Article ID: 2005
Some dragonflies in East Asia have adapted to traditional paddy cultivation by matching their phenology to the paddy growth cycle, water regime, and the forest and grassland landscapes surrounding the paddy fields. An endangered dragonfly, Sympertrum uniforme, lays eggs in reservoirs that supply water to paddy fields and is highly influenced by traditional water management regimes. Here, we studied the effects of water management of reservoirs on S. uniforme in Ehime Prefecture, Japan. The water-level management regimes and adult abundances (mature and immature) were surveyed at selected reservoirs. Samples of sand and gravel were collected at each reservoir just below the maximum water level. The samples were kept dry throughout the winter, watered the next spring, and larvae that hatched were counted. Many larvae hatched from the sand and gravel samples, which were collected from areas that dry out in winter. For one reservoir, although the water management regime and spawning rate were similar to those at other reservoirs, few larvae hatched, and the adult emergence rate was low.
