Science Serving Maryland's Coasts


Resilience of Vallisneria americana in the Chesapeake Bay

Principal Investigator: 

Katharina A. M. Engelhardt

Start/End Year: 

2016 to 2018


Appalachian Laboratory, University of Maryland Center for Environmental Science

Co-Principal investigator: 

Maile C. Neel, University of Maryland, College Park, Department of Plant Science and Landscape Architecture

Strategic focus area: 

Resilient ecosystem processes and responses


Past catastrophic declines of submersed aquatic vegetation (SAV) in the Chesapeake Bay (CB) have reduced habitat extent and compromised the ability of SAV beds to resist environmental change or recover after a disturbance. As a result, many SAV beds are small and ephemeral with diminished capacity to function as sediment filters, shoreline buffers, and habitat for fish and shellfish. The objective of this study is to contribute to management solutions that enhance the resilience of SAV beds in the CB. We argue that quantifying connectivity among SAV beds is a research priority because if informs managers as to spatial structure needed for disturbed SAV beds to be recolonized or rescued by seeds, turions or plants dispersing from other SAV beds. We further argue that connectivity among SAV beds enhances genetic and phenotypic diversity, which provides the raw material for acclimation and adaptation. In support of these arguments we plan to test three hypotheses that determine whether 1. connectivity drives persistence and rate of recovery; 2. connected patches are higher in genotypic diversity; and 3. genotypes differ in functional traits and plasticity. We propose to work with Vallisneria americana, a SAV species that is abundant in fresh and oligohaline portions of the CB and is a target of restoration. Prior research funded by Sea Grant has shown us that V. americana in the CB is not one panmictic population, rather genetic substructures exist. Experiments provided evidence that populations differ in genotypic and phenotypic diversity. We propose to expand on this knowledge with an exciting interdisciplinary research program that integrates a) spatial and temporal analysis of SAV bed persistence and connectivity using digital annual coverages of SAV; b) genetic variation in ~700 V. americana genotypes sampled across 3 focus areas - Susquehanna Flats and Fishing Battery, Elk River, and Central Bay and c) in-depth greenhouse experiments with 100 genetically identified genotypes that evaluate functional diversity within populations and determines how this diversity affects resilience through flower and turion production. Results of the proposed project will inform strategies for selecting donor beds and provide the information necessary for prioritizing management areas to maximize connectivity among SAV beds and ensure resilience. We will communicate our conclusions to managers and policy makers within the Chesapeake Bay community (Maryland Department of Natural Resources, the Chesapeake Bay Foundation, and the Chesapeake Bay Program) through presentations, an outreach brochure, a podcast, and informal information exchange. We further propose to organize a SESYNC working group that will bring together scientists and economists to synthesize knowledge of SAV resilience across species and locations. This working group will include and reach out to managers, policy makers, students, and teachers to broaden perspectives and provide educational opportunities.