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Water Quality Report: Pig frogs still AWOL from Sanibel Island

A recent survey of frogs and toads identified by their grunts, ribbits, and trills discovered the pig frog is the only one of nine species still missing after Hurricane Ian lashed the island in September 2022
Sanibel-Captiva Conservation Foundation
A recent survey of frogs and toads identified by their grunts, ribbits, and trills discovered the pig frog is the only one of nine species still missing after Hurricane Ian lashed the island in September 2022.


It’s official: The pig frogs are still missing from Sanibel Island and foul play is all but confirmed. Hurricane Ian is the only suspect.

The Sanibel-Captiva Conservation Foundation’s first frog survey of 2024 was held in early June in conjunction with a rainstorm – a great time to listen for frogs calling out for each other, which is also how they are counted – and the ribbits heard were encouraging in terms of species that have bounced back since Hurricane Ian.

But no pig frog. Better known as Southwest Florida’s famed bullfrog, it’s the champion grunter of all frogs. The noise it makes is between a pig and an alligator bellowing for a mate. And pig frogs rarely grunt alone.

Pig Frogs courtesy Audubon Florida
Hear pig frogs

Late last year, biologists first mentioned pig frogs disappeared from the island at the same time Hurricane Ian blew through, but hopes were that the creature would have made its way back to the Sanibel River on the island by now.

Given their almost scary bellowing for a mate common this time of year, there is no doubt the SCCF researchers involved in the frog survey would have heard the amphibians if any remained on the island.

Healthy frogs equals healthy water

Just like a canary in a coal mine can quite quickly let people in the vicinity know if the air is turning toxic, frogs and toads have adapted incredible ways to indicate whether water quality and overall environmental health are in balance or in danger.

At the same time, from tadpoles to the days after they die, frogs contribute positively to the environmental health of the ecosystem in which they live. The animal helps control harmful algae blooms, is a natural pest control service, and recycles nutrients.

Tadpoles feed on the disgusting stuff which there is no need to mention. Considering their numbers, that helps in no small way to keep down nutrient levels that can lead to blue-green algae, brown tides, and diatom blooms.

Frogs consume insects and larvae harmful to water quality — and humans — such as disease-carrying mosquitoes that breed in stagnant water.

Then the creatures recycle nutrients in the opposite way they did as tadpoles by being a provider. You know what I mean.

When frogs die and their bodies decompose they contribute nutrients into the water that aquatic plants find perfect for their growth. The plants produce oxygen and provide habitat for other creatures, completing the amphibians' circle of life.

Frogs have super-sensitive skin that allows them to detect environmental changes, particularly in water quality.

If at any point along the way, frog numbers dwindle or deformities increase it's a sign of an out-of-balance environment.

The pig frogs were in a perfectly fine ecosystem, just doing their thing, when Hurricane Ian lashed the island in late September 2022.

And then they were gone.

Counting frog by ribbit

The SCCF’s Mike Mills and Nadine Cobb went out after sunset to visit monitoring stations throughout the island and were met with a cacophony of toad and frog noises that was music to their ears.

The chart shows how many times researchers heard eight of the nine species of frogs and toads identified in early June during a survey; only one is still missing — the pig frog that the scientists had hoped they would hear signaling the amphibian's return to the island after Hurricane Ian
The chart shows eight of the nine species of frogs and toads researchers identified in early June during a survey; only one is still missing — the pig frog researchers had hoped they would hear signaling the amphibian's return to the island since Hurricane Ian

“After a very dry and hot late dry season in April and May, many wildlife species, particularly frogs, reacted explosively to the heavy downpour,” Mills said. “Sanibel erupted with the sounds of calling frogs, as puddles and other temporary wetlands filled with water.”

Some frogs really do emit a noise that sounds like a "ribbit," such as the Pacific tree frog's high-pitched, repetitive call.

The male American bullfrog in search of a mate is known for its deep, resonant call that sounds as if the creature might be saying "jug-o-rum."

The green treefrog emits a musical trill as it varies in frequency and duration. The spring peeper makes noises that sound like a "whistle" or, unsurprisingly, a "peep."

Toads and frogs share the same biological classification in the order Anura but have differences that separate them at the species level.

Toads tend to have drier, warty skin and prefer living on dry land. Frogs typically have smooth, moist skin and are more likely to be found in or near water.

Pig frogs may still be missing, but other species like the rare squirrel tree frog are working to ensure the next generation

Three tree frogs – the green one, the Cuban one, and the rare squirrel one – were heard from as well as three toads, the native southern, the exotic cane, and the eastern narrow-mouthed.

The southern leopard frog and the small exotic greenhouse frog also made enough noise to be detected throughout the island.

“Frog species will call out of season from time to time with extreme weather conditions such as a large rain after a long period of drought,” Mills said. “Or unseasonably hot weather during the winter.”

Return of the pig frog

This is not the first time in Sanibel’s 6000-year history that a hurricane's storm surge submerged the island and caused the demise of the pig frog.

Time and again pig frogs made their way back to Sanibel, perhaps on floating mats of vegetation, which is how many species colonized the island.

Like last year, the lack of pig frogs during this year's count is notable, but the SCCF researchers do not think it will be any more permanent than all the other times the pig frog population was wiped from the island.

“As the summer rains increase with frequency,” Mills said, “we expect that we will hear the familiar call of the pig frog again.”


Florida Fish and Wildlife Conservation Commission found through testing the red tide organism, Karenia brevis, at background concentrations in one sample collected offshore of Southwest Florida over the past week. The agency will continue to watch for more significant concentrations of K. brevis using satellite imagery nearshore and offshore.

The one sample that found background concentrations was offshore of Sarasota

No reports of fish kills suspected to be related to red tide were received over the past week.

Respiratory irritation was not reported in Florida over the past week.

The Clinic for the Rehabilitation of Wildlife on Sanibel Island reported no more animals died of red tide this week after two birds died several weeks ago.


The Florida Department of Health continues to find the components of blue-green algae near the Davis and Alva boat ramps.

The Lee County Environmental Lab reported the same, as well as blue-green algae filaments, were moderately abundant upstream of the Franklin Locks as streaks with accumulation along the lock.

Satellite imagery from Lake Okeechobee showed the presence of an algal bloom, but cloud cover and wind prevented the area from being estimated. On June 8, the bloom covered 300 square miles, or 65 percent, of the surface of the lake.

 The agency reminds residents that winds and tides tend to push the components of blue-green algae around, so people in that region should be watchful for the potentially toxic bloom.

What is red tide?

Red tide is one type of harmful algal bloom caused by high concentrations of the toxic dinoflagellate K. brevis, which is a type of microscopic algae found in the Gulf of Mexico.

Red tide typically forms naturally offshore, commonly in late summer or early fall, and is carried into coastal waters by winds and currents. Once inshore, these opportunistic organisms can use nearshore nutrient sources to fuel their growth.

Blooms typically last into winter or spring, but in some cases, can endure for more than one year.

Is red tide harmful?

K. brevis produces potent neurotoxins that can be harmful to the health of both wildlife and people. Wind and wave action can break open K. brevis cells and release toxins into the air. This is why you should monitor conditions and stay away from beaches where red tide is in bloom.

People in coastal areas can experience varying degrees of eye, nose and throat irritation during a red tide bloom. Some individuals with chronic respiratory conditions like asthma or chronic lung disease might experience more severe symptoms.

Red tide toxins can also affect the central nervous system of fish and other marine life, which can lead to fish kills.

What causes red tide?

A red tide bloom develops naturally, but recent studies have discovered mankind's infusion of other nutrients into the mix can make the red tide last longer or get stronger. But biology (the organisms), chemistry (natural or man-made nutrients for growth) and physics (concentrating and transport mechanisms) interact to produce the algal bloom. No one factor causes the development of a red tide bloom.

What is blue-green algae?

Blue-green algae, also known as cyanobacteria, are a group of organisms that can live in freshwater, saltwater or brackish water.

Large concentrations, called blooms, can change the water color to blue, green, brown, orange or red. Some cyanobacterial blooms can look like foam, scum, or mats on the surface of freshwater lakes and ponds. As algae in a cyanobacterial bloom die, the water may smell like something with a naturally unpleasant odor has now started to rot, too.

Is blue-green algae harmful?

Different types of blue-green algal bloom species can look different and have different impacts. However, regardless of species, many types of blue-green algae can produce toxins that can make you or your pets sick if swallowed or possibly cause skin and eye irritation.

The FDEP advises staying out of water where algae is visibly present as specks or mats or where water is discolored. Pets or livestock should not come into contact with algal bloom-impacted water or with algal bloom material or fish on the shoreline. If they do, wash the animals right away.

What causes blue-green algae?

Blue-green algae blooms occur when the algae that are typically present grow in numbers more than normal. Within a few days, a bloom can cause clear water to become cloudy.

Winds tend to push the floating blooms to the shore where they become more noticeable. Cyanobacterial blooms can form in warm, slow-moving waters that are rich in nutrients. Blooms can occur at any time, but most often occur in late summer or early fall.

If any major type of water quality alert is issued, you can find the details here in WGCU’s Water Quality Report.

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