16 Reefscape Ecology Within the South Pacific
247
16.2 Polynesia Mana Network
16.2.1 Description of the Network
Polynesia mana coral monitoring network (Fig. 16.1) was initially set up in French
Polynesia in 1993, in the context of a long term monitoring of the health of coral
reefs. It now covers a dozen sites in the five archipelagos of ten islands, Moorea,
Raiatea, Tahiti, Tetiaroa (Society Islands), Nengo Nengo, Takapoto, Tikehau (Tuamotu Archipelago), Nuku Hiva (Archipelago Marquesas), Tubuai (Austral Islands),
South Marutea (assimilated to the Gambier Archipelago). This action initiated on
the French Polynesian territory has been extended across the southern Pacific in
recent years. Node Polynesia Mana (part of the Global Coral Reef Monitoring
Network—GCRMN) now includes seven countries or territories (Cook Islands,
French Polynesia, Kiribati, Niue, Tokelau, Tonga, and Wallis and Futuna), which
represent a total land area 6,000 km
2 for 347 islands and an Exclusive Economic
Zone (EEZ) of 12 million km
2 . This area of 13,000 km
2 of coral reefs is the main
natural resource for 500,000 inhabitants, whether in terms of food, financial resources through tourism, aquaculture, intensive or extensive (black pearls, seaweed,
clams, fish) or other forms of exploitation of the environment (e.g. collecting shells,
aquarium fish for the international market).
During the twentieth century, these countries have undergone rapid development
resulting in urbanization, increased population and agricultural and industrial development. This development is concentrated on a few islands (i.e. 15 islands on
347 subjects), resulting in degradation of coral reefs in the most populated areas
(Gabrié 1998; Guards and Salvat 2008; Wilkinson 2008). The other islands are,
for the moment, relatively unaffected by this development. Centralizing industry has
increasingly tended to reinforce the flow of people from the remote to the more populated islands to meet the demand for dietary protein and to access a more westernized
lifestyle.
16.2.2 Benthic Assessment Methods
The photo-quadrat method is used to measure the permanent percentage of coral
cover while distinguishing Scleractinian coral genera in a reproductible manner on
the same area. The values obtained on the same reef plot are updated every 2 years.
The method involves photographing a 20 m long and 1 m wide (20 m
2 ) rectangular
surface area. A steel cable of 20 m is strongly stretched between two poles by means
of a turnbuckle. On this cable, a series of clamps fixed at regular intervals enables
for setting an aluminium frame (1 × 1 m size of internal contours) at 20 successive
positions. At each position, the frame is photographed (Fig. 16.2a) so that the band
of 20 m
2 can be accurately represented. The method used for data processing is the
Point Intercept Quadrat (Weinberg 1981). Eighty-one points are superimposed over
each quadrat photographs (Fig. 16.2b) and are systematically distributed offset lines.
247
16.2 Polynesia Mana Network
16.2.1 Description of the Network
Polynesia mana coral monitoring network (Fig. 16.1) was initially set up in French
Polynesia in 1993, in the context of a long term monitoring of the health of coral
reefs. It now covers a dozen sites in the five archipelagos of ten islands, Moorea,
Raiatea, Tahiti, Tetiaroa (Society Islands), Nengo Nengo, Takapoto, Tikehau (Tuamotu Archipelago), Nuku Hiva (Archipelago Marquesas), Tubuai (Austral Islands),
South Marutea (assimilated to the Gambier Archipelago). This action initiated on
the French Polynesian territory has been extended across the southern Pacific in
recent years. Node Polynesia Mana (part of the Global Coral Reef Monitoring
Network—GCRMN) now includes seven countries or territories (Cook Islands,
French Polynesia, Kiribati, Niue, Tokelau, Tonga, and Wallis and Futuna), which
represent a total land area 6,000 km
2 for 347 islands and an Exclusive Economic
Zone (EEZ) of 12 million km
2 . This area of 13,000 km
2 of coral reefs is the main
natural resource for 500,000 inhabitants, whether in terms of food, financial resources through tourism, aquaculture, intensive or extensive (black pearls, seaweed,
clams, fish) or other forms of exploitation of the environment (e.g. collecting shells,
aquarium fish for the international market).
During the twentieth century, these countries have undergone rapid development
resulting in urbanization, increased population and agricultural and industrial development. This development is concentrated on a few islands (i.e. 15 islands on
347 subjects), resulting in degradation of coral reefs in the most populated areas
(Gabrié 1998; Guards and Salvat 2008; Wilkinson 2008). The other islands are,
for the moment, relatively unaffected by this development. Centralizing industry has
increasingly tended to reinforce the flow of people from the remote to the more populated islands to meet the demand for dietary protein and to access a more westernized
lifestyle.
16.2.2 Benthic Assessment Methods
The photo-quadrat method is used to measure the permanent percentage of coral
cover while distinguishing Scleractinian coral genera in a reproductible manner on
the same area. The values obtained on the same reef plot are updated every 2 years.
The method involves photographing a 20 m long and 1 m wide (20 m
2 ) rectangular
surface area. A steel cable of 20 m is strongly stretched between two poles by means
of a turnbuckle. On this cable, a series of clamps fixed at regular intervals enables
for setting an aluminium frame (1 × 1 m size of internal contours) at 20 successive
positions. At each position, the frame is photographed (Fig. 16.2a) so that the band
of 20 m
2 can be accurately represented. The method used for data processing is the
Point Intercept Quadrat (Weinberg 1981). Eighty-one points are superimposed over
each quadrat photographs (Fig. 16.2b) and are systematically distributed offset lines.