1999 Progress Report: The Choptank River: A Mid-Chesapeake Bay Index Site for Evaluating Ecosystems Responses to Nutrient ManagementEPA Grant Number: R826941
Title: The Choptank River: A Mid-Chesapeake Bay Index Site for Evaluating Ecosystems Responses to Nutrient Management
Investigators: Malone, Thomas C. , Boicourt, William C. , Cornwell, Jeffrey C. , Harding Jr., Lawrence W. , Stevenson, J. Court
Institution: University of Maryland Center for Environmental Science
Current Institution: Horn Point Laboratory
EPA Project Officer: Packard, Benjamin H
Project Period: September 15, 1998 through September 14, 2001 (Extended to September 14, 2002)
Project Period Covered by this Report: September 15, 1998 through September 14, 1999
Project Amount: $596,097
RFA: Ecological Effects of Environmental Stressors Using Coastal Intensive Sites (1998) RFA Text | Recipients Lists
Research Category: Ecosystems , Ecological Indicators/Assessment/Restoration , Environmental Statistics
Objective:The primary goal is to develop and examine methods for detecting responses to anthropogenic stresses in the Choptank River Index Site and to establish the site as a sentinel of change for a broader domain of coastal plain ecosystems. Of particular interest are the impacts of meteorological fluctuations and nutrient management in the Choptank drainage basin on water quality and living resources in the estuary. The intent is to resolve responses caused by human activities from the variability imposed by nature, to develop key indices of ecosystem change, and to predict trends and their consequences.
Progress Summary:The success of our effort toward establishing the Choptank River Index Site was due in part to design, but also to fortuitous events. The first event was the drought of 1999, with the resulting low runoff from land providing an extreme case from which to compare normal or wet years. A strong additional boost to this project's fortune has come from new research awards for highly complementary studies, and from cooperative interactions with other research and monitoring efforts. The primary achievements of this first year have been the establishment of the monitoring program, a set of special studies, and the development of a simple nutrient exchange model for the Choptank River. This model (Carstensen, et al., 1999) has been calibrated, not only with historical data, but also with data acquired from the monthly Coastal Intensive Site Network (CISNet) surveys.
Two primary sampling strategies are being used to attack the problem of detecting ecosystem change within a background of natural variability. In addition to traditional shipboard sampling and retrospective data analyses, new high-resolution sampling technologies have been used to measure key variables. These techniques include remote sensing from aircraft and continuous, autonomous measurements from buoy-mounted sensors reporting in real time via radio telemetry. The use of both traditional and innovative techniques has a dual purpose: to employ advanced technology to aid the process of developing indices of ecosystem health, and to carefully examine the benefits of these (often more costly) methods in the monitoring process. Monthly shipboard and remote surveys along the 60-km axis of the Choptank River were initiated in January 1999. In conjunction with these surveys, 11 aircraft remote sensing flights were conducted on the Choptank and Patuxent Rivers to measure chlorophyll and temperature distributions. Chlorophyll concentrations were low in both tributaries compared with long-term averages. These low concentrations were likely associated with low flow from the rivers and tributaries of the Chesapeake Bay during the protracted drought, and mirrored low chlorophyll concentrations in the main stem of the Bay.
The Choptank River CISNet Buoy was launched at the Castle Haven Narrows in the lower Choptank River estuary in February 1999. Continuous temperature, salinity, fluorometry, and meteorology sensors were affixed to the Castle Haven Buoy and to the Dover Bridge in the upper estuary. Similar sensors and ISCO whole-water samplers were attached to three dock-based sites along a lateral transect extending across the lower Choptank River and up a primary tributary, the Tred Avon River. Atmospheric nutrient samplers were placed at a variety of locations within the Choptank watershed and on the Castle Haven Buoy. A new W.S. Ocean nitrogen sampler was successfully deployed on the buoy.
These serial and continuous measurements were complemented by special-focus studies of higher intensity, aimed at questions concerning scientific process and monitoring technique. Twelve marsh cores were used for determining sedimentation rates and rates of nutrient burial. These cores, in conjunction with nine dated cores previously dated, will provide critical information on the spatial variability of these burial processes. High-resolution sampling using towed, undulating vehicles (SCANFISH, ACROBat) in conjunction with three monthly surveys revealed remarkable spatial detail of structure and exchange in the Choptank River with the adjacent Bay. A fixed tower was deployed near the Choptank Buoy to provide in situ optical data for the aircraft overflights.