Scientists thought dead plant material were primarily powering the Everglades. Algae says not so fast.
Scientists have long known that both algae and decaying plant material help sustain the Everglades. But by tracking the sources of energy supporting fish and other aquatic organisms across the ecosystem, researchers found that algae often contributed more than expected. The findings offer a clearer picture of how one of the world's largest wetlands functions and may help scientists predict how it responds to restoration and environmental change. The study was led by James Sturges, Ph.D. candidate in Department of Earth and Environment, and a team of researchers from FIU's Institute of Environment. It was published recently in PLOS One.
Green energy sources include algae, epiphytes, and phytoplankton and other similar organisms. They are generally more nutritious and lead to faster energy turnover. Brown energy sources consist of dead organic matter, decaying plant material.
"You need both," Sturges said. "The brown pathways play a big role in stabilizing the base of the food web. In a post-disturbance setting, like following a hurricane, the green pathway consumers would be less abundant, or they wouldn't be there at all and start to come back as production increases again."
Researchers studied food webs across a range of Everglades habitats, from freshwater marshes to mangrove forests and coastal waters.
This included nine locations during the wet and dry seasons. While some locations relied on brown energy sources as the primary energy source, the majority relied on green energy sources. Only two locations switched between green to brown during the two seasons.
A variety of factors can influence energy sources in marine environments including natural seasonal changes, extreme weather events like hurricanes or droughts, sea level rise, fish migrations and more.
These pathways are not static on a daily or annual scale," Sturges said, "but having that baseline and understanding where the system is will help us understand how our restoration efforts are changing the energy moving through the systems."
According to Sturges his research is now focusing on refining food web studies. By using fewer but more representative species, he aims to better understand the driving changes across different habitats.
Sturges conducted this research as part of the NSF-supported CREST Center for Aquatic Chemistry and Environment and the Florida Coastal Everglades Long-Term Ecological Research Program.
