Gratiot Lake Internships
Headwaters Students Study Lake's Ecology
Amber Kenny was the first participant in the Headwaters Resident Ecology Research Internships at Gratiot Lake. While a Senior at Houghton High School in 1999, Amber studied the ecology of Gratiot Lake clams under the tutelage of Diane Raven and Mike Scheiwe of Headwaters Environmental Station. The group stayed at the Conservancy's Noblet Field Station to pursue the research.
Amber collected and released over 250 clams from the Lake and the Little Gratiot River. She measured their size and weight and assessed their age by counting the bands and ridges in the shells. She found that two species of clams, Elliptiocomplinata and Pyganadongrandis inhabit the Lake. Marion Havelick, a Wisconsin malacologist who specializes in clams, helped with the final species determination.
By placing some of the clams in an aquarium, Amber was able to observe their movements and siphoning behavior. Amber noted that clams move about a lot more than you would imagine.
Because clams are bottom dwellers and obtain their food in these sediments, they are good indicator species of the health of the lake. Tissue from a few clams was collected for future analysis of the presence of mercury, a heavy metal which is a pollutant in many lakes in the Great Lakes region.
Amber assisted Sandra Harting, a biologist with special expertise in toxicology, when she came to Gratiot to measure data on the pH, dissolved oxygen level, clarity, and conductivity of the lake water. Amber assisted as Harting took a core sample of the bottom sediment. Further lab analysis of this sample did not indicate high levels of mercury.
Amber also examined the gills of fish in order to observe the relationship that the clams have to fish in these waters.
Tiny clams spend the first part of their lives attached to the gills of fish. At this stage they can be observed with a hand lens. As they mature they drop off to bottom sediments.
On completion of her three week project, Amber presented an informative slide show.