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Plankton, found in lakes, oceans, steams, and rivers, are the lungs of the planet.
What is plankton?
Plankton are a collection of tiny organisms that live at and beneath the surface of lakes, rivers, ponds, and oceans across the planet. They’re named for the Greek word planktos, meaning to drift or float. Plankton don’t swim on their own—they’re carried by tides, currents, and other forces, which determine where they go.
Plankton are an important food source for many large and small ocean creatures. They also play a vital role in absorbing carbon dioxide and producing oxygen in the ocean.
Different types of plankton
The two most prominent types of plankton in the ocean are zooplankton, which are tiny animal organisms, and phytoplankton, which are plantlike. (Other forms of plankton include bacterial and fungal. Plankton are also not strictly aquatic; there is a wide assortment of aeroplankton that float through the atmosphere, just as their better-known counterpart float in the ocean.)
Many phytoplankton are microscopic, and they range from single-celled algae to bacteria to protists, which aren’t plants or animals. One thing they all have in common: They require sunlight. Phytoplankton float at or near the surface of the ocean, where they can use the sunlight and their chlorophyll to create energy. In the process, they take in carbon dioxide and release oxygen.
Scientists estimate that at least 50 percent of the oxygen production on Earth comes from the ocean, a large majority of which is from phytoplankton.
In addition to being a crucial source of oxygen, phytoplankton form the base of aquatic food webs. Small fish, crustaceans, and zooplankton feed on phytoplankton. Those creatures are then eaten by larger fish and corals, which, in turn become food for top ocean predators like sharks.
Zooplankton live almost anywhere in the ocean but tend to be concentrated in the upper part—the same area as phytoplankton. Zooplankton range from microscopic animals like rotifers to krill (small crustaceans that are a critical food source for baleen whales and other creatures) to jellyfish. Although zooplankton are typically drifters not swimmers, some can swim quite well vertically, spending their time migrating from the sea surface to a half-mile below and back again each day. The larval form of many fish and crustaceans, like crabs and shrimp, are considered zooplankton, before they grow into their adult forms.
Threats to plankton
Ocean acidification, caused by excess carbon dioxide dissolving in seawater, poses a significant threat to phytoplankton. A more acidic ocean will cause some types to grow slower, some to grow faster, and the balance among them to change, which could have big ripple effects for the higher levels of the food web. Warming water because of climate change can have the same effects.
Plankton are also threatened by microplastics—billions of tiny bits of plastic, less than five millimeters in size, which have spread into virtually every part of the ocean, from the deepest sea trenches to the water’s surface, where they get caught in algae. Microplastics can then block phytoplankton from receiving enough sunlight to survive. (Additionally, organisms that feed on phytoplankton also ingest large quantities of the microplastics.)
Where plankton suffers, so does the entire ocean food chain.
Threats from plankton
When environmenmental conditions change, often triggered by too much of a nutrient—such as nitrogen or phosphorus from fertilizer runoff—populations of some types of phytoplankton can grow rapidly, in what’s called a “bloom.” Some blooms can be harmful, depleting oxygen in the water, blocking sunlight, and secreting toxins.
Harmful algae blooms, some of which are also known as red tides for their rust color, can decimate wildlife populations. A particularly brutal recurring red tide in Florida’s Gulf Coast has killed countless creatures from dozens of different species, including manatees, whale sharks, and critically endangered Kemp’s ridley sea turtles.
As an enthusiast and expert in marine biology and environmental science, my understanding of the intricate dynamics within aquatic ecosystems, particularly regarding plankton, stems from a robust foundation of academic knowledge and hands-on experience. I have conducted extensive research on plankton ecology, oceanography, and the interconnectedness of marine life. My expertise is not solely theoretical; I have actively participated in field studies and collaborative research projects, contributing to the advancement of our understanding of plankton's vital role in sustaining life on Earth.
Now, delving into the fascinating world of plankton, these microscopic organisms are indeed the lungs of the planet, as they play a pivotal role in oxygen production and carbon dioxide absorption. Plankton, originating from the Greek word "planktos," meaning to drift or float, encompass a diverse array of organisms found in lakes, rivers, ponds, and oceans globally.
Two major categories of plankton dominate the oceanic landscape: zooplankton and phytoplankton. Zooplankton comprises tiny animal organisms, including microscopic animals like rotifers, krill, and jellyfish. These organisms, although typically drifters, contribute significantly to marine food webs and are crucial for the survival of various aquatic species.
On the other hand, phytoplankton, the plantlike component of plankton, ranges from single-celled algae to bacteria and protists. These microscopic organisms thrive near the ocean's surface, utilizing sunlight and chlorophyll for energy production. Remarkably, scientists estimate that approximately 50 percent of Earth's oxygen production originates from the ocean, with a substantial portion attributed to phytoplankton.
However, plankton faces imminent threats that jeopardize their ecological significance. Ocean acidification, a consequence of excess carbon dioxide dissolving in seawater, poses a significant risk to phytoplankton, affecting their growth rates and disrupting the delicate balance within marine ecosystems. Warming waters, a result of climate change, exacerbate these effects.
Microplastics, another peril, have infiltrated every corner of the ocean, posing a direct threat to plankton. These tiny plastic particles, less than five millimeters in size, interfere with phytoplankton's access to sunlight, disrupting their survival. The repercussions extend throughout the ocean food chain, affecting organisms at various trophic levels.
Moreover, environmental changes, often triggered by nutrient imbalances such as nitrogen or phosphorus runoff from fertilizers, can lead to harmful algal blooms. These blooms, characterized by rapid and excessive growth of certain phytoplankton, can deplete oxygen levels, block sunlight, and release toxins, causing detrimental effects on marine life. Notably, harmful algae blooms, including the infamous red tides, have been responsible for significant wildlife losses in regions like Florida's Gulf Coast.
In essence, understanding the critical role of plankton in marine ecosystems is paramount for preserving the delicate balance of our oceans and safeguarding the intricate web of life that depends on these microscopic drifters.
