If 90% of the Atlantic Ocean’s Plankton Were Gone, We Would Know About It
July 27, 2022
By Isabel PlowerOn 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 (Goes) Foundation showed 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 its post, and the Seaspiracy post was flagged for misinformation after both had been 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 undergo peer review. Thus the study’s 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 represent 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 — more factors that could affect the count.
Additionally, The Sunday Post over-reported the scope of the study, claiming that it collected samples from the entire Atlantic Ocean when it actually collected samples only 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, head of the Continuous Plankton Recorder Survey. For perspective, the Survey has collected over 265,000 samples since 1958.
The Sunday Post responded to the criticism with an updated story and headline reflecting the limitations of the study. 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 produce photosynthesis, converting sunlight into chemical energy with oxygen as a byproduct. Since phytoplankton account for so much of global photosynthesis, they are among the world’s most important sources of oxygen. If plankton numbers were to decline as drastically as 90%, there would be a significant reduction in atmospheric oxygen.
Further, plankton are a major carbon sink. Through photosynthesis, phytoplankton consume carbon dioxide on a scale equivalent to forests and other land plants. Much of this carbon is incorporated into the phytoplankton’s shells and sinks into the deep ocean when they die. But some carbon moves to different levels of the ocean when 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 a slight change in phytoplankton populations can affect this process, which, in turn, will affect 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 zooplankton to enormous whales. Phytoplankton also indirectly supply the other trophic levels with energy as primary consumers are eaten by secondary, tertiary, and quaternary consumers. If the plankton population were to undergo a dramatic decline, 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. 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.
Plankton populations may not be vanishing before our very eyes. But their numbers are changing, and these changes could seriously disrupt ecosystems and vital biological processes. There is a need to monitor plankton populations. But this must be done in a scientifically sound manner so as to avoid the climate doomspeak perpetrated by The Sunday Post article and other organizations that picked up and amplified the article’s sensational message.
For more information, see the companion “Tip of the Iceberg” podcast episode here.
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