Life‐history traits of the fairy shrimp Branchinella kugenumaensis are highly variable between neighboring rice paddies in Japan
2022
Yasui, Yukio
In addition to unpredictable natural ephemeral wetlands (e.g., temporal pools after rainfall), artificial environments such as subdivided rice paddies in Japan are challenging environments regarding organism adaptation because of remarkable spatiotemporal heterogeneity. Because different paddies are managed by different farmers, the timing, duration of irrigation, and application of agrochemicals are largely different among neighboring paddies. I investigated the occurrence, adult body size, and female fecundity of the fairy shrimp Branchinella kugenumaensis in a terraced rice field (31 selected from approximately 100 paddies in a valley approximately 1200 m in length) in Kyoto, Japan. The duration of inundation varied from 47 to 86 days, which was sufficiently long for the sexual maturation of the shrimp. At most stations, shrimps repeated oviposition during an approximately 20‐day adult lifespan with adult growth. At a few stations with the longest inundation, located in the uppermost part of the river, the shrimps continued adult growth and reproduction for approximately 40 days (long‐reproducing type [LR]). At a few stations with the shortest inundation, located at the mouth of the valley, the shrimps seldom showed adult growth, and the second generation occurred after drainage and reirrigation (short‐reproducing type [SR]). In the early days of adulthood, the SR females produced significantly more eggs than the LR females of the same body length, but the LR females achieved maximal body size and fecundity at the end. The SR may perform conservative bet‐hedging (early reproduction in small size), but the LR could be results of genetic differentiation or phenotypic plasticity.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library