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Autonomous underwater multi-probe system for coastal area / shallow water monitoring

Illustrative diagram of the actions of three floats during an operational cycle

The value of services provided by the coastal seas, including estuaries, to human welfare can be estimated to be higher than those of terrestrial or open ocean systems. Coastal waters supply food via fisheries, renewable and non-renewable resources like sand and hydrocarbons, sites for recreation, and sites for waste disposal, and especially for effective nutrient cycling.

Human activities have modified the aquatic ecosystems in multiple ways. As an outcome most fish stocks are overexploited, contaminants and habitat loss affect the survival of many species, and eutrophication has influenced the functioning of food web. Thus, the ecologically and economically sustainable use of coastal areas is threathened in many ways.

The relevant spatial and seasonal scales for biological variability are often related to hydrophysical events; these are mostly unpredictable and practically impossible to cover by traditional monitoring with sparse sampling. Current sampling limitations thus restrict our understanding of the role of environmental conditions for ecosystems functioning. Quantative diagnostics of the factors affecting e.g. the phytoplankton distribution and productivity requires that these will be sampled at relevant scales.

The overall objective of SWARM is to develop a detection platform that can measure the physical, chemical, and biological coupling of coastal ecosystems and provides a better opportunity for water resources management, allowing for example the detection of key processes and key locations for harmful algal blooms.

Two third generation SWARM floats
The unit on the right shows the inside structure including diving engine, computer board, acoustic and Iridium modems but is lacking the battery pack. The unit on the left has the outer shell and Iridium antenna in place.

Scientific objectives and approach

The scientific objective of SWARM is to design, implement and test a novel highly redundant underwater monitoring system for shallow water areas. The system consists of multiple, homogenous, small size, reasonably priced, robust and easy to use underwater robotic floats that can perform two-week missions autonomously.

The floats control their buoyancy but move otherwise freely with the water currents. They communicate with each other and with the control station (acoustic modem / GSM / satellite), and localize themselves. In addition to measuring pressure, temperature, and salinity the system observes certain algal groups with a novel fluorometer.

Forecasts of algal blooms, their appearance areas and dispersion patterns is extremely difficult. There exists no proper monitoring system capable of continuously and widely enough covering the critical areas. In this project a platform that can measure biological and physical variability at the scale relevant for single event (meter - kilometer and second-day scale) will be developed and tested in the Baltic Sea.

Expected impacts

The quality of waters within Europe can clearly be considered as one of the common European resources and the quality of this resource is naturally important to all of the surrounding countries and beyond. Only through common EU decisions and constant monitoring of these decisions can a long and lasting development of these resources be achieved. The target of SWARM is to introduce a system that can be widely used for this monitoring.

3D view of the track of a simulated float over seven days, with vertical depth exaggerated by a factor of 20
Red dots indicate all floats' actual positions, the blue dot is the float's estimate of its own absolute position, and the green dots are the active float's estimates of the other floats' relative positions. Each surfacing is separated by twelve hours. The shape of the sea bottom is shown in the background, with a horizontal resolution of 1.8km. The total distance traveled by the float during the time shown is roughly 30km.