2011 Chlorophyll Sampling Results



October 18, 2011

The Day - October 18, 2011 started out cloudy and windy but cleared by noon. Weather is important to record as the chlorophyll molecule absorbs sunlight, using this energy to build carbohydrates. This means that bright sun levels are linked to increased algal and phytoplankton production, and it is this productivity that we are measuring with our chlorophyll a sampling.

Methods - The sampling methods are described in the main chlorophyll page. Note in our 2011 data:

Units: 2011 results are listed in ug/L yet 2005 results are listed in mg/m3. How does the unit 'ug/L' compare to 'mg/m3' Micrograms/liter (ug/L) are the same as milligrams/cubic meter (mg/m3) and are completely interchange.


Examining trends in the data. A trend line is a straight line used to connect multiple points in the data or the best fit connecting the data. The steepness of the trend in the data indicates the strength of the trend, the flatter the line the lower the strength of the trend. Once a trend line has been established an R2 value is used to see how well the line fits the data, in other words is there a consistent relationship between the two variables being plotted on the graph (in our case this is chlorophyll and RMs)? A perfect match would be a value of 1.0, a strong relationship would be 1.0-0.7, and a moderate linear relationship would have values between 0.7 and 0.4. Our value of 0.022 falls very low suggesting that there is not a strong relationship between river mile and chlorophyll. This means we would not want to make predictions on chlorophyll levels in the river just using river miles.

Results for the 2011 samples show four areas in the estuary where there were spikes in chlorophyll productivity. Canarsie Pier in Jamaca Bay, Memorial Beach in Nyack, Ulster Landing Park in Saugerties and Cohotate Preserve in Athens had chlorophyll levels that reached higher than 2.0 ug/L. However, looking at the overall chlorophyll sample data plotted by River Mile (RM) the readings were relatively low with a dozen sites falling below 0.3 ug/L.

Below is a chart of those sections of the river with the highest and the lowest Chlorophyll readings.

Chlorophyll Readings > 2.0 ug/L   Chlorophyll Readings < 0.3 ug/L
Location RM ug/L 5 highest   Location RM ug/L 8 lowest
Canarsie Pier -6.5 2.56 This year the highest levels of chlorophyll from our sample locations was represented by levels over 2.0 ug/L. They included only the four sites listed to the left.   Brighton Beach -9 0.14 This year the lowest levels of chlorophyll from our sample locations was represented by levels below 0.3 ug/L. They include the dozen sites listed to the left.
Memorial Beach, Nyack 28 5.62   Valentino Pier, Brooklyn -2 0.17
Ulster Landing, Saugerties 97 7.02  

Governor's Island, Upper Bay

-1 0.06
Cohotate, Athens 115 2.51   HRPT Pier 40 2 0.21
        HRPT Pier 45 2.5 0.09
        HRPT Pier 95 5 0.18
        GW Bridge 12 0.12
        Englewood Boat Basin 13 0.07  
          Alpine Boat Basin 18.5 0.13  
          Croton Point Park 35 0.15  
          Cold Springs 55 0.22  
          Quiet Cove Poughkeepsie 78 0.16  
          Saugerties Light House 102 0.27  
          Hudson Waterfront 118 0.25  

What are some of the parameters that can impact chlorophyll levels in the river?

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