Thousands of acres of seagrass lost in Lemon Bay and Charlotte Harbor

By Phyllis Wojcik, Charlotte County Environmental Caucus, June 14, 2021

Betty Staugler, National Oceanic and Atmospheric Administration (NOAA) Harmful Algae Bloom liaison, Florida Sea Grant University of Florida and Nicole Iadevaia, Coastal & Heartland National Estuary Partnership (CHNEP) presented “Seagrass Trends in Charlotte Harbor: Current Findings and Ongoing Efforts” to the Charlotte County Commissioners at their meeting on June 8, 2021.

Seagrass beds are identified as critical habitat by federal, state, and local agencies, benefiting the marine ecosystem by providing food, habitat, and nursery for 70% of species of seafood harvested recreationally and commercially. Seagrass beds play a dual role as indicators of clean water as well as cleaning the water by reducing nutrients, nitrogen, and phosphorus. Excess nutrients favor bottom algal growth which smothers seagrass, and microscopic algal growth which decreases light penetration vitally needed for seagrass growth.

The economic value of natural resources was discussed with the primary economic driver being tourism, particularly charter boat fishing. From 2018 to 2020, Lemon Bay lost 12% of its seagrass habitat or approximately 347 acres.  From 2018 to 2020, Charlotte Harbor lost 23% of the seagrass habitat or approximately 4,615 acres.

The commissioners requested some actionable items. One reason for the loss is the overflow of nitrogen and phosphorus washing into the water from the increasing number of people who live along the waterfront, Staugler and Iadevaia said. The nutrients are no longer filtered by wetlands following the replacement of marshes with canals, the building of canal-side sea walls, continuing presence of private septic systems and fertilizer use. Because of the economic and environmental significance of seagrass habitat, many Florida agencies conduct regular monitoring.

Betty Staugler had started a Citizen Science program “Eyes on Seagrass” in 2019. Members of the Charlotte County Environmental Caucus began participating in monitoring seagrass this spring and summer. Interested individuals can participate by first going through a training led by CHNEP. Sign up for this training at https://www.chnep.org/monthly-volunteer-events  to be held at 10 AM on June 19th at Punta Gorda City Hall, 326 W. Marion Ave, Punta Gorda, FL 33950.

The Charlotte County Environmental Caucus monitoring group collected data at 3 locations on the west wall of Charlotte Harbor, snorkeling in the warm waters. When conducting the seagrass monitoring at each site, a 50 meter transect line was set out and a quadrat was used as a guide to collect the data at 10-meter increments. The steps in monitoring included latitude & longitude, water conditions, tide, wave action, depth, sediment type, percent of total macroalgae, percent seagrass, density of epibiota (organisms living on plant surface), identifying the various species of seagrass found, blade height. Collections of sediment and macroalgae were made and sent to the University of Florida lab for further studies.

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