A Red Tide of Death for Turtles

Since October, hundreds of dead and sickened sea turtles have been washing ashore on the beaches of Southwest Florida.

The cause? An annually occurring natural phenomenon known as Red Tide.

red tide california
A Red Tide near La Jolla, California.

What is Red Tide?

Red Tide is the result of excessive growth of the algae Karenia brevis. As the name suggests, it often turns the sea a rusty red colour.

So what is it that makes Red Tide so deadly? The red algae produces a chemical that is toxic to marine organisms. This can be fatal when the algae is present in great enough quantities.

This year has been worse than most for the seasonal algal bloom. Most blooms begin in the late fall and dissipate by April. Sadly, this Red Tide is still going strong well into the summer. It is suspected to remain a problem for several months to come.

CROW (Clinic for the Rehabilitation of Wildlife)
CROW (Clinic for the Rehabilitation of Wildlife), Florida

At-Risk Sea Turtles Dying

Two at-risk sea turtles are most affected by this Red Tide: Loggerhead and Kemp Ridley. Many of the turtles found on beaches have been adults — part of what makes this bloom so devastating to their conservation. Turtles can take between 25 to 30 years to reach maturity, and will lay thousands of eggs over decades. Only about one in 1,000 of these eggs will survive to adulthood. So the death of so many adults has the potential to stunt the recovery of these protected sea turtles for decades to come.

Red Tide isn’t the only type of algal bloom that poses a risk to wildlife. While you won’t see a Red Tide in freshwater, you may have observed scummy, foamy or discoloured water in a pond or lake near you. These unsightly features are also caused by algae blooms.

Freshwater algal bloom
Freshwater algae blooms may produce toxins, but can also lead to anoxia.

Freshwater Algal Blooms

Freshwater algae blooms may produce toxins, but can also lead to anoxia (a depletion of oxygen available in the water) when the algae dies and decomposes — killing fish. These blooms can also be harmful to humans, and can irritate the skin and eyes of swimmers or even make you sick.

Caused by Humans

There are some human-caused factors that may in part be responsible for the severity of this year’s Red Tide.

  1. Climate change has been increasing ocean temperatures worldwide, favouring algae growth.
  2. Nutrient pollution is largely the result of human activities, like farming, where fertilizers can contaminate nearby water through run-off. Nutrient pollution increases levels of nitrogen and phosphorus in the water, and provides algae with the food it needs to grow out of control.

Prevented by Humans

Luckily there are some things we can all do to help prevent nutrient pollution:

  • Avoid using fertilizers and pesticides on your lawn or garden.
  • If you have a septic system, ensure that it is properly maintained, so that leaking sewage doesn’t contaminate local bodies of water.
  • Use phosphate-free detergents, cleaning products and personal care products.
  • Build a shoreline buffer on your property using native vegetation to intercept contaminants.

Learn other ways you can help using CWF’s Love Your Lake Shoreline Property Resources. Or, learn more about our turtles at HelpTheTurtles.ca.

We’ve Got Turtle Eggs!

Turtles face many threats, including habitat loss, traffic mortality, and nest predation.

snapping turtle nesting on shoulder

Many predators, such as raccoons and skunks like nothing more than to feed on some freshly laid turtle eggs. While nest predation is a natural threat, in many areas nest predators occur at higher than normal levels and they can eat most of the turtle eggs laid every year. Protecting the eggs helps give turtles a fighting chance and offsets some of the road kill that occurs every year.

One way to protect a turtle nest is through a nest cage. While nest cages can be used to protect some nests in natural areas, those on roadsides cannot be caged, since cages may interfere with traffic and the work of road maintenance crews.


Download Nest Protector How-To

Unfortunately, gravel road shoulders make for attractive nesting locations for turtles. The loose gravel and sand make it easy for turtles to dig their nests, and sunny roadsides provide the necessary warmth the eggs need to hatch. Roadsides can be dangerous though, to both the nesting female, and the hatchlings that may end up on the road.

Excavating a nest
Excavating a nest

Another option is to collect the eggs once they have been laid and hatch them in captivity. That is what CWF is doing this year in the Ottawa area. Egg collection does require permits from the provincial government as incorrect incubation can cause the eggs to not develop or hatch.

Collecting turtle eggs is not as easy as it may sound. After a female turtle has laid her eggs, she packs the soil back into the hole and there is often no sign of the nest. The surest way to find a turtle nest is to find the female in the process of laying her eggs. This can involve a lot of searching in the evening, when most turtles are most apt to lay their eggs.

Great care has to be taken not to startle the turtle, or she may abandon her search for a nesting site until another evening. Once the female has finished nesting, we carefully dig up the nest and collect the eggs. After many long nights, the Turtle Team gathered more than 400 eggs from roadside nests!

Prepped eggs for the incubator
Prepped eggs for the incubator

The eggs are kept in a special reptile egg incubator that maintains a constant temperature. The incubator contains eggs from two species at risk: Blanding’s Turtles and Snapping Turtles.

Blanding’s Turtle eggs are oval, whereas Snapping Turtle eggs are round, like tiny ping-pong balls! Blanding’s Turtle clutches contain about a dozen eggs, whereas Snapping turtle nests contain 30-40 or more eggs. The eggs from each nest are placed in a separate container filled with damp vermiculite, an artificial potting soil mixture.

For most kinds of turtles, the sex of the hatchlings depends on the temperature of the nest. Colder summers will generally produce more male turtle hatchlings, whereas hot weather will lead to more females hatching out. Our incubator is set to a temperature somewhere in the middle to produce a roughly equal mix of male and female hatchlings.

Field researchers after preparing the incubator bins
Field researchers after preparing the incubator bins

The first eggs of the year were collected in early June, and will hopefully start to hatch in early August. After the eggs hatch, the hatchlings from each nest will be released near the site of their nest and close to water.

Road mortality and habitat destruction are some of the greatest threats facing turtles today. Protecting nests through caging and off-site incubation is an important step we can take to help preserve turtle populations.

Learn other ways how you can HelpTheTurtles.ca.