Biomass diversity and stability of food webs in aquatic ecosystems

The diversity-stability hypothesis in ecology asserts that biodiversity begets stability of ecological systems. This hypothesis has been supported by field studies on primary producers in grasslands, in which the interaction between species is mostly competition. As to ecosystems with multitrophic predatory interaction, however, no definite consensus has been arrived at for the relation between trophic diversity and ecosystem stability. The stability index suitable to ecosystems with predatory interaction is given by MacArthur's idea of stability and its formulation by Rutledge et al. More suitable indices of stability (relative conditional entropy) are proposed in this study for the comparison of different ecosystems, and the validity of the diversity-stability hypothesis for food webs (networks of predation) with many trophic compartments in natural aquatic ecosystems is examined. Results reveal that an increase in the biomass diversity of trophic compartments causes an increase in the whole systemic stability of food webs in aquatic ecosystems. Hence, evidence of the whole systemic validity of the diversity-stability hypothesis for natural aquatic ecosystems with ubiquitous multitrophic predatory interaction was obtained for the first time.