except to 30ups where LC50 to 96hs (67.86) was higher. Fig. 1 shows the AT to 6`, at different salinities and nitrite concentrations. The AT was not affected by exposure to nitrite in shrimps maintained at 33ups. However, AT increased significantly in animals acclimated to 30 and 25ups, due to presence of nitrite in the water; with the exception of those exposed to 100mg/l of nitrite and 30ups, which recorded a higher percentage of DPPH remaining respect to control (74 and 59, respectively). In conclusion, P. muelleri is more susceptible to nitrite at hypo-osmotic conditions, and the measurement of AT only can be used as a biomarker of pollution by nitrites under this conditions.