Global seagrass ecology: Biogeography of Zostera marina community dynamics

Background/Question/Methods

Ecosystem processes are mediated by interactions between resource supply, consumer pressure, and community composition, with the balance shifting along environmental gradients. A frontier in basic and applied ecology is understanding how these multifarious processes interact, and organizing the complexity into predictive models. One promising way forward is the comparative-experimental approach, integrating standardized experiments with observational data. Through the Zostera Experimental Network (ZEN, www.zenscience.org) we utilize this approach to study the community ecology of eelgrass (Zostera marina), the most widespread marine plant and foundation of important but threatened coastal ecosystems throughout the northern hemisphere. 

Results/Conclusions

In the summer of 2011, 2012 and 2014, parallel field surveys and experiments were conducted at 15-50 sites to measure correlations between mesograzer species diversity and eelgrass genetic diversity, predation pressure, and seagrass dynamics. Biodiversity was positively correlated with plant and grazer biomass and production across our global gradients in environmental factors. Predation pressure in these systems decreased with grazer biomass and latitude, while grazer biomass was influenced by both eutrophication and habitat complexity. These results largely corroborate controlled, small-scale biodiversity experiments and suggest that impacts of biodiversity loss on ecosystems will be of comparable magnitude to those of other global change factors.