Hydration time influences microcrustacean hatching in intermittent wetlands: in situ and ex situ approaches

Organisms living in intermittent wetlands present adaptations to cope with the inundation-desiccation process. Microcrustaceans are commonly found in intermittent wetlands because they present reproductive strategies able to synchronize with the hydroperiod. To know the dynamic of the microcrustaceans, that inhabit these wetlands of the subtropical coastal plain, which predominate the Pampas biome in Brazil, we analyzed the influence of hydration time and temperature on the hatching of microcrustaceans, comparing in situ and ex situ approaches. We followed hatching 34 days after in situ flooding and tested three temperatures (10, 15, and 20°C) 30 days after laboratory flooding. In both approaches, we classified the hydration time as the beginning, middle, and end of the hydroperiod. We recorded a total of 41 taxa distributed in Cladocera (26 taxa), Ostracoda (8), Copepoda (3), Anostraca (1), and Conchostraca (1). We observed that in situ hydration time was the most important factor for hatching. Ex situ hydration time was also important, but the increase in temperature positively affected the hatching of organisms. We also found that in both approaches, the beginning of hydration time is the most important period for the hatching of microcrustaceans.