Evaluation of Potential Environmental Drivers of Algal Blooms in Central American Crater Lakes

Recent global studies indicate that rising temperatures may be fueling the proliferation of algal blooms in lacustrine systems. In Central America, recurring algal blooms in endorheic lakes have appeared only within the last fifteen years. Mirroring a similar situation occurring in Lake Atitlan in neighboring Guatemala, El Salvador’s Lake Coatepeque - a 26 km2 volcanic crater lake - is one such system whose recent (c. 2020) algal blooms have raised concerns among local authorities due to the Lake’s importance to the economies of nearby communities. The Lake’s algal blooms - which at times occupy up to a third of the water’s surface - are also apparent in the satellite imagery. We compiled Earth observation data from 2003-2024 to evaluate trends and potential drivers, including daytime and nighttime water surface temperature, incident radiation, precipitation, and the normalized difference vegetation index for the surrounding watershed which drains into Lake Coatepeque. Chlorophyll a concentrations and estimates of water turbidity were also extracted from the satellite data record. Preliminary analysis suggests that various environmental factors might be at play in triggering the algal blooms. The water surface temperature has been shown to increase over the last ten years, in tandem with increases in long-wave incident radiation and the concentrations of photosynthetic pigments. This work analyzes long-term trends on water temperature, algal bloom presence, precipitation, runoff and land cover changes to identify the main potential drivers of algal blooms in these crater lakes. Given the similarities between the proliferation of algal blooms in Lake Coatepeque and Lake Atitlan, the NASA/ USAID SERVIR program aims to apply an analogous predictive model successfully implemented for the latter to help local decision-makers in monitoring efforts by identifying when algal blooms are likely to occur in Lake Coatepeque.

December 11, 2024

12:00 AM

Washington DC

American Geophysical Union (AGU) Fall Meeting