Red Tides in Costa Rica: Are They Increasing, and Are They Dangerous?
“I found a beach that’s not so long from my place with no red tide,” a foreigner living in Guanacaste posted on Facebook in January 2022. “Do we know when the red tide will end?,” asked someone else. Two months on, and many more expats are still concerned about the “mareas rojas” they’re seeing in beaches close to home.
The first thing we should say about red tides, in Costa Rica or anywhere else, is that their cycles usually vary. There’s no “red tide season,” so it’s not easy to determine when there will be one and where, much less when they will end. This is a natural phenomenon that comes in different forms and shapes, but natural nevertheless.
Although they can be dangerous to animals and humans, there’s no reason to be alarmed unless authorities send alerts about red tides in specific places. Common sense will likely keep you away from a sea that has a red tide, because if you swim near them you might experience allergies, rashes or eye irritation, among other symptoms.
The most dangerous thing about red tides for humans lies in what they do to mollusks we eat, such as mussels, clams, oysters, or mangrove cockles. In fact, Costa Rican authorities issued a preventive sanitary measure in December 2021, still in force, that bans the extraction and sale of mollusks in some Pacific shores because of red tides.
At the same time, the Caribbean coasts have been experiencing the massive arrival of sargassum, an algae that makes it to the beach thanks to strong currents. The Center for Research in Marine Sciences (Cimar) has explained that, similar to other Caribbean countries, this might have impacted marine ecosystems and led to economic losses.
We reached out to the National Animal Health Service (Senasa), one of the institutions in charge of monitoring red tides, and they explained that this is a natural phenomenon, that it can last for weeks or months, that there are many different types of “mareas rojas,” and that there are protocols in place for how to act when they appear.
What are red tides?
Red tides are sometimes the result of certain ocean currents. Other times, they are caused by human activity, and it is expected that climate change, which will increase temperatures of ocean water, could lead to a higher concurrence of red tides. Senasa recommends people to get used to see them, and act accordingly.
The University of Costa Rica (UCR), which has a research center that monitors and studies this phenomenon, explains that “red tides are a proliferation of aquatic microalgae that can be seen with the naked eye as a stain in the sea, with a different color than normal.” These tiny organisms can only be seen through a microscope.
These types of algae are part of phytoplankton, which feeds most marine species and is referred to as “the main food of the sea” by the UCR. Among the animals that eat them are, precisely, mollusks. Their proliferation is affected by climatic factors such as wind, rain and temperature, according to the University’s researchers.
Why is the water red?
Climatic conditions make some microalgae adapt and displace other organisms in water. This is why they have the ability to form agglomerations in a marine area, as explained by Maribelle Vargas, from the UCR’s Microscopic Structures Research Center (Ciemic). “When this happens, we are in the presence of an algal bloom or red tide.”
The toxin they release when they do this is red, hence the tide turning red. Coralina Sheridan, marine ecologist and researcher at the UCR, says that the red tide “is very common in the northern parts of the Pacific, especially in the dry season.” Sadly, there is no publicly-available database of the concurrence of red tides in Costa Rica.
This scientist argues that “it is a cause for alarm that the red tide stays for a long time,” because the conditions it needs to thrive (like lack of oxygen or high temperatures) certainly don’t make life easier for anyone in the ecosystem. If those conditions are kept, damage to ecosystems is inescapable.
Should I swim when there’s a red tide?
Scientists consulted for this article and others cited in already published materials regarding this phenomenon in Costa Rica agree that red tides are not often problematic. However, it is not recommended to swim on a beach that has a red tide, because the toxins some algae release might have negative effects on people.
For example, those toxins could cause dermatitis if a person is allergic to them, or they can make for a sticky water that affects wounds, or they can even release toxins into the air that cause headaches for some people who breathe near them. This is not the case with every red tide, but out of prevention it’s better to stay away and be safe.
Let’s take, for example, the Ministry of Health’s recommendations in the presence of red tides in the Pacific in December 2018. Minister Daniel Salas said back then that, even though they still hadn’t detected toxins in mollusks, it was better for people to not get in water that was red, as it could hurt their eyes, skin or even respiratory tract.
Red tides and climate change
According to the Washington Post, in 2018 researchers at the University of Florida and the University of North Carolina said that “climate change will severely affect our ability to control blooms, and in some cases could make it near impossible.” Scientists at the US Environmental Protection Agency say this has to do with rising ocean temperatures.
“Scientists have found, in particular, that the kinds of algae and bacteria that can produce toxins or cause disease proliferate greatly compared to other less harmful species when there is an increase in water temperature, even above levels typically seen in mid-summer in Florida,” a paper from the University of Florida confirms.
“We can predict, therefore, that with a warmer ocean, the abundance of microorganisms will increase. It may be the case that the harmful species will grow at a faster rate than other species. (…) if the ocean waters around Florida become warmer, it is reasonable to expect more frequent problems with the harmful microorganisms mentioned above.”
This increase in red tides would be additional to the red tides that have naturally ocurred since forever. It is unknown at the moment if the red tide concurrence that some Costa Rican coasts have been experiencing as of late has to do with climate change and rising sea temperatures or are just part of a natural cycle.
Friends. We all love playas del coco And many of us come to live in enjoy the beach. Red Tide is a big concern these days. Yes red tide is both naturally occurring and from interference by human pollution. It’s important for everyone to understand what’s happening to our beautiful beaches. I’ve compiled some information to help people be more aware. Action should be taken by the authorities in the area. Please read the article and comment below. May we all be blessed again with beautiful crystal clear waters
RED TIDE IS BOTH A NATURAL OCCURRENCE AND INTERFERENCE FROM HUMAN POLLUTION
Red tides aren’t just the scourge of beachgoers; they’re also deadly to marine life like fish, birds and even manatees. And they can have a serious impact on human health, too.
A red tide occurs when the population of certain kinds of algae known as dinoflagellates explodes, creating what’s called an “algal bloom.” Scientists sometimes refer to red tides as harmful algal blooms or HABs.
When millions of these microscopic algae reproduce and cluster in one area of the ocean, they can change the color of the water, according to the Centers for Disease Control and Prevention. A rusty shade of red is often seen, though the color may range from pink or orange to brown or yellow.
There are three types of algae associated with red tides. In the Gulf of Mexico, Karenia brevia is especially prevalent along the west coast of Florida and the Texas shore.
Farther north, Alexandrium fundyense is found on the Atlantic coastline from New England into Canada, while Alexandrium catenella is common throughout the Pacific, from Mexico to Alaska, and along the coasts of Australia and Japan.
A number of factors can cause an algal bloom to grow. Low salinity, a high nutrient content in the water and warmer-than-usual surface water temperatures are usually cited as contributing to a red tide’s formation.
What are 2 factors that affect salinity?
Factors affecting the salinity in the ocean water are: Evaporation, Precipitation, and Fresh water (water from sewers) mixing with ocean water, ground water and glaciers increase the percentage of salt content in the ocean.
What causes high nutrient levels in water?
Nutrients, such as nitrogen and phosphorus, occur naturally, but most of the nutrients in our waterways come from human activities and sources—fertilizers, wastewater, automobile exhaust, animal waste.
The algae linked to red tides contain a toxin that affects the nervous and digestive systems of animals. Red tides are usually accompanied by a massive die-off of fish, as well as the birds and other animals that feed on fish.
Even larger animals that feed on fish, shellfish and other marine life can be killed if they consume enough of the toxin. A red tide in Florida this month has been blamed for a significant die-off of manatees, while another red tide in 2012 may have caused a large number of squid deaths in California.
Humans are also vulnerable to the toxic effects of a red tide. Wave action can release the algae’s toxins into the air, causing respiratory problems among people near the shoreline, particularly those with asthma, emphysema or other respiratory illnesses.
Because the toxins can accumulate in shellfish, red tides often cause outbreaks of parasitic shellfish poisoning (PSP) and amnesic shellfish poisoning (ASP). Both illnesses affect the nervous systems; ASP can cause dizziness and disorientation, and in extreme cases, PSP can cause respiratory paralysis, resulting in death by asphyxiation.
Red tides occur worldwide, and some reports indicate their occurrence is on the rise, according to the National Oceanic and Atmospheric Administration (NOAA). The phenomenon now takes place almost every summer along Florida’s Gulf Coast, for example, and global warming may be contributing to the increase.
Researchers at NOAA used computer models to determine how warming ocean temperatures might change the timing and frequency of the algal blooms associated with red tides.
“We found that, not only will the risk for toxic blooms increase within the present-day bloom season, which is typically between July and October, but the bloom season itself will also expand,” Stephanie Moore of NOAA’s West Coast Center for Oceans and Human Health, told National Geographic(opens in new tab).
Email Marc Lallanilla or follow him @MarcLallanilla. Follow LiveScience on Twitter @livescience. We’re also on Facebook & Google+. Original article on LiveScience.com.
What are 2 factors that affect salinity?
Factors affecting the salinity in the ocean water are: Evaporation, Precipitation, and Fresh water mixing with ocean water, ground water and glaciers increase the percentage of salt content in the ocean.
What causes high nutrient levels in water?
Nutrients, such as nitrogen and phosphorus, occur naturally, but most of the nutrients in our waterways come from human activities and sources—fertilizers, wastewater, automobile exhaust, animal waste.
As South Florida cities wait to see whether red tide has invaded their waters, Gov. Rick Scott and state officials attempted to diminish any potential human responsibility for the enormous bloom that has devastated Gulf coast marine life, referring to it as “naturally occurring.”
The toxic algae that drove away swimmers — coughing and sneezing — and littered west coast beaches with dead fish made a rare appearance on Florida’s southeast coast this week, leading to beach closures in some areas.
After forming in the Gulf of Mexico, red tide can reach the Atlantic coast by riding the Gulf’s Loop current, which threads the Florida Straits and forms the Gulf Stream, the current that skims the Atlantic coast. Palm Beach County, where it was first detected, is at higher risk because that’s where the Gulf Stream passes cloest to land.
Miami-Dade County sampled water at four beaches Tuesday and expects to have the results Thursday. Deerfield Beach took water samples and expects results Wednesday.
Although Palm Beach County had planned to reopen beaches Wednesday, the county announced Tuesday evening that beaches would remain closed “in an abundance of caution” from Kruesler Park in Lake Worth north to the Martin County line.
“Lifeguards and staff at these locations are reporting continued irritation,” the county said in a news release.
A forecast from the National Oceanic and Atmospheric Administration predicts red tide conditions in the medium range through Friday in Palm Beach County, which could affect those with chronic respiratory issues and cause mild symptoms in others.
A news release issued Tuesday by the governor’s office, announcing the steps he was taking to combat the problem, refers to red tide as “naturally occurring” no less than seven times. The phrase also appears in the first sentence of the Florida Fish and Wildlife Conservation Commission’s announcement that red tide had been detected in Palm Beach County. The governor used the phrase again Tuesday in a debate with U.S. Sen. Bill Nelson, whom he is challenging.
Deerfield Beach resident Leon Smith rides his beach cruiser Tuesday wearing a construction dust mask. (Joe Cavaretta/South Florida Sun Sentinel)
But while red tide itself is natural, scientists say there’s evidence that massive blooms may be partly caused by human activities, such as fertilizers washing off farms and the discharge of fertilizer-laden water from Lake Okeechobee into the Gulf of Mexico.
“The occurrence of red tide, you could argue, is natural,” said Larry Brand, professor of marine biology and an expert on red tide at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science. “But the abundance of it now is the result of human activities, basically nutrient runoff from land.”
Although a minor red tide bloom had existed on the Gulf coast for 10 months, he said, it grew enormously after the Army Corps of Engineers released nutrient-rich water from Lake Okeechobee to the Gulf through the Caloosahatchee River.
“No one can argue the nutrients in Lake Okeechobee are natural,” Brand said. “That used be nice clear water, nice sandy bottom. Now it’s huge layers of nutrient-rich mud on the bottom. It’s a huge mess. Obviously the politicians don’t want to take any of the blame for this.”
Asked whether the state wildlife commission’s position was that human activities had nothing to do with red tides, spokeswoman Susan Neel responded by email, “Red tides were documented along Florida’s Gulf coast in the 1840s. Fish kills near Tampa Bay were even mentioned in the records of Spanish explorers.”
Scientists say there are potential sources of the nutrients that could fertilize red tide growth, some human-caused, others not. These include the Mississippi River, dust blown across the Atlantic from Sahara Desert and the upward movement of nutrient-rich water from the deep ocean.
Karl Havens, professor of fisheries and aquatic sciences at the University of Florida and director of the Florida Sea Grant program, said there needs to be more research to definitely link fertilizers washing off land to heavy blooms of red tide. He suspects the most recent bloom started with Hurricane Irma, which deluged the west coast with rain.
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“This year a huge amount of nutrients flowed into the Gulf and coincided with a huge red tide,” he said. “Can I say the nutrient pollution definitely fueled the red tide? I can’t say. Does it make sense? Yes.”
Richard Stumpf, an oceanographer with the National Oceanic and Atmospheric Administration, blamed the bloom partly on the weakening of the seasonal winds that usually push algae blooms away, allowing one to remain near land and grow during the summer. During that time, it would have fed on nutrients from any source, saying there’s no single source and they use whatever’s available, whether it’s from agricultural runoff or any other source.
During their debate Tuesday, Nelson blamed Scott for the severity of the outbreak, saying it’s the result of reduced environmental oversight and funding under his administration.
“All of this, the result of putting more pollution in the water supply that goes into the lakes and streams and rivers,” Nelson said. “And as a result, you see the result. You put pollution in the water, it will grow the algae in the heat of summer.”
Scott claimed he’d increased environmental funding, particularly for Everglades restoration and attacked Nelson for failing to get federal funding to swiftly finish renovations to the dike around the lake, which would reduce the need for the harmful discharges to the ocean.
“I put up state dollars, and finally in the last year, I went to the President and went to Congress and have gotten the money,” he said. “And the dike will be finished by 2022.”
In the race to replace Scott, Democratic gubernatorial nominee Andrew Gillum took advantage of the issue, releasing a campaign commercial Tuesday featuring footage of dead fish and Florida’s landscape as he said, “The toxic air, red tide and algae blooms around Florida are an economic and environmental disaster. No corporate profit is worth sacrificing our clean air and water.”