Phytoplankton: An Invisible Army Saving the Planet

When we talk about protecting the Earth, we think of forests, greening cities, and reducing emissions. But there is a hero we almost never remember, though he does most of the work for us. He is invisible to the eye, he lives in the oceans, and his population is counted in billions in every drop of water. This is phytoplankton. Without him, there would be no life on land, no familiar climate, and even no air we breathe. He produces from 50 to 80% of all oxygen on the planet. He absorbs carbon dioxide like a giant filter. And he is threatened because we don't notice how we are destroying his environment.

Who are these invisible beings

Phytoplankton are microscopic algae and cyanobacteria that inhabit the upper, illuminated layer of the ocean. They drift with currents, cannot actively swim, but their role in the ecosystem is colossal. Like plants on land, they use sunlight, carbon dioxide, and mineral substances for photosynthesis. In the process, they release oxygen and create organic matter that is the basis for the entire marine food chain — from zooplankton to whales.

These organisms are incredibly diverse: from single-celled diatoms to colonial forms that can be seen with the naked eye as a green film on the water surface. Their size ranges from a micron to several millimeters, but their total biomass is comparable to that of all terrestrial plants. They are the foundation of oceanic life and one of the main regulators of the climate.

The planet's oxygen shield

We often hear the phrase “the lungs of the planet” in relation to the Amazon rainforest or the Siberian taiga. But in fact, the main lungs of the Earth are the ocean. It is phytoplankton that provides most of this breathing. Scientists have calculated that every second breath you take is due to these microscopic organisms. They not only produce oxygen but also absorb carbon dioxide that we emit into the atmosphere by burning fossil fuels.

The mechanism is called the “biological pump”. Phytoplankton takes carbon from the atmosphere and converts it into organic compounds. Part of this carbon, when the algae die, sinks to the bottom of the ocean and remains there for millennia. In this way, the ocean sequesters an enormous amount of carbon, mitigating the consequences of global warming. If phytoplankton suddenly disappeared, the concentration of CO₂ in the atmosphere would increase so much that the climate would become completely different — and most likely, unsuitable for life in its current form.

Threats to phytoplankton: from warming to pollution

The irony of fate is that the same carbon dioxide that phytoplankton absorbs is one of the main threats to its existence. The rise in ocean temperature causes the stratification of water masses: warmer water, less dense, remains on the surface and does not mix with the deeper water, rich in nutrients. And phytoplankton needs not only light and CO₂ but also minerals — nitrates, phosphates, iron. Without them, it cannot reproduce. Therefore, warming has led to a decrease in phytoplankton productivity in some regions by 10–20% over the past few decades.

In addition, the acidification of the ocean caused by the absorption of CO₂ threatens species with calcareous shells, such as coccolithophores and pteropods. Their shells simply do not form in acidic water. This destroys the entire food chain. And pollution by microplastics and chemicals is also not harmless: toxins accumulate in the cells of phytoplankton, passing on further up the chain to fish, marine birds, and whales.

Protecting phytoplankton — protecting ourselves

What can we do? First, reduce CO₂ emissions, switch to renewable energy sources. Second, reduce plastic and chemical waste pollution in the ocean. Third, create marine protected areas where industrial activity is limited. Fourth, support scientific research that will help understand how phytoplankton responds to changes and how we can help it adapt.

This is a challenging task, but it is achievable. Every decision we make — from choosing transportation to our attitude towards waste — affects the ocean, and thus phytoplankton. Protecting this invisible army is not an abstract ecological slogan. It is a question of our own survival. As long as phytoplankton lives, we live. And we should remember this every time we look at the sea.
© elib.pk

Permanent link to this publication: