A Paleolimnological Examination of the Acidity Trends in Two Kettle Ponds along the Eastern Seaboard

Chrysophytes, microscopic algae composed of siliceous scales, were used to evaluate acidity trends in two kettle ponds. Snow Pond is in Truro, Massachusetts, along the Cape Cod National Seashore. Peskowesk Lake is located in Kejimikujik National Park on the Atlantic Canadian Province of Nova Scotia. Both ponds are acidic, poorly buffered waterbodies. Snow Pond lies adjacent to Route 6, the main road which runs through all of Cape Cod, while Peskowesk is remotely located in the middle of Kejimikujik with no public road access to the shore. Monitoring data from the Cape Cod National Seashore dating by to 1984 indicates increased acidification in the past few years, while the monitoring data from Parks Canada dating by to 1987 indicates stable pH levels. The downcores of both ponds showed the flora characteristic of very acidic waterbodies. Snow Pond showed a relatively consistent floral composition until the surface sediment, when there appeared a notable increase in the percent abundance of the acidobiontic taxa M. canina and M. hamata, simultaneously with the disappearance of the acidophilous taxon M. lychenensis. Peskowesk Lake also exhibited consistent floral compositions throughout all strata except at 5cm, where there appears a notable spike in alkalinity marked by the presence of M. akrokomos. Results of this study suggest the Snow Pond has been undergoing recent increased acidification, while acidity levels of Peskowesk Lake have remained steady. The sudden taxonomic shift at 5cm from an acidobiontic taxa dominance community to an alkalibiontic taxa dominance community indicates abrupt and short-term forest disturbance.