Melting glaciers losing nutrient strength, raising concerns for marine life

Alaska’s Retreating Glacier Losing Vital Nutrients, Study Finds (Image: Canva)

Is the world’s melting ice losing its nutritional power? Scientists at the Scripps Institution of Oceanography, University of California–San Diego, think so. Their new study reveals that fast-retreating glaciers in Alaska release meltwater poorer in essential nutrients than stable ones nearby.

Retreating Glacier, Weaker Nutrient Flow
The research compared two glaciers on Alaska’s Kenai Peninsula — Aialik Glacier, which remains largely stable, and the Northwestern Glacier, which has retreated nearly 15 kilometres since 1950. The study, titled “Tidewater cycle drives alpine glacial sediment plume geochemistry”, found that the retreating glacier’s meltwater contained much lower levels of iron and manganese, vital nutrients that support plankton growth.

The sediments from Aialik Glacier held around 18% bioavailable iron, while those from the retreating Northwestern Glacier had only about 13%. For manganese, the drop was even sharper — 26% in the stable glacier compared to 14–15% in the retreating one.

Why Does It Matter for Oceans and Life?

Glaciers shed sediment-filled water as they melt, which brings minerals that nourish marine ecosystems. But what the researchers found is that if glaciers are rapidly retreating, their sediments are stuck longer in pools of meltwater before entering the ocean. This chemical weathering process alters mineral makeup and makes nutrients harder to use by marine life.

In other words, receding glaciers dump more mud in the ocean, but the mud contains fewer nutrients. So, while sediment flow rises, its “nutritional value” for marine ecosystems declines. This nutrient loss can affect plankton, the base of the oceanic food web, and eventually impact fish populations.

Could the Same Happen in the Himalayas?
Although the study focused on Alaska, its warning extends to India’s Himalayan glaciers, which are retreating fast. Shrinking glaciers are already altering river flows and forming new glacial lakes. If similar processes occur, the quality of meltwater feeding Indian rivers could fall, affecting coastal ecosystems and fisheries.

Marine zones depending on glacial nutrients may see changes in plankton growth and fish stocks. That could influence livelihoods of coastal communities and fishing economies that rely on these waters.

Looking Ahead: Beyond Glacier Count
The Scripps researchers said their conclusions come from only two glaciers, but the pattern is worrying. Tracking glacier retreat alone is no longer enough. Scientists now need to examine what type of water and sediment glaciers release as they melt.

For India, expanding glacier monitoring to include meltwater chemistry could reveal how Himalayan changes affect river health and marine ecosystems. Understanding this link may be crucial for predicting future water and food security.