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Using Bacterial Growth Efficiency as an Index of Salt Marsh Function
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Project Title: Refinement of Bacterial Growth Efficiency as an Index of Salt Marsh Function
Research Locations: Chesapeake Bay, MD
Last Update: February 9, 2004
A tremendous amount of effort has been put toward restoring coastal salt marsh habitat in recent years. Although many restoration projects have been completed, there is no true test to determine if restored marshes function like natural marshes. Because of their short generation time, naturally occurring marine bacteria react faster than any other group of organisms to disturbances in the ecosystem. Such sensitivity makes them an ideal index of ecosystem change and recovery. This project refined techniques for using bacterial growth efficiency (BGE) as a monitoring tool in assessing the success of salt marsh restoration, and created a methods manual to help coastal managers utilize BGE as an indicator of salt marsh health.
Bacterial Growth Efficiency as an indicator
Bacterial growth efficiency (BGE) is the rate at which bacteria convert dissolved organic matter into biomass. Because microorganisms can be an important food source for many organisms at the bottom of the food web, such as clams, worms, and snails, the production of aquatic ecosytems is related to BGE. In turn, BGE is regulated by the amount and quality of organic materials available to bacteria, as well as by the availability of nutrients, particularly nitrogen and phosphorus. Changes in microbial activity can therefore reflect the functional health and productivity of a marsh.
Results
Investigators studied two restored salt marshes and compared their BGE over time to that of a pristine marsh. Results revealed that BGE increased progressively in the restored marshes, and that the physiological differences between the pristine and restored environments narrowed with time. However, long-term data suggests that BGE is consistently lower in restored marshes than in natural marshes. These findings are important because although visual measures of marsh health, such as the regrowth of vegetation and the colinization of microscopic animals in sediment, showed the marshes had regained natural function, a lagging BGE suggested the marshes had not yet fully recovered.
An online management seminar
This project was featured in a two hour web-based management seminar organized at the North Carolina NERR. Investigators discussed details about the project and showed a video of their complete methodology. The seminar can be viewed online at: http:// www. coastlive.org.
Technology transfer - developing the BGE methods manual
To make this information readily available to managers, researchers created a manual describing in detail the methods used in the project.
View and download the manual at: http://ciceet.unh.edu/news/newellMethods/
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Project Coordinator
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Dr. Roger Newell (410) 221-8410 |
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Start -End Date:
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09/01/2001 - 09/01/2002
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NERR Reserve(s):
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Chesapeake Bay, MD
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For more information: |
Dolores Jalbert Leonard |