A Predictive Model for Investigating Seagrass Paleoecology, Biogeography and Diversity

Seagrasses are highly productive components of coastal ecosystems that play significant roles in the flow of nutrients and the modulation of physical conditions within the world's oceans. However, in spite of the significant role seagrasses play today, the fossil record contains little evidence of the distribution and abundance of seagrass species in the past and many questions about their biology, ecology, and evolutionary history remain. We have developed, and present here, a parameter driven numerical model of global seagrass biogeography and diversity appropriate for paleontological and paleoecological investigations. The global distribution of seagrasses in our model is dependent on four input parameters, water temperature, water salinity, water depth, and photosynthetically available radiation at depth. With these limited inputs, our model captures both the location and biodiversity of modern seagrass distributions well. The simplicity of our model and its robust representation of modern conditions give it tremendous flexibility for applications throughout the ~70 Ma long history of seagrasses. Paleo ocean temperatures, salinity, water depths, and incident radiation are available from paleoclimatic/proxy datasets and/or numerical simulations of past environmental/climatic conditions, thus permitting investigations into time specific seagrass biogeography and diversity throughout its evolutionary history. In addition, the simplicity of our model allows for theoretical investigations of seagrass paleoecology and response to environmental changes. Both applications will contribute significantly to furthering our understanding of seagrasses, seagrass dominated ecosystems, and the roles they have played in the earth system over the past 70 Ma.