As rising seas and worsening storm surges from hurricanes increasingly threaten shorelines around the bustling northern end of Biscayne Bay, a Miami city commissioner has made a proposal confusing: no new mangroves in city parks.
The ordinance sponsored by City Commissioner Joe Carollo would prohibit the planting of new mangroves or “tall-growing plants” to protect waterfront views.
When the ordinance was presented for first reading at the commission meeting on May 12, Carollo said he postponed it to give the city manager more time to consider it. Carollo, whose neighborhood runs along the Miami River from Southwest 2nd Avenue to Dolphin Expressway, did not respond to requests for interviews.
Since the 1970s, the bay near Miami has been designated an aquatic reserve in an effort to restore habitat, including mangroves, which are home to manatees, sea turtles, crocodiles and around 180 other rare and endangered species.
Despite the shields, conditions in the bay deteriorated. Seagrass beds have withered and disappeared and persistent algal blooms have spread. In 2019, the National Oceanic and Atmospheric Administration warned that the bay was undergoing a regime shift and risked losing its once-clear waters. In 2020, the greatest fish kill in recent memory littered the north end with floating carcasses.
Banning the planting of new mangroves in parks would not only thwart decades of restoration work, but remove an essential tool for making Miami more resilient to the impending impacts of rising seas, said Rachel Silverstein, executive director of Miami Waterkeeper.
“Mangroves actually protect the coastline. They reduce wave energy and protect us from storm surges. They work better than levees,” she said. “The City of Miami will be a national laughing stock if it goes ahead and bans mangroves in the world’s most vulnerable city to sea level rise.”
In response to questions, the Miami-Dade County Division of Environmental Resource Management said the proposal also contradicts efforts by the two governments to jointly develop resilience plans.
“This proposed change is inconsistent with many resilience efforts the County and City have worked hard together to achieve,” a statement read. “The placement of mangroves as part of a living coastline is extremely beneficial to both the Miami River and Biscayne Bay, providing many ecosystem services including shoreline stabilization, mitigating the effects of wind and sea waves. storm, providing essential habitat for many marine species and improving the water quality of the Bay.
The 40-mile-long bay was once lined with mangroves that weaved a protective net along the shore. The arching roots of the props helped stabilize the sandy banks and housed young snook, tarpon and other fish. But over the years, as Miami exploded, about 80 percent of the trees were replaced with levees north of the Rickenbacker Causeway.
Growing threats from rising seas, including worsening hurricane storm surges, have now put the hardy trees back in the spotlight. Not only do they repel and weaken waves, but dense forests can sequester carbon and trap mud that can help extend shorelines that disappear under rising waters.
Last year, Miami-Dade County rejected a U.S. Army Corps of Engineers plan that called for the construction of flood walls, asking instead to create a local plan that included more mangroves.
“They gave us a 30-foot high concrete wall in Biscayne Bay and it’s not going to work as well as the mangroves,” Silverstein said. “People really need to consider the urgency of the problem of sea level rise and storm surges and assess the options we have to deal with it. And mangroves are really one of our best defenses and they offer us multiple advantages.
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