Tolerance response to ammonia and nitrite in hatchlings paralarvae of Octopus vulgaris and its toxic effects on prey consumption rate and chromatophores activity

Abstract

Ammonia and nitrite are among the most important water quality parameters. The aim of this study was to determine the acute toxicity of unionized ammonia and nitrite on newly hatched Octopus vulgaris paralarvae. Concretely, survival, feeding and chromatophore activity were examined under different NH3 and NO2 − concentrations. The median lethal concentration (LC 50) determined for 24 h was 10.7 ppm for NH3 and 19.9 ppm for NO2 −. Based on these results, a concentration range was chosen to test the effect of this environmental contaminants in feeding and chromatophore activity (range between 2.5 and 20 ppm for feeding and 10 and 30 ppm for chromatophore activity), resulting in modifications in both parameters. In fact, a significant decrease (P < 0.05) in Artemia nauplii consumption by the paralarvae was observed with an increase in NH3 and NO2 −. Similarly, the chromatophore activity was also affected by concentration of these contaminants, with decreasing response (P < 0.05) when submitted to stressful situations, as the ammonia and nitrite concentration was increased.