Monday, September 10, 2018

OSCAR Student Christopher Martin Analyses Stable Isotopes of Aquatic Species in the Potomac River

The research project I am currently engaged with is a stable isotope analysis of aquatic species between two separate tidal water embayments of the Potomac River.  To run stable isotope analysis, tissue samples were needed from each species.  Vegetation was taken from the leaves of aquatic plants, muscle tissue from fish, feet from clams, and the bodies of snails.  To retrieve muscle tissue from fish, we spent several days boating on the water to collect the fish using sein nets and trawling.  We euthanized them by over anesthetizing them, then returned to the lab where we cut muscle tissue from along the back and near the tail.  We then dehydrated it over several days in an oven, powdered it with a mortar and pestle, then shipped it off to another lab for processing.

The snails involved a particularly interesting method for extraction, as they were too small to simply be pulled from their shells. To acquire their bodies, I had to grind up dozens of tiny snails with a mortar and pestle (shells and bodies together), then use hydrochloric acid to burn away the sodium bicarbonate shell material. The acid reacted with the shell material at a far more rapid rate than the organic material, making it a simple solution for acid washing the unwanted material away and leaving behind the purely organic matter I needed to run stable isotopes.