Red tide’s deadly toll

Red Tide warning sign at Bonita Beach, Florida

Red tide’s deadly toll

For nearly a year, the Southwest Florida coastline has been transformed into a marine graveyard with tons of fish, turtles, manatees, and dolphins all perishing from the toxic bloom.
For nearly a year, the Southwest Florida coastline has been transformed into a marine graveyard with tons of fish, turtles, manatees, and dolphins all perishing from the toxic bloom.
UM News

CORAL GABLES, Fla.– The unusually long red tide event that has devastated Florida’s west coast for more than 10 months is taking an incredible toll on the state’s marine life. Hundreds of thousands of fish, hundreds of manatees, sea turtles and dolphins, and even a 21-foot whale shark are among the casualties, many of them washing up dead on Florida beaches.

Jill Richardson, program director and senior lecturer in the Department of Marine Ecosystems and Society at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, answers questions posed by News@TheU on how red tide in the Gulf of Mexico is impacting marine life.

How big of an impact will the harmful algal blooms have on marine life?

The impacts of red tide events can be devastating. In fact, this event was deemed an Unusual Mortality Event, or UME, just recently. Under the Marine Mammal Protection Act, a UME is defined as “a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response.” This declaration implicates a certain level of urgency and establishes the formation of a multidisciplinary working group of scientists who work with various stranding groups to develop a strategic investigation plan. It also provides access to additional funding, which is critical to a timely and thorough response. Since these events are typically associated with a large number of animal mortalities, particularly when compared to historical data, the impacts can be broad and quite devastating. Additionally, when you consider the cumulative effects of multiple UMEs on a single species or stock, the future starts to look very bleak.

View Special Reports and Features

Testing algal blooms
Taming a toxic stew

Research being conducted by UM scientists could lead to a better understanding of harmful algal blooms fouling Florida’s southwestern coast.

Aerial view of a hurricane
Are powerful storms causing exceptional red tide events?
A connection seems to exist, but a Rosenstiel School scientist says more research is needed to make a conclusive determination.

Rotting fish dot the shoreline at Bonita Beach, Florida

What’s the impact on endangered species?

Just in the Florida Panhandle region, more than 500 dolphins died during four Unusual Mortality Events between 1999 and 2006, and red tide was responsible for those deaths, and these are just the UMEs related to harmful algal blooms. At some point, certain populations, especially those that are endangered such as the North Atlantic right whale, may not be able to “keep up” with the loss and eventually go extinct or “functionally extinct.” What’s scary is that these things are happening during our lifetimes, and there are likely to be many species on this planet our children and grandchildren will never have the privilege to witness.

Could these die-offs have an effect on the health of our oceans?

Marine mammals are considered “sentinels of the sea” and are thought to provide important clues about the health of our ocean ecosystems. So when large numbers of marine mammals start dying, it’s a sign that ocean health is declining. These dolphin are sentinels of the health of Florida’s coastal ecosystems, with some clear implications regarding the public health impacts of harmful algal blooms. Acute exposure likely causes a very painful death, characterized by hemorrhaging and neurologic dysfunction. Chronic exposure to biotoxins is also believed to compromise the marine mammal immune system, making them more susceptible to other diseases.

Can anything be done to save marine life facing exposure to red tide?

We need to keep our water clean, and more research is needed regarding what causes these algal blooms. I think there is some consensus that warm temperatures and eutrophication play a role in the blooms, which will only be exacerbated as our planet warms and coastal development continues. I think it’s important to raise awareness and start productive conversations about what can be done to preserve these increasingly degraded coastal ecosystems. Marine mammals are getting caught in the onslaught of environmental change, and they are trying to tell us something. Now it’s our job to ensure their lives are honored by rethinking how we utilize and interact with the ocean before it’s too late.