One of Hydromea’s VERTEX AUVs provided the first 3D map ever of water quality parameters of Lago Cadagno in Ticino, Switzerland. The AUV was fitted with a complete EXO2 sonde from YSI measuring a multitude of parameters such as temperature, oxygen, turbidity and Chlorophyll-A in parallel. In addition to the EXO2 sonde, the AUV also carried a custom fast temperature sensor developed by Hydromea, capable of measuring temperature with a sub milli-Kelvin resolution at a rate of 250 samples per second.
The mapping effort is part of a 3 year collaborative project between Hydromea, Ecole Polytechnique in Lausanne (EPFL) and the University of Geneva. Lago Cadagno is of particular scientific interest as it is clearly divided between an upper and a lower layer and remains permanently stratified. Between those two layers a very dense layer of anaerobic and phototrophic bacteria causes bio-convection, a very rare phenomenon in nature. The fast temperature sensor was deployed to examine the bio-convection phenomenon by measuring millimeter-sized turbulence caused by the bacteria.
The VERTEX was particularly well suited to map the bacterial layer. Its small size (70cm, 7kg) allowed for a deployment from a small platform. Using its unique thruster configuration it was able to move forward at a very slow speed (20cm/s) to account for the sensor response time, while remaining level.
Upcoming experiments will see up to 5 VERTEX AUVs deployed simultaneously to investigate complex physical-biological phenomena in Swiss lakes.