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Sodium dynamics in a northern ecosystem
D B Botkin1, P A Jordan, A S Dominski
1School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06520.
Summary
Sodium availability in vegetation is a key factor controlling moose populations on Isle Royale. Aquatic plants offer a rich sodium source, potentially supporting moose if they can store the element.
Area of Science:
- Ecology
- Wildlife Biology
- Animal Nutrition
Background:
- Moose (Alces alces) populations on Isle Royale are influenced by resource availability.
- Sodium is an essential element for large herbivores, but its dietary sources can be limited.
- Previous research has underestimated the sodium content of freshwater aquatic vegetation.
Purpose of the Study:
- To analyze terrestrial sodium sources and estimate the sodium requirements of moose on Isle Royale.
- To investigate the role of sodium availability in regulating moose population dynamics.
- To assess the contribution of aquatic vegetation to moose sodium intake.
Main Methods:
- Analysis of sodium content in terrestrial and aquatic plants consumed by moose.
- Estimation of moose sodium requirements based on physiological needs.
- Correlation analysis of sodium and chloride concentrations in water plants.
Main Results:
- Terrestrial vegetation on Isle Royale is notably low in sodium.
- Submerged and floating-leaved aquatic plants exhibit significantly higher sodium concentrations.
- Consumption of aquatic plants during summer could meet moose sodium requirements if the element can be stored.
Conclusions:
- Sodium availability, particularly from aquatic sources, is a critical limiting factor for the Isle Royale moose population.
- Freshwater aquatic plants represent an underappreciated but vital sodium reservoir for moose.
- The high sodium content in aquatic plants, often exceeding chloride, suggests NaCl uptake is feasible.