Environmental Change at High Latitudes

Abstract

Paleolimnological techniques have been used successfully to reconstruct environmental change in the Arctic and Antarctic. Diatoms are powerful indicators of environmental change because their community composition responds to changes in environmental conditions. As more regional diatom calibrations throughout the high latitude regions are achieved, the autecology of diatom taxa can be quantified and transfer functions for the driving environmental variables developed. In most instances, environmental variables related to physical, chemical, and climate-related characteristics are the main drivers affecting diatom distribution across polar aquatic bodies. A decline in ice cover and increase in growing season length results in an increase in diatom diversity as well as increased productivity, and increased thermal stratification in lakes (vs. shallow ponds). Because the siliceous cell wall preserves well in sediments, diatoms are among the most commonly used organisms used in paleolimnological analyses. Polar latitudes are experiencing amplification of the current global warming trend and as such, analyses of diatoms from high latitude lake and pond sediments are revealing the timing and extent of these trends. Diatom-based paleolimnological analyses are also being used to track the environmental impact of excess nutrient additions to lakes. Similar findings have also been reported from marine ecosystems.