The Indian Ocean Coral Reef Fish Monitor

The Indian Ocean Coral Reef Fish Monitor

A coral reef conservation project part-funded by the Darwin Initiatives

The Indian Ocean Coral Reef Fish monitoring project is the successor to the REEFWATCH project launched in 1982 by the Tropical Marine Research Unit based at the University of York. Reefwatch was the first scheme to attempt to use volunteer and non-professional divers to help survey and monitor the distribution and status of the world's coral reefs. Reefwatch II builds on previous experience and focuses on surveys of the distribution and abundance of key families of coral reef fish as a means of understanding and conserving the biodiversity of coral reefs within the Indian Ocean Region.

The Value of Coral Reefs

Coral Reefs are not only one of the world's most fascinating and impressive natural environments, they are also an important resource both to local people, and to humankind as a whole. The underwater beauty and great variety of fish, corals and other marine life has become well known, both from television and the explosive growth in popularity of SCUBA diving. But reefs are also a vital source of fish and other food to millions of people living in coastal regions throughout the tropics; they harbour an immense diversity of species among which are many of conservation significance; others may have genetic value and the potential to produce new medicines or be suitable for use in aquaculture. Most recently, for some developing countries, coral reefs have acquired enormous value as a tourist resource, the foreign exchange to be earned from diving and coastal tourism potentially justifying the protection of reefs within marine parks and reserves.

Damage to Coral Reefs

Despite their value, coral reefs through much of the globe have during the last few decades been increasingly effected by pollution and other forms of human impact. Corals have only a limited ability to clear themselves of sand or sediment. Increased amounts of sediment in coastal water, occurring as a result of coastal infill projects, dredging or upriver soil erosion, have killed much of the coral on some reefs in areas such as the Arabian Gulf and South-east Asia. Elsewhere corals have suffered from overgrowth of algae occurring as a result of increased levels of nutrients due to sewage pollution or excessive use in farming. In the Caribbean and Western Pacific there has in some recent years been extensive bleaching and death of corals believed due to increased ocean temperatures. Human activity may also have caused extensive destruction of corals by an indirect mechanism. In Australia and Japan there have during some recent periods been widespread population outbreaks of the Crown-of-thorns starfish (Acanthaster planci) which feeds on coral tissue, while in the Western Indian Ocean and, in the past, in the Caribbean, high population densities of sea-urchins have damaged reef areas through the erosion caused by their scraping mouth-parts. There is increasing evidence that these population outbreaks may be partly the result of over-fishing of the predatory fish species, such as emperors (family Lethrinidae) and triggerfishes (family Balistidae), that feed on them.

D. savignyi erode reef substrate

A. planci feeding on hard coral polyps

Monitoring Coral Reef Fish

Both for their own sake, as a conspicuous and diverse element of the reef fauna and because of their wider ecological significance, some families of reef fish present valuable groups for monitoring the health of reefs, and for investigating factors underlying the high species diversity characteristics of reef ecosystems. Some fish, such as species of butterflyfish (family Chaetodontidae) feed non-destructively on coral tentacles; they are also conspicuous and easily recognised. Consequently they have been proposed as useful indicator species of reef development and condition. Many families such as snappers (family Lethrinidae) and groupers (family Serranidae) and triggerfishes (family Balistidae), that feed on them.

The Indian Ocean Region

The region including the Red Sea and Arabian Gulf, East Africa and the islands of the central Indian Ocean, has been selected as the focal area for this study. While this is the reef area closest to Britain and Europe, many reefs have yet to be assessed scientifically. Some reef areas are relatively unexploited or influenced by human activity. Others sustain large human populations which threaten to degrade the reefs on which the people depend. Yet others are becoming the basis of a large tourist industry. At the same time the region offers valuable opportunities for understanding mechanisms responsible for the high number of fish species occurring on reefs.

Reefwatch II

Reefwatch II is a project designed to involve volunteers and non-specialist scientific and other staff in the surveying of coral reefs and the monitoring of reef fish populations. Some relatively simple and well-established methods are used to describe the main features of each reef site, and to census the numbers of fish of selected families present at two or more standard depths. Methods have been improved as a result of experience gained during the original Reefwatch programme and by other research laboratories and organisations. Particular emphasis is placed on training of observers and on subsequent checking for accuracy to insure that data being collected is adequate and reliable. Data collected during the project is lodged both with the project database in York and with the Environmental Agency or other relevant authority in the country concerned. Data is also copied to IUCN (the World Conservation Union), WWF (the World Wide Fund for Nature) and UNEP (the United Nations Environment Programme) through their World Conservation Monitoring Centre (WCMC) in Cambridge. Reports are published describing and analysing the data available for different areas. Survey work in association with the project is now being undertaken in 10 or so countries of the region.

The Data Sheets

Typically work on the project requires completion of two types of data sheet at each coral reef site being recorded. This can be done by a single diver (normally in the company of a buddy) on no more than an occasional basis, or a team of divers may be involved in recording a series of sites on a once off or regular basis. The first data sheet is the Site Basic Information Sheet. One part of this sheet, completed above water, requires information about the exact location of the site and other key background information about the area and the observer. The other part of the Basic Information Sheet is completed underwater (using pencil on waterproof paper) and involves a simple semi-quantitative assessment of the shape of the shape of the reef, of the density of corals and of the extent of any apparent environmental impacts. The second type of data sheet are those on which the fish counts are recorded. These are transparent sheets which are placed over a coloured fish identification chart of the fish families being surveyed. Both are fixed to an underwater clip-board.

Counting Reef Fish

Fish are censused by swimming along a depth contour for a distance of 200 metres counting all the individuals of the relevant family present within a distance of 5 metres to either side of the contour. Counts can be repeated for each of the four main families or groups of families being monitored by the project. These are 1. Butterflies & Angelfishes (Chaetodontidae & Pomacanthidae), 2. Emperors & Snappers (Lethrinidae & Lutjanidae), 3. Groupers (Serranidae), 4. Triggerfishes & Pufferfishes (Balistidae & Tetraodontidae). Similarly counts can be repeated at two or more standard depths. Observers can specialise in identification and counting of a single family (or group of families) of fish. Most volunteers begin by returning counts for only one group of fish, most frequently butterfly & angelfish, which are probably the easiest to identify and of greatest interest for reef monitoring and biodiversity studies.


Volunteers and organisations participating in the work receive a project instruction manual which describes the methods in more detail. The manual is intentionally kept short and clear to facilitate use by non-specialist divers. Previous experience, including a review of the performance of schemes using volunteers and non-professional staff for surveying and monitoring reefs, has highlighted the importance of training. Emphasis is placed on testing to ensure that observers reach an acceptable standard of fish identification and counting. Training proceeds through recognition of fish to the family level, before species within selected families are learned. Checking involves testing against sets of slides or video sequences and comparison of performance on the reef against experienced observers simultaneously swimming the same lengths of reefs.

How the Data is Used

Copies of the basic information sheets and fish counts are returned to York, either directly or via the local Environment Agency, National Park or University. Data is checked for quality before being input to a computerised database. Currently a database programme called FoxPro is used linked to a mapping programme called Quickmap. This enables maps to be drawn and regularly updated showing the distribution and abundance of target species. Further analysis of data is carried out using statistical software. This can indicate differences in fish abundance or species diversity between different areas, for example a marine park and an adjacent unprotected area, or one part of the region and another. Data for commercial species can also be inserted into a fisheries model that is being developed to assess whether stocks are being over-fished. Participating groups are also encouraged to prepare brief reports presenting their own data.

How to Participate

The project is particularly designed for use by local organisations involved in reef or coastal zone management (such as environmental agencies, marine national parks or fisheries departments) and by SCUBA diving groups or centres based in or planning expeditions to countries within the region. Collaborating national agencies include the Egyptian National Parks and the Kenya Wildlife Service. The project is also suitable for use by individual divers, especially those living in the study area. However, unless they are already experienced at reef fish identification, they will need to be able to undertake the necessary training, ideally by visiting York or another participating organisation. The project will normally aim to send a staff member to provide a 5 or 10 day training programme for government agencies wishing to join the scheme.

If you believe you or your organisation may be able to participate in the scheme please contact: INDIAN OCEAN REEF FISH MONITORING PROJECT, TROPICAL MARINE RESEARCH UNIT, UNIVERSITY OF YORK, YORK YO1 5DD, UK. You may also contact the Research Unit by Fax: (+44) 1904 - 432860 or by e-mail : RFGO1@ Please explain clearly the scope of the survey work you may be able to undertake and how you suggest you or your group may be able to complete the necessary training.

The Darwin Initiative is a biodiversity conservation programme of the United Kingdom Department of the Environment.

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