Ice and biological monitoring on the Pemigewasset River

River ecosystem phenology in an increasingly ice-free world: Ecological monitoring sites on the Pemigewasset River

Ran across one of our sensors and want to learn more?
You've come to the right place!

Who we are:

We are a team of scientists working at Hubbard Brook Experimental Forest from both Duke University and the Cary Institute of Ecosystem Studies. Our research aims to understand how rivers in the Northeast are responding to warmer winters.

What are we doing on the Pemi?

To understand how the river's biology is responding to changing winters, we are monitoring two things: ice cover and river metabolism, which is the balance between river respiration -- what we, and stream organisms, do to breathe -- and photosynthesis.

Along the Pemigewasset River, we are measuring ice cover by taking photos each day of the river from a fleet of field cameras (see below). These camera images will be paired with remote sensing imagery taken from satellites that pass over the river about every 8-16 days (see NASA remote sensing background information).

We measure river metabolism through our water quality sensors; each sensor measures oxygen at 20-minute intervals all day long. The more photosynthesis in the river, the more oxygen there will be; at night, when there is no photosynthesis, we can measure respiration, which uses up dissolved oxygen in the stream (see Do rivers have rhythm?).

Water Quality Sensors

We put our sensors into protective plastic cases to prevent damage from ice, debris, and other rocks in the river. If you look closely, you can see the sensor through the holes in the logger case. You will also see a light monitor on the outside of the case. This logger lets us know when it is light or dark outside.

Here's what some data looks like:

GPP = gross primary productivity; IQR = interquartile range; DOY = day of year (for example, 1 = Jan 1)

Field Camera Imagery

Our field cameras are located at different locations along the river's edge. Daily photos help us identify how much water is in the stream, what portion of it is ice or snow covered, and most importantly, the timing and duration of ice cover on the river. All of these factors are not only important for the organisms in the stream but also for us. Frequent ice breakups and ice jams can often cause flooding in our neighborhoods.

If you think you found one of our sensors or field cameras or if you have any further questions, feel free to reach out to me at [email protected].

USGS site at Lincoln, NH

USGS site at North Woodstock, NH

USGS site at Plymouth, NH