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Miami, mangroves and a living shoreline

By DEBORAH HAGGETT - Garden Club of Cape Coral | Jun 3, 2022

A current debate in Miami has me revisiting my previous article about mangroves published in the Cape Coral Breeze on June 26, 2020. This debate is a response to a confluence of recent events: frequent flooding in the Miami area, decreased water quality in Biscayne Bay, a proposal by the Army Corps of Engineers to build 30-foot-high concrete walls in the Bay (rejected by Miami-Dade County) and a proposed ordinance within the Miami City Council to prohibit planting new mangroves within city parks as an effort to protect waterfront views.

The following excerpts from the June 2020 article provide a description of mangroves and some background about the use of mangroves as a strategy for shoreline stabilization, improved water quality and habitat restoration:

When it comes to protecting our shoreline during storms, we can thank the mighty mangroves. Florida is home to approximately 10 species of mangroves, of which three are most common. They are the red, black and white mangrove trees. Red mangroves are typically found along the coastline and are identified by their reddish, aerial root system which reaches deep into the water below. These arching roots give the red mangrove the appearance of walking in the water which has led to a colloquial name, the “Walking Tree.” It is the tallest of the three species growing anywhere from 20 to 75 feet.

The black mangrove is typically found in swamps and hammocks with heights 40 to 60 feet. They may also be found along the coastline with red mangroves. Interestingly, the leaves of the black mangrove secrete salt drawn from the marsh, which was harvested by early settlers.

The smallest of the three, the white mangrove can grow as a shrub or can range from 20 to 40 feet. It is found at higher elevations than the red or black mangrove and has peg roots or no visible aerial roots.

Not only do these mangrove varieties play a vital role in protecting our wetlands by filtering salt water, preventing erosion and providing a valuable habitat for shore and aquatic life, but a recent study found mangroves are a frontline defense to flooding and storm surge during hurricanes. It was estimated that during Hurricane Irma, over 500,000 Floridians were protected by mangroves and over $1.5 billion of losses were prevented. In Lee County alone, mangroves prevented $802 million in losses (Narayan, S., Thomas, C., Matthewman, J., Geselbracht, C. C., Nzerem, K., & Beck, M. W. (n.d.).

Given the value of mangroves, it is no wonder that the mangrove forests are protected by law. As homeowners we can help protect this essential resource by remembering there are legal ramifications for disrupting the vital mangrove ecosystem. Specifically, it is illegal to remove mangroves; however, there are exemptions related to pruning them depending on their location and size. For detailed legal requirements, please see floridadep.gov or hire a certified professional mangrove trimmer, PMT.

Understanding the benefits of mangroves as protectors of the shoreline as well as the wish for unobstructive views brings to light the question, “How do we construct a solution in which the best of both worlds is honored?” Marbelys Garriga, PhD candidate from FIU Institute of Environment, is studying quantifiable effects of manmade structures such as retaining walls and seawalls compared to natural structures such as mangrove and oyster forests.

She suggests a compromise: Maintain current legislation limiting the pruning of mangroves in endangered environments, while allowing trimming in areas where they are planted as “ecological engineering infrastructure” (Nicoletti, 2021). This compromise keeps the valuable root system intact allowing for a protected living shoreline while at the same time limiting the height of the trees and protecting coastal views. Rather than an either/or paradigm, thinking in terms of a both/and model suggests a solution where living shorelines “benefit precious water resources, protect wildlife, and help ensure humans can continue to live in coastal communities” (Garriga, cited in Nicoletti, 2021).

Deborah Haggett is a Lee County Master Gardener Volunteer and a member of the Garden Club of Cape Coral. Visit us at www.gardenclubofcapecoral.com

References

Narayan, S., Thomas, C., Matthewman, J., Geselbracht, C. C., Nzerem, K., & Beck, M. W. (n.d.). Valuing the Flood Risk Reduction Benefits of Florida’s Mangroves. The Nature Conservancy. Retrieved May 21, 2022, from http://www.conservationgateway.org/SiteAssets/Pages/floridamangroves/Mangrove_Report_digital_FINAL.pdf

Nicoletti, A. (2021, November 10). Ph.D. student fights for mangroves — not concrete seawalls — on Miami’s shorelines. FIU News. Retrieved May 21, 2022, from https://news.fiu.edu/2021/ph.d.-student-fights-for-mangroves-not-concrete-seawalls-on-miamis-shorelines

Staletovich, J. (2022, May 20). Mangroves help fight hurricanes. Now Miami wants to ban planting any more at city parks. WLRN. Retrieved May 21, 2022, from https://www.wlrn.org/news/2022-05-19/mangroves-help-fight-hurricanes-now-miami-wants-to-ban-planting-any-more-at-city-parks

Vinson, A. (2019, July 31). Mangroves – University of Florida, Institute of Food and Agricultural Sciences. UF/IFAS Gardening Solutions. Retrieved May 21, 2022, from https://gardeningsolutions.ifas.ufl.edu/plants/trees-and-shrubs/trees/mangroves.htmla

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