Satellite data reveals changing productivity in UK and north-east Atlantic watersA new Plymouth Marine Laboratory study shows how long-term Earth observation data can help track changes in the marine ecosystems that support fisheries, biodiversity and climate regulation.
Long-term satellite observations are giving researchers a clearer picture of how the productivity of the seas around the UK is changing in response to environmental pressures.
A study led by scientists at Plymouth Marine Laboratory (PML) has analysed more than 20 years of satellite data to investigate trends in net primary production across the north-east Atlantic. Net primary production measures the rate at which microscopic marine algae, or phytoplankton, use sunlight and carbon dioxide to create organic matter. This process supports much of the marine food web and plays an important role in ocean carbon cycling.
The research, published in Frontiers in Remote Sensing, used a 21-year time series from 1997 to 2018, drawing on the European Space Agency’s Ocean Colour Climate Change Initiative data. By analysing satellite-derived information across different marine regions, the team found that productivity increased during the late 1990s and early 2000s, before declining across much of the study area in the years that followed.
The decline was most evident in parts of north-west European coastal waters, including areas of the Irish Sea, North Sea and western English Channel, as well as parts of the Norwegian Sea. The study also found regional differences, with some areas, including the Celtic Sea, showing more stable or increasing productivity over the same period.
Researchers linked many of the observed changes to shifts in sea surface temperature and mixed layer depth. These physical conditions influence how nutrients and light are distributed in the upper ocean. As surface waters warm and stratification changes, nutrients from deeper waters may become less available to phytoplankton, limiting growth in some regions.
The study also highlights changes in the timing of seasonal productivity. In some areas, peak production appears to be occurring earlier in the year. Such shifts could affect the timing of food availability for zooplankton and fish larvae, with potential implications for marine ecosystems, fisheries and food security.
The authors note that the satellite record is still relatively short in climate terms, but stress the importance of maintaining high-quality, long-term Earth observation datasets. Continued monitoring will be essential for understanding how ocean warming, changing stratification and other climate pressures are affecting the base of the marine food web and the ocean’s role in regulating carbon.
Plymouth Marine Laboratory researchers are now extending this work to examine whether similar patterns can be seen across other regions of the Atlantic using longer satellite records.
This research highlights the vital role of the Earth observation sector in helping society understand and respond to environmental change. Satellites provide consistent, long-term measurements across vast and often hard-to-reach areas, making it possible to detect shifts in ocean health, climate, biodiversity and natural resources at a scale that would otherwise be impossible.
Read the original article here – https://pml.ac.uk/news/detected-from-space-20-years-of-data-shows-declining-photosynthesis-in-uk-and-surrounding-waters/
