Print PageAlong with environmental tolerances and biotic interactions, dispersal represents a key determinant of whether an organism will persist in a given ecosystem. In the case of aquatic plants, major mechanisms of dispersal of seeds and vegetative structures among waterbodies are thought to include waterfowl, moose, and, more recently, human boats and trailers. Association with boater movement has received particular emphasis for its role in promoting biological invasion by vegetative fragments of aquatic plants. However, we hypothesize that movement through this pathway comes with a fitness cost: plant fragments desiccate during transport, resulting in reduced establishment success as a function of time or distance traveled.
We compared the desiccation rates of ten aquatic plant species following simulated overland transport to explore whether desiccation tolerance or resistance could explain establishment success. We air-dried plant fragments from each species for three different durations (0, 1, or 3hr), and then returned fragments to water to monitor survival and growth. Analyzed macrophytes included species native and introduced to North America as well as species with diverse physical architectures. We compared species’ desiccation rates and differences in survivorship between species. To relate this to potential real-world dispersal differences, we calculated maximum distances of overland travel that each species might be able to survive given our experimental results.
Results/Conclusions
Desiccation rates and recovery from similar lengths of desiccation time differed significantly between plant species and may thus be an indicator of aquatic plant dispersal capabilities. Logistic regression indicated that percent weight loss provided a significant predictor of whether a desiccated plant fragment would succeed or fail to recover upon returning to an aquatic environment. The relationship between desiccation weight loss and recovery differed between species. Under conditions of temperature and air flow like those simulated in our experiments, on average, a 20cm fragment of Hydrilla verticillata, the species with the fastest desiccation rate, would be likely to survive a trip of 9.8km or less, while a similar fragment of Myriophyllum heterophyllum, the species with the slowest desiccation rate would be likely to survive a trip of up to 54.9km. Our results illustrate the potential to improve understanding, prediction, and management of the anthropogenic dispersal of aquatic plants.
