R/P-61

Impact/Outcome:

This section describes how this project has advanced scientific knowledge and/or made a difference in the lives of coastal residents, communities, and environments. Maryland Sea Grant has reported these details to the National Oceanic and Atmospheric Administration (NOAA), one of our funding sponsors.

RELEVANCE: Effective management of submerged aquatic vegetation (SAV) beds in Chesapeake Bay requires improved understanding of how water quality, climate, and other factors influence the beds' growth and survival. Early SAV simulation models have failed to reproduce observed trends of SAV recovery. One research project by this investigator was undertaken to help refine SAV simulation models and improve site selection for restoration. Another research project by the same investigator focused on the Susquehanna Flats' SAV bed in the upper Chesapeake Bay. The bed experienced a dramatic, but unexplained, resurgence and then was disrupted by back-to-back tropical storms in 2011. Restoration of SAV is important for improving water quality and fish habitat in the Chesapeake Bay.

RESPONSE: The principal investigator on this project is W. Michael Kemp, University of Maryland Center for Environmental Science, Horn Point Laboratory. The researchers have conducted aerial photo surveys and have collected samples for water quality and plant biomass analyses during several field visits. They also measured temperature, salinity, oxygen, chlorophyll, and turbidity.

RESULTS: Strong feedback processes are likely important in hastening recovery, according to time-series data about water quality that were collected inside and outside SAV beds. The growth of SAV improved water clarity within SAV beds, which in turn facilitated the further growth of SAV. This growth was influenced by high river discharge from the Susquehanna River caused by storms; the sediment-laden discharges tended to degrade water quality, but only extreme storms tended to overwhelm the feedback processes. During drought years, river flow declined; water quality improved, providing favorable growth conditions; and the bed expanded.

Researchers have met with colleagues from numerous agencies who have expressed interest in the study's implications for improving water quality models. A better understanding of the processes affecting the bed's growth may influence computation of TMDL (total maximum daily load) allocations, which restrict the loads of nutrients and sediments that may be released into the Bay. The researchers also presented their results to teachers and high-school and college biology students.