Gennifer M. RubinFollow

Date of Award

2023

Document Type

Honors Thesis (Open Access)

Department

Colby College. Environmental Studies Program

Advisor(s)

Denise Bruesewitz

Second Advisor

Peter Countway

Abstract

Episodes of cyano-harmful algal blooms (cyano-HABs) are hypothesized to be exacerbated by the effects of climate change. However, the dynamics of the interactions between elements of climate change and toxigenic cyanobacteria proliferation are not well defined. China Lake is the drinking water source for 7 municipalities in the Kennebec County and is one of many lakes in central Maine that has been subjected to high levels of cyano-HABs and microcystin toxin contamination in recent years. Monitoring the toxicity of these blooms in relation to various aspects of climate change may lead to identification of the major drivers of microcystin production in cyanobacteria. Quantitative polymerase chain reaction (qPCR) analysis of lake water samples can detect low-level presence of the microcystin producing gene mcyE in cyanobacteria. This method of toxin analysis is emerging as one of the most efficient in estimating toxin presence in lakes. eDNA analysis via qPCR provides species specific toxin producing gene quantification, allowing for identification of dominant toxin producing species trends as well as trends in the presence and absence of toxin producing genes during bloom seasons. During the 2022 bloom season, China Lake experienced cyano-HABs dominated solely by Microcystis until midway through the bloom season when sole dominance shifted to Dolichospermum. Presence of microcystin production potential was significantly correlated with low temperature and low drought index for toxin produced by Dolichospermum, however there were no significant drivers in the presence of the mcyE gene for Microcystis. This study is one of many research efforts contributing to the Maine eDNA Project, and provides insight into the nuances of examining drivers of cyanotoxin production to elucidate the functioning of cyano-HABs.

Keywords

Climate Change, Limnology, Public Health, Cyanobacteria

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