6 Things You Need to Know About Algal Blooms
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6 Things You Need to Know About Algal BloomsBy: Nina Phillips
Published: October 10, 2023
https://a-z-animals.com/blog/things-you-need-to-know-about-algal-blooms/
Algal blooms are growing into a bigger and bigger deal every year. You’ve probably heard about them at some point. They can slow down the seafood industry, as some areas grow unsafe to harvest from. If you have a dog, or pets, or enjoy swimming, you may get a warning about avoiding local lakes and bodies of water during outbreaks.
Despite most people having heard about algal blooms, many are unclear about exactly what they are, what causes them, and the dangers of the blooms. Keep reading below to learn important information about algal blooms.
1. It’s Not Always Algae
Despite the name, algal blooms aren’t always algae. Sometimes, an algal bloom can be caused by algae, but it’s just as likely to come from algae-like bacteria.
Both algae and bacteria are microorganisms, but there are some differences between them. For one, while they can both be found in all bodies of water, algae is limited to water while bacteria can be found anywhere.
The most common organisms to cause algal blooms are cyanobacteria, golden algae, dinoflagellates, and diatoms. If you live near the ocean, you may have also heard of terms such as red tide, brown tide, or even green tide.
Cyanobacteria
Cyanobacteria is most known for causing blue-green algal blooms, so-called due to the blue-green color they often create in and on top of the water. They may also be red or brown. These blooms are harmful to humans and animals, even if they don’t produce toxins. They also lead to a rotting plant smell as they start to die off. They are found most often in lakes.
Golden Algae
Golden algae originally was only found along the coasts. Over the last few decades, it has started creeping up into rivers and lakes and causing blooms. It does a lot of harm to fish or other animals with gills as it has toxins that directly affect the gills. These algal blooms haven’t yet been shown to harm humans or pets.
Red Tide
Red tides are most commonly caused by dinoflagellates that have a red pigment known as peridinin. Because of this red pigment, they will turn the body of water they inhabit red during a bloom. Several different species of bacteria and algae can cause this tide. They are commonly found along all coasts, including the east and west of the US, the Gulf of Mexico, and Florida’s coasts.
Green Tide
Green tides come about from algae or macroalgae. These are dangerous for wildlife because they out-compete local sea grass and coral reefs, which causes habitat loss. These blooms are found throughout the world.
Brown Tide
Brown tides are also caused by macroalgae. They are a non-motile species. These blooms occur around the northeast and mid-Atlantic estuaries in the US. Brown tides have been found to cause pretty serious damage to the habitats they bloom in.
2. Algal Blooms Are Caused by Warm Temperatures and Runoff
Algae and bacteria in water aren’t bad. Almost any body of water has both. The issue is when the levels become unhealthy. This is when algae and bacteria ‘bloom’. Essentially, the term algal bloom is used when algae or bacteria grow fast and create large colonies.
Natural Causes of Algal Blooms
Algal blooms occur naturally in any body of water. In oceans, upwelling can cause a change in the nutrients on the surface of the ocean. Upwelling is when water from the bottom of the ocean rises. It brings nutrients up with it. An upwelling often occur near the coast when temperatures in the ocean and air above the ocean are different. The rise of nutrients often feeds bacteria and algae enough to cause a big bloom.
Water temperature, turbidity, and water pH also play a huge role in algal blooms. Heat allows for more algal growth because water doesn’t mix as much when it’s warm. So algae can sit on the surface more and get plenty of light. It is also easier for algae to move around in than cool water.
Lower pH also increases algal blooms. Algae and bacteria need carbon dioxide to grow. Usually, if water is acidic, it’s a sign that there’s more carbon dioxide in the water.
Water turbidity is the term for how much stuff is in the water. The higher the turbidity, the more silt, nutrients, chemicals, algae, and gunk that are in the water. This usually means that there’s more for algae and bacteria to eat and makes the water the perfect incubator for algal blooms.
While these do occur naturally, the warming of the earth and hotter days do play a part in increasing the number of blooms that occur every year for the reasons above. For example, climate change is increasing the time when algal blooms are most common. While they used to occur mainly during the summer, it’s becoming more and more common to see them still occurring well into the winter.
Direct Man-Made Causes of Algal Blooms
There are more direct ways humans cause algal blooms as well. The biggest causes are from agricultural, sewer, and city run-off when it rains.
Agricultural pollution includes almost any by-product from farming practices. Manure from animals is full of nitrogen and phosphorus that cause huge algal blooms. The same goes for fertilizer used on plants. Insecticides, pesticides, and fungicides also lead to algal blooms.
Sewage from people is another main problem. If sewage overflows because of rain, or if there’s a leak in a pipe, the waste will leach into the ground, and eventually make its way down to the nearest body of water with rain.
Gas, oil, food trash, and grime from cities also get swept up every time it rains. The run-off from cities will also get into the water at some point. Eventually, the water will make its way to the ocean, or a lake.
These are the ones that cause the most issues because they provide constant pollution. Every time it rains, more and more run-off enters the water. Studies have found that humans cause 1.62 million tons of phosphorus into freshwater every year. That number doesn’t account for any other type of pollutant, nor does it cover how much phosphorus gets into brackish water or saltwater like estuaries and the ocean.
3. They Can Occur in Any Body of Water
As you might have guessed by now, algal blooms occur in any body of water. Because algae and bacteria thrive in fresh and salt water, it’s possible to find blooms occurring in estuaries, reservoirs, bays, lakes, rivers, oceans, ponds, and most other natural bodies of water.
Some bodies of water have slightly different forms of algal blooms, but since algae and bacteria are present in any body of water, they occur everywhere and in every body of water in the world.
4. Some Algal Blooms Are Harmful to People and Pets
While for the most part, algal blooms are safe for people and pets, some are incredibly dangerous. Currently, the estimations are that less than one percent of all algal blooms actually produce toxins. However, the number of algal blooms producing toxins is growing every year.
Furthermore, blue-green algal blooms, caused by cyanobacteria, are dangerous to people and animals even before toxins are released. The effects are less dangerous, but touching blue-green algal blooms, ingesting, or inhaling the spores can cause harm to people and animals.
During algal blooms, you also don’t want to eat any of the wildlife from the area. They carry toxins that can harm you even if the animal is fully cooked.
5. They Can Have Negative Effects on the Environment
Smaller algal blooms are part of the natural cycle of water. Microorganisms are the bottom tier on the food web for many bodies of water. This means that pretty much every animal in the ocean depends on them in some way.
Some animals eat microorganisms directly, while others eat the animals that eat microorganisms. Getting occasional bursts of this necessary part of the food web helps to increase growth in other animals.
However, frequent, and large algal blooms cause more harm than good. Just like the toxins from these blooms can hurt people and pets, they have the potential to hurt wildlife as well. If the blooms are big enough, they can be absorbed into drinking water to contaminate it. They may also cause acid rain.
Dead Zones
The most obvious issue is the harm to areas of oceans and lakes. When bacteria or algae start to die off in large numbers, they are eaten by other bacteria. The byproduct of these algal blooms being eaten removed large amounts of oxygen from the water.
In large enough numbers, these create dead zones. Animals in these areas have to leave or will die. This means that large areas of the ocean or lake will host no life until oxygen can enter the area again.
Some areas don’t get oxygen back. Currently, there are an estimated 166 dead zones throughout the world. These dead zones may get repeat algal blooms that keep eliminating the oxygen, or they may be too big and be in areas where there’s not enough of a current to bring in more oxygen.
It is possible to fix these dead zones, but only by eliminating the source of the constant algal blooms in the area.
6. You Can Report a Bloom if You See One
Algal blooms often appear in the form of thick scum on the surface of the water. It may be foamy or mat-like. It may also look like someone poured a bucket of paint into the water. Sometimes, the water may be a completely different color. Blue, green, red, and brown are the most common colors you’ll see.
If the algal bloom is toxic, it’s also possible to see animals washing up dead on the shore. If you see these signs, you can spread a warning by reporting the algal bloom. Whether you believe the algal bloom to be toxic or not, the EPA encourages anyone who sees signs of a bloom to report it so they can monitor it and take water samples to determine if the water is safe or not.
Each state has its own reporting system and program, so it’s a good idea to get familiar with your local reporting agency. You can also use their resources to keep track of where breakouts are occurring so you don’t risk harming yourself, your family, or your pets.
Summary of the Algal Bloom Information You Need to Know
List Number Summary of Information 1 Though called algal blooms, some are caused by bacteria. 2 Agricultural, city, and waste run-off and rising temperatures play a big role in the number of algal blooms in any given year. 3 No natural body of water is safe from algal blooms, so long as bacteria and algae can grow there. 4 In addition to hurting wildlife, some blooms can hurt people and their pets. 5 Algal blooms are sometimes helpful for the environment but are becoming increasingly more harmful. 6 If you see algal blooms, report to your local agency.