Water quality monitoring

 Oxygen is necessary for many aquatic species to survive. This test tells you how much oxygen is dissolved in water for fish and other organisms to breathe. Most healthy water bodies have high levels of DO. Certain water bodies, like estuaries, naturally have low levels of DO in the water. Lots of organic debris (fallen leaves, sewage leak) can cause a decrease in DO concentration. Microorganisms, in the process of decomposing the organic material, use all the oxygen in water. How does oxygen get in water in the first place? Much of the oxygen in water comes from plants during photosynthesis and also from air as windblows across the water’s surface and waves 

 pH, a measure of acidity, ranges from 0 (highly acidic) to 14 (highly alkaline), with 7 being neutral.  Most water sources fall between 6.5 and 8.5.  Since our bodies are primarily water (pH 7), substances close to this neutral pH tend to be most compatible with our physiology.  This is also true for aquatic life.  Increased acidity in water can be detrimental, particularly to invertebrates.  Their calcium carbonate (CaCO3) exoskeletons, being alkaline, are vulnerable to acidic conditions.  High acidity can hinder their development, especially during their planktonic larval stages.  Furthermore, increasing water temperature can also raise acidity, contributing to ocean acidification, a process that threatens the base of the marine food web. 

 Some organisms prefer cool water, while some like it warm. Most aquatic organisms are cold-blooded. This means that the temperature of their bodies matches the temperature of their surroundings. Reactions that take place in their bodies, like photosynthesis and digestion, can be affected by temperature. It is also important to know that when the temperature goes up, water will hold more dissolved solids (like salt or sugar) but fewer dissolved gases (like oxygen). The opposite is true for colder water. Plants and algae that use photosynthesis prefer to live-in warm water, where there is less dissolved oxygen. Generally, bacteria tend to grow more rapidly in warm waters. Colder water contains more oxygen, which is better for animals like fish and insect larvae. 

 Salinity Is the saltiness or dissolved salt content of a body of water. Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a thermodynamic state variable that, along with temperature and pressure, governs physical characteristics like the density and heat capacity of the water. Salinity is measured in ppt. Freshwater ranges from 0-.5 ppt, brackish water ranges from .6-29.9 ppt and 3saltwater in our oceans range from 30-35 ppt. 

 Turbidity refers to the clarity of water, or how clear it is. This determines how much light gets into the water and how deep it goes. Excess soil erosion, dissolved solids or excess growth of microorganisms can cause turbidity. All of these can block light. Without light, plants die. Fewer plants mean less dissolved oxygen. Dead plants also increase the organic debris, which microorganisms feed on. This will further reduce the dissolved oxygen. No dissolved oxygen means other aquatic life forms cannot live-in the water. After testing these parameters, make a note of the time of year, current weather conditions, cloud cover, air temperature and any other environmental observations that may affect the test.

 Nitrates can contaminate water sources, particularly groundwater and surface water, through runoff from fertilized fields, leaking septic systems, and animal waste. High levels of nitrates in drinking water can pose health risks. A process called eutrophication occurs when there is an excess of nitrates in surface water and leads to algal blooms or red tide in our estuary and nearshore habitats. 

 Plankton tows are a valuable tool for collecting microscopic marine life.  A net with a collection jar attached is towed through the water, capturing plankton while allowing excess water to escape through the mesh.  Longer tows generally collect more plankton.  A microscope is then needed to examine these tiny organisms.  

 The Durney Key photo posts are fixed 4x4 structure designed to help track changes over time. By using this post, visitors can take photos from the same position, height, distance, and angle each time, ensuring consistency. We invite everyone visiting Durney Key to contribute their photos.  These images will be invaluable in documenting the long-term impact of our efforts, creating a visual record similar to a time-lapse video