SARASOTA — Tropical Storm Debby had significant impacts on the region’s beaches, dragging sand off in many places and piling it up in others, scientists with Mote Marine Laboratory announced Thursday.
That impact took its toll on sea turtles.
The storm moved north through the Gulf of Mexico of Southwest Florida’s coast Aug. 3-4, around the time it strengthened from a tropical storm into a Category 1 hurricane.
Before the storm, Mote’s Sea Turtle Patrol found 4,353 nests along Sarasota County beaches with 2,958 still active.
Nearly 4 out of 5 of those nets “were impacted to varying degrees,” with about 40% being washed out, scientists said in a news release.
“The storm’s powerful waves and high tides led to the overwash and washout of many of the still active nests,” the news release said.
August totals saw 1,131 active nests remaining on the beaches.
Jake Lasala, a Mote staff scientist and the program manager for its Sea Turtle Conservation & Research Program, said the combination of storm surge and tidal influence impacted nests.
“Debby was expected to bring 3-5 (feet) of storm surge and, coupled with the new moon, tidal influence would be higher. Each storm is different, but the data from NOAA suggested a significant impact for the beaches in the region, regardless of storm severity,” Lasala said in a news release.
Both erosion and accretion can make it more difficult for hatchlings to escape from their nests. Mote is hopeful data from the nests will help them understand storm impacts on incubation conditions.
Not all is despairing for the sea turtles, especially with their evolutionary adaptations for survival, according to Senior Biologist and Conservation Manager of Mote’s Sea Turtle Conservation & Research Program Melissa Macksey.
And the Coastal Wildlife Club in Englewood reported the emergence of hatchlings from a rare leatherback sea turtle nest following the storm.
“Tropical Storm Debby is a reminder of the ongoing need to understand and protect these remarkable creatures as they continue to adapt to their ever-changing environment,” Macksey said.
WATER QUALITY
Scientists for Mote Marine Lab also set out to see if Tropical Storm Debby’s path through the Gulf of Mexico had any long-term ramifications for the region’s ecosystems like Sarasota Bay.
With the help of volunteers, they found impacts on water quality and sea turtle nesting.
Traditionally, Mote has conducted comprehensive water sampling throughout Sarasota Bay through the National Environmental Laboratory Accreditation Program.
As a result, it was able to implement rapid response water quality sampling to assess Tropical Storm Debby’s impact on the bay’s delicate ecosystem, the news release said.
Turbidity and water color were found to be elevated in the bay.
“Elevated true color indicates an increase in substances such as dissolved organic matter in water, while elevated turbidity indicates increased particulate matter in the water — both of which were likely caused by massive amounts of stormwater resulting from the intense rainfall of TS Debby in the Sarasota Bay watershed,” the news release said.
Elevated turbidity and true color can reduce sunlight penetration, also known as light attenuation, in Sarasota Bay. This can cause problems for photosynthesizing organisms in the water like seagrasses.
Scientists also recorded a significant spike of nitrate and ammonia in Sarasota Bay.
“High that normal nitrate and ammonia concentrations may lead to increased bacteria and algal blooms that can make the water murky and potentially lead to low oxygen concentrations in specific locations,” the news release said.
If such blooms are composed of toxin-producing species, they may harm marine life, human and pets who come in contact with the water, according the study.
Samples also indicated a drop in dissolved oxygen levels in certain areas of the bay.
“When oxygen levels are as low as some Mote water samples indicate, it can stress or even kill marine life, which could lead to fish die-offs and other ecological impacts.”
Emily Hall, Manager of Mote’s Ocean Acidification and Chemical and Physical Ecology Research Programs, said that storms like Debby can have a “profound” impact on coastal environments.
“These preliminary findings suggest that the storm has had a significant impact on water quality in Sarasota Bay,” Hall said in a news release. “We are particularly concerned about the high nutrient and low dissolved oxygen concentrations, which could have serious implications for marine life in the affected areas.”
During the weeks following Tropical Storm Debby, Mote’s Beach Conditions Reporting System observations reported a slight increase in dead fish spotted on beaches.
Prior to Debby, six sites in Sarasota County reported dead fish, whereas after Debby, 31 sites in Sarasota County reported dead fish.
They have since returned to normal, according to the news release.
“Long-term water quality analyses will be vital for elucidating the storm’s full impact and guiding any necessary mitigation efforts,” the news release said.
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