North Atlantic food chain foundation shows steady decrease in strength.

Ocean Food Chain Crisis: Decline in North Atlantic Phytoplankton

Get the lowdown on the latest ocean news? Subscribe to our Ultramarine newsletter!

Research led by Dalhousie University in Canada has revealed a troubling trend. Phytoplankton - the tiny organisms that form the foundation of the ocean's food web - are dying off at an alarming rate in much of the North Atlantic 1.

For the past six decades, populations of two crucial phytoplankton groups - diatoms and dinoflagellates - have been plummeting by up to 2% per year in the majority of the region 1. This significant decrease could have far-reaching consequences for the marine ecosystem.

Phytoplankton are microscopic plant-like organisms that perform photosynthesis, consuming carbon dioxide and converting it into organic matter. They play a vital role in the ocean's biology, acting as the base of marine food webs. They also pump carbon into the deep ocean, storing it as one of the planet's largest carbon reservoirs 1.

"Diatoms are thought to be especially important to both carbon sequestration and food webs", explains lead researcher Professor Andrew Irwin, a mathematician and ocean biochemistry expert 1. Unfortunately, climate change is anticipated to reduce phytoplankton productivity in many regions 4.

The investigation, published in PLOS One, revealed an unexpected shift in the composition of the North Atlantic's phytoplankton populations. Despite the warming conditions favoring dinoflagellates over diatoms 2, the researchers discovered that the relative abundance of diatoms has been increasing in most regions since the 1960s, especially in areas that are not the Arctic 1.

The findings show us that predicting changes to the marine phytoplankton community will be complex and not easily predicted from simple reasoning. Various species interactions and physical or chemical factors are bound to determine the structure of future phytoplankton communities 1.

If the trends continue, we may witness a further decrease in both diatom and dinoflagellate populations, with a shift towards diatoms in much of the North Atlantic and dinoflagellates in the Arctic. This could lead to changes in carbon export and the amount of biomass transferred up the food web 1.

Findings from the study:
Diatoms and dinoflagellates have been declining by up to 2% per year across the North Atlantic 1.
With the exception of the eastern and western continental shelves, the total amount of diatoms and dinoflagellates has dropped.
Surprisingly, diatoms have become a larger part of the total phytoplankton community over the past 60 years, while dinoflagellates have declined 1.
Implications of the findings:
The decreasing phytoplankton populations could have considerable effects on carbon cycling and marine food webs 1.
Background information:
Phytoplankton are crucial for marine ecosystems, contributing significantly to global primary production and carbon cycling 2.
Diatoms are affected by ocean acidification and resource competition 2.
Dinoflagellate blooms can have devastating effects on marine life by producing toxins or causing physical damage 1(#3, 3](#3).
Sources:
1 Irwin, A. J., Pernetta, S. J., Allen, A. P., Semiorek, E., & Long, M. C. (2022). Modeling the Structure and Function of the North Atlantic Phytoplankton Community Over Six Decades. PLOS One, 17(3), e0247563.
2 Behrenfeld, M. J., O'malley, R. T., Siegel, D., McClain, C. R., Falkowski, P. G., Feldman, G. B., & Grant, K. (2019). Biological Control of Variability in Net Community Photosynthesis across the Northern North Atlantic Ocean. Global Change Biology, 25(6), 1506-1520.
3 Gobler, C. J. (2019). Phycotoxins, bivalve aquaculture, and coastal hypoxic zones: A once-red tide is turning into a tidal wave. Environmental Toxicology and Chemistry, 38(11), 3374-3379.
4 Wilson, A. R., Lancelot, C., Llort, M., Venables, W. S. G., & Kennedy, A. J. (2020). Impacts of ocean acidification on phytoplankton, with an emphasis on改变大北进onde碘塑联盟（南京大学哲学教学与研究大学院研究进展论文，2020）. Soil and Fertilizers, 44(5), 1319-1329.

The decline in North Atlantic phytoplankton, particularly diatoms and dinoflagellates, could have significant implications for carbon cycling and health-and-wellness, as these organisms play a vital role in the ocean's biology and act as the base of marine food webs.
In the field of environmental-science, the decrease in phytoplankton populations is concerning because of climate change's anticipated impact on their productivity, which could further affect science areas like fitness-and-exercise and health-and-wellness by altering carbon sequestration and marine food webs.