Date of Award


Publication Type

Master Thesis

Degree Name



Great Lakes Institute for Environmental Research


MacIsaac, Hugh


Cladocera, Great Lakes, Hamilton Harbour, Invasive Species, Monitoring, Non-Indigenous Species




Non-indigenous (NIS) have negatively impacted ecosystems worldwide. When a species is introduced, its population will generally be small. This is the best time to eradicate NIS, however, detection at this stage is difficult. I hypothesize that rare species will be more easily found as they become abundant, when sampling effort is increased, and morphologically distinct species are more likely to be detected. I spiked different densities of NIS into zooplankton samples from Hamilton Harbour to simulate rarity and assess detection rate with both microscopy and FlowCAM. My results indicate a positive relationship between detection and abundance, counting effort, and distinctiveness. FlowCAM can process more data, but morphologically similar taxa will be distinguished more readily with microscopy. This study provides tools to monitor rare aquatic species as well as a means to combat NIS at the frontiers of invasion and provides a way to further test hypotheses of establishment and invasion.