by Ken Kostel

With researchers from Lamont-Doherty, students and teachers from Pearl River, Clarkstown South and Croton Harmon High Schools captured and identified fish near Piermont Pier during last year's snapshot of the Hudson River estuary.

For many residents of New York City and upstate communities, the Hudson River is such a constant presence that it can sometimes fade into the background of daily life. On Wednesday, October 12, however, Earth Institute researchers will contribute to the efforts of volunteers and students from Troy to Brooklyn in putting the Hudson front-and-center by capturing a scientific "snapshot" of the river's estuary.

This year Lamont-Doherty Earth Observatory will participate in the third annual Hudson River Estuary Program Snapshot Day as both education partners and as researchers. Students and teachers from Pearl River, Clarkstown South and Croton Harmon High Schools will work with Lamont graduate students and researchers at Piermont Pier to explore the physical, biological and chemical properties of the Hudson River. In addition, students throughout the estuary will collect chlorophyll samples and sediment grabs that Lamont researchers will analyze in labs at the Observatory's Palisades campus.

The event is sponsored by the New York State Department of Environmental Conservation's Hudson River Estuary Program. In 2004, more than 1,000 students participated at seventeen sites along the river. On Thursday, teams made up of students and expert volunteers will collect data at 25 sites. The event helps to recognize National Estuaries Day, which celebrates these remarkably productive and valuable ecosystems.

"Snapshot Day provides a unique opportunity for us to gather data from multiple locations on the river at the same time, something we can't normally do" said Margie Turrin, education coordinator of the Hudson River Group at Lamont-Doherty. "It also gives us a chance to introduce students to the world of science and scientific research right in their own back yard."

The third annual Hudson River Estuary Program Snapshot Day will involve local students in gathering and analyzing data about the physical, biological and chemical state of the Hudson estuary at 25 sites from Troy to Brooklyn.

The estuary is a 153-mile stretch of the lower Hudson from Troy to New York Harbor where fresh water and salt water mix and where twice-daily tides dominate over the river's current. In addition to the plants and aquatic animals teams find, they will also log physical and chemical characteristics of the water including temperature, pH, salinity and dissolved oxygen. All the teams will forward their data to the Estuary Program and Hudson Basin River Watch for posting on a website within 48 hours.

With this data, students will be able to study, among other things, how distribution of fish species varies with salinity or observe how, at any given time, the influence of ocean tides differ from place to place along the estuary.

Last year, white perch and young striped bass were found throughout the estuary, but sunfish were caught only in fresh water from Cold Spring north and Atlantic silversides were recorded only from the Tappan Zee Bridge south. This year, August and September have been dry, causing the leading edge of sea water entering the Hudson to reach much further north than in 2004. Students will see if the distribution of the river’s fish species has changed as a result.

"In the end, students will be able to see how what they have found fits in with the rest of the estuary," said Turrin. "Hopefully this will show them that the Hudson River is a dynamic system, that changes from place to place and year to year. Hopefully it will stimulate them to come up with further questions to study, keeping the river at the center of our attention throughout the year."