How Can We Use Data to “Paint” an Underwater Picture of the Hudson River Estuary?



Shane Riordan

New York Harbor School, Brooklyn


Summer Research Program for Science Teachers

 August 2006




Students Will Be Able To (SWBATo):


·    Test least two of the water quality parameters by independently following protocols with at least 95% accuracy as determined by GLOBE or equipment manufacturer’s quality control protocols.

·   Operate sampling equipment safely and effectively as judged by a qualified instructor.

·    Determine the effect of variations in the aforementioned parameters, and how  that might influence the quality of the water.


1.      Water quality test kits. 

2.       Student protocols for kits, and student data sheets to record data. 

3.      Access to waterfront location or research vessel.

4.      For classroom centered part of activity, access to graphing paper.

5.      CTD data from partners at Barnard.

6.      Background information on salinity, temperature, depth and density. 

7.      Profile map that illustrates (with landmarks and longitude and latitude) the depth contours of the Hudson River from the Verazzano Narrows to the George Washington Bridge.

8.      Chart of New York Harbor

9.      Crayons to color in the temperature, salinity and density profiles


Either in class before the trip, or as one of the stations on the trip, students should receive some background information on salinity, conductivity, and dissolved solids, temperature and other aspects of water quality.  The relationship between proximity to ocean or the freshwater source and the resulting salinity levels of the estuary should be addressed.  Conducting the demonstration of cold salt water’s behavior in warm fresh water would be a good visual activity.


 Initial outdoor lesson should take place aboard a student accessible research vessel in the New York Harbor Estuary (Schooners Pioneer, or Lettie G. Howard or Sloop Clearwater, or small vessels from Rocking the Boat, Floating the Apple, Harbor School or East River Apprenticeshop), or a waterfront location. The introduction to this topic can be in a large group.  Topic could also be introduced over the course of two stations.  Students will break up into smaller groups after introduction.  Students will be in small groups conducting the various sampling projects at various learning stations on board the vessels.


Begin by asking students what they think the bottom of the New York Harbor Estuary might look like?  What might be down there?  Do you think it might look the same everywhere?  Why or why not?

Development 1

Bring out a chart.  As a way to help describe the bottom, solicit from students what the “numbers” on the chart mean.  Once students remember that the numbers indicate depth, ask them if the depth of the estuary is the same everywhere.  What might cause the depth to differ?  Once students ascertain that the depth is different due to different heights of the estuary bottom, bring out a “map” showing the horizontal profile of the estuary.  Point out the start point of the map (Verazzano Narrows).  Have students find it on the chart and in “real world”.  Point out the end point of the map (George Washington Bridge).  Have students find it on the chart and in the real world.

Development 2

Ask the students if they think that the water from the top to the bottom is the same.  What might be different?  Gradually solicit temperature from them as a function of depth.  The closer to the surface, the warmer the water generally is.  Ask them where we are located in proximity to the ocean.  Does the ocean’s proximity influence the water?  Solicit that tides will push salt water from the ocean up into the estuary.  Where would the salt water be?  Utilize their prior knowledge from the salt tank demo to hypothesize where more saltwater might be found.  Use the motivation and development as an introduction into how do we define water quality.  What else uses the water that is an important resource to us? Get them to start seeing the Hudson as a nursery for fish, crustaceans and shellfish.  All of these animals were once part of a major commercial fishery that was worth 40 million dollars a year.  Why is the fishery no longer active?

Development 3

Each Learning Station will focus on one of the following parameters:

·         Ph – seawater

·         Dissolved Oxygen in seawater

·         Salinity

·         Turbidity

·         Water temperature

Each station will include time to discuss the importance of each parameter.  If time in small groups does not allow this then time in larger group should be set aside to provide this basic information.  If necessary, temperature can be combined with DO.  The last station will have a chart detailing what values the above parameters need to be in order to support native species of the Hudson.


Students will have to report what they found in their small groups to the large group at the end of the day before we disembark or after we are on the dock.  Any variation in values will be discussed to determine why there might have been a difference.  Finally, students will be asked to determine what species of native Hudson River flora and fauna could live in the Hudson based on the water quality we determined.  Was this consistent with what we caught in the net?  Students will fill out report sheets and upload any relevant data onto the GLOBE website the next class period.

Classroom Follow Up –“Painting the Hudson”

Having been introduced to the basics of water sampling from a research vessel, students will now participate in an activity that will demonstrate how scientists can use this data to help them create a better understanding of the natural world.

Students will work in groups to interpret and graph CTD data from Barnard College’s Environmental Measurements class.  Every fall, the Environmental Science Department at Barnard College conducts CTD casts at various depth along a transect of the Hudson from the Verazzano Narrows to the George Washington Bridge.  CTD stands for Conductivity, Temperature, and Depth.  Conductivity is a measurement of the amount of dissolved solids present in the water column, temperature refers to how hot or cold the water is, and depth refers to how far below the surface of the water the measurement point was.  The CTD casts are made at various depths along the river in order to create a vertical and horizontal profile of the above mentioned physical characteristics.  This information is then in turn graphed to present the data in a format that allows students to accurately see how the water in the estuary will align itself based on its temperature, salinity, and density.  Students will color in the profiles according to a set key, so as to visually represent the fact that there are different layers to the system.


Students will divide into small groups and graph a small section of the data.  The graphs will be put together at the end to create a large display showing the salinity and temperature as a function of location within the estuary.  The Earth Science Teachers will use the same data to help construct graph to display the density as a function of location in the estuary.

This data can then be utilized in class as part of a lesson and project to explain salinity and temperature profiles of different portions of the New York harbor Estuary and to reinforce the fact that salinity fluctuates in the estuary based on location and depth.


National Science Standards


Identify questions and concepts that guide scientific investigations.

Formulate and revise scientific explanations and models using logic and evidence.

Recognize and analyze alternative explanations and models.


Standard A Science as Inquiry

Use technology and mathematics to improve investigations and communications.

Standard A Science as Inquiry

Use technology and mathematics to improve investigations and communications.


Standard A Science as Inquiry

Communicate and defend a scientific argument.


Standard A Science as Inquiry

Design and conduct scientific investigations. Designing and conducting a scientific investigation requires introduction to the major concepts in the area being investigated, proper equipment, safety precautions, assistance with methodological problems, recommendations for the use of technologies, clarification of ideas that guide the inquiry, and scientific knowledge obtained from sources other than the actual investigation. The investigation may also require student clarification of the question, method, controls, and variables; student organization and display of data; student revision of methods and explanations; and a public presentation of the results with critical response from peers. Regardless of the scientific investigation performed, students must use evidence, apply logic, and construct an argument for their proposed explanations.