Ph.D., Entomology, University of Minnesota, St. Paul, MN (2014)
Advisor: Leonard C. Ferrington, Jr.
Dissertation: Communities in Freshwater Coastal Rock Pools of Lake Superior, with a Focus on Chironomidae (Diptera).
B.S., Fisheries and Wildlife (Entomology and Biology Minors), University of Minnesota, St. Paul, MN (2007)
A.A.S., Park and Recreation Management, Vermilion Community College, Ely, MN (1998)
Exposed freshwater shores have received little ecological attention. At Isle Royale, an archipelago in Lake Superior, coastal areas have a moderated climate due to the large, deep lake. This project was instigated because 1) little was known about coastal ecosystems at Isle Royale, 2) unique aquatic species were expected in this habitat, 3) potentially disastrous impacts from shipping accidents could cause population losses of sensitive species, and 4) long-term shifts in climate could influence communities via warming conditions and erratic precipitation. Focal habitats were pools on the open shore, formed in bedrock depressions from precipitation, ground water, overland flow, and wave wash. The focal study taxon was Chironomidae, a diverse family of aquatic flies, well-known for variable responses to pollution and ecological gradients.
Results showed a surprisingly species-rich (n = 102) and diverse assemblage. Moderate to extreme range expansions and novel habitat use were documented. Distinct communities were observed between two vertical zones, based on distance from the lake. Differences in seasonal emergence occurred close to the lake, but emerging assemblages were similar across seasons above lake influence. Some evidence supported both biogeographic community variation based on distances between islands and control of emergence events by water temperature. However, there was no evidence that pool depth or potential for desiccation influenced chironomid occupancy. Nutrients (phosphorus, nitrogen, and carbon) were the most important factors driving chironomid assemblage differences. Pools higher on the shore showed nutrient input from upland habitats, while pools lower on the shore appeared to have nutrients flushed out by wave action and replaced with low-nutrient water. Comprehensive habitat mapping revealed high pool densities, with an extraordinary number on Passage Island, arguably the most threatened locality to shipping pollution. Also, Passage Island had the highest density of Pseudacris triseriata, a frog species with a remarkably narrow habitat use at Isle Royale. Overall, a diverse community was revealed in what superficially looks like unremarkable habitat. Apparent similarities to northern and western shores of Lake Superior suggest this study of basic aquatic ecology and physical structure describes reference conditions for coastal management across much of the lake.
Egan, A. T., L. C. Ferrington, T. Lafrançois, M. B. Edlund and J. McCullough. 2015. Spatial arrangement and metrics of freshwater coastal rock pools applied to amphibian conservation. Limnologica 51: 101-109.
Egan, A. T. and T. J. Gostomski. 2013. Landbird population trends at Isle Royale National Park, Michigan: 1996-2012. Natural Resource Technical Report NPS/GLKN/NRTR—2013/692. National Park Service, Fort Collins, Colorado.
Egan, A. T., J. D. Kaplan, K. B. Tischler and D. L. McCormick. 2013. Breeding atlas for the common loon (Gavia immer) at Isle Royale National Park, Michigan. Natural Resource Report NPS/ISRO/NRR – 2013/728. National Park Service, Fort Collins, Colorado.
Egan, A. T. 2009. Breeding bird monitoring at Isle Royale National Park, Michigan: 1996-2008. Natural Resource Technical Report NPS/GLKN/NRTR-2009. National Park Service, Fort Collins, Colorado.
Egan, A. T and L. C. Ferrington. 2014. Seasonal Variation in Chironomid Emergences from Freshwater Coastal Rock Pools. Oral presentation to International Symposium on Chironomidae, České Budějovice, Czech Republic.
Egan, A. T and L. C. Ferrington. 2013. Forest to Freshwater: Chironomidae community structure in coastal rock pools of Lake Superior. Oral presentation to Society for Freshwater Science Conference, Jacksonville, FL.
Egan, A. T. 2012. Aquatic communities of coastal rock pools as management indicators for climate change and shipping lane pollutants in the Great Lakes. Oral presentation to the Western Great Lakes Research Conference, Ashland, WI.
Egan, A. T. and L. C. Ferrington. 2011. Early season emergence of Chironomidae from coastal rock pools at Isle Royale National Park, Michigan. Poster presentation to the North American Benthological Society Conference, Providence, RI.
Egan, A. T. 2009. Breeding bird monitoring at Isle Royale National Park: 1996-2008. Oral presentation at the Western Great Lakes Research Conference, Ashland, WI.
Egan, A. T. 2008. The synthesis of research and education at Isle Royale National Park. Oral presentation to the Great Lakes Network Conference: Linking Research and Education, Indiana Dunes, IN.