Nearly 10,000 acres of lush seagrass disappeared from Florida Bay between 1987 and 1991, causing massive ecological changes in the area near the Florida Keys. Abundance of herbaria, Thalassia testudinum, more commonly known as the turtle, a staple species of the Florida Bay ecosystem, declined dramatically during what is considered one of the largest declines in seagrass cover in recent history.
Researchers from the University of South Florida, the Florida Fish and Wildlife Conservation Commission (FWC) and the University of North Carolina at Wilmington have documented the response of seagrass beds after death. Their collection of detailed data over more than 20 years over the vast impact area has provided unique insight into the resilience of seagrass beds or the ability of a coastal ecosystem to recover after significant loss. This study, published in Scientific reports, is extremely timely as the work provides a framework for how future recovery from new seagrass mortality, recorded in 2015 at the same location, may still be possible.
Seagrasses play an important role in much of the Gulf of Mexico and the Caribbean Sea, providing critical habitat and feeding grounds for many species of fish, turtles and other wildlife. They are considered one of the most productive ecosystems in the world and in Florida Bay they contribute to a sport fishing industry worth hundreds of millions of dollars a year.
Susan Bell, a distinguished university professor at USF, first learned of the large-scale death of seagrass beds in Florida in 1987 when she received a call from a longtime fishing friend who noticed the disappearance of seagrass beds and large quantities of dead seagrass. Bell informed his colleagues at FWC, who began to detail what was going on in an approximately 15 square mile stretch of the bay.
For more than 10 years, researchers have seen little or no change in seagrass beds, especially in eelgrass levels. However, after another decade of monitoring, researchers have reported a return to pre-death levels for turtles in the region. The study shows that the entire sequence of death, algal blooms and recovery took 17 to 23 years. The long duration of the study and the large area over which data was systematically collected were specific to seagrass recovery reports. Additionally, most studies of marine populations recovering from some kind of disturbance have been linked to human intervention, such as removing a source of pollution, but in this case recovery has not required any action. human activity.
“While the fact that this system recovered after the 80s death was fantastic, we really wanted to uncover the mechanisms that enabled recovery,” said Bell, faculty member in the Department of Integrative Biology at USF. . “What we are discussing are a number of characteristics that underlie the recovery of the seagrass beds: the system was remote, the seagrass remains that remained after death served as a catalyst for the repopulation and the presence of several species. of seagrass increases the chances of recovery. “
In the latter case, two opportunistic seagrass species were the first to increase in abundance after death and likely facilitated the return of the turtles.
Bell believes this study may serve as a framework for other regions experiencing seagrass dying, including once again in Florida Bay, which is still in the midst of the extinction that began in 2015. Their work is preventing that assessing ecosystem resilience could take decades to detect, requiring long-term studies. Researchers continue to study the changes in Florida Bay, but hope that with the right conditions the area can return to normal again.
“Today, this monitoring program provides some of our best information on the state of the system,” said Brad Furman, study co-author and researcher at FWC’s Fish and Wildlife Research Institute. “Studies like this allow us to set recovery expectations, which we did not have in the 1990s, which is extremely important as we watch the bay react to the latest deadly event.”