Submerged Aquatic Vegetation in the Hudson River Estuary: Incorporating Genotypic Identity and Richness into Restoration Design

Abstract

Dynamic tidal estuaries are characterized by fluctuating environmental conditions that can hinder the recovery and long-term persistence of submerged aquatic vegetation (SAV) beds. Within the Hudson River, Vallisneria americana populations have struggled to recover following major storm events in 2011 and continue to be affected by the loss of shallow-water habitat. Incorporating fine-scale genetic variation enhances adaptive capacity and recovery of SAV beds following disturbance. To evaluate the role genotypic diversity can play in restoration, I conducted controlled greenhouse experiments examining the growth and reproductive responses of four Hudson River-native Vallisneria americana genotypes to common environmental drivers. The same genotypes were subsequently planted at Stockport Flats, a freshwater tidal reach of Hudson River estuary, to evaluate survival and growth under field conditions. Greenhouse experiments revealed significant genotypic differences in clonal expansion, sexual reproduction, and overwintering turion formation across substrate, aeration, and fertilization treatments. In contrast, field trials demonstrated that habitat conditions largely masked underlying genetic differences and were the primary drivers of plant survival and growth. These findings suggest that greenhouse screening can identify robust, high-performing genotypes for restoration; however, the benefits of genotype selection may not be seen in the field until habitat stressors and unfavorable conditions are addressed. Findings from this work were synthesized into a handbook for practitioners that provides guidance on genotype sourcing, greenhouse propagation, and field deployment techniques for genotype-guided SAV restoration in estuarine systems.