Multiple invasions decimate the most imperiled freshwater invertebrates

Area of Science:

• Ecology
• Freshwater Biology
• Invasive Species Research

Background:

• Freshwater ecosystems are vulnerable to invasive species and environmental changes like eutrophication.
• Long-term monitoring is crucial for understanding ecological shifts and species dynamics.

Purpose of the Study:

• To analyze long-term changes in mollusc communities in Oneida Lake, New York.
• To assess the impacts of eutrophication, habitat alteration, and invasive species on native and non-native molluscs.

Main Methods:

• Analysis of historical and contemporary mollusc surveys from Oneida Lake (1915-2023).
• Examination of species composition, density, and richness changes over time.
• Correlation of observed changes with documented environmental stressors and invasions.

Main Results:

• Eutrophication and habitat alteration led to significant declines in native gastropods and unionids by 1967.
• Invasive zebra and quagga mussels initially increased native gastropod richness but extirpated unionids.
• The round goby invasion caused a sharp decline in gastropods, with partial recovery of other species in deeper zones.

Conclusions:

• Molluscan communities are highly sensitive to cumulative impacts of eutrophication and invasive species.
• While some invaders initially mitigated negative effects, overall native mollusc populations have been decimated over the past century.
• Ecosystem recovery is complex and can be depth-dependent, highlighting the need for comprehensive management strategies.