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 zooplankton 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.

Eudiaptomus gracilis and Eudiaptomus graciloides are amongst the most common calanoid copepods in Europe and co-occur in many lakes. To understand their ecological dynamics, it is essential to know their responses to environmental variation. The finding that E. graciloides exhibits diapause in winter, whereas E. gracilis reproduces throughout the year indicates that the two species might differ in their temperature responses. We measured embryonic and naupliar development times, clutch size (number of eggs per sac), hatching percentage and body length of the first copepodid stage (CI) of both species under non-limiting food conditions at different temperatures. Special attention was given to individual variability on development times and to the use of the gamma density function (GDF) for fitting the probability of moulting. Results show that E. gracilis exhibits just slightly faster development times, lower individual variability, higher hatching percentage and larger clutches than E. graciloides and that extreme temperatures affected E. gracilis less intensely than E. graciloides. GDF was a good tool for estimating individual variability in the different experiments.

Wetlands are one of the most altered natural systems due to the creation and development of agricultural landscapes. Some of agriculture’s impacts are in relation to water quality decreases, due to the use of potentially toxic herbicides or pesticides, and they are responsible of ecological alterations. This study shows the negative effect that two pesticides generate in a population of the copepod Arctodiaptomus salinus in an aquatic ecosystem that is surrounded by intensive olive tree cultivation. Adult females and egg sacs of that calanoid copepod were exposed to different concentrations of copper sulphate and the pesticide dimethoate, to examine their tolerance response. The adult lethal concentration obtained was lower than the regular dose of pesticide used in olive agriculture. These results also reflect the negative effect over A. salinus secondary production as a consequence of the increase in females and nauplii mortality and by the hatching rate reduction.