As sea rise and worsening storm surges from hurricanes increasingly threaten the shores around Biscayne Bay’s busy north end, a Miami city commissioner has made a puzzling proposal: no new mangroves at city parks.
The ordinance sponsored by City Commissioner Joe Carollo would prohibit planting any new mangroves or “tall-growing plants” to protect waterfront views.
When the ordinance came up for first reading at the commission’s May 12 meeting, Carollo said he’d postponed it to give the city manager more time to look at it. Carollo, whose district runs along the Miami River from Southwest 2nd Avenue to the Dolphin Expressway, did not respond to requests for interviews.
Since the 1970s, the bay near Miami has been designated as an aquatic preserve in an effort to restore the habitat, including mangroves, that help shelter manatees, sea turtles, crocs and about 180 other rare and threatened species.
Despite protections, conditions in the bay have spiraled downward. Seagrass meadows have wilted and vanished and persistent algae blooms have spread. In 2019, the National Oceanic and Atmospheric Administration warned the bay was undergoing a regime shiftand in danger of losing its famously once gin-clear waters. In 2020, the largest fish kill in recent memory littered the north end with floating carcasses.
Putting a ban on planting new mangroves at parks would not only counter decades of restoration work, but would remove a critical tool for making Miami more resilient to looming impacts from sea rise, said Miami Waterkeeper Executive Director Rachel Silverstein.
“Mangroves actually protect the shoreline. They reduce wave energy, and they protect us from storm surge. They work better than seawalls,” she said. “The city of Miami will be a national laughing stock if they go ahead and ban mangroves in the most vulnerable city in the world to sea-level rise.”
In response to questions, Miami-Dade County’s Division of Environmental Resources Management said the proposal also contradicts the two government's efforts to jointly develop resiliency plans.
“This proposed change is not consistent with many of the resiliency efforts the County and City have been working hard together to achieve,” a statement said. “The placement of mangroves as part of a living shoreline is extremely beneficial to both the Miami River and Biscayne Bay, providing many ecosystem services including shoreline stabilization, mitigating the effects of wind and storm surge, providing essential habitat for many marine species and enhancing the water quality of the Bay.
The 40-mile-long bay was once lined with mangroves that wove a protective net along the shore. Arching prop roots helped stabilize sandy banks and harbored young snook, tarpon and other fish. But over the years, as Miami boomed, about 80 percent of the trees were replaced with sea walls north of the Rickenbacker Causeway.
Increasing threats from sea rise, including worsening hurricane storm surges, have now put the sturdy trees back in the spotlight. Not only do they fend off and weaken waves, the dense forests can sequester carbon and trap mud that can help expand shores disappearing under rising waters.
Last year, Miami-Dade County rejected a U.S. Army Corps of Engineers plan that called for building flood walls, asking to instead create a local plan that included more mangroves.
“They gave us a 30-foot high concrete wall in Biscayne Bay and that will not work as well as mangroves,” Silverstein said. “People really need to look at the urgency of the sea level rise and storm surge issue and to evaluate the options that we have for dealing with it. And mangroves truly are one of our best defenses and they provide us with multiple benefits.”
