Post-embryonic developmental plasticity of Arctodiaptomus salinus (Copepoda: Calanoida) at different temperatures

Abstract

Ephemeral and semi-permanent saline wetlands undergo frequent unpredictable disturbances such as episodes of high salinity or desiccation. Organisms living in these systems are adapted to survive and develop in very fluctuating and unpredictable conditions and, therefore, could help us to understand life cycle strategies and plasticity in the context of global warming. Arctodiaptomus salinus is a common species occurring in such environments and is often the main constituent of their zoo-plankton community, which is characterized by low diversity and short trophic webs. Despite the qualitative and quantitative importance of A. salinus in these systems, no attention has been paid to the effect of temperature on its population dynamics. For this reason, variability in post-embryonic development times and stage-specific mortality of A. salinus were studied for the temperature-range over which this species occurs. Mortality was higher in earlier naupliar and first copepodite stages. The highest developmental variability and mortality occurred at the highest temperature. Developmental instability could explain the high variability at high temperatures and the fluctuating speed of development throughout the successive stages. The interaction between mortality and developmental variability might be an important mechanism ensuring persistence of A. salinus populations in these fluctuating and stressing environments.