Date Approved

8-2016

Graduate Degree Type

Thesis

Degree Name

Biology (M.S.)

Degree Program

Biology

First Advisor

Amy L. Russell

Second Advisor

Meg Woller-Skar

Third Advisor

Maarten Vonhof

Abstract

Microcystis aeruginosa is a species of cyanobacteria capable of producing a hepatotoxin called microcystin. As toxic M. aeruginosa overwinters in the sediments of lakes, it is ingested by some mayfly larvae, such as those of Hexagenia spp., and thus

microcystin bioaccumulates in these insects. When Hexagenia emerge from lakes to

reproduce, they provide an abundant, albeit temporary, food source for many terrestrial

organisms such as bats. Little brown bats, Myotis lucifugus, likely feed opportunistically

on aquatic insects. To test if microcystin moves from aquatic to terrestrial ecosystems via trophic transfer, we 1) tested bat feces for the presence of Hexagenia mayflies and 2) tested bat livers and feces for microcystin. In June 2014, in correspondence with the

Hexagenia emergence, bat feces were collected from underneath a maternity roost near

Little Traverse Lake (Leelanau County, MI). On 20 and 27 June we caught 19 female M.

lucifugus, which were euthanized, and collected their livers and feces. DNA was

extracted from feces, amplified with a Polymerase Chain Reaction (PCR), and sequenced. Concentrations of microcystin in liver tissue and feces were determined using an enzymelinked immunosorbent assay (ELISA) and liquid chromatography with tandem mass spectrometry (LC-MS/MS). Hexagenia were present in the diet of M. lucifugus and the most likely source of microcystin. Our analyses reveal that microcystin was also present, with higher concentrations in the bat feces than the livers. Additionally, histopathology results of three bat livers with highest concentrations of microcystin show little to no cytological damage from the toxin. From these data, it appears that M. lucifugus are not highly affected by the ingestion of microcystin.

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