Plankton, the tiny organisms thriving along the coastlines, are the unsung heroes of most ecosystems – a wide range of marine lives, from scallops to whales, live on green planktons.
But what if this only life-sustainer of the ocean’s bounty of animals is in peril and killed off, the whole ecosystem is thrown off balance, and the entire marine life is on the verge of extinction?
Unfortunately, these are today’s bitter realities that make these creatures with massive roles in the ocean face intensifying pressure to keep surviving.
Why are plankton important, and how the loss of these organisms can pose a threat to ocean life? Let’s unpack.
What Are Plankton?
The word ‘plankton‘ originates from the Greek word ‘Planktos,’ meaning drifter. They are a community of more than 11,000 microscopic species found in the water (both fresh and salty) that are nonmotile, cannot propel themselves against the tidal force, and thus, stay in a drifting condition. The individual living organisms that comprise of plankton are termed plankterse.
Most plankton are unicellular microorganisms of around 1-inch length. However, you will find multicellular plankton with a larger physical extent, for instance, jellyfish and crustaceans. Plankton size can vary from 0.002mm (even smaller than human RBCs/red blood cells!) to around 20cm.
Types of Plankton
Plankton can be categorized based on various criteria – size, time of wandering in the water, etc. But in general, they can be divided into two categories:
- Phytoplankton
- Zooplankton
Let’s dive deeper into these two classes of plankton.
Phytoplankton
Phytoplankton are autotrophic elements of plankton that can drift by the thousands in each drop of water in the top 100 meters of the ocean. They are single-celled, keep themselves suspended in the fresh/salty water, and photosynthesize using chlorophyll to convert light energy into chemical energy. Some most common types of phytoplankton are – diatoms, green algae, cyanobacteria, coccolithophores, dinoflagellates, etc.
How much phytoplankton would grow on the water surface is a variant of multiple factors – the amount of carbon dioxide they inhale, the nutrient concentration of the sea surface, pH and salinity of seawater, and most significantly, the availability of sunlight that can infiltrate and promote photosynthesis.
Like plants on land, these tiny seagrasses require soil nutrients, for instance, calcium, nitrogen, a small amount of iron, etc., to grow optimally. Some phytoplankton species can even contribute to nitrogen fixation and reproduce in low-nitrogen water bodies.
When the sea condition is optimal, their population explodes, leading to phytoplankton blooms.
Types of phytoplankton:
- protists – developed eukaryotes or single-celled algae
- photosynthetic bacteria
Zooplankton
Zooplankton are the macroscopic/microscopic community of plankton consisting of aquatic mites, rotifers, insect larvae living on the topwater layer, crustaceans, etc.
While living on phytoplankton and free-floating algae, they act as primary consumers, and when they feed on other inferior zooplankton, they are secondary consumers.
While most zooplankton like krill, copepods, and arrow worms float on the water surface for their entire lifecycle, zooplankton like crabs spend only a portion of their life as plankton.
Why are Plankton Important
Plankton Form the Ocean Food Web
Phytoplankton are the biggest contributor to the ocean food chain and one of the substantial food sources of aquatic organisms – from microscopic zooplankton to multi-ton whales, almost every marine life feasts on phytoplankton. They also turn sea nutrients into organic matters that are fed up through the entire aquatic food web. Invertebrates and some fishes also feed on planktons that, in turn, are consumed by larger animals like whales. It is the biggest migration on Globe contributed by a chain of animals and can even be tracked from space. The consequence is that without plankton, these lives in the sea would encounter massive starvation.
However, the massive bloom of toxic red dinoflagellates produce life-threatening biotoxins resulting in the death of hundreds of marine lives.
Role in Carbon Cycle
Phytoplankton, while producing food through photosynthesis, take up carbon dioxide from the atmosphere, and move it into the deep sea layers as organic compounds as they demise and sink. As the oceans act as a massive active sink of holding and trapping GHGs, the role of phytoplankton in the carbon cycle and in reducing GHG emissions is beyond mention. Now, scientists plan to increase iron concentration in specific water layers to boost plankton bloom and trap more C02 in the seawater.
Source of Oxygen
Plankton reduce 50% of atmospheric Carbon dioxide produced by anthropogenic human activities, like using conventional carbon-based fuels, unplanned farming, depleting forests, etc. Plus, with 71% of the Globe covered with water, the oxygen produced by these green plankton as one of the three byproducts of their photosynthesis process comprises around 70% of the total oxygen required.
What is Killing Plankton?
Plankton contribute to maintaining ecological balance and providing food for the lives on the earth, including humans, yet our inhuman activities have put these life-saving creatures into extinction!
Studies reveal that since 1950, around 40% of plankton have already been extinct.
But what’s killing plankton? Let’s look into:
- While the impact of recent abrupt climate changes on the life cycle of plankton is still under research, researchers consider it a cause of the catastrophic reduction in the plankton numbers. Some phytoplankton can reproduce better in cooler water. And as the sea temperature rises at a breakneck pace, phytoplankton are declining – they require the high nutrient concentrated deep seawater to get intermixed with surface water in places where optimal sunlight is available to boost growth. But as the topwater layer gets hotter, it fails to meld with lower-layer waters, and in turn, phytoplankton don’t get enough nutrients.
- The pH of the world’s seawater has dropped from 8.24 to 8.04 in the last 82 years, and it is predicted to reach 7.95 in the coming two decades. The result would be the initiation of a massive trophic cascade destabilization in the ocean ecosystem, leading most carbonate-based (coccolithophores) plankton to death. Consequently, all primary and secondary consumers, including zooplankton, fishes, invertebrates, and marine mammals feeding on plankton, will be on the verge of extinction within the first 3-years of a trophic cascade.
- It’s not new that seawater is constantly getting polluted with plastics – synthetic/semi-synthetic polymers that take up to 20 to 500 years to decompose based on the material! What’s alarming is that researchers find that small fishes and zooplankton consume this chemical-based toxic material. Further, plastics dumped into the oceans block sunlight from penetrating the water layers. They thus hinder phytoplankton from photosynthesizing and oxygenating the seawater. It contributes to the death of plankton resulting in deoxygenation and suffocation of the sea.
How to Save Plankton?
Let’s go through the simple yet effective steps you can take to save plankton:
- Limiting the consumption of animal-based products can significantly reduce your carbon footprint, and it will help you contribute to maintaining ecological balance.
- Use organic-based products and pesticides as much as possible in fields – the lesser the chemical toxins get into the seawater, the better it is for plankton.
- Cutting the use of synthetic products and plastic and switching to bio-based plastics can bring a huge difference in saving aquatic organisms.
- Poke Yoke in Manufacturing: Preventing Errors at Their Source - February 6, 2026
- Integrated Payment Systems: Fueling Scientific Advancement Through Efficient Funding - January 12, 2026
- Professional Distribution Center Cleaning Services Explained - December 13, 2025