Thursday January 18, 2024
PhysOrg —
A research team that includes Dr. Angus Atkinson of the Plymouth Marine Laboratory and Dr. Axel Rossberg from Queen Mary University of London has discovered a hidden amplifying mechanism within the ocean’s food web. Their findings, published in Nature Communications, reveal that when climate warming reduces phytoplankton levels by just 16%–26% (as projected by global models in regions like the North Atlantic), the carrying capacity for fish plummets by 38%–55%.
Global-scale computer models tend to agree that there will be a decline in phytoplankton in low and mid latitudes as the water warms and the surface layers become insulated from the supply of nutrients from below. In the North Atlantic, for example, plankton have already declined over the last 50 years. However, what happens further up the food web—up to the stocks of commercially exploited fish—is far from clear.
Some models suggest little change in fish and others project a major decline and importantly, the mechanisms vary greatly from model to model. These discrepancies show that we are still far from knowing how these food webs work.