ocean algae blooms

What Can Algae Blooms in the Ocean Teach Us About Climate Change?

Read Time: 4 minutes

The ocean and our climate are intricately connected. The largest bodies of water on the planet absorb the majority of the sun’s radiation and act as carbon dioxide sinks. The oceans also contribute heavily to weather, creating rainfall and storms on land. However, as the oceans get warmer, they collect more heat and distribute the warmth around the globe. This can increase climate change, although it does also help prevent as many hot spots from accumulating. Oceans are home to a vast array of plants and animals, many of which we have yet to discover. Algae, also called phytoplankton, are an essential part of the marine ecosystem and the annual algae blooms tell us more about our climate than you’d think.

What Is an Algae Bloom?

An algae bloom occurs when the conditions are right for phytoplankton to reproduce rapidly. You may have seen small examples in a pool or pond, where the water suddenly turns greenish. In more modest bodies, this is often harmful since the algae eat up most of the oxygen, which can suffocate marine animals. Some algae blooms, however, can be beneficial.

The blooms that happen every year are vital to many species. Phytoplankton and zooplankton form the base of the marine food chain, and practically every animal in the oceans depends on them for survival. Some of the largest marine animals eat only zooplankton, which has to eat phytoplankton to live.

This means that the existence of phytoplankton, and the yearly algae blooms the ocean experiences, are a vital part of helping the oceans exist as we know them. If any part of that process were to cease, the oceans themselves would begin to starve. The only animals that could survive such a dramatic change would be those animals that dwell in the abyss.

The Good and the Bad

The sudden burst of algae that occurs in the North Atlantic is large enough to be seen from space. It’s an incredible event, but one we know shockingly little about. Phytoplankton are just like plants on land. They use CO2 and excrete oxygen, which can be great for sucking some additional CO2 out of the air.

This might lead to confusion. If phytoplankton gives off oxygen during photosynthesis, why do algae blooms represent a danger to marine life? The answer isn’t in the algae’s growth, but in its death. The decay process uses oxygen, and a sudden die-off of algae can deplete oxygen so much that other marine life can suffocate. Some kinds of algae also produce neurotoxins when they die, further damaging marine life. These types of blooms, and others that are known to produce biotoxins, are called harmful algal blooms (HAB).

Climate Change and HABs

Algal blooms are one other thing that is being affected climate change. There was a great deal of suspicion that warming ocean waters would lead to an increase in algal blooms, but it wasn’t until recently that researchers were able to prove this on an oceanic level.

The study, which was published in Nature, demonstrated that algal blooms aren’t just becoming more frequent, but that harmful blooms are the ones that seem to be flourishing. This is unfortunate, because it puts additional stressors on marine life at a time when they could really use a break.

Since they affect the very basis of the food chain, any changes in phytoplankton can quickly work their way up the rest of the food chain. Some of these blooms are helpful and can bring in larger marine life from all over the ocean for feeding. In order to be beneficial, though, the blooms have to walk a careful tightrope. Too few algae can mean a bloom might not occur and can damage the food chain, while too much algae, especially if it’s the wrong kind, can have the same outcome.

The two species the study examined are harmful to people, and can potentially poison shellfish. While the findings are cause for concern, the way this novel information was gathered was a breakthrough. Scientists have struggled for years to understand blooms, and now they finally have the chance to do so.

How the Algae Blooms Are Studied

Right now, scientists are learning some amazing new things about the blooms. Before, they had to depend on satellites to study them. The problem was that they couldn’t see anything during cloud cover, which meant there was practically no way to study the waters for consecutive days. By changing to deep-sea robots that can gather information regardless of weather, they can suddenly learn much more.

These robots float beneath the waves, so they’re mostly safe from storms. These machines, called biogeochemical profiling floats or BGFs, spends days about a mile below the surface, in sleep mode. Every few days, they will wake up and rise to the surface, collecting data along the way, before dropping down and going back to bed.

The way these floats works allows them to operate for longer time periods, and they can be configured with different sensors that let them gather information based on what the team is trying to learn. When researching algae, scientists are looking at factors like ocean temperatures, nutrient levels, acidity and oxygen content. They’ve learned that algae are growing almost all the time, even during the winter, and that the more it grows during the low periods, the more explosive the bloom is during the spring. This is a crucial factor that might help predict algae blooms in the future.

For being so close to home, we know surprisingly little about the oceans and the tiniest flora and fauna that live there. Hopefully, by learning more about them, we can begin to make better predictions about how they will change and, as a result, how they will change us.

Category: Environment

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Article by: Megan Ray Nichols

Megan Ray Nichols is a freelance science writer and science enthusiast. Her favorite subjects include astronomy and the environment. She encourages discussions in these fields. Megan is also a regular contributor to Datafloq, The Energy Collective, and David Renke's World of Space. When she isn't writing, Megan loves watching movies, hiking and stargazing.Love what you're reading on Schooled By Science? Don't forget to subscribe today.