Scientists have discovered a significant shift in the Antarctic plankton population over the past 25 years, which could have far-reaching effects on the marine food web and carbon storage. A study combining satellite data with ocean sampling has found that climate change is driving changes in phytoplankton species composition.
Researchers used ESA’s Climate Change Initiative (CCI) data to build machine-learning models, which were then combined with in-situ samples to track changes in different phytoplankton groups over time. The results show a decline in diatoms across the Antarctic continental shelf between 1997 and 2023, but an increase in cryptophytes following sea ice retreat in 2017.
Smaller phytoplankton groups, such as haptophytes and cryptophytes, have increased in number over the past quarter century. The study also found a shift after 2016, coinciding with a sharp loss of Antarctica sea ice, which led to a rebound in diatom populations due to changes in environmental conditions.
The Antarctic marine environment is home to two main types of phytoplankton: diatoms and haptophytes. Diatoms are single-celled, disc-shaped algae that provide an important source of food and form an essential carbon sink. However, the loss of sea ice has altered their population dynamics, which could have implications for the climate.
Satellite data can detect changes in phytoplankton populations by analyzing the colour of the sea’s surface. The European Space Agency’s Copernicus Sentinel-3 sensor provides detailed measurements of light reflected off the ocean’s surface, allowing researchers to identify different phytoplankton groups and their locations.
The study highlights the importance of monitoring phytoplankton changes due to climate change. A decrease in diatoms could weaken the biological carbon pump, leading to less carbon dioxide being transported to the deep sea. Therefore, more research is needed to understand these changes and monitor the health of marine ecosystems.
Source: https://www.esa.int/Applications/Observing_the_Earth/Space_for_our_climate