# Impacts of the 2023 Marine Heatwave in the Florida Keys: Detection and Analysis of a Mass Coral Bleaching Event Using Spaceborne Remote Sensing Imagery

## TL;DR

This study shows how satellite imagery can detect coral bleaching during a 2023 heatwave in the Florida Keys, supporting future monitoring efforts.

## Contribution

The study demonstrates the potential of Planet’s SuperDove satellite imagery to detect coral bleaching events.

## Key findings

- Bleached corals showed higher reflectance in SuperDove’s band 2 (492 nm) compared to healthy corals.
- SuperDove satellite imagery can detect signals of coral bleaching at Horseshoe Reef and Cheeca Rocks.
- Validation using multiple data sources confirmed the satellite’s ability to detect bleaching changes.

## Abstract

Coral reefs are facing several stressors, such as increases
in
sea surface temperature, eutrophication, and hurricanes, resulting
in reef-decline worldwide. In the Florida Keys, these stressors, especially
elevated temperatures, have triggered widespread coral bleaching as
well as a cascade of simultaneous negative impacts, such as increased
disease, accelerated reef erosion, and severe ecosystem degradation.
In the summer of 2023, the Florida Keys and the Caribbean experienced
a mass bleaching event due to a record-breaking marine heatwave with
ocean temperatures exceeding 38 °C. This study investigates whether
remote sensing using Planet’s SuperDove sensor could detect
this mass coral bleaching event at Horseshoe Reef and Cheeca Rocks
in the Florida Keys. We validated these data using several sources:
NOAA photomosaic data, NASA airborne fluid lensing from two campaigns
(before and during bleaching), and underwater orthomosaic data from
July 2023. We were able to detect a signal change using the SuperDove
sensor between healthy and bleached coral. Bleached corals have a
higher reflectance in SuperDove’s band 2 (492 nm) compared
to healthy coral. The results of this study supports the use of Planet’s
SuperDove satellite imagery for long-term monitoring of coral bleaching,
though confirmation with high-resolution refraction-free data are
still needed.