Can the Coloration of Lakes in Satellite Imagery be Used to Predict its Biological, Chemical, and/or Physical Properties?

The Yukon Kuskokwim Delta region of Alaska consists of over 100,000 small lakes, it is one of the largest lake-dense regions of Alaska. These small lakes are critical aquatic ecosystems that provide habitats for wildlife and play an important role in carbon and nutrient cycling. Lakes in the Yukon Kuskokwim Delta have a wide range of visible and near-infrared satellite spectra, which can vary over small spatial scales. These spectral differences may provide insight into properties of these small shallow lakes. Therefore, we wanted to investigate the relationship between the spectral data and differences in these lakes' biological, chemical, and/or physical features.

To better understand lake variability and properties across the Yukon Kuskokwim Delta region, we sampled 16 lakes across three sample areas (each area ~60km apart) in the vicinity of the Izaviknek-Kingaglia uplands. At each lake we measured temperature, dissolved oxygen, specific conductivity, and pH, and collected surface water for analysis of chlorophyll , dissolved organic matter (DOM), chromophoric dissolved organic matter (CDOM), total dissolved nitrogen, and inorganic nutrients such as nitrate, ammonium, and phosphate. We also measured lake depth, surveyed vegetation, and collected lake sediments. We found high spatial variability across lakes in these physical, chemical, and biological characteristics. For example, there was a 100-fold variation in lake chlorophyll concentration and almost two-fold variation in lake pH (5.4-10.1), which were associated with variations in lake spectral data (Sentinel2, bands 3, 4, 8).

Understanding associations between satellite imagery of shallow lakes in the Yukon-Kuskokwim Delta can further inform the region's lake ecology, geomorphology, and hydrology, which is critical due to rapid landscape changes that are occurring across this region.