Link between cattle and the trophic status of tropical high mountain lakes in páramo grasslands in Ecuador

Extensive cattle grazing in the high-altitude páramo grasslands of Ecuador's Andes significantly influences the trophic status of tropical mountain lakes, with cattle abundance emerging as a key predictor of chlorophyll-a concentrations. A survey of 30 lakes in Cajas National Park revealed that higher cattle presence correlates with increased phytoplankton biomass and shifts in community composition, favoring diatoms and dinoflagellates over chlorophytes. Notably, Lake Culibrillas in Sangay National Park, where livestock farming is more intensive, exhibited chlorophyll-a levels more than double those observed in Cajas NP lakes, marked by a pronounced dinoflagellate bloom. Despite these increases, water quality remained low in eutrophication terms (0.02–1.8 µg/L), suggesting that while current grazing practices do not cause severe degradation, further intensification could deteriorate lake conditions. The study highlights the potential ecological risks of expanding livestock farming in páramo ecosystems.

Van Colen, W., Mosquera, P. V., Hampel, H., & Muylaert, K. (2018). Link between cattle and the trophic status of tropical high mountain lakes in páramo grasslands in Ecuador. Lakes & Reservoirs: Science, Policy and Management for Sustainable Use, 23(4), 303–311. Portico. https://doi.org/10.1111/lre.12237