|| 要旨トップ | 目次 |||日本生態学会第61回全国大会 (2014年3月、広島) 講演要旨
一般講演（口頭発表） G1-13 (Oral presentation)
Predator-prey body mass ratio (PPMR) determines species coexistence and food web dynamics. In addition, community PPMR is an indicator to the degree of omnivory in size-based food webs. However, how environmental factors affect community PPMR is not fully understood. To study what factors influence community PPMR, trophic positions of size-fractionated zooplankton samples are determined through stable isotope analysis, and community mean PPMR is estimated from linear size-trophic relationship. Environmental factors including inorganic nitrogen, phosphate, silicate, phytoplankton concentration, and C/N in POM are considered in our analysis. Generalized linear mixed model analysis reveals that logarithm of community mean PPMR is negatively correlated with concentration of nitrogenous and siliceous nutrients. Furthermore, there is a significantly positive relationship between C/N in POM and community PPMR. Our results indicate that sufficient resource is related to smaller community PPMR, inferring predator preference to large prey in eutrophic condition. Lower C/N in the basal trophic level is also correlated to small community PPMR, pointing out that better quality of producers may support more high trophic, large prey for predators.