Trophic pyramids reorganize when food web architecture fails to adjust to ocean change

Warmer oceans change composition of food webs

23 December 2020

Ocean warming may lead to an increase in the biomass of species at the bottom of the food web, such as algae and cyanobacteria, but a decrease in the species that feed on those primary producers.

Researchers from the University of Adelaide in South Australia exposed an experimental coastal seafloor ecosystem to the warmer water and higher ocean acidification conditions consistent with forecasts for the end of this century under a high-emissions scenario.

They found that while ocean acidification alone didn’t significantly alter either the structure or composition of the food web, ocean warming of 2.8 degrees Celsius saw primary producers, particularly turf algae and cyanobacteria, increase both in productivity and biomass. At the same time, the biomass of the shellfish, molluscs and crustaceans that eat those primary producers dropped by around 40%.

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References

1. Science 369, 829–832 (2020). doi: 10.1126/science.aax0621