Abstract
Clam shrimps are small crustaceans typical of temporary ponds. To survive in these highly variable and unpredictable environments, they produce resistant eggs. These settle on the bottom of pools where they remain dormant, forming a cyst bank. We investigated the effects of light and temperature, both of which break the dormancy of Eulimnadia colombiensis eggs. Dormancy was not broken below 25°C, irrespective of the effect of light. Hatching was highest (27.8% of eggs) at 30°C in continuous light. Light also influenced the development of eggs, and some nauplii hatched spontaneously without drought stress. Methods are suggested for the cultivation of this species in tropical areas.
Highlights
Members of the Class Branchiopoda are common in temporary pools
Dead nauplii were found among the set great of eggs. Both temperature and light regime are critical in the breaking of dormancy of Eulimnadia colombiensis cysts
At small temperature intervals (±1°C) and in absence of light, the gradual increase in the hatching rate strongly suggests that temperature is an important stimulus in breaking dormancy
Summary
Members of the Class Branchiopoda are common in temporary pools. These environments usually occur in hot, semi-arid, flat regions (Rabet and Thiery, 1996; Demeter, 2005). The genus Eulimnadia Packard, 1874 (Family Liminadiidae) found in these microhabitats includes 48 species (Rabet, 2010) and has androdioic sexual system This reproductive pattern is characterized by the presence of males and hermaphrodites genetically different, but phenotypically similar, differing only by the presence clasper (Sassaman and Weeks, 1993; Weeks et al, 2009). Dormancy breaking happens only when internal factors are activated, a mechanism known as “diapause” (Brendonck, 1996) This mechanism, linked to the “bet-hedging” strategy (asynchrony in hatching eggs of the same litter), can greatly reduce the chances of local extinctions, if the environment be altered abruptly, without the organisms have time to respond to changes (Seger and Brockman, 1987; Cáceres and Tessier, 2003; King and Masel, 2007; Benvenuto et al, 2009)
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