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Too Much of a Good Thing: Excess Nutrients in Estuarine Systems
11/19/2010 | Medea Steinman, (Ocean Systems)
Tags: 11.17.10 webinar, estuaries, concept mapping

A healthy eelgrass bed.
A healthy eelgrass bed.
Estuaries are bodies of water that freely connect to the sea and are diluted by freshwater draining off the land. These water bodies and their conditions are also influenced by tides.

Dr. Linda Kalnejais, an oceanographer at the University of New Hampshire, studies the effects that pollutants have on estuaries. She pointed out that 22 of the 32 largest cities in the world are located on estuaries. As a result, these unique ecosystems receive significant levels of pollutants.

For her talk, Linda focused on nutrients. These include chemicals like nitrogen, phosphorous and iron, which are necessary for the survival of organisms. However, when they accumulate in excess, nutrients can endanger the health of organisms by creating poor water quality conditions, even dead zones.

Salinity data collected from the Great Bay buoy - including the "Patriots Day Storm" which caused a rapid drop in salinity in April.
Linda shared some interesting graphs that illustrate how drastically salinity levels can change in estuaries and, therefore, how many fewer species are adapted to survive in these environments. Her first concept map is loaded with assets about the water cycle, watersheds, nutrients, and various sources contributing to water flow in estuaries, including the atmosphere and ocean.

In her second concept map, also chock full of assets, Linda explains the healthy role nutrients play for primary producers and other organisms living in estuaries. The map also illustrates the cascade of negative effects that an overabundance of nutrients can have in these systems.

Dr. Linda Kalnejais' second map showing the effects of excess nutrients on estuaries. (Click to enlarge)
Dr. Linda Kalnejais' second map showing the effects of excess nutrients on estuaries. (Click to enlarge)

Educator Sharon Gallant has a background in geosciences and teaches environmental science at Gardiner Area High School in Gardiner, Maine. She has been a strong proponent of environmental stewardship activities for students at her school. Their activities have included recycling projects, carbon footprint assessments, lighting improvements, motion-sensitive vending machines, and invasive plant removal. She also makes active use of concept maps in her classes. Sharon gave an outstanding webinar presentation that explained why concept mapping can be so effective for various purposes. Her talk was clear and rich and she referenced a large number of maps in a very engaging way. One attendee told me after the webinar that despite having no knowledge of concept mapping beforehand, he was inspired to use the technique to communicate with colleagues about projects in his nonprofit organization.

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