Modeling local effects on propagule movement and the potential expansion of mangroves and associated fauna: testing in a sub-tropical lagoon

Abstract

Local effects on the rates of spread of mangrove and associated epifauna were modeled for the Indian River Lagoon, Florida, USA. The model divided the 200-km-long lagoon into 157,330 cells. Data from a hydrodynamic model were used to generate current vectors for each cell at 10-min intervals. Each cell was assigned a habitat type, and releases or recruitment of mangrove propagules or epifauna larvae were based on the suitability of these habitats. Multiple species were included in the model, each with its own life-history parameters. All individuals were followed over 8 years or until mortality occurred. Adults could reproduce and release new larvae or propagules. The mean rates of spread predicted by the model were <1 km year⁻¹ for all species, which were less than the 2 km year⁻¹ predicted for mangroves along this coast. Spread rates were also found to differ among the five inlet source sites used in the model. Epifaunal invertebrate populations spread at similar rates, but spread more rapidly from mangrove habitats than from dock habitats. These results demonstrate that local differences in hydrodynamics and habitat distributions influence the broader regional rates of spread likely to occur with climate change.