Can sensor buoys improve environmental monitoring?
The marine environmental monitoring programmes aim to give accurate annual mean values of the measured parametres. They comprise a good basis for long-term estimations of changes in the sea. But a short poisonous algal bloom could pass unnoticed. Therefore, Umeå Marine Sciences Centre (UMSC) now investigates if a sensor buoy which collects data on an hourly basis could improve the environmental monitoring programmes and make them more efficient. The work is carried out within the research programme Ecochange.
-This is one way to evaluate the design of the marine environmental monitoring programmes, says Ulf Båmstedt, Professor in Marine Ecology, Ecochange coworker and manager at UMSC.
Together with post doctor Sonia Brugel and senior lecturer Johan Wikner, both Ecochange coworkers, and the UMSC vessel crew he performs an experiment with a sensor buoy placed in the Öre River estuary. The buoy is anchored on a fixed distance from the bottom and collects data every hour on light, temperature, salinity, oxygen, turbidity, coloured dissolved organic matter and chlorophyll. The height and frequency of the waves as well as the water level are also registered.
Complementary measurements in the surroundings
Every week the buoy is brought out of the water and data is downloaded from the instrument before it’s put back in its original position. Then complementary measurements from the water surface and down to the bottom are performed with a similar instrument at about twenty stations in the surrounding areas of the buoy. The stations are allocated in a plume-like pattern from the estuary towards open sea.
-The measurements at the surrounding stations give complementary information on the mixture between river water and sea water and how it affects the turbidity and the occurrence of algae and coloured dissolved organic matter. The stationary buoy gives information on short-term effecs of increased river water inflow or turbulent mixture caused by e.g. lagre amounts of precipitation or temporary stormy weather, which can affect the algae, Ulf Båmstedt explains.
The experiment is carried out within the research programme Ecochange as part of a subproject aiming to improve the design of environmental monitoring programmes.
-We’re examining if sensor buoys could be used as a complement to measurements from ships. Some parametres regarding e.g. waves can’t be measured from a ship. In addition, it’s not economically or practically possible to measure every week, and much less so every hour, from a ship. On the other hand many parametres, e.g. biological production and algal composition, can’t be measured with sensor buoys. So the buoys won’t be able to replace the sampling and measurement from ships within a forseeable future.
How well functioning the sensor buoy is, still remains to be seen. The measurements will go on until the sea freezes, and will continue after the thaw in spring. Data is continuously processed and evaluated and will be presented at scientific meetings during 2013, with a final editing before international publication after the field season next year.