RECENT ENVIRONMENTAL HISTORY OF THREE EASTERN LAKE ONTARIO EMBAYMENT ECOSYSTEMS

Three embayments of eastern Lake Ontario were studied at the ecosystem level to identify changes in their recent environmental history and investigate any potential influences of artificial water-level stabilization in the last 42 years. Ecosystem components analyzed from embayment and wetland cores included diatom assemblages, wetland plants, pollen profiles, sediments, nutrients, and metals. Diatom assemblages were used to identify changes in lake conditions. Shannon diversity was determined for all assemblages and correspondence analysis (CA) was used to determine major shifts in assemblage composition. Juniper Pond is a system dominated by benthic diatom species associated with wetlands and mildly acidic waters. Several major environmental changes are evident in the diatom community shifts throughout the (107cm) core. An increase in planktonic taxa occurs concurrently with the Ambrosia horizon and may be a response to increased water levels and turbulence due to loss of forest cover. Little Sodus and South Sandy are open water systems dominated by planktonic Aulacoseira species that rely on turbulent conditions. Benthic-epiphytic taxa associated with wetlands are also present in the South Sandy core. These are more dominant in the early 1800's prior to a major erosional event. All three embayments exhibited water-level assemblage changes most-likely related to Lake Ontario. However, assemblages in all three systems were more strongly influenced by increased nutrient conditions following human activities in the watershed resulting in major shifts in assemblages and declines in overall diversity. Only Little Sodus appears to show a recovery in the surface sediments.