Learn about the Back Bay Restoration Foundation and how you can help to restore Back Bay for the wildlife and future generations.
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Learn about the Back Bay Restoration Foundation and how you can help to restore Back Bay for the wildlife and future generations. |
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Site Index
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WATER QUALITY MONITORING PROGRAM Each month for the past 12 years, BBRF representatives have collected and tested water samples from around Back Bay. We currently test the water monthly, but the samples are taken to the Department of Environmental Quality (DEQ) every other month. We now sample seven sites along the western and northern boundaries of the Bay as part of the DEQ Tidewater regional Office’s Ambient Water Quality Monitoring See map. At each site, field tests including temperature, salinity, pH, conductivity, and dissolved oxygen are performed with one instrument called the Quanta. Through a grant from the Waterwheel Foundation and the band Phish, we were able to purchase the Quanta which has greatly facilitated our water quality monitoring. The bimonthly samples that we take are stabilized with ice and sent to the DEQ laboratory in Richmond for analysis of the following criteria: fecal coliforms, nutrients, and solids suspended in the water. For a separate description of each measurement criteria, see the discussion below. Testing occurs for chlorophyll on a quarterly basis; chlorophyll is an indicator of algal growth in the water. DISSOLVED OXYGEN Like land animals, aquatic animals need dissolved oxygen (DO) to live. Oxygen dissolves readily into water from the atmosphere at the surface and is also produced by aquatic plants. Without turbulence or currents in the water, the oxygen mixes slowly. The capacity to absorb oxygen is higher is cooler and less saline water. Living organisms increase their activity in warm water, requiring more oxygen at a time when more oxygen is used by algae and decaying material - therefore summertime fish kills. DO levels below 3 parts per million (ppm) are stressful to most aquatic organisms and above 5ppm are usually required for growth and activity. SALINITY Salinity, expressed in parts per thousand, is the total of all salts dissolved in water. Salt content affects the distribution of animal and plant species according to the amount of salinity they can tolerate. Back Bay salinity is influenced by Currituck Sound, the North Landing River, fresh water inflow from tributaries and wind driven tides. Values are generally low compared to sea water (3.5 parts per thousand). Conductivity is a measure of water’s ability to conduct electricity and increases with salinity. NUTRIENTS Various forms of the nutrients nitrogen and phosphorus are measured. Derived from fertilizer, animal wastes and air pollution, nutrients in excess promote algal growth that can block sunlight from reaching desirable submerged aquatic vegetation (SAV). After algae die and sink to the bottom, they are decomposed by bacteria, which require oxygen for their metabolism possibly causing oxygen depletion. TEMPERATURE Water temperature is one factor in determining which species may exist in an aquatic system. Temperature affects feeding, reproduction and the metabolism of aquatic animals. Optimum habitat temperatures may change for each stage of life. All species can tolerate slow, seasonal changes better than rapid changes. Thermal stress and shock can occur when temperatures change more than 1 to 2 degrees in 24 hours. Runoff from heated surfaces such as roads, roofs and parking lots can increase temperature while overhanging vegetation can lower temperatures by shading. pH A range of 6.5 to 8.2 is optimal for most organisms for this common measure of acidity (<7) or alkalinity (>7). Rapidly growing algae of SAV remove carbon dioxide from the water during photosynthesis, which can result in a significant increase in pH. Indirect effects of pH changes can affect aquatic life. For example, toxic metals from runoff trapped in sediment are released into the water at lower pH levels. SOLIDS Turbidity, cloudiness of water, is caused by suspended solid matter, which prevents light from passing through the water. SAV needs that light for photosynthesis. Sediment from disturbed or eroded soil, is a major contributor to turbidity. Sediment can also bury eggs and bottom dwelling creatures. Laboratory analysis is now the method used to determine suspended solid amounts. In the past secchi depth determined turbidity by gauging the loss of visibility of this disk painted with black and white quadrants. FECAL COLIFORMS These disease causing bacteria are found in the feces of warm blooded animals. Potential sources for Back Bay include waste from farm animals, humans and pets. Nanney Creek is identified as a site with excessive levels of fecal coliforms from an unconfirmed source. |
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©Back Bay Restoration Foundation, 1999-2003. All rights reserved. The Back Bay Restoration Foundation is a charitable 501(c)(3) tax exempt organization. Call BBRF at 757-426-3643 or email us at 'b' 'b' 'r' 'f' at infionline.net for more information. |