Date of Award


Document Type

Honors Thesis (Open Access)


Colby College. Biology Dept.


Catherine Bevier

Second Advisor

Chris Moore

Third Advisor

Judy Stone


Najas minor (European naiad), a relatively new invasive aquatic plant to the state of Maine, is thought be spreading more aggressively than previous invasive aquatic plants have. Once established, N. minor grows into dense monocultures that replace all native plant species, leading to a disruption in ecosystem functioning, a loss in food and habitat for invertebrates and fish, and a decrease in the recreational value of a waterbody. Understanding the natural history of N. minor – how it is dispersed and how long seeds can survive – is important for understanding the invasive potential of the species. However, no previous studies have assessed the effectiveness of waterfowl as dispersal vectors of N. minor or if N. minor seeds can remain dormant in the sediment for multiple years. In this study, I fed N. minor seeds to captive domesticated mallards to see if seeds could survive passage. I collected and searched excreta for surviving seeds and tested the viability of all seeds recovered. I recovered a median of 10.7% of seeds from the excreta, 50% of which were still viable, suggesting that waterfowl can disperse N. minor. My dormancy study did not yield any results. I then created a spatially-explicit probabilistic model in R to assess the potential distribution of N. minor in Maine in twenty five and fifty years. While wildlife can disperse invasive species to new areas, human activities are still the biggest pathway for the spread of invasive species, and preventative actions should be taken whenever possible.


Invasive Aquatic Plants, Waterfowl Dispersal, Seed Dormancy, Endozoochory, Probabilistic Model