TEMPERATURE VARIATION IN WESTERN MAINE PONDS

Horns, Cranberry, and Tumbledown Ponds are located in western Maine along the Appalachian Trail on Bigelow and Tumbledown Mountains. They range in elevation from 2,437 to 3,130 feet and in size from three to eight acres. These ponds are of significant ecological and recreational value; some are stocked with fish or are used as a water source for hikers. At present, historic records of seasonal markers such as ice-out dates are only available for larger, lower elevation lakes to assess the response of these lakes to changing climate. By analyzing high-resolution water temperature data of these small, high elevation ponds, we hope to better understand their relationship to similar climate forcings. At each pond, loggers are placed in at the surface, two meters down, and at the bottom. Water temperature is logged every twenty minutes, resulting in high-resolution data sets. There are summer temperatures for all three ponds and a year-round record at Tumbledown. Loggers at Tumbledown show seasonal markers including fall turnovers, winter stratification, and ice-out. Surface temperatures at all three locations have similar daily trends, although the lowest elevation pond is slightly warmer. The timing of turnover events is similar at all three locations. Bottom temperature changes at Tumbledown and Horns Pond are similar, including a rapid mid-summer temperature increase of several degrees attributed to a turnover event. Comparison to meteorological records in the future will determine what relationship wind speed and direction, air temperature, insolation, and precipitation have on water temperature and the timing of turnover events. Long-term monitoring of these high elevation locations will help to determine how sensitive these small ponds are to climate change.