|
Impact of hydrologic connectivity on wetland sustainability and dissolved organic carbon dynamics in Polar Bear Pass, Bathurst Island, Nunavut
Anna Abnizova and Kathy L. Young, York University, CANADA
ABSTRACT A large regional wetland exists in the Polar Bear Pass National Wildlife area, Bathurst Island (75o40', 98o30'). No information exists on the intra-or inter-seasonal patterns of water flow through these areas, and details on how nutrients travel from the terrestrial landscape into these large wetland systems are absent. Therefore, a detailed hydrological investigation was conducted in summers of 2007 and 2008. A water balance framework was applied to a series of ponds and their catchments to determine temporal and spatial regimes of precipitation input, evaporation loss, runoff and catchment storage. Water transfers into ponds from hillslope streams and nearby late-lying snowbeds were tracked throughout the season. During the warm and dry 2007 season, ponds located in ice-rich terrain and/or hydrologically linked to a water source maintained stable water tables, while others, isolated and only dependent on summer rain quickly became desiccated. Little snowcover occurred in 2008 and late-lying snowbeds and streams dried out quickly during a warm and dry period. However, frequent and large rain events in the latter part of the 2008 summer field season soon revived hillslope streams, allowing the eventual recharge of ponds to freshet levels. The most common state of carbon transfer via hydrological pathways, dissolved organic carbon (DOC) is critical for freshwater systems productivity. Preliminary analysis of 2008 seasonal trends in DOC fluorescence in ponds and hydrologic pathways indicate that DOC is allochtonous (terrestrial origin) during the snowmelt flushing and becomes autochthonous (indigenous) as the season progresses and ponds become isolated. These results show that connectivity to a hydrologic linkage and its role in moving carbon are important in sustaining ponds during variable climatic conditions and perhaps climate change. |