Chironomus salinarius KIEFFER is a common species of brackish environments such as coastal lagoons. These lagoons are characterized by a large range of salinity. This indicates that C. salinarius can tolerate important variations of salinity. We examined the effect of salinity on survival and time of development of C. salinarius in order to determine its environmental tolerances and preferences. Eleven levels of salinities were tested (0, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 g l− 1). Too few individuals survive in environments with salinity level over 35 g l− 1.The survival was optimal for low salinities (0 and 5 g l− 1) and high salinities (20, 25 and 30 g l− 1), and weak at intermediate levels (10 and 15 g l− 1). The time of development increased with the increase of salinity levels. These results suggest the existence of two physiological strategies, depending on the salinity level. The alternation between these two strategies is highlighted at intermediate levels of salinity with a lower survival rate. This alternation between two physiological strategies has already been observed for other organisms.
