COMPARING ANDEAN AND INTERANDEAN LAKES AT DECADAL AND CENTENNIAL SCALES

Ecuador encompasses a wide variety of unique ecosystems including the Andean Páramo, the Interandean Plateau, and the lowland Amazon forest. Within the last few decades, Ecuador has experienced pulses of urban development and tourism, accompanied by increasing global temperatures and associated climatic changes. Lakes are sensitive to changes in their watershed, and thus, changes in the surrounding environment are recorded in their sedimentary records. Many of these lakes serve as water sources for nearby populations, making it important to understand lake dynamics on varying time scales. One way to study lake systems is to observe changes in the diatom assemblage. Diatoms are sensitive to a number of changes in lake systems such as temperature, nutrients, light availability, and salinity. Dr. Miriam Steinitz-Kannan collected diatom samples and recorded physico-chemical variables from over fifty Ecuadoran lakes in the late 1970’s to the 1980’s. Thirteen of these lakes were re-sampled in February and July of 2017, providing a unique opportunity to compare Andean and Interandean lake change on a relatively short time-scale. Principal components analysis (PCA) and temporal beta diversity indices (TBI) were used to observe changes in lake physico-chemical variables and diatom assemblages between two time points including historic (1970-1980s) and modern (2017). Generally, Andean lakes and Interandean lakes exhibit different physico-chemical characteristics, and therefore different diatom assemblages. Between the historic and modern time points, lakes show a high resilience to change, with only two Interandean lakes showing statistically significant differences, likely a result of the proximity to human settlement.