Benthic invaders control the phosphorus cycle in the world's largest freshwater ecosystem

Area of Science:

• Aquatic Ecology
• Invasive Species Biology
• Biogeochemistry

Background:

• Aquatic ecosystem productivity relies on nutrient supply.
• Dreissenid mussels (zebra and quagga) have invaded the Laurentian Great Lakes, altering their ecology.
• Phosphorus (P) is the limiting nutrient for Great Lakes productivity.

Purpose of the Study:

• To investigate the impact of dreissenid mussels on phosphorus (P) cycling in the Great Lakes.
• To determine if invasive mussels regulate P availability in this large freshwater ecosystem.

Main Methods:

• Mass balance analysis was used to assess P cycling.
• Quantified the role of quagga mussel biomass and activity in P sequestration and benthic exchange.

Main Results:

• The quagga mussel is the primary regulator of P cycling in the lower four Great Lakes.
• Mussels sequester large amounts of P in their tissues, intensifying benthic P exchanges.
• Great Lakes P availability is now regulated by mussel population dynamics, suppressing external inputs.

Conclusions:

• A single invasive species can profoundly impact geochemical cycles in large aquatic ecosystems.
• The spread of dreissenids will likely affect nutrient cycling and water quality in North American and European lakes for decades.