Glacier retreat alters downstream fjord ecosystem structure and function in Greenland

Glacier retreat in Greenland not only changes the primary productivity of downstream fjord ecosystems but also the ecosystem structure and functioning, according to seasonal sampling of two downstream fjords. The melting of the Greenland Ice Sheet is accelerating, with glaciers shifting from marine to land termination and potential consequences for fjord ecosystems downstream. Monthly samples in 2016 in two fjords in southwest Greenland show that subglacial discharge from marine-terminating glaciers sustains high phytoplankton productivity that is dominated by diatoms and grazed by larger mesozooplankton throughout summer. In contrast, melting of land-terminating glaciers results in a fjord ecosystem dominated by bacteria, picophytoplankton and smaller zooplankton, which has only one-third of the annual productivity and half the CO2 uptake compared to the fjord downstream from marine-terminating glaciers.

Automated summary

Glacier retreat in Greenland alters the primary productivity, ecosystem structure, and functioning of downstream fjord ecosystems. Monthly sampling in two fjords in southwest Greenland in 2016 revealed that subglacial discharge from marine-terminating glaciers sustains high phytoplankton productivity dominated by diatoms and grazed by larger mesozooplankton throughout summer. On the other hand, melting of land-terminating glaciers results in a fjord ecosystem dominated by bacteria, picophytoplankton, and smaller zooplankton, with only one-third of the annual productivity and half the CO2 uptake compared to the fjord downstream from marine-terminating glaciers.