How climate change skews phytoplankton blooms—and leads to fewer fish

Written by
Joseph Albanese for the High Meadows Environmental Institute
July 24, 2020

Climate change—fueled by high carbon emissions—may be adversely impacting the feeding behavior of some species of juvenile fish, potentially leading to smaller overall fish populations.

Princeton University researchers including Jorge Sarmiento, Princeton’s George J. Magee Professor of Geoscience and Geological Engineering, Emeritus, discovered that Earth’s warming climate has shifted the historic timetable of when phytoplankton—microscopic marine algae that form the base of many aquatic food webs—blooms. In temperate and polar ecosystems, these blooms are occurring between two or four weeks earlier than has been historically typical.

Many fish larvae routinely subsist off phytoplankton as a major food source. But if these species are unable to obtain adequate quantities of this vital source, they run the risk of starvation. The long-term effects of this could have dire consequences for the species’ future reproductive rates as fewer individuals survive into adulthood.

But even for the fish that do survive this critical stage, the researchers contend, the lack of adequate supplies of phytoplankton means that that they will be slower-growing and more likely to be eaten by predators. 

Many of the world’s coastal communities that rely on fishing as an important form of subsistence would also be impacted by smaller fish stocks.

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