Eutrophication monitoring system near the Sopot beach (southern Baltic)

• The system is a useful tool for coastal managers and scientists.
• It may be used as an early-warning, e.g. for cyanobacteria blooms.
• High frequency measurements are more reliable than occasional ones.
• The results allow to follow trends of eutrophication.
• The coherent results may be used for modelling eutrophication.

An in situ continuous system for monitoring eutrophication has been installed at the Sopot pier (Gulf of Gdansk, southern Baltic). It includes a multiprobe for seawater monitoring, a meteorological station and the infrastructure for on-land transmission, storage and processing of data. The multiprobe sensors provide information on parameters reflecting the overnourishment in seawater (e.g. chlorophyll, phycocyanin). All the parameters are measured continuously at fixed intervals (every 3 s). The compatibility of the system with the discrete monitoring method and its representativeness for the whole coastal zone are assessed. The averaged values from the station measurements are more reliable than discrete, occasionally measured data, and allow tracking of trends. This system supports coastal monitoring, may serve as an early-warning system, signalling when water samples should be collected for phytoplankton microscopic and chlorophyll spectrophotometric analyses. The meteo data can be used for modelling the abundance of macrophyta and cyanobacteria blooms. The linear stochastic model based on one season data was developed, indicating that chlorophyll and phycocyanin variability was explained in ca 70% by NE and NW winds in the current and previous weeks. In comparison with periodic control, which may miss the extreme values, this is a new approach to beach management. This eutrophication monitoring system may be helpful in coastal management and a useful tool in the assessment of ecosystem status for environmental scientists. Nevertheless, the system is not a ready to copy scheme, location of such station at each other site needs previous consideration and testing.