| dc.description.abstract | Environmental DNA (eDNA) has proven to be a valuable tool in detecting rare or
invasive species, particularly within the Great Lakes and surrounding aquatic ecosystems.
Recent work has shown that sedimentary eDNA (sedDNA) can reveal temporal changes
in ecological community composition and can potentially be used to provide restoration
guidelines for impacted ecosystems. However, uncertainties currently exist regarding the
application of eDNA techniques in both sediment and aquatic freshwater ecosystems. For
example, little is known regarding how diel movements affect the short-term persistence
and transport of invertebrate eDNA within freshwater lakes and streams. In this study, I
examined the effectiveness of both aqueous eDNA and lake sedDNA sensitivity to the
presence of Mysis diluviana, a keystone macroinvertebrate species. Water and sediment
samples were collected from five lakes at the IISD-Experimental Lakes area in
Northwestern Ontario. Mysis sedDNA was extracted from sections of both freeze and
gravity cores and tested using quantitative polymerase chain reactions (qPCR) to evaluate
preservation and down-core presence. Day and night eDNA samples were analysed
during the fall and compared across the epilimnion, metalimnion, and hypolimnion to
assess the short-term persistence within a stratified lake. Water samples were collected
between June until October of 2019 from a stream connecting two of the study lakes to
examine the effect that seasonal variation within a stream may have on downstream
sedDNA distribution. My results demonstrated that the occurrence of Mysis eDNA in
dated sediment freeze cores closely matched known historical distributions. Further, the
absence of significant day/night differences in Mysis eDNA between thermal layers in the
fall indicates the persistence of eDNA in water over short time intervals. Similarly, high
concentrations of Mysis eDNA in streams during fall compared to summer months
provided further evidence for persistence as well as transport among lakes during certain
time periods. My work demonstrates a valuable method to reconstruct past occupation
histories and provide restoration guidelines of impacted ecosystems when applied to
sediments by indicating candidate lakes for potential biological reestablishment, as well
as indicates spatiotemporal factors that should be considered in the design of eDNA
surveys. | en_US |
