Variation in reproductive traits of the river prawn, Macrobrachium nipponense (De Haan, 1849) (Caridea, Palaemonidae) among different sites in southern Taiwan

Abstract Previous studies have revealed that reproductive traits of the Oriental river prawn Macrobrachium nipponense (De Haan, 1849) (Palaemonidae) can differ markedly across populations, though the environmental factors responsible for such variation are unknown. We therefore conducted monthly surveys of these prawns to determine their reproductive traits over two years at four study sites in southern Taiwan. The temperature, dissolved oxygen concentration, conductivity, and turbidity in Long Luan Lake significantly differed from the other sites, yet levels of reproductive trait parameters were intermediate among all. The aforementioned environmental factors were similar between the two Sihchong River sites and Mudan Reservoir, yet the river populations had the highest values in all reproductive traits. The river’s substratum was comprised of >60% of cobbles and boulders, whereas <5% of the substratum of the reservoir and lake consisted of such rocks. We therefore suggest that this difference in substrate composition may be linked to the significant differences in reproductive traits observed.