CANAPE: Monitoring at Lake de Leijen

23 July 2018 - Published by Harry Mach
With the first full summer of the CANAPE project under way, our project teams are out and about, making the most of the good weather to get a head start on their activities.

In Friesland, NL, our partner Van Hall Larenstein University of Applied Sciences (VHL) has begun their study of Lake de Leijen, with the objective of better understanding the behaviour of the lake. They have developed a methodology to measure spatial variation in lake water quality, using several sensors mounted on a floating raft.

The results will enable testing of the regional water authority's water flow model for the lake, and provide insight into the occurrence of 'sweet spots' for growth of aquatic macrophytes. This will further our understanding of the behaviour of shallow peatland lakes, helping us improve their water quality in the future. 

VHL are now able to measure spatial variation of several parameters linked to the source of water. Using the monitoring equipment they are monitoring Electrical Conductivity, Calcium, Chlorine,of nitrogen (ammonium and nitrate), turbidity and light penetration, and (indirectly) the growth of algae. In order to keep the monitoring equipment level with the surface of the water, the equipment has been mounted on a converted surfboard (pictured above) and is towed alongside a small inflatable boat. 

When VHL's fish monitoring with the support of local citizen scientists begins in 2019, fish movement patterns will be overlayed with water quality data currently being gathered, which will provide information on the effect of fish activity on turbidity. 

Even though the study is at an early stage, already interesting discoveries have been made, such as the discovery of shining pondweed (Potamogeton lucens). In the 1950's de Leijen was reported to host large fields of shining pondweed, but these disappeared in the 60's and 70's, and attempts to reintroduce it in the mid 2000s were not successful.  Its discovery, and the recording of its location in the water may reveal interesting data when cross referenced with the water quality information gathered in the survey. 

Below - Potamogeton lucens

Potamogeton Lucens