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Sanctuary Rocky
Intertidal Open
Ocean & Endangered
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Water quality in many surface waters in the contiguous forty-eight states fails to meet the goals of the Clean Water Act of 1972. The severity of the problem is illustrated by the nutrient-rich water (largely derived from rainfall runoff from farms) entering the Gulf of Mexico from the Mississippi River. The river has created a plume in the Gulf, called the ‘dead zone,' which can be 7,000 square miles in size. Fortunately, water quality in Monterey Bay is good compared to the Gulf of Mexico, since it is well mixed with the Pacific Ocean. Nevertheless, surface waters in Pajaro Valley, the Elkhorn Slough Estuary (in areas with limited mixing with the bay), and Salinas Valley have elevated nitrate levels. Vegetative buffer strips can successfully reduce pollutants generated by rainfall runoff from entering surface waters. Vegetative buffers are areas of vegetation that capture pollutants physically or transform them to non-mobile (such as soil organic matter) or gas (such as di-nitrogen, nitrous oxide) forms. Their success is best documented along the Atlantic Coastal Plain, but has been promoted in many states. With funding from the National Oceanic and Atmospheric Administration, vegetative buffer strips were established in Elkhorn Slough to test their efficacy in removing sediments and nutrients before they entered the Slough. Three treatments -- an annual grass, a mix of native perennial grasses, and an "unplanted" (weedy) treatment -- of buffers were established to receive runoff from row crops. All buffer treatments successfully reduced sediments within the first few meters of the buffers after above-ground biomass had become well established. Sediment removal was due to increasing water infiltration and slowing runoff velocities in the buffers that allowed sediment deposition. However, nutrient capture is more complicated because its removal is biologically mediated. In contrast to the Atlantic Coastal Plain, rainfall along the Monterey Bay coast is restricted to the winter months; thus processes that remove nitrogen vary dramatically on a seasonal basis. I found that nitrogen was captured by growing plants and soil microbes in the winter and spring, which suggested that grass buffers assimilate nitrogen from agricultural runoff. In contrast to the winter and spring, plant material and soil microbes died in the summer and fall. Because of their death, nitrate and ammonium forms of nitrogen, which were previously captured in the spring, were released into the soil. High concentrations of soil nitrate in the fall can be carried to the Slough after the first rainfall events through subsurface flow. Results from all three treatments suggest that nitrogen retention by vegetative buffers in California may not be as successful as grass buffers in other parts of the country. Nitrogen cycling in soils is one source of the trace gas nitrous
oxide -- a greenhouse gas. In the buffers established, the estimated
trace gas emissions were extremely high. Therefore, even though
nitrogen is being removed from groundwater before entering Elkhorn
Slough, some of the nitrogen is converted to a greenhouse gas.
Vegetative buffers convert a water pollutant into an atmospheric
pollutant, although the significance of this source of nitrous
oxide is currently under investigation. This study should be used
to highlight some limitations for using vegetative buffer strips
to reduce nitrogen pollution. Instead, vegetative buffer strips
should be seen as only one potential strategy and used in concert
with other strategies to control nitrogen losses from agricultural
fields. Marc Los Huertos
On Earth Day 2000 the Monterey Bay National Marine Sanctuary helped lead the charge in the largest simultaneous water quality monitoring effort to occur in California. More than 120 trained volunteers participated in "Snapshot Day," a Sanctuary-wide volunteer monitoring event designed to increase public awareness about water quality issues affecting watersheds that drain to the Sanctuary. Armed with test tubes, thermometers, buckets, and cameras, volunteers fanned out into the Sanctuary's eleven major watersheds, from Pacifica to Cambria. By early afternoon, volunteers had tested eighty-nine rivers and creeks at 122 different sampling sites, spanning over 300 miles of the central coast. They monitored for air and water temperature, dissolved oxygen, pH, conductivity, nutrients, and bacteria levels. The results showed overall water quality in many of the Sanctuary's watersheds to be very good. The volunteer data did indicate problems, however, in several watersheds. Eighteen sampling sites displayed high levels of fecal coliform bacteria, indicating waters unsafe for contact. Sixteen sites were found to have high levels of nitrates or phosphates, which can have negative impacts on aquatic life. These contaminants were found in both urban and rural locations. Several rivers and creeks also showed low levels of oxygen, which all aquatic animals need to breathe.
The data collected from Snap- shot Day help establish much-needed baseline information about the health of Sanctuary watersheds as well as flagging potential problem areas. Currently, fewer than 5 percent of California's water bodies are tested on a regular basis by government agencies, due to lack of funds and/or staff. The information collected from. Snapshot Day in 2000 and subsequent years can be used by resource managers to help make planning decisions and protect Sanctuary resources better. Snapshot Day was organized as part of the Monterey Bay Sanctuary Citizen Watershed Monitoring Network, established by the Coastal Watershed Council, the Center for Marine Conservation, the Regional Water Quality Control Board, and the California Coastal Commission in partnership with the Sanctuary's Water Quality Protection Program. The Network supports the year-round efforts of approximately twenty existing volunteer monitoring groups throughout the Sanctuary and its watersheds. Its goals are to ensure high quality data, to facilitate public and agency use of that data, and to increase public stewardship of local waterways within the Sanctuary's watersheds. For a more detailed look at Snapshot Day results, see the Snapshot Day Report on the Sanctuary's Web site: montereybay.nos.noaa.gov/ monitoringnetwork/welcome.html.
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For comments or question please refer to the Webmaster Last modified on: Jan 15, 2000 |
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