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The Very Bottom Of The Food Chain Is In Danger

Never underestimate the power of plankton

The Very Bottom Of The Food Chain Is In Danger

Plankton feeds everything from huge whales to other plankton, but this barely-visible foundation of much of our marine food systems might be at risk. As shifting weather patterns and global warming continues to escalate, now more than ever scientists are struggling to learn as much as they can about these tiny microorganisms.


The name for plankton comes from the Greek—meaning “wandering” or “free floating”—and it’s a blanket term used to describe several different types of oceanic microorganisms: there’s the plant-like phytoplankton, the animal-like zooplankton, bacterioplankton, as well as groups of certain viruses.

“Culturally, we’re indoctrinated to be impressed by large things and we kind of ignore the tiny things,” said Laura Faye Tenenbaum, a science writer for NASA and a former oceanography teacher for Glendale Community College. “I’ve always been inspired by delicate creatures.”

Mike Behrenfeld, a professor at Oregon State University who specializes in marine algae, studies the effect that the periodic ocean warming episodes that result in El Niños have on ocean currents—which influence plankton development and, in turn, everything we eat.

“Changes in the amount of plankton have really big impacts on marine mammals and fisheries,” he says. “Those changes in the production of plankton at the bottom of the food web ripple all the way through to the larger animals, as well as humans.”

El Niños can affect fish distribution due to the shifting currents and changes in ocean temperature. This can harm local economies, as fisheries struggle to make up for losses of certain fish they traditionally rely on. Market squid like cooler water, for instance, so they go north during El Niños, away from the California fisheries they usually inhabit. And Pacific salmon decline in population during El Niño events, hurting Washington and Oregon fishing communities.

When an El Niño event is followed by La Niña, as scientists are predicting will likely happen this fall, it can really shake up phytoplankton populations, according to the National Oceanic and Atmospheric Administration, pushing species such as certain types of rockfish and whiting further north. This happens in large part due to the movement of plankton. Fish, like humans, follow the food, which is pushed northward in such ocean-warming events.

Behrenfeld is currently working as the principal investigator for the North Atlantic Aerosols and Marine Ecosystems Study, a five-year collaboration between NASA and Oregon State University that investigates plankton blooms in the North Atlantic Ocean.

Although it may seem somewhat complicated at first, a plankton bloom is simply anywhere that has a large concentration of plankton. Have you ever driven by a local pond in summertime and noticed it has turned green? Well, that’s a bloom.

Plankton bloom

So, in these bloom episodes, there are two major things going on, one being that abundant phytoplankton become an almost never-ending banquet for zooplankton, which are a staple in the diet of almost every sea creature we love to eat—everything from mollusks to mammals (of course we don’t eat these). In addition to this moveable feast, the phytoplankton are being eaten by zooplankton or killed by viruses, releasing a bunch of different chemicals into the ocean. In a sense, the ecosystem is also digesting these little microscopic morsels.

As the ecosystem works through the plankton, many of the chemicals produced during the process are then taken up into the atmosphere to form clouds, aided by the wind and spray from waves. These microscopic organisms also produce nearly half of the world’s oxygen, which means they play a huge role in regulating our climate.

Behrenfeld said that part of the NAAMES project is also studying the effects of global warming and its effect on phytoplankton growth. However, according to both Behrenfeld and Tenenbaum, teasing out the human component is complicated.

“Oil pollution is a problem; it kills the plankton directly and also indirectly because it blocks the sun. And there is way too much oil being spilled in our oceans. Plastic pollution sucks as well,” Tenenbaum says. “As far as the impact of climate change on plankton, that’s at the cutting edge of what scientists are looking into now.”

Behrenfeld echoed Tenenbaum, stating that how global warming and climate change has affected plankton growth is the “million dollar question” scientists like him are trying to answer.

Although we humans might be negatively affecting plankton growth (like just about everything else in nature) Tenenbaum said she’s certain that these tiny organisms won’t be going anywhere any time soon. If anything, they stand to outlive us.

“Plankton have lived on this earth for hundreds of millions of years, whereas humans have only been around for 3 to 5 million,” Tenenbaum says. “The fossil record will (show) our plastics and other human made materials in it, but plankton will be here after we’re gone.”

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