Red tide riddles uncovered.
This new research, published as a special edition of the scientific journal Harmful Algae shows the food sources that support Karenla brevis, the organism that causes Florida's red tides, are more diverse and complex than previously known.
The five-year group of studies aimed to reveal which nutrients support blooms of K. brevis and the extent to which coastal pollution might contribute to red tide in Southwest Florida. Understanding all the factors that contribute to blooms is important for reducing their impacts on coastal communities, where they can significantly affect public health and local economies, researchers say.
The multi-partner project was funded by the National Oceanic and Atmospheric Administration's Ecology and Oceanography of Flarmful Algal Blooms Program (ECOFIAB) and documented the microbiology, physiology, ecology and physical oceanography factors affecting red tides in new detail. Fourteen research papers, including several from Mote Marine Laboratory scientists, were published in the special issue of Harmful Algae, which provided a synthesis of results and offered suggestions for resource managers addressing red tide in coastal Southwest Florida.
"Right now, we have few options for controlling or reducing red tide blooms, so we have to focus on how we can help communities mitigate the impacts," said Dr. Cynthia Heil, Senior Research Scientist at Bigelow Laboratory for Ocean Sciences in Maine, who co-edited the special issue of Harmful Algae and was formerly with Florida's Fish and Wildlife Conservation Commission's Research Institute. "Data go a long way toward increasing our understanding. The complexities we found also show why the continuation of large-scale, multi-faceted collaborative research is necessary to understand why Florida red tides are so frequent and harmful in this region. These studies also pointed to the need for expanding coastal observing systems that can help predict the movements of blooms once they are formed. That way, resource managers can help coastal residents prepare for impacts."
For the study, researchers studied four K. brevis blooms (2001, '07, '08 and '09, plus the non-bloom year 2010), documenting 12 nutrient sources in Southwest Florida waters that feed blooms--some man-made, some natural. The research even found several new nutrient sources never before associated with K. brevis.
The findings supported the idea that blooms start 10 to 40 miles offshore, away from the direct influence of land-based nutrient pollution, but that once a bloom moves inshore, it can use both human-contributed and natural nutrients for growth. The project blended nutrient studies with physical oceanography, shedding new light on how blooms are brought to shore.
"Nature is messy, but this project has put several new pieces in place," said Dr. Kellie Dixon, Mote Senior Scientist and co-Principal Investigator for the ECOHAB project. "Until now, we had not looked at this many of the 12 sources and their specific quantities simultaneously. Some of the sources, like nutrients released from the sediments, had never been measured in Southwest Florida's coastal waters until we studied them for this ECOFIAB project."
The project's findings are important for resource managers tasked with reducing bloom impacts on humans and coastal wildlife. "Until now, effective management of harmful algal blooms caused by K. brevis was complicated because we didn't know enough about how different nutrient sources and forms taken up by K. brevis interacted with the physical environment," said Matt Garrett of FWC's Fish and Wildlife Research Institute, who managed the ECOHAB project. "This project provides data that can help inform management recommendations on how to control nutrient sources and possibly improve forecasting models."
--View abstracts from the journal Harmful Algae at: mote.org/harmfulalgaeabstracts.