The Choptank watershed is an ecologically and economically valuable resource and designated Habitat Focus Area. We are collecting and synthesizing biological, chemical, and physical data to characterize the condition of the watershed and identify land use impacts on the environment. This project provides baseline information to assess management actions to improve water quality and health of estuarine and coastal habitats, building on previous ecological assessments around the Chesapeake Bay.

Why We Care
The Choptank River and watershed provides food and habitat such as wetlands, oyster reefs, and freshwater streams for many Chesapeake Bay species including commercially important striped bass, blue crabs, and oysters. It supplies valuable seafood and supports agriculture as well as recreational fishing, boating, hunting, and other activities. As population growth and development in the region continue to increase, the watershed’s residents, county planners, and state managers are facing major challenges in their efforts to preserve fisheries, wetlands, and other valuable ecological resources.

Designation as a NOAA Habitat Focus Area (HFA) has served as a catalyst in the Choptank River Complex for the integration of activities related to habitat restoration, science and monitoring, and community engagement. To understand changes and progress in the watershed, it is critical to better understand human stressors and ecosystem variability, to investigate baseline conditions, and predict how these conditions may change over time due to changes in climate, land use conversions, and competing economic and social priorities. NCCOS scientists are conducting an assessment to characterize the ecological condition of the Choptank watershed and to provide a baseline of information for measuring the success of restoration activities. This information is useful to managers balancing the practical requirements of a growing human population against the integrity of the Chesapeake Bay ecosystem.

The project is being conducted by NCCOS scientists in collaboration with other NOAA scientists and in partnership with the NOAA Office of Education, Maryland Department of Natural Resources, and Creighton University.

What We Did and Are Doing
The team created a Digital Atlas of the Choptank HFA, consisting of three products: a baseline status report, an online mapping tool, and a distributable geospatial database. The researchers compiled GIS data sets in Phase I of the Choptank ecological assessment. The three products of the Digital Atlas focus on collecting and integrating information on several key topics for natural resource management, specifically:  landcover, shoreline condition, water quality, benthic invertebrates, submerged aquatic vegetation, fish, and oysters. The status report provides information on the current status and trends in resources and environmental variables. The online mapping tool allows users to focus their analysis on particular areas and to integrate information on environmental variables and resource distributions. The distributable geospatial database allows experienced users to conduct customized analyses and produce tailored results. Together, these products will provide researchers, managers, and the public with a greater understanding of natural resources and environmental factors in the Choptank HFA.

In the Tred Avon River, an important tributary of the Choptank, the impacts of land use characteristics on the health of the aquatic ecosystem are being assessed in a 3-year study (2015–2017). This study is targeting selected tributaries representing different land uses (developed, row crop, and mixed forest) in the Tred Avon. In our analysis of the information collected during the study, we will look for correlations between the conditions found and influencing factors such as land use or other patterns. The work builds on previous ecological assessments conducted in the Chesapeake Bay using a suite of observations focused on water quality and aquatic organism health.

Analysis of these indicators and their relationship to land use revealed patterns that provided insight into the trade-offs between land development and aquatic ecosystem health. The researchers are examining the following indicators at each of eight sites in the Tred Avon River:

•  Water quality (temperature, salinity, dissolved oxygen, turbidity, nutrients, and chlorophyll-a)
•  Benthic habitat condition and health
•  Sediment and fish tissue contaminants
•  Fish community composition (abundance and diversity)
•  Fish health assessment

The team converted, calibrated, and corrected WorldView satellite imagery of the Choptank watershed collected in 2015. Further, they conducted ground-truthing exercises in both 2015 and 2016 to verify and estimate wetland coverage, riparian buffers and other physical habitat features. Ground-truthing allows satellite image data to be related to real features on the ground, enables calibration of remote sensing data, and aids in the interpretation and analysis of what is being sensed. The data provide a baseline of wetland health and plant biomass and productivity against which future restoration activities in the region can be measured. High resolution maps created from the satellite imagery will be useful for assessing marsh health and vegetation growth.

A suite of models is being applied to evaluate current nutrient-related water quality conditions and to quantify ecosystem services of nutrient removal through filtration by oysters at restored oyster reefs and aquaculture sites. Estimates of oyster ecosystem services will be used by an economist for a valuation study to assess the benefits of oyster restoration in the Choptank watershed.

Insights gained from the digital atlas, Tred Avon ecological assessment, remote sensing of vegetation in the Choptank, and eutrophication and oyster modeling studies will provide a baseline of information against which restoration efforts in the Choptank HFA can be measured. This information will be valuable to county land planners as population growth continues to increase in the region and may be applicable to other tributaries of the Chesapeake Bay similarly affected by increasing growth and development.

Next Steps
The Choptank ecological assessment is being conducted to establish its baseline condition and to look for linkages between types of land use, or other stressors, and ecological condition of adjacent waters. We will combine data assimilation and mapping capabilities with a suite of bio-indicators to assess habitat quality. A holistic evaluation of ecosystem health can better inform management decisions and establish benchmarks for restoration efforts. Ultimately, much of the science developed and integrated through this project will be provided to management partners, such as the National Marine Fisheries Service, Maryland Department of Natural Resources, and the Chesapeake Bay Program.

This project will engage local, state, regional, federal, and non-governmental stakeholders to inform them of the digital GIS-based atlas and high resolution marsh vegetation maps and to address their information needs to best apply the atlas and mapping products to their management decisions.

Treasuring the Choptank: Residents and Scientists Envision a Healthier Chesapeake Bay (VIDEO)
Watch this short video to find out more about what NOAA and its partners are doing to restore the Choptank River: