Hurricane Dorian Mandahl Drone Flight
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~ August 29, 2019
The eye of Hurricane Dorian passed over St. Thomas on August 28, 2019 as a Category 1 storm. The following day, ClimateChangeVI.org launched drone flights over the Mandahl Bay Eco-system to evaluate any immediate impact the storm may have had on wildlife.
Post-storm flights are intended help answer the question: “Where does lagoon life go when severe storms strike”?
The series consists of four videos.
The most notable finding is what appears to be a visible concentration of life in the east and north east region of the lagoon compared to a significant absence in the bay, channel and swimming hole.
The impact to geography, wildlife and fauna appears upon immediate inspection appears to be similar to an average thunder storm with one exception: The incredible clarity of the water in the bay, channel and swimming hole/salt pond.
There is absolutely no evidence of storm surge, wave action or watershed run-off!
An overflight of the beach showed a line of dried sargassum that had been washed onto the sand in prior weeks. The dead sargassum sediment layer did not change in position, size, density or range. This indicates that there were no above-average waves acting upon the Mandahl beachline.
Further evidence of minimal water action is presented in the back lagoon where live sargassum remains entangled with mangrove roots and a lack of disturbance to shallow area algae and aquatic plants.
Animal life, it seems, retreated into the protective canopy of mangroove roots ringing the back lagoon. These early morning flights revealed a post-storm life exodus from this sheltered region. At least seven spotted eagle rays can be seen. Three sea turtles are also swimming out from the refuge. The ripples of dozens of schools of fry and sprat are visible. Tarpons are observed surfacing to breathe and there are numerous hunting circles of white mullets .
The morning-after bird count turns out to be quite normal for this time of year with no indication that any extraordinary precautions were taken by birds to avoid the storm.
LONG-TERM IMPACTS
Even though Hurricane Dorian has had a mild visual effect on the region, day after imagery cannot conclude that certain effects or changes will not present in the future.
Wind burn on leaves and tree limbs, for instance, sometimes appears days, weeks or months after an event.
Wildlife that seems healthy today, can become ill or die from storm-induced stress, injury, infection or dietary change.
As accumulated water on the hillsides continues to run-off, human waste and pollutants could still play a ‘storm effects’ role in changing wildlife response and outcomes throughout the next few weeks.
Each new drone mission adds a new layer of comparative imagery showing the evolution of the bay.
By close mapping of the area over time, we hope to be able to predict future impacts as we engage with the government’s mandate for mitigation, preservation and restoration of Mandahl Bay while protecting its indigenous use.
Aerial Videography Consultant
Vince Danet – Danet Operations Group
Vince provides Rangers with training, supervision and aerial drones during their Mandahl APC/APR aerial wildlife observation missions. He also conducts quarterly Eco-system survey flights of the region for ClimateChangeVI.org
