An “invisible forest” of phytoplankton is flourishing in parts of our warming oceans, according to new research.
An “invisible forest” of phytoplankton is flourishing in parts of our warming oceans, according to new research.
Phytoplankton are tiny, free-floating organisms responsible for around half of the Earth’s “primary production” through the process of photosynthesis.
A recent study conducted by researchers from the University of Exeter investigated the phytoplankton at the ocean’s surface and the underlying “subsurface” layer to understand how climate fluctuations are impacting them.
Published in the journal Nature Climate Change, the study reveals that these two groups of phytoplankton are responding in different ways.
Over the last decade, the total “biomass” (the amount of living material) of subsurface phytoplankton has increased due to rising temperatures.
In contrast, surface phytoplankton has seen a reduction in chlorophyll, which makes them less green; however, their total biomass has remained consistent.
Using 33 years of data from the Bermuda Atlantic Time-series Study (BATS) in the Sargasso Sea, the study indicates that the “surface mixed-layer” (the turbulent area near the ocean’s surface) has become shallower as the ocean has warmed quickly over the past decade.
“Understanding these trends is crucial since phytoplankton serve as the base of the marine food web and play a significant role in absorbing carbon dioxide from the atmosphere,” explained Dr. Johannes Viljoen from the Department of Earth and Environmental Science at Exeter’s Penryn Campus in Cornwall.
“Our research demonstrates that phytoplankton living in deeper waters, which thrive in low-light environments, react differently to ocean warming and climate change compared to their surface counterparts.
“We generally depend on satellite data to track phytoplankton, but subsurface populations remain unseen by satellites.
“This study emphasizes the shortcomings of satellite observations and highlights the pressing need for better global monitoring of phytoplankton beneath satellite visibility.”
Co-author Dr. Bob Brewin noted that alterations at the foundation of the food web can significantly impact marine ecosystems, affecting everything from tiny zooplankton to larger fish and marine mammals.
“The future of phytoplankton will greatly affect biodiversity and our climate,” he added.
Dr. Viljoen further stated, “Ongoing monitoring of these deeper phytoplankton will enable scientists to gain a better understanding of the ongoing changes in the ocean that might otherwise go unnoticed.”
The research conducted by Dr. Viljoen and his colleagues Dr. Brewin and Dr. Xuerong Sun, all affiliated with the Centre for Geography and Environmental Science, is supported by a UKRI Future Leader Fellowship awarded to Dr. Brewin.
