Foraminifera are everywhere. In addition to being some of the dominant
organisms in the oceans, forams are also found in brackish water environments
like lagoons and estuaries, as well as absolutely freshwater environments.
These low-salinity forams don't make the dramatic tests that the marine
ones do, so it's been hard to differentiate between them until recently.
Our laboratory sits on the west bank of the Hudson River, in New York
State. We are at the upper end of a long estuary that extends about
160 miles south, to New York City. This estuary, as well as being very
is home to a wide variety of different organisms, and the populations
change as the salinity increases downriver.
Two researchers, McCrone and Schafer, did a traditional survey of the
Hudson River for foraminifera in the late 1960's, finding them as far
north as Haverstraw (at the top of the Tappan Zee). However, we think
that many types may have been missed, because the method they used relies
on the cells' ability to make tests. Many forams don't make tests at
all, and other won't make them under some conditions. We have been searching
for foraminifera throughout the estuary, using DNA signatures to identify
the forams instead of test shape.
Of course, there's no way we could do this work alone. The crew and
student volunteers aboard the Half
Moon, a replica of the first European ship to explore the Hudson
River estuary, have enthusiastically embraced our research project.
Check out their Website for their stories and photos of Playing in Mud
for Science. Hannah Giles, a now-college freshman, went hunting for
forams in a pond near her home as a high-school student. Our work on
freswater forams, in collaboration with the Pawlowski lab at the University
of Geneva, was published in 2003 (Holzmann, M., Habura, A., Giles, H.,
Bowser, SS., and Pawlowski, J. Freshwater foraminiferans revealed by
analysis of environmental DNA samples. Journal of Eukaryotic Microbiology
50(2):135-139), and work is continuing.