Wireless Sensor Networks promised to do for observation systems what consumer electronics have done for areas like photography—drive down the price per observation (photograph), introduce new functionality and capabilities, and make, what had been a relatively exclusive set of technologies and capabilities, ubiquitous. While this may have been true for some terrestrial sensor networks there are issues in the marine environment that have limited the realization of ubiquitous cheap sensing. This paper reports on the lessons learned from two years of operation of wireless sensor networks deployed at seven coral reefs along the Great Barrier Reef in north-eastern Australia.

A “StingerCam” camera system provided high temporal resolution image data on the presence of large cubozoan jellyfish over nearly five years on the tropical coast of northeastern Australia. There was strong seasonality in the occurrence of Chironex fleckeri and an unnamed species of the family Carybdeidae (Morbakka spp.). Jellyfish of both species were only found between December and May of each year; primarily in the wet season. It was estimated that jellyfish were released from polyps from September. From a sample of >1000 C. fleckeri and 493 Morbakka we determined the temperature and salinity range in which these taxa were detected being between 21.7°C–31.6°C and 25.2–34.9 PSU for C. fleckeri, and 20.2–30.2°C and 25.4–35.4 PSU for Morbakka sp. Daily wind speed influenced detection rates with less jellyfish observed in winds that exceeded 28 km h−1. Data reduction software greatly improved processing time by identifying images without jellyfish with an accuracy of 93–98% in the two case studies used here, an image series from a night when jellyfish were highly active and in winter when jellyfish were absent. The StingerCam not only provided strong ecological data and information of high utility to reduce the risk of envenomation to the public, but also detected boney fishes, sharks and marine reptiles. We conclude that StingerCams are an effective way of collecting data to determine the range of physical conditions that jellyfish can tolerate and this information can be used in predictive models; especially given a global focus on climate change.

This paper describes the design, installation and operation of a high-speed, real-time coral reef observing system network at Heron Island, within the Australian Great Barrier Reef. As part of the Queensland Integrated Marine Observing System (Q-IMOS) node of the Australian Integrated Marine Observing System (IMOS), a low data rate wireless sensor network has been operational at Heron Island since 2008. In 2013 a new surface reef pole and underwater cabled Ethernet network were installed on the edge of the Heron Island Reef lagoon, with telemetry back to the Heron Island Research Station achieved using a 300 Mbps wireless 802.11 link. The reef pole provides a network bridge to an underwater-cabled Ethernet network, and also provides an 802.11 wireless access point for the remainder of the Heron Island reef lagoon. Internet protocol networks provide for an extensible architecture, enabling the easy connection of any type of oceanographic instrument, camera or video system to the observing system. Acoustic monitoring receivers for fish tracking are connected to the network to allow for real-time monitoring. The underwater-cabled network is modular in design allowing for easy repair, expansion or reconfiguration of the network for any future requirements. This paper discusses the design considerations, system components and results of using affordable wireless 802.11 networks in a harsh marine environment for coral reef observing systems.

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