When glaciers and ice sheets melt: consequences for planktonic organisms.

Area of Science:

• Ecology
• Limnology
• Climate Change Science

Background:

• Glacier and ice sheet melt, driven by climate change, is increasing the number and size of new proglacial and ice-contact lakes globally.
• Turbid meltwaters from glaciers, rich in mineral suspensoids (glacial flour), characterize these unique aquatic ecosystems.
• Despite their prevalence, the ecology of these turbid, glacier-fed aquatic environments remains poorly understood.

Purpose of the Study:

• To discuss the ecological consequences of glacier meltwaters on planktonic organisms.
• To highlight the challenges posed by glacial flour and low light levels to planktonic communities.
• To explore the potential impacts of changing turbidity and related factors on biodiversity and ecosystem function.

Main Methods:

• Literature review and synthesis of existing research on glacier-fed lakes and their plankton.
• Analysis of the physical and chemical properties of glacial meltwaters and their effects on aquatic life.
• Discussion of food web structures and community dynamics in response to environmental changes.

Main Results:

• High mineral content (glacial flour) in meltwaters challenges filter-feeding zooplankton (e.g., *Daphnia*) and heterotrophic nanoflagellates.
• Turbid meltwater lakes exhibit truncated, microbially-dominated planktonic food webs.
• Low underwater light limits primary production but reduces UV radiation stress; meltwaters can provide nutrients stimulating prokaryotic and, in some cases, phytoplankton production.

Conclusions:

• Glacier retreat and associated meltwater changes significantly alter planktonic ecosystem structure and function.
• Understanding these impacts is crucial for predicting future biodiversity, biogeochemical cycles, and ecosystem trajectories in glacier-fed environments.
• Further research is needed to fully comprehend how turbidity and related factors drive community composition and adaptation.