The Zebra mussel (D. polymorpha) has in the last twenty years become the dominant species of shellfish in various fresh water systems throughout North America. Its ability to outlive periods of low plankton (its main source of food) count suggests that another method of obtaining nutrition may exist. One of these alternate pathways may be through directly absorbing dissolved organic carbon [DOC] (decayed matter derived from various organisms that is no longer in particulate form) from the water the zebra mussel filters. Recent study has suggested that the process, which has been generally accepted as non-existent, may actually occur. To test this hypothesis, the following experiment has been designed:

Two experimental groups will be represented. Two hundred mussels will be split up into two groups, "A" and "B." Each group will be fed a strain algae that has been derived various species living in the San Francisco Bay area. However, the algae that will be fed to group B will be labeled with Carbon-13, an stable isotope of the element that would allow for its tracking. Using this isotope, it will be possible, once the algae has been prepared and dissolved in the water, to track the ratio of 13C to 12C present in the mussels after they have been fed the algae. Therefore, if the mussels uptake DOC, then both groups will uptake the DOC, except that group A will take up "regular" C12-labeled DOC and group B will take up C13-labeled DOC. Discovering whether zebra mussels take up DOC will determine whether they take up dissolved organic matter, since carbon is the main constituent of organic matter. The expected outcome is that D. polymorpha will uptake dissolved organic matter.

This study was funded by NSF 010450-1011046.