Case Study Description
As climate change continues to melt Arctic ice and increase water temperatures, it is important to understand how ecosystems will respond and change over time. Lakes in the Arctic are covered in a thick layer of ice for most of the year, so we don’t truly know what is happening with lake metabolisms and ecosystems during that time.
Location and Methods
Vendy Hazukova, a PhD student at the University of Maine, has been conducting research on how lake metabolisms change from being ice-covered to after the ice melts during the summer. The research took place in several Arctic lakes in Greenland. These lakes in particular presented a unique environment to study since they are in a relatively dry Arctic environment with low precipitation.
In order to understand the metabolisms of the lakes, Hazukova and the research team deployed miniDOT® and miniPAR Loggers in each lake in the study. The loggers were vertically attached to each other with a string and then to a buoy that was deployed through a hole drilled in the ice in the spring by the researchers and retrieved late in the summer. The buoy was placed about a meter below the assumed ice depth so neither the buoy nor the loggers would become frozen in the ice.
PME’s loggers were favored, according to Hazukova, because “…they are fairly small and very useful for long-term deployments, which is something we are really interested in.”
Hazukova’s study chose the miniDOT Logger because of its ability to take high frequency, precise dissolved oxygen measurements which were vital to the experiment and the understanding of whether photosynthesis or respiration was dominant in each lake. The miniPAR Logger was chosen for its precision in measuring light quantities. The miniPAR was used to determine how much light was actually getting through the thick ice layer.
The data collected from the miniPARs and miniDOTs, deployed for about four months, gave the researchers the information they needed to calculate the lake metabolisms and how they changed over time. The data also provided an easy comparison between summer lake metabolisms and under-ice lake metabolisms.
Another important piece of the data collected was the ability to calculate if algal growth is possible under the ice, which will inform the dissolved oxygen levels of the lake, as well as whether photosynthesis or respiration is more prevalent.
The research team attached miniWIPERs to the loggers to prevent biofouling over the four month deployment. Hazukova reported that when the loggers were retrieved, the miniWIPERS kept the sensing surfaces completely clean while the rest of the logger bodies were covered in algae.
For more information on this research project, watch our interview with Vendy Hazukova below.
The miniDOT Logger is a completely submersible instrument that logs dissolved oxygen and temperature measurements. The oxygen sensor is an optode that measures dissolved oxygen concentration in water through a fluorescence method. Data are recorded to an internal SD card. Operation of the miniDOT Logger such as setting the time and sample interval can be accomplished via the USB cable.
The miniPAR Logger is a portable, submersible instrument for measuring diffused sunlight through water, or PAR (Photosynthetically Active Radiation). The miniPAR also contains a tilt sensor to ensure proper orientation, as well as a temperature sensor. Data are recorded on an internal SD card.
The miniWIPER is a self-contained, completely submersible, wiping device that can be used with a variety of sensors, including the miniDOT and minPAR Loggers. It can be programmed to wipe at various intervals, and is powered by two AA Lithium batteries. A small brush rotates over the sensor in order to perform a complete wipe of the sensor surface, and then rests away from the sensor to allow for accurate and continuous monitoring. The wiper is used as an anti-fouling device and may reduce the growth of various organisms on the sensor.