MEMOIRE DE FIN D’ETUDES
Sensor Network Implemented on the Great Barrier Reef
Réseau de capteurs implémenté sur la grande barrière de corail
Par William Pagnon
Jury :
Jean-Baptiste Renard (parrain)
Mr Durouchoux (président)
Dr Nicole Bordes (chef de projet)
ESIEA – Date de soutenance : 23/08/2006
Table of Contents
List of figures / Liste des Figures
Acknowledgements / Remerciements
Résumé
Abstract
Chapter Outline / Survole des Chapitres
Stage Environment / Environement du Stage
State of the Project at the Start of the Training Course / Etat d’Avencement du Projet à
l’Arrivé du Stagiaire
State of Art / Etat de l’Art
The Great Barrier Reef / La Grande Barrière de Corail
The Coral and its Environment / Le Corail et son Environment
The Scientific Communities Around the GBR / La Comunitée Scientific Autour de la GBC
Method of Monitoring the Coral / Méthode de Surveillance du Corail
What is Threatening the Great Barrier Reef? / Qu’est-ce qui Menace la GBC?
The Sensor Network and its Applications / Réseau de Capteurs et leur Applications
The Sensors / les Capteurs
Wireless Propagation Theory / Theorie de la Propagation sans Fil
Google map API.
Technical Dimension of the Project / Dimension Technique du Projet
Overview / Vue Generale 33
Data used in the project / Données utilisées dans le projet
Archived data / données archivées
Live Data Capture / Capture de Données Temps Reel
Project Architecture / Architecture de projet
The Protocol / Le Protocole
The Server / Le Serveur
The Database / La base de Donées
The GUI / L’Interface Utilisateur
The Console Mode / Le Mode Console
Architecture of the Python Programs / Architecture des Programmes Python
The Website / Le Site Web 46
Example of Data mining Extraction Through the Presented System / Example d’Extraction
de données à travers ce System
Conclusion of the Technical Part / Conclusion de la Partie Technique
Human and Management Dimensions Internal to the Company / Dimension Humaine et
Managerial interne à la companie
Discussion
References
Annexes
Annexe 1: Glossary
Annexe 2: Colour Scale of HotSpot and DHW 69
Annexe 3: Class from SensorNet_GUI.py with there function:. 70
Annexe 4: Classes from the other python program:. 72
Annexe 5: Package installation 74
Annexe 6: Installation instruction: 75
Annexe 7: website bookmarks used for the project . 76
Annexe 8: Example of python program, Class_com.py. 79
List of figures
Figure 1 : Station météorologique ou bouée sur le récif Davis, AIMS 7
Figure 2 : weather station or buoy on Davies reef, photo courtesy of AIMS . 9
Figure 3 : internal architecture of the University of Queensland 12
Figure 4 : Internal Human Structure Of The Vislab Laboratory Hierarchy 13
Figure 5 : Architecture of QPSF . 14
Figure 6 : Presentation of the area (straight line) cover by the GBRMP [4] . 18
Figure 7 : Amount of COTS observed during the Broadscale Manta surveys [5] . 20
Figure 8 : Example of COTS specimen feed on coral [7] 21
Figure 9 : Maximum temperature observed in the world after the El Nino phenomenon [9] 22
Figure 10 : The Degree Heating per weeks observed for the last 90 days for the same period [9] 22
Figure 11 : Maximum temperature observed nowadays [9] . 22
Figure 12 : The Degree Heating per weeks observed for the last 90 days nowadays [9] 23
Figure 13 : Effect of degree heating per month over the past and the future on the coral (a) [5] 25
Figure 14 : Effect of natural catastrophe per decade over the past and the future on the coral (b) [5] 25
Figure 15 : Poster representing the different technologies involve’ in the Security network sensor project of US [12]. 26
Figure 16 : Cut of the tunnel view where a sensornet cable in optic fibber is installed [14] 27
Figure 17 : graph of the sensor cable monitoring [14]. 27
Figure 18 : Thermocouple with its storage and communication system desired for the SensorNet project [11] . 29
Figure 19 : Representation of the method of faking electromagnetic waves for different frequencies from subrefraction (low frequencies) to trapping (high frequencies) [1] . 30
Figure 20 : Example of use of Google Map in the website developed during the project. 32
Figure 21 : Overview of the data streaming from buoys to final users 33
Figure 22 : Map of the existing monitoring site on the GBR, PNG and West Australia 34
Figure 23 : Weeder electronic board that capture data from thermocouple [17] 35
Figure 24 : Scheme of the stream of the data from the thermocouple to the computer that simulate the buoy 35
Figure 25 : Technical architecture of the SensorNet software project. 37
Figure 26 : Protocol of the network dialogue between the buoy and the server . 39
Figure 27 : Database scheme 41
Figure 28 : Connexion panel of the GUI interface. 42
Figure 29 : Selection panel with the customised or assisted tool and its mouse interactive grid selection
Figure 30 : Presentation of an example of graphic generated by the mouse interactive grid selection
Figure 31 : 3D graphic selection and map of the GBR with buoys plot on from the latitude and longitude selected
Figure 32 : Program architecture of the python programs . 46
Figure 33 : Website architecture . 47
Figure 34 : First part of the webpage displayed when all the options are selected 48
Figure 35 : Second part of the web site with all the options selected 48
Figure 36 : Full webpage generated for the case study 49
Figure 37 : Graphic generated on the GUI for the case study 50
Figure 38 : Saved picture file of the graph on PNG format for the case study 51
Figure 39 : Example of mathematical operation in SQL from the GUI
Figure 40 : Graph from the website of the simulated buoy sensors for live data
Figure 41 : graph from the GUI of the simulated buoy sensors for live data
Figure 42 : zoom in of the graph from the GUI of the simulated buoy sensors for live data
Figure 43 : photo of Vislab with the Access Grid node environment with multi conversation and software utility running through 3 power wall projectors
Figure 44 : presentation of the website used for archaeological data instead those of the GBR
Figure 45 : example of the GUI used for archaeological data instead of those from GBR
Figure 46 : XYZ Stage developed as Access Grid physical tool possibility example
Figure 47 : Chart of the trend estimate of employed persons in Australia.
Figure 48 : Chart of the trend unemployment rate in Australia
Acknowledgements
My deep gratitude for the following people without whom this thesis would not have been possible:
– Nicole Bordes for allowing me to work on the SensorNet project
– Bernard Pailthorpe for his advice and orientation in the project
– David Gwynne for his precious advice in programming
– Chris Willing for his advice and his explanation of the project and its structure
– Jean Baptiste Renard for his advice during my internship
– Jean-Baptiste Bérard for the information provided on the Marine Biology of the coral.
– Andreas Vaszolyi for his help in the grammar correction of this thesis
Résumé
La conservation de la biodiversité marine est fondamentale pour maximiser les avantages sociaux et économiques à long terme de la planète. La Grande Barrière de Corail (GBC) est considéré un des environnements les plus riches au monde. Sa conservation est devenue une préoccupation mondiale. Pour mieux comprendre l’évolution de cet environnement unique, un projet à long terme de réseau de capteurs déployé sur la GBC a été élaboré par l’Université du Queensland (UQ) de Brisbane, l’Université James Cook (JCU) de Townsville et l’Institut Australien de la Science Marine (AIMS) sous l’union de la fondation du Queensland pour les sciences parallèles (QPSF).
Dans ce projet, mon objectif était de fournir une approche et un développement de logiciel qui consistera à rendre disponible à des utilisateurs finals des données venant d’un réseau de sondes qui pourront être visualisées et manipulées grâce à plusieurs outils se connectant à une base de données. Ce logiciel servira de structure de base pour développer l’application finale qui sera employée par les scientifiques pour extraire des connaissances à partir de ce réseau de capteur. Ce logiciel donne également une bonne idée des possibilités que peut fournir une telle structure générale pour n’importe quelles données spatiales temporelles rassemblées par l’intermédiaire d’un réseau de capteurs comme par exemple, astronomique ou archéologique. Le but final de ce projet est de développer une surveillance totale de la GBC par le biais d’un réseau de capteurs qui fournira tout type d’informations sur la qualité de l’eau, des températures aussi bien qu’une visualisation constante de la GBC par capteurs CCD. Les sondes seront essayées à l’avenir sur le récif Davies ; où une station météorologique est déjà installée. Le récif Davies est situé dans la GBC à latitude 18°50’S, longitude 147°41’E à environ 70km de Townsville.
Précédemment, la communication sans fil basé sur des micro-ondes de 10.5 GHz avait été testée avec succès sur ce même récif. Ce serra certainement cette technologie qui sera employée pour créer un réseau en Ad Hoc entre les bouées et les serveurs. Pour simuler les données récoltées par les bouées, j’ai utilisé une base de données de AIMS qui représente les températures de différentes Stations météorologiques situées sur la GBC et récoltées toutes les 30 minutes depuis 10 ans. Ces données ont été régulièrement récupérées par bateau ou par une liaison haute fréquence de 3.3MHz (qui n’a pas prouvé son efficacité) sur 149 bouées au total répandues sur la GBC. Ainsi, dans ce projet, il a été décidé lorsque l’implémentation viendra de recevoir les données directement par une liaison sans fil de 10.5 GHz de la bouée à la station terrestre, où les données peuvent circuler par toutes les bouées ou les serveurs (selon le meilleur chemin) pour être finalement stockées dans une base de données. Pour simuler les données en temps réel, une carte électronique, déjà disponible dans le laboratoire, fournira quatre mesures de thermocouples placés derrière différents ventilateurs dans la salle d’ordinateurs de Vislab. Au final, l’envoie des données a été mis en application avec succès d’une bouée à la base de données par l’intermédiaire de logiciel serveur et client.
Sur la base de données ont été développés trois utilitaires pour manipuler les données : Une interface graphique qui fournit une table des données choisie par une commande SQL avec un outil de sélection des données via la souris pour produire à souhait des graphiques. Un mode console a été développé pour accéder aux données sans avoir besoin d’autre chose qu’un Shell.
Finalement, un site Web a été développé pour que toute personne puisse s’informer sur les températures de la GBC durant les 10 dernières années. Ce site Web inclut une carte implémentée via Google Map, des graphiques et une table de Meta information concernant les bouées et leurs capteurs. La prochaine étape de ce projet consistera à employer plusieurs cartes électronique de capteurs afin de simuler plus d’une bouée et ainsi pouvoir simuler un réseau complet avec la gestion temps réel par multi tâche de plusieurs bouées et le routage dynamique des données par ring buffer.
Figure 1 : Station météorologique ou bouée sur le récif Davis, AIMS
Abstract
The conservation of marine biodiversity is fundamental to maximizing long-term social and economic prosperity and sustainability. The Great Barrier Reef (GBR) is considered one of the richest environments in the world and its preservation has become a global concern. To better understand the evolution of this unique environment, a long term project involving a sensor network installed on the GBR was conducted by the University of Queensland (UQ), Brisbane, James Cook University (JCU) from Townsville and the Australian Institute of Marine Science (AIMS) under the Queensland Parallel Science Foundation (QPSF).
On this project, my objective was to provide an approach of a software implementation to stream the data from the sensors to the final users, who will be able to visualize and manipulate the data with several tools through a database. This software will serve as a basic structure in developing the final application that the scientists will use to extract data from the sensor network. It will also provide an idea of the possibilities of a general structure for any spatio-temporal data collected via a Sensor Network (like astronomical or archeological data).
The final aim of this project is to develop a total monitoring of the GBR using a sensor network to provide information about water quality and temperature as well as a constant video visualization of the GBR. The sensors will be tested in the future at Davies Reef, where a weather station is already installed. Davies Reef is located on the GBR at latitude 18°50’S, longitude 147°41’E, about 70km from Townsville.
Previous tests of the reef with wireless connection based on microwaves have been successfully conducted and will certainly be the technology used to link the network. To test the computer program, I have used data from AIMS of the last 10 years from a previous project, which was to store the temperature from the buoys every 30 minutes. Those data were regularly collected by boat or by a low DataStream HF radio (that did not prove its efficiency) from 159 buoys spread on the GBR. Thus, in this project, it was decided (for the final implementation) to receive the data directly with a 10.5 GHz wireless network from the buoy on the earth station, where the data can be streamed from all the buoys or the servers to be stored on a database.
To simulate live data, a sensor board from Weeder Technology, already available in the lab, will provide four temperature sensor measurements, placed behind different fans of computers in the computer room of Vislab. As a result, the stream of data was successfully transferred from a buoy to a database via a software server. Three ways have been developed to manipulate the data. Firstly, a GUI that provides a grid of data selected by an SQL command and where the data displayed are ergonomically selectable to generate the desired graph. Secondly, a console mode has been developed to access data using only a shell. Finally, there is a website providing information about the temperature of the GBR over the past 10 years. This website includes a map navigation tool, Google Map, graphs and tables of meta-information about the buoys and the sensors. The next step in this project will be to use several boards to simulate more than one buoy and deal with them in multithread with different scenarios to obtain a dynamic routing of the data.
Figure 2 : weather station or buoy on Davies reef, photo courtesy of AIMS
Chapter Outline
Stage Environment:
Here I will present the different organisations involved in this project and the links between them as well as the internal human architecture of the Vislab laboratory and its field of activity.
State of the Project at the Start of the Training Course:
I will present studies done before the start of the training course and the objectives from this project attributed to JCU and myself for UQ.
State of Art:
In this section I will approach the different aspects of the GBR and the SensorNet project. Firstly I will provide information about the GBR as such, before dealing with the coral and its environment. I will then describe the different organisations undertaking research on the GBR in Australia and around the World, before explaining the method of monitoring the coral with examples gathered through diving, boat and satellite observation of the coral. Specifically, I will describe the threat to the coral on the GBR. Next, I will turn to some examples of sensor network applications already in use, before explaining the constraints upon building sensors.
The wireless propagation theory experimented last year on the GBR which will certainly be used to stream the data will be explained. Finally, I will finish this part with a brief presentation of the Google Map tool used for the website.
Technical View of the Project:
This is the technical part of the report where the application developed during this training course will be presented. An overview of the project will be followed by a description of the data used to validate the software and a description of the project architecture. I will then elaborate the various parts of the project by describing the protocol, the server, the database, the GUI, the console mode and the website. I will finish this part by giving a case study that will lead us to the main function of the applications and a conclusion for the technical part.
Human and Management Dimensions Internal to the Company:
I will explain the environment in which I worked, and the relation I had with the staff of the laboratory and JCU the partner of the project.
Discussion:
Here I will explore possible improvements to the project, and a side project involving an XYZ stage. Then the different aspect concerning my ESIEA formation and the place of the communication in our societies will be discussed. I will finish by briefly describing my eighteen months in Australia.
Stage Environment
The training course was conducted at the University of Queensland (UQ) in the Vislab Laboratory located in the Information Technology and Electrical Engineering (ITEE) building. This laboratory is part of the School of Physical Science (SPS) which is itself a part of the Faculty of Engineering, Physical Sciences and Architecture (EPSA). EPSA is one of seven faculties at UQ. UQ was founded in 1910 and is one of the top eight universities in Australia [22]. It is also well recognized at an international level for its strengths in teaching and research. The following tree shows the position of Vislab in the university’s structure.
Figure 3 : internal architecture of the University of Queensland Vislab is a University research and development laboratory created in 2003 by Bernard Pailthorpe, Nicole Bordes and Chris Willing. This research centre specialises in data analysis, computational and experimental science as well as grid and data computing. They constantly engage in projects at the cutting edge of technology like e-archaeology, Kepler workflows, molecular modelling or high resolution displays. These are just few examples of this laboratory’s work. Some of these projects are done by the staff of the laboratory but most of them are the main projects of graduate or undergraduate students (in an internship position like me or as thesis student from the University).
Another Vislab Laboratory was created previously at the University of Sydney in 1992 by Bernard Pailthorpe. This laboratory is still active at the University of Sydney. See below the laboratory’s hierarchy, with status are from lowest to highest. Professor Bernard Pailthorpe and Nicole Bordes established the laboratory, with Chris Willing, who manages the lab. Doug Kosovic manages the informatics maintenance service of the lab. David Gwynne is the data specialist of the team and it is with him that I began to conceive and develop the project. Terry Simmich arrived two months before the end of my training course, his main task is to coordinate and develop tools for archaeological research. Two new people are expected to manage their main project Access Grid, a multi application management tool for videoconferencing. The staff contracts are generally for one year renewable. My position is as an occupational trainee responsible for the SensorNet project. Several students who are doing occupational training or doing their thesis for UQ work on small research and development projects.
Figure 4 : Internal Human Structure Of The Vislab Laboratory Hierarchy
The SensorNet project was proposed by QPSF. QPSF is an incorporated body established in October 2000, consisting of seven Queensland public universities. The organisation was funded by the Department of State Development, Trade and Innovation of the Queensland Government. This foundation has several projects in which some or all the universities work together. To increase the possibilities of this foundation the universities have made a strong investment in High Performance Computing Infrastructure (HPCI) since its inception in 2001. QPSF’s major HPC facilities are housed at, and maintained by UQ however each university also houses HPC facilities. Those facilities allow the QPSF members to share resources for work on data projects such as the SensorNet project. They also use the Access Grid (multi application management tool for videoconferencing) to communicate and share applications in real time. See below the architecture of this foundation.
State of the Project at the Start of the Training Course
The main project I worked on during this training course was SensorNet. The aim of this project was to develop, in collaboration with JCU, a sensor network system deployed in buoys around all the GBR to monitor different parameters like temperature, chemical properties of the water. In the future a camera will capture pictures of the ecosystem of the GBR. The project was created three years ago but the technical approach was developed only last year. When I am arrived, a thesis made the previous year by Jared Sanderson called Data Capture and the Management of Data Streaming from a Network of Sensors [17] helped me by providing a temperature database recording by AIMS. This project dealt with the sharing and the storage of a large archival collection of data across a connected grid of computers. This was achieved using the Storage Resources Broker (SBR) system to spread the data potentially to several databases on a networked grid of computers. The development of a new wireless communication using wave propagation through the upper layer of the sea level was successfully tested by Stuart Kininmonth, et al, in 2005 [1]. Some coding to experiment on the sensor boards was done in Python to capture data and display it in a graph on a web page. Those tests were done by Chris Willing and David Gwynne. During this training course, I was responsible for the aspects of the project involving the software development, under the guidance of David Gwynne. We used the videoconference system Access Grid (originally developed by Argonne National Laboratory [21]) to communicate with JCU which is currently working on their own hardware and software implementation.
JCU was initially only in charge of the hardware implementation for the buoys and the different relays with an ad-Hoc network which sends the data stream to the database (as will be described later in this thesis). Their aim is to find a hardware solution capable of resisting the extreme conditions to which the buoys and the relay are exposed on the GBR. For instance, the microprocessor and associated electronics must be resistant to temperatures greater than 50°C because they are fully exposed to the elements. The buoys must utilise solar and wind power to ensure extended autonomy, providing a use-time for the buoys. Other concerns about the sensors include diverse aggression (such as shark attack) and other factors which can compromise the result or destroy the sensors; e.g. organic deposits like algae on the sensors. The communication system between the buoys and the final server involves ad-hoc wireless at a frequency of 10.5GHz that will use the surface layer of the sea to guide the signal to the relay server or the final server. This specific wireless communication was developed in 2005 (as mentioned before) and will be explained in the State of Art section. My laboratory directed the system’s software implementation, from buoys to user. As the hardware was not already chosen, we developed a software solution as generic as possible to allow implementation in a wide range of embedded systems ranging from the simplest processor to the most sophisticated. In order to develop and test our solution we used an external electronic board sensor from Weeder Technology [2]. This board provides the values of four temperature probes to a computer by a serial connection. We will see further the criteria of this board in detail. The programs of the buoy, the server, the GUI and the console mode have been developed in Python to maintain compatibility with the rest of the system if necessary. Driver in C language, for the Weeder board, has been developed to provide the possibility to create a C program for the system in the buoys and in the relay or server. The software in C language for the buoy and server is currently being developed by David Gwynne and will be available in the future. This version will decrease the size of the code and the processing time to increase the routing time. These conditions are necessary in order to implement the program in a low consumption system in terms of memory, electricity and processing. We use a PostgreSQL database system to store the data where indexation and primary key have been used to increase its efficiency. The GUI interface and the console mode will be used by the final scientific user to manipulate the data in the Database. Finally, the website is tailored for a wide range of users, utilising PHP for the web server and JavaScript for the client using Google Map to provide interactive information.
State of Art The Great Barrier Reef:
The GBR World Heritage Area is located three quarters of the way to the northern tip of Queensland on the East cost of Australia, ranging from the south of the Tropic of Capricorn to the coastal waters of Papua New Guinea. This area cover about 2300 km and lies between 24°30’N-10°41’S and 145°00’-154°00’E [3].
The GBR is the largest World Heritage area with its 33,126,500 ha of Marine Park and the most extensive coral reef in the world. It was declared World Heritage in 1981. The GBR comprises some 2,800 individual reefs including 750 fringing reefs, which range in size from under 1ha to over 1,000 ha [3]. The GBR is only two million years old and evolved during the quaternary period when ice formed and melted in higher latitudes causing major sea level
fluctuations. The shape of each reef is quite different and is classified into three categories:
the Barrier Reef (or Wall Reef), most northerly of the GBR; the Platform Reefs, which comprise the majority of the reefs (ovular shaped and found between seaward side of the continental shelf and the mainland); and the Fringing reefs, found growing out from the shores of continental islands and the mainland.
At its conclusion, this project will provide precious information on the complexity of the water circulation and quality in those areas, which has created a complex ecosystem. The properties of the Coral Sea, land run-off, evaporation, southeast trade winds, forced upwellings due to strong tidal currents in narrow reef passages, and coastal water including mangroves, are all affecting the water circulation and thus the coral stability. The impact of people on water quality is also not well known. These complex parameters must be monitored and compared in order to understand their influence on such a fragile ecosystem. The map below presents the GBR Marine Park area described here.
Figure 6 : Presentation of the area (straight line) cover by the GBRMP [4]
The Coral and its Environment:
The Coral reefs flourish, apart from rare exceptions, mainly in the tropical latitudes 30° north or south of the equator. In the ecosystem of the GBR, there are approximately 356 reef building corals belonging to about 60 genera. They represent almost 75% of the known genera in the entire Indo-Pacific region [3]. Only the southernmost of reefs show a significant reduction in the number of species. Although many of the populations probably receive recruits only from neighbouring ones, they are part of a vast interconnected network in which larvae drifting from reef to reef and island to island ensure that populations are not isolated.
Coral cover decreases and increases quite dramatically because of cyclones, Crown of Thorns Starfish (COTS), and coral bleaching, but there are no long-term declines in coral cover or diversity. Even on inshore Fringing reefs, where human impacts are highest, there are no indications of any general decline since the El Niño event in 1998 [5].
The GBR contains over 300 species of coral, creating an environment for more than 1,500 species of fish, 4,000 species of molluscs plus a great diversity of sponges, anemones, marine worms, crustaceans, algae and finally a wide range of marine mammals [5]. Coral live in symbiosis with fish providing them a nutritious and protective environment. COTS is a parasite that feeds on the coral and can be damaging for the reef if in overpopulation. Coral also maintains a special symbiotic relationship with a microscopic organism (algae), especially zooxanthallae [6]. These organisms provide their hosts with oxygen and a portion of the organic compounds they produce through photosynthesis. When stressed, many reef inhabitants have been observed expelling their zooxanthallae in large amounts. Coral is an important component of our ecosystem and must be preserved at all costs to keep the equilibrium the coral reef provides. In addition the ocean provides oxygen thanks to this ecosystem of coral and other different animals, and vegetal that affects life from the ocean to the earth.
The Scientific Communities Around the GBR :
Scientific research on the GBR started with the GBR Committee (now called the Australia Coral Reef Society) in 1922 and the British GBR Expedition in 1928-29. Nowadays, for local and visiting overseas scientists, field stations are operated by UQ at Heron Island, The University of Sydney at One Tree Island, the Australian Museum at Lizard Island, JCU at Orpheus Island and AIMS in Townsville [3]. The latter two have extensive coral reef research programs that cover the full ambit of science disciplines.
Increasingly, these communities have lobbied the industries and the stakeholders around the Queensland coast to sponsor the monitoring and educational project on the GBR. The Australian Government has also developed Reef Check training to accredit volunteer teams on the preservation of the GBR [5]. Most of the financial support for this operation is provided from the dive tourism industry and other commercial businesses around the GBR.
Globally, the International Coral Reef Initiative (ICRI) established in 1994 and the Global Coral Reef Monitoring Network (GCRMN, founded in 1996) plays an important role in the preservation of coral in the international domain. Their objectives are to link existing organisations and people to monitor ecological and social, cultural and economic aspects of coral reefs within interacting regional networks. A significant example of their action is the rezoning of the GBR World Heritage Area where 33% of the total area has since 2004 become protected from extractive industries such as fishing and collecting [5].
Method of Monitoring the Coral:
Monitoring the coral is a challenge that will lead us to a better understanding of the complexity of the ocean system by realising the importance of the coral in this area. This kind of study leads to more precise climatic model as well as a better evaluation of the human impact on the Earth and the natural evolution of the coral. The GBR is one of the most monitored coral sites in the world but nonetheless, information gathering covers only about 5% of it (some 2,800 reefs) [5]. I will now present various examples of monitoring systems in order to demonstrate the spectrum covered by this field of studies.
The AIMS long-term monitoring program is designed to provide information about key groups of organisms on appropriate spatial scales. Broadscale Manta Tow surveys [19 and 23] have now been carried out through 11 latitudinal sectors over 21 years (1985-2006) and played a significant role in the understanding of the interaction of the coral with its environment, especially for the COTS phenomenon [5] which is a good indicator of the state of a reef. Each year, the perimeters of 100 reefs are monitored. To make this survey, a diver is towed by a small boat around each reef where it stops every 2 minutes to allow the diver to count the number of COTS. The density of COTS at which coral damage is likely corresponds to 0.22 COTS per two-minute tow and if this rate is greater than 1, the reef is definitely damaged. An interesting result of this study shows that some reefs have been unaffected by COTS since the beginning of the monitoring program in 1985 which is the start of the study [5].
Figure 7 : Amount of COTS observed during the Broadscale Manta surveys [5]
You can observe in the preceding charts the mean coverage of hard coral by this study over the years. Each chart represents a part of the GBR coverage from a. to d. that splits the GBR in four parts respectively from north to south. The right vertical scale represents the average of COTS observed per tow. Below is an example of COTS feeding on a coral reef. The COTS can also feed on different encrusting organisms when coral is scarce, such as algae, gorgonians and even other COTS.
Figure 8 : Example of COTS specimen feed on coral [7]
AIMS also has two vessels which conducted 50 research trips between them in 2002-2003 and operated for an average of 257 days. Their laboratories enable research such as DNA analysis, cell culture, microbiology, chemical isolation and fermentation etc [8] The shortcomings of this kind of monitoring rest with the use of a boat to collect samples from the GBR and the evident problem of regularity when the sample is not taken for climatic or human reasons.
Nevertheless, it is still useful to study the different organisms that populate the GBR. In the future, the SensorNet project will certainly turn to sensors incorporating a micro chemical lab that will regularly test certain properties of micro organisms.
Coral reefs are predominantly monitored by satellite, which provides a precise picture of the extent of coral bleaching and can detect anomalies with special filters. It also monitors the temperature of the ocean with infrared radiometers installed on the satellite. One of those projects developed by NOAA Satellite and Information Service, called HotSpot provides twice weekly a map of the state of coral bleaching around the world…
Download Sensor Network Implemented on the Great Barrier Reef.pdf
Source: vislab.uq.edu.au