El Nino frequency threshold controls coastal biotic communities

El Nino has profound influences on ecosystem dynamics. However, we know little about how it shapes vertebrate faunal community composition over centennial time scales, and this limits our ability to forecast change under projections of future El Nino events. On the basis of correlations between geological records of past El Nino frequency and the species composition of bird and fish remains from a Baja California bone deposit that spans the past 12,000 years, we documented marked faunal restructuring when major El Nino events occurred more than five times per century. This tipping point has implications for the past and future ecology of eastern Pacific coastal environments.

Automated summary

El Nino has significant impacts on ecosystem dynamics, but its influence on vertebrate faunal community composition over centennial time scales is poorly understood. By examining correlations between geological records and bird and fish remains, we found that major El Nino events occurring more than five times per century led to marked restructuring of faunal communities, which has important implications for the past and future ecology of the eastern Pacific coastal environments.