The restoration of damaged ecosystems utilizes vast resources and ecological knowledge to build functioning and resilient ecosystems. Biodiversity restoration, a critical step in this process, increases the likelihood that present species are well-adapted to the environment or can complement each other in resource use. At the population level, genetic diversity can increase establishment rate, increase resistance to invasion, and enhance resilience in a changing world. Submersed aquatic vegetation (SAV) provides vital ecosystem functions in freshwater and estuarine systems, such as attenuating waves, capturing sediments, immobilizing nutrients, and providing food web support. In the twentieth century, increased nutrient loading in many aquatic systems led to widespread declines in SAV. Recovery of SAV is impeded by continued chronic light limitation, and by low restoration survival due to transplant and environmental stresses. To test the importance of genetic identity on aquatic plant establishment and performance, I planted 24 genotypes of the submersed aquatic macrophyte Vallinsneria americana at three field sites in the Hudson River Estuary, predicting that genotypes would differ in their survival and performance. I established colonies of clonal propagules called turions in biodegradable bags anchored to the riverbed, predicting that this method would reduce transplanting stress and increase survival and establishment.
Results/Conclusions
Colony survival was high at two of the sites (0.55 and 0.81, respectively), but the third site was completely washed away. The two surviving sites showed variation in the height of the plants produced (p<0.05) and their overall biomass (p<0.01). These results highlight the importance of restoration site selection, and suggest that the method of planting turions in bags anchored to the riverbed increase the likelihood of colony success. Turions are useful for restoration planting because of they are easy to plant and transport and are not prone to transplanting stress. Prior to planting, all turions were weighed and measured. An initial genotypic variation in turion size (p<0.001) persisted throughout the growing season until the plants were harvested, after about ten weeks of growth. The genotypic variation was reflected in plant height (p<0.05) and number of shoots (p<0.01) but not in overall biomass, suggesting that genotypic identity should be taken into consideration in SAV restoration planning. Although large turions initially produce larger plants, it is important to incorporate a range of genotypes to ensure the long-term success of the population. The overall results of this experiment provide recommendations to aquatic managers for restoration site selection and methodology.