Modeling Past Variation in Florida Manatee Survival, Breeding, and Movements Rates to Establish Baselines for Aquatic Ecosystem and Restoration Research Completed

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The Science Issue and Relevance: Agricultural run-off, sea level rise, oil spills, harmful algal blooms, habitat degradation, hurricane strikes, and climate, land-use and ocean change are some of the challenges to natural resource and ecosystem services management in the coastal southeastern U.S. These issues are being addressed with large-scale ecological programs, such as the Gulf of Mexico Restoration and Everglades Restoration. The Florida manatee is an important iconic component of SE coastal ecosystems. Living in canals in urban centers, natural estuaries, tidal creeks and rivers, and coastal artesian springs, manatees are endemic to the SE, but their reputation is national and international in scope. A large ecotourism industry has been built around the species. They are also vulnerable to natural and human-related stressors. Changes in annual survival and breeding rates and movement rates among critical habitats have been documented with changing conditions, making the Florida manatee a high-profile indicator of ecosystem change. Along with other indicator species, manatees can play an important role in landscape-scaled, integrated research to understand the drivers of ecological change and to monitor success of management and policy actions. To include manatees in ecosystem restoration research requires baseline estimates of past manatee demography changes in response to past stressors and management actions. 

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Methodology for Addressing the Issue: Long-term monitoring data in the Manatee Individual Photo-identification System (MIPS) developed and coordinated by WARC-Sirenia Project in collaboration with Florida’s Fish and Wildlife Research Institute and Mote Marine Laboratory, are the basis for modeling manatee demography rates. This region-wide program monitors individually identifiable manatees known by unique scar patterns. After a sustained upgrade of the database we now have comparable data covering 17-30 years of monitoring in 4 regional management units. There are sufficient data and annual variation to assess and compare impacts of multiple factors on survival, breeding, and probabilities. Environmental indices of red tide severity and winter cold severity have been developed and used to model and test explanatory predictions of cause and effect in years past; analyses of other stressors are in progress. To ensure continuity of future data and analyses, we are developing and implementing new monitoring designs and analytical models that account for changing patterns of manatee use of historic warm-water monitoring sites, which otherwise can bias estimates and limit future comparisons.

Future Steps: Work with partnerships designing large-scale programs to identify the most important parameters and spatial and temporal scales needed for landscape and restoration research, as well as the major stressors and drivers of change of common interest to those programs. Establish collaborations to develop a pilot monitoring network integrating other indicator marine vertebrate species, such as sea turtles, sturgeon, and dolphins. Develop common methods and metrics important to comparative assessments of restoration actions on the suite of species. Provide reference baseline estimates of past annual survival, breeding and movement rates to those programs.      

Location of study: Coastal Gulf of Mexico