Wireless Sensor Networks provide real-time measurements of bio-physical environmental variables. The wireless interconnectivity of these sensors and bi-directional communications means these sensor networks can be controlled by a central land-based control system. This centralisation in data collection and control of the sensor network allows for adaptive sampling in real-time, with the ability to increase sampling frequency to capture fine-scale changes in conditions in response to large-scale events as they occur. The added benefit of the current Wireless Sensor Networks is their adaptability in instrumentation, with the capacity to change and add to current sensor arrays allowing them to be tailored for specific projects.
These Wireless Sensor Networks have been deployed in the Great Barrier Reef to collect data to assist in the understanding of the interaction between heat and light on coral bleaching events and the impact of upwelling from the Coral Sea on the productivity of the Great Barrier Reef ecosystem. Current Wireless Sensor Networks are currently established at Heron Island, One Tree Island and Orpheus Island.
Each Wireless Sensor Network site has a local base station, using a tower or other high point to provide a high-speed link to the mainland. For sites close to the mainland coast, 3G/4G phone technologies are used and for sites further away, a mix of microwave and satellite communications technologies are used instead.
A series of relay poles are installed at each reef site, using a spread-spectrum radio or 802.11 wireless networking to communicate with each other and the base station, or to any other device within range. Typical range coverage over water is approximately 2 km from pole to pole and approximately 1 km from pole to buoy.
Buoys are moored around the reef in regions of interest, providing the platform to which sensors are mounted. A smart controller on each buoy provides the real-time link, allowing the transmission of data and communications with the base station. A weather station is also mounted on one rely pole at each Wireless Sensor Network location providing information on meteorological conditions.
Any area covered by the Wireless Sensor Network where 802.11 wireless networking installed will have Wi-Fi and restricted internet access. Due to the size and spacing of poles in each network location, this range generally covers most of the reef lagoon, allowing the connection of additional wireless devices and therefore additions to the sensor arrays installed.
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Australia’s Integrated Marine Observing System (IMOS) is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). It is operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent.