Churned up

Global Change Biol. (2011)

Invasive species have been shown to threaten the diversity and health of marine ecosystems. However, an invader in the oxygen-deficient waters of the Baltic Sea may be providing an important ecosystem service, according to model simulations.

Joanna Norkko of Åbo Akademi University, Finland, and Daniel Reed of Utrecht University, The Netherlands, and colleagues used a reactive transport model to examine the impact of invasive worms on nutrient cycling in marine sediments in the Baltic Sea over a ten-year period. They show that by churning up the sediments, the worms enhance the level of iron-bound phosphorus in the mud, and reduce the concentration of bioavailable organic carbon. Worm-induced preservation of these iron–phosphorus complexes facilitates their conversion into less digestible compounds, promoting the retention of phosphorus in marine sediments.

The researchers suggest that by helping to sequester phosphorus — a key nutrient in surface waters — in marine sediments, invasive worms could reduce the potential for eutrophication in the overlying waters.


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Armstrong, A. Churned up. Nature Geosci 4, 658 (2011).

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