Marine zooplankton contribute differentially to community synchrony across a 37-year time series

Community synchrony-the tendency for species within a community to fluctuate similarly to other species-is tied to environmental variability through the responses of species in the community to environmental drivers. If species respond similarly to the environment, environmental variability will increase synchrony, as community synchrony is a composite property of species-level dynamics. We used a 37-year time series of marine zooplankton to explore temporal patterns in community synchrony, the relationship between environmental variability and community synchrony, and the relationship between taxa-level contributions to community synchrony and population dynamics. Environmental variability was unrelated to annual community synchrony estimates, taxon density was related to taxon-level contributions to community synchrony, and taxon-level contributions to community synchrony have become less correlated over time (i.e. taxa are not maintaining their relative rank in synchrony contributions year to year). Numerically dominant taxa contributed more to community synchrony, but not because of their numerical dominance. Instead, taxon-scale temporal variability was a strong indicator of contribution to synchrony, suggesting more stable taxa contribute more to overall community synchrony. Collectively, this highlights the inherent link between community synchrony and the population processes that in aggregate constrain resulting community dynamics, while finding no support that more variable environments will alter community synchrony.