February 17, 2023 - Colors of the Coast of Florida

Colors off the Coast
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Jewel-toned waters created a bright halo around much of Florida on
February 14, 2023, when the Moderate Resolution Imaging
Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a
true-color image of the region.

Most of the radiant blues and greens can be seen floating in the Gulf
of Mexico off of Florida’s western coast, part of a swatch stretching
from Apalachicola on the Florida Panhandle to Florida Bay. Florida Bay
sits between the Everglades and the Keys at the western tip of the
state. A band of slightly duller tones also colors the Atlantic Ocean
between Jacksonville (north) and Fort Pierce (south). Bright peacock
blue in the southeast section of the image surrounds the Bahamas.

While the color surrounding the Bahamas are a daily occurrence caused
by the shallowness of the underwater banks surrounding the islands, the
colors in the Gulf of Mexico and Atlantic are more unusual. They are
almost certainly primarily caused by sediment pouring off the land or
stirred up by waves over the relatively shallow water of the West
Florida Shelf after a strong mid- to upper-level cyclone passed over
the state on February 12. Sediment appears tan as it floats at the
surface of water, but changes color as it sinks, first to green and
then to blue.

Phytoplankton, microscopic plant-like organisms, are also likely
contributing a little color. These algae-like organisms live in the
waters in this location year-round, and when conditions are favorable
can reproduce explosively to cause large, colorful, blooms that are
easily seen from space. Sediment carries nutrients, which creates a
favorable environment for phytoplankton growth.

One notable type of phytoplankton is an organism called Karenia brevis,
which is the cause of “red tide”. As it grows and spreads, K. brevis
can release a toxin, or rather a cocktail of toxins, called
“brevotoxins”. At very low levels, the organism is harmless, but in
high concentrations a bloom of red tide can be deadly, especially to
fish, dolphin, sea turtles, and manatees. It can cause respiratory and
immune problems in people, and when people eat shellfish that have
consumed K. brevis, it can make people quite sick. Red tide has been
reported along parts of the West Coast of Florida during much of
February. According to the Florida Fish and Wildlife Conservation
Commission, during the past week K. brevis was detected in 135 samples
from and offshore of Southwest Florida and one from Northwest Florida.
High levels (greater than 100,000 cells per liter of water) were
detected in 58 samples from Southwest Florida, including Manatee
County, Sarasota County, Charlotte County, and offshore of Lee County.

Image Facts
Satellite: Terra
Date Acquired: 2/14/2023
Resolutions: 1km (721.3 KB), 500m (1.8 MB), 250m (3.8 MB)
Bands Used: 1,4,3
Image Credit: MODIS Land Rapid Response Team, NASA GSFC



https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2023-02-17

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