We Would Know if 90% of the Atlantic Ocean’s Plankton Were Gone

Plankton populations are changing, but we cannot feed into climate doom and assume that they're vanishing forever.

Source: Marek M.

On July 17, 2022, the Scottish newspaper The Sunday Post published an article titled “Our empty oceans: Scots team’s research finds Atlantic plankton all but wiped out in catastrophic loss of life.” The article claimed that a research report by Global Oceanic Environmental Survey Foundation (Goes) found that 90% of Atlantic plankton have vanished. 

The sensational headline was soon posted on the social media accounts of environmental awareness organizations like Save the Reef and Seaspiracy, who called the findings “another nail in the coffin of our dying ocean.” The posts were shared thousands of times. However, Save the Reef eventually deleted the post and the Seaspiracy post was flagged for misinformation after they were scrutinized by the scientific community. 

The criticism was directed at the fact that The Sunday Post cited the preprint manuscript of the Goes Foundation study, meaning that the findings have yet to be peer-reviewed. As such, their methods and results may not hold up against scientific scrutiny. For example, the Foundation’s decision to develop its own filter to collect samples, instead of using standard plankton trawls, could present a flaw in the study’s methodology. This is supported by the fact that all 13 vessels employed in the study returned the same results. The preprint also does not mention when the samples were collected or what magnification was used to detect the plankton, which could lead to lower counts. 

Additionally, The Sunday Post over-reported the scope of the study, claiming that it collected samples from the entire Atlantic Ocean when it actually only collected samples from a limited area within the equatorial Atlantic. Moreover, the Goes Foundation only collected 500 data points, which is “a literal drop in the ocean” according to David Johns, the Head of the Continuous Plankton Recorder Survey. For perspective, the Survey has collected over 265,000 samples since 1958. 

As a consequence of this criticism, The Sunday Post updated its story and headline to reflect the limitations of the research. The headline now reads: “Our empty oceans: Scots team’s research reveals loss of plankton in equatorial Atlantic provoking fears of potentially catastrophic loss of life.” 

David Johns also spoke with USA TODAY and asserted that a 90% reduction in the Atlantic plankton population would be “catastrophic and instantly noticeable.” This is because plankton provide many vital ecosystem services. For instance, phytoplankton account for about half of the photosynthesis on the planet. Like land plants, phytoplankton have green chlorophyll pigments that capture sunlight. The phytoplankton then undergo photosynthesis, which converts the sunlight into chemical energy and produces oxygen as a byproduct. Since phytoplankton account for so much of global photosynthesis, they’re also one of the world’s most important producers of oxygen. Consequently, if their numbers declined as drastically as 90%, there would be a significant reduction in atmospheric oxygen. 

Furthermore, through photosynthesis, phytoplankton consume carbon dioxide on a scale equivalent to forests and other land plants, making them a major carbon sink. Some of this carbon is incorporated into the phytoplankton’s shells and sinks into the deep ocean when they die. Meanwhile, some carbon is transferred to different layers of the ocean if the phytoplankton is consumed. This movement of carbon is referred to as the biological carbon pump and it annually transfers about 10 gigatons of carbon from the atmosphere to the deep ocean. Even slight changes in phytoplankton populations can affect this process, which, in turn, affects atmospheric carbon dioxide concentrations and global surface temperatures. 

Phytoplankton are also the foundation of the aquatic food web. As primary producers, they provide sustenance for the primary consumers, which include everything from microscopic, animal-like zooplankton to enormous whales. They also indirectly supply the other trophic levels with energy as primary consumers are eaten by secondary, tertiary, and quaternary consumers. Likewise, if the plankton population declined dramatically, there would be corresponding decreases in the populations of every marine species that depends on them. 

At the same time, plankton populations have not been entirely stagnant. According to David Johns, some plankton populations are increasing, while others are decreasing. Regardless of the kind of population shift, Johns says many of these changes are in response to climate change. For example, large numbers of a Pacific diatom were found by the Continuous Plankton Recorder Survey in the North Atlantic after an unusually extended ice-free period. The diatom had previously been absent from the region for over 800,000 years. According to the Survey, the species may be evidence of a trans-Arctic migration which could be “an indicator of the scale and speed of changes that are taking place in the Arctic as a consequence of climate warming.” While it is unclear what the exact consequences of this trans-Arctic migration may be, it is likely that it will affect the biodiversity, productivity, and health of Arctic systems. 

While plankton populations are not vanishing before our very eyes, they are changing. And although these changes may not be entirely negative for the plankton themselves, they could seriously disrupt ecosystems and vital biological processes. As a result, plankton populations absolutely need to be monitored. However, this must be done in a scientifically sound manner so as to avoid the climate doom perpetuated by The Sunday Post article and the corresponding organizations that amplified its sensational message.

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Isabel Plower

Isabel Plower is an Associate Producer for The Sweaty Penguin, contributing graphics and copy for social media, animating penguins for TikTok, and researching and writing episodes.


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