COAST's interdisciplinary team focuses on gathering the scientific data needed to provide management recommendations for our threatened coastal and marine ecosystems.

Marathon Wastewater
Underwater Transect Imagery at Crane Point Hammock, Marathon Florida: August 5, 2021

Seawater sampling in nearshore waters at Crane Point Hammock has revealed sucralose concentrations over 200 ng/L, indicating a human wastewater impact. There is concern that partially-treated wastewater from shallow injection wells located at a nearby wastewater treatment facility could be the source of this sucralose.

To further examine the sampling site, COAST’s Executive Director Brian Lapointe recorded video imagery along a ~ 75 meter benthic transect taken from offshore to the onshore mangrove fringe on August 5, 2021.

Still images from the video transect provided additional evidence that a buoyant groundwater plume from the shallow injection well is discharging along this coastline, resulting in contamination with nutrients and other wastewater pollutants. The first image at the offshore end of the transect (Fig. A) showed turtle grass (Thalassia testudinum) blades with heavy epiphyte loads, characteristic of nutrient-impacted waters. Moving closer to shore along the transect blooms of fine, filamentous red macroalgae and calcified green macroalgae (Halimeda sp., Penicillus sp.) became abundant, providing additional evidence of nutrient enrichment (Fig. B). Thick blooms of filamentous red macroalgae and calcified green macroalgae continued along the transect (Fig. C, D, and E); the macroalgae included scattered mounds of the green seaweed Avrainvillea nigricans f. spongiosa, a form of macroalgae associated with nutrient-rich habitats in the interior of mangrove lakes. Within 10 meters of shore, the benthos changed markedly to a thick brown, organic-rich detritus (Fig. F, G) and the water became turbid and discolored with a greyish tint (Fig. H). Little, if any, seagrass or macroalgae were present in this inshore zone and the surface water was noticeably cooler than the water on the bottom. These observations suggest a buoyant plume from submarine discharge of cooler groundwaters along the mangrove fringe at Crane Point Hammock.


COAST's commitment to preserving Florida’s water quality extends back more than four decades. Over this time, Executive Director and Principal Investigator Dr. Brian Lapointe has dedicated much of his research to identifying the pollution sources that drive harmful algal blooms and ecosystem decline throughout Florida and the wider Caribbean region. His research findings have guided planning decisions throughout the region and have transformed stormwater, waste, and wastewater infrastructure to reduce the impacts of nutrient pollution.

Focus on Science

COAST does not make political statements. While our research is often quoted by people on both sides of controversial issues, our allegiance is to science. COAST's reputation and ethics will not be compromised by making political statements. In an era when politics often interferes with solving environmental problems, our role is to provide an impartial voice that advocates for sound science. The answer to our problems is found in looking at evidence -- cause and effect -- to uncover what nature is telling us. As a result of this stance, community leaders and decision-makers often seek our input to make crucial water quality improvements.