Coastal red tide and inland (freshwater) blue-green algae have killed large numbers of fish and blighted beaches with tainted waters along both the Atlantic and Gulf coasts of South Florida for many years. This problem has escalated in recent years and cannot be solved in the short term, but some remediation is possible using a range of approaches. Nutrient-filtering wetlands are already being restored and more are needed. Construction of a large storage reservoir for Lake Okeechobee has been proposed with $1.6 billion in funding expected to be approved this year by the US Congress. There is a large amount of muck in the bottom of the shallow waters of Lake Okeechobee, which contains a tremendous amount of nutrients. These semi-fluid, fine-grained, organic-rich sediments can easily be dredged and have been shown in other areas of Florida to contain Cd, Cu, Cr, Ni, Pb, Zn and Co below critical levels for agricultural usage, thus they could potentially be used as fertilizer. This would reduce the nutrient feed to the blue-green algae that have slimed canals and bays in Southeast Florida and significantly reduced beach water quality. While red tide blooms on the Florida Southwest coast dates back to the 1500s, its persistence is believed to be related to excessive nutrients, including those from the influx of the freshwater algal slime. Clay has long been used by several Asian countries to help control harmful algal blooms. In early efforts, the clay was sprayed from boats on top of a red tide, causing it to sink to the ocean bottom and die. Studies on impacts of the ensuing sediments on benthic organisms led to the development of modified clays that are being used currently in China, Korea and Chile. Coincidentally, there are several large phosphate mines in the Tampa area with clay being a byproduct. It is suggested that this clay could be modified as has been undertaken by the Institute of Oceanology, Chinese Academy of Sciences to control harmful algal blooms (HABs) in Southwest Florida.

Remediation of harmful algal blooms in South Florida

2019 Spring National Meeting

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