Egg Production of Annual Fish Austrolebias cyaneus and Cynopoecilus nigrovittatus Occurs Throughout Their Entire Life Cycle to Survive in a Temporary Wetland

Annual fishes inhabit small temporary ponds that dry up seasonally. Survival in temporary ponds requires specific physiological, morphological, and/or life cycle adaptations. Annual fishes exhibit a complex reproductive strategy with resistant eggs to survive droughts. Here, we investigate the fecundity of the annual fishes Austrolebias cyaneus and Cynopoecilus nigrovittatus individually and in interaction in situ throughout the hydroperiod (early inundation, drying, and late inundation) of a temporary pond. The monospecific treatment of Austrolebias cyaneus showed no effect on fecundity regarding body size, weight, and flooding phase. In the monospecific treatment of Cynopoecilus nigrovittatus , there was a positive effect of female body size and sampling period on the number of eggs, which was higher in the late flooding phase. In the interspecific treatment, Austrolebias laid fewer eggs in the early flooding phase when compared to the monospecific treatment, and Cynopoecilus nigrovittatus showed a reduction in the number of eggs, considering the entire hydrological cycle. These results obtained from wild populations should help to fill the knowledge gap on biological traits, which impairs the understanding of the ecology of annual killifish in small temporary wetlands.