Why Monitor Our Waters?

How can real-time monitoring help the Indian River Lagoon?

Monitoring conditions in the Lagoon is equivalent to what doctors do for patients. They use the information that they get from their monitors in order to determine what is wrong with a patient and to be sure that whatever they are doing is making the patient better and not worse.

ORCA's goal is to provide the information that is needed to determine what aspects of the Lagoon have become unhealthy and what we can best do to put things back in balance.

All animals have a set of preferred environmental conditions in which they thrive. Outside that range they may survive but not thrive. Far enough outside that range they will die.

Factors like temperature, salinity (how much salt is dissolved in the water), dissolved oxygen (how much oxygen is in the water), pH (how acidic the water is) all impact animal survival. Animals may have a wide range of tolerances for some factors and a narrow range for others. By monitoring these factors we can help assure that the environmental factors stay within a range that will optimize survival.

Learn the definitions and normal ranges of environmental variables measured by Kilroy in the Indian River Lagoon: Kilroy Terminology.

A few examples of questions that can be answered and problems that can be addressed with monitoring:

  • How long are oysters being exposed to salinity levels below their tolerance during dumps from Lake Okeechobee?
  • How much is the sun being blocked by turbid (cloudy) water coming out of the drainage canals?
  • What are the major contributing sources of nitrogen to the lagoon? (Nitrogen fuels algae blooms) Is it coming from agriculture, lawns, septic systems, or waste water treatment?)
  • What events precede decreased dissolved oxygen and fish kills?
  • What is the acidity of the water and how is it impacting shellfish growth?

By answering these questions we can determine where best to spend limited resources including tax dollars. We can also provide feedback to stakeholders as to whether management goals are being met and funds effectively spent.

An example of a direct effect

Artificial wetlands and storm water treatment areas are used to reduce nutrient loading from the watersheds. There is a physical limit to the amount of water that can be successfully diverted through a wetland - natural or artificial. If the flow through the wetland becomes energetic enough to erode the fine sediments, then the fine sediments, which naturally filter the water themselves, become contaminants and are transported by the water, often to become problematic elsewhere. Real-time feedback from Kilroy's™ flow and turbidity measurements can assure optimum flow and therefore maximum benefit from natural and artificial wetlands.

Water temperature (°C) - influences the distribution of plants and animals that reside within certain temperature ranges. As water temperature increases, dissolved oxygen decreases. Ocean temperatures can range between about -2 and +40° C. Off shore Fort Pierce waters normally range between 20-30° C. Indian River Lagoon waters range between 5-35° C.

Salinity value measured in Practical Salinity Units (PSU) - a measure related to the dissolved salt content of water. Average ocean salinity is 35 grams of salt in 1000 grams of water, which is expressed as 35 parts per thousand or 35 ppt or 35‰. Salinity and dissolved oxygen have an inverse relationship; as salinity increases the amount of oxygen that can dissolve in water decreases.

Dissolved oxygen concentration measured in mg/l (parts per million or ppm). Air equilibrated seawater (35 ‰ at 10° C) is 8.6 mg/l. Levels below 5 mg/l may be stressful for many aquatic creatures and levels below 1-2 mg/l for a few hours can result in fish kills. Large nutrient inputs can stimulate algal blooms, which generate oxygen as they photosynthesize but when the algae die decomposer organisms break down the organic material and consume oxygen in the process leading to a drop in dissolved oxygen.

pH is a measure of how acidic or basic a solution is on a scale from 0-14; with 0-6 acidic, 7 neutral, and 8-14 basic. A difference of 1 pH unit means a 10 times difference in acidity. pH of surface seawater has dropped from about 8.25 to 8.14 since pre-industrial revolution, which represents a 29% increase in acidity. Increasing acidity inhibits calcification in corals and shellfish.

Turbidity measured in Nephelometric Tubidity Units (NTU) - a measure of water cloudiness. Turbidity increases with growth of phytoplankton, sediment run-off from the land, and bottom sediment disturbances as from storms, dredging or boat traffic. High turbidity prevents sunlight from reaching submerged aquatic vegetation such as sea grass, which provides food for manatees and critical habitat for fish and invertebrates such as shellfish and shrimp. According to Florida DEP "Potential turbidity-producing activities should not increase surface water turbidity by more than 29 NTUs above natural background conditions for all classes of surface water in the state of Florida."

Nitrate measured in ppm or mg/L - is a nutrient that can trigger algae blooms including red tides, which produce toxins that may be injurious to marine organisms and humans. At levels over 30 ppm nitrate may be directly toxic to marine organisms.

Flow direction measured in degrees where 0° (or 360°) is N, 90° is E, 180° is S and 270° is W - is the direction water is flowing. Flow direction (also known as the bearing) changes with the tides. Water movement can transport organisms, oxygen, nutrients, sediment, and wastes.

Flow speed measured in meters per second (m/s) - determines how rapidly organisms and substances are transported.

Depth measured in meters (m) - refers to the depth below the water surface where a particular Kilroy is installed. It is a relative measure, which tracks changing tides and storm surge.




Kilroy Monitoring
View map of Kilroy Monitoring Systems for State of Florida project.
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Eighty percent of all pollution in seas and oceans comes from land-based activities. Three-quarters of the world's mega-cities are by the sea.

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