James Nelson, postdoc on the Plum Island LTER project, caught mummichogs and used a new technique that marks the bones of fish with a fluorescent dye (Calcein) that can be used to determine a fish’s growth rate. The dye does not harm the fish and cannot be seen in normal light, so the fish’s natural behavior is not affected. Once marked with the Calcein, the bony structures will glow green under ultraviolet light.

Green To Measure Growth: Assessing Eutrophication's Effects on Mummichogs

As part of his research on preserving healthy and productive salt marshes, James Nelson, postdoctoral researcher at the Plum Island Sound Long Term Ecological Research site, turned 28,500 mummichogs green last summer.

Dr. Nelson explains: "Salt marshes, such as the Great Marsh along the northern Massachusetts coast, are highly productive landscapes that provide a great number of ecosystem services. Some of the more well known ecosystem services provided by salt marshes are protection from storm surge and runoff filtration. There is another major service salt marshes provide that ecologist have long theorized about but rarely demonstrated and that is the export of food to adjacent habitats in the form of fish.

"Each year in the spring the productivity engine of the marsh gets switched on and begins to produce enormous amounts of biomass in the form of small fish. These fish, primarily mummichog (Fundulus heterclitus), follow the pulse of the tides to feed on the abundant food in the relative safety of tidal creeks throughout the spring and summer. As the temperatures dip into the fall season these little fish must move out of the shallow tidal creeks and into deeper waters, where they become prey for larger fish such as striped bass (Marone saxatilis). Essentially, salt marshes act as food factories that package large amounts of production in a short period and then export that production to organisms in other systems. In fact, we have observed a strong correlation between the amount of mummichog produced and the number of striped bass. Therefore, maintaining healthy and productive salt marshes will help to maintain productive offshore fisheries

"Human-caused nutrient pollution, however, is a major threat to the stability of this important ecosystem service. My work focuses on the effects of 'eutrophication' or human-caused nutrient pollution on the secondary (fish) productivity of salt marshes.To examine this I employ a number of techniques with the primary goal of answering two main questions: first, how does nutrient pollution change the number of fish the salt marsh can support? >>>>