The volatilome reveals toxicity, microbial composition, and indicators of ecosystem stress in a critical Oregon freshwater lake

Abstract

Toxins commonly produced by cyanobacterial blooms in freshwater lakes are a serious public health problem. The conditions leading to toxin production are currently unpredictable, thereby requiring expensive sampling and monitoring programs globally. We explored the potential of volatile organic compounds (VOCs) to indicate water toxicity and microbial community composition in Upper Klamath Lake, OR. Elastic net regularization regression selected 29 of 229 detected m/z + 1 values (corresponding to unique VOCs) in models predicting microcystin toxicity that outperformed or significantly improved upon regression models based on environmental parameters, such as chlorophyll, pH, and temperature. Several m/z + 1 values are tentatively identified as epinephrine pathway metabolites, indicating organismal stress associated with microcystin production. Unique sets of m/z + 1 values were also identified by elastic net regression that predicted the relative abundance of the most dominant bacterial phyla, classes, and cyanobacterial genera. These results show that VOCs may be a key component of lake monitoring strategies.