Millennium AtollThe Millennium Atoll
Caroline/Millennium Atoll Lagoon, Republic of Kiribati: Natuurhistory of an almost untouched ecosystem
Qatie L. Barott, Jennifer E. Caselle, Elizabeth A. Dinsdale, Alan M. Friedlander, James E. Maragos, David Obura, Forest L. Rohwer, Stuart A. Sandin, Jennifer E. Smith, A number of studies were conducted to characterise the Millennium Atoll Lagoon's physics and biology during a research mission in April 2009.
The Millennium is a secluded atoll in the Central Pacific of the Republic of Kiribati and belongs to the Southern Line Islands group. Atoll is one of the few relatively untouched marine eco-systems left. It is fenced in high and was characterised by net-shaped cliffs in the middle of the atoll.
Depths peaked at 33. 3 metres in the centre of the lake, averaging between 8. 8 and 13. In the lowest areas large decks of Favia matthaaii were found, which probably formed a basis on which the dominating coral (Acropora spp.) developed into a net-like one.
Benthian seaweed cooperatives mainly comprised crust seaweed (CCA), microfilamentary lawn seaweed and scattered stains of Halimeda and Caulerpapp. It is probably an important home for a number of important types of livelihoods, such as the black tip sharks and the Napoleon wrasses, which are widely used in other parts of the globe but were widespread in the Millennium Bay.
It is also rich in Tridacna maxa (giant mussels). The Millennium Laguna offers an outstanding example of a relatively unspoilt atoll. The Millennium marine community, like most global reefs, may be endangered by climatic changes and the associated global warming, ocean degradation and rising as well as the occasional depletion of indigenous resources, which are hard to control and implement due to the atoll' s shelter.
The remoteness of Millennium has made it possible to stay one of the few almost untouched marine eco-systems in the worid, but it is essential that this eco-system is protected so that it can live for coming generation. The Millennium is one of the most distant reclaimed altolls on the planet and is home to some of the most unspoilt natural reefs.
Previously known as Caroline Atoll and Caroringa, Millennium is a member of the Line Islands group in the Central Pacific Ocean (10°00?S, 150°13. 5?W; Fig. 1) and part of the Republic of Kiribati. The Millennium stretches from east to hard country from 10 km to 10 km from left to right and from right to right.
There is a large main laguna that makes up most of the centre of the atoll, which measures about 6 km x 0.5 km, and the flat cliff surrounds most of the 39 or so islands. At only 3 metres above the surface, the Millennium's surface is the most threatened by sea-level rises, according to the United Nations.
Illustration 1. Cartography of the Millennium-Lagune and the investigated locations. B ) Satellite image of Millennium with information on the entry to the Laguna, the wreck, the former Laguna entry and the measured locations, B) Plan of the interpolated deeps within the Laguna. The Millennium is far from the centres of the world' s people, the nearest is 834 km away in Papeete, Tahiti, and is relatively unaffected by historical man.
In 1883 an expedition to Millennium to visit a sunset that led directly over the isle took place,. Between 1873 and 1895, guano was also mined and it is reported that about 10,000 tonnes were mined from the atoll, a relatively small amount in comparison to other islets in the region,,.
The Millennium has been largely deserted since the early 1940', probably because of its isolation from the large conurbations, the shortage of freshwater and the difficulties in anchoring and access to the lake. The three Kepler and Kepler explorations to the Millennium from 1988-1990, resulted in the Republic of Kiribati terminating Urima's lease.
Since 1993, however, the Keplers have reported that Urima has taken up again to fish on the atoll. In more recent times, the first celebrations of the new millennium took place on 1 January 2000. The reorientation of the 1995 Border made the Isle the first country to welcome the beginning of the new millennium and the atoll was re-named Millennium in honour of this occasion.
The Millennium has a rich local wildlife (89% in 1990), among them Prisonia grandi is a forest, Birgus latro (coconut crabs) and a multitude of sea birds that nest, with few inversive species (e.g. coco palms and Polynesia rats[Rattus exulans]),. The only known studies of the sea life in the Laguna were a common US-USSR and USSR exploration in 1988, but for temporal and logistic reasons most of the Laguna was excluded.
Short observation of the flora of the lagoon can also be found in the Kepler reports,. A number of subsea explorations were carried out throughout the entire lake in April 2009 to characterise the variety and wealth of the Southern Line Islands' fishing and petroleum species during a research mission to the Southern Line Islands. It is the first comprehensive overview of the Millennium Lagoon's maritime heritage.
It also includes our observation of evidence of man-made activities in the Laguna, despite its remoteness, and the possible importance of this activities for the studied maritime populations. The deep sounding was carried out arbitrarily around the Laguna with a hand-held deep sounding with the help of satellite-based recording.
The surveys were carried out in all areas of the Laguna with the exception of the northernmost one. ArcGIS was used to create a mapping of the logged deeps and habitats (Figure 1). There have also been observed changes in the structure of the area. There were two trans-ects at each of the four lagoons covering four regions: Southern (L1), South-Central (L4), North-Central (L7) and Northr (L6) (Figure 1).
The transect was carried out on SCUBA at a depth of 3-5 metres and covers an area of 25 m×1 metres, with the exception of the transect at site L7, which was 10 metres and 14 metres respectively due to the smaller corals at this point. Then, Benthian species were divided into the following groups: corals, CCA, grassweed, macroalges, tridacna (giant clams) and others.
The corals were listed at each of the above locations and at another site (L5). The transits were randomly carried out around the Laguna, among them 6 around the patches in the south of the Laguna, 10 along the fringe of the northcentral area and one around the patches in the north-central area.
Depth ranges from less than 1 meter along the perimetre coral to ?-5 meters around the patches. With the help of belt cut measurements the frequency of the day-active fishs in the layer of rock with the Laguna was evaluated. The bottom of all surveyed species was found to have the smallest detectable taxion and the overall length (TL) was reckoned to be the next 5 cm age group.
Scuba diving also surveyed non-second range fish to assess the total biodiversity at each site. At 9 dive sites, scuba-divers have made 18 measurements of shore transects, measuring both the habitat of the reefs and the edges of the reefs in the lake without any plan. Watersamples were taken from different places in the laguna with 5-liter diving tanks.
From each site two replica specimens were taken, with the exception of the low Laguna, in which four replica specimens were gathered. Atoll margins are slightly elevated above low ebb, with waters exchanged in and out of the Laguna via the coral shelf and via canals and grooves along the edge of the canal.
Most of the time, the movement of the waters in the lakes is influenced by waves, tides and winds,. On the basis of our optical observation, the waters flow into the reef at high tides and are held back by the absence of deeper passages through the coral cliffs, so that at low tides the waters inside the reef remain higher than those outside the atoll.
As the waves push through and over the coral cliffs, the tides flood the Millennium-Lagune, generating the east-west current dynamic within the Laguna. Most of the water seems to be drained through the biggest sewer at the southeastern end of the atoll (Figure 1A), which creates an extra north-south current.
7m below sea level, along the rims of the basins that approach the cliffs (Figure 1B). Most of the lowest basins (>30 m) were situated in the centre of the Laguna (Figure 1B), much lower than the previously existing max. estimations of water levels of ? m. Situated on the south-eastern border of the lake and bordering the southern island, the biggest tunnel into the lake (of course, on the basis of a 1883 atoll chart; Figure S1) has been blown up to allow vessels to penetrate the lake and be protected from waterborne threats (Figure 1A).
The canal is, however, extinct and does not reach completely into the Laguna. One of the most prominent shipwrecks from 1993 is currently located on the perimetre riff just South of that passage (Figure 1A). There are still obvious signs of bodily harm to the corrosive fuselage due to the fuselage's corrosive fuselage causing great changes in the Benthian communities around the canyon.
Most of these are over water and are clearly discernible, but a number of routes to the side of the pass that leads to the Laguna are under water and present a possible danger to vessels. This rod appears to be the remains of deserted fishing pens or was placed to prevent the vessel from entering the water.
Other man-made shipping threats that once occurred inside the lake were routes that were fortified between some of the coral cliffs in the south of the lake, possibly to prevent unauthorised boats from entering the area. A small sailing yacht was moored in the lake during the course of the explor.
He had taken the vessel to one of the coral reefs and lived in the lake for about four month with the intent of several more. He was the master of the lake, where he harvested sea birds, sea turtles, sea birds, shrimps and mussels for his own use and harvested lobster from the shore, which was conserved and marketed in the nearby harbours, mainly in Polynesia, France.
There are at least three large habitats in the Laguna, which differ in their composition via east-west and north-south-gradient. At first, the islands are surrounded by the cliffs and the associated back cliffs and comprise the whole ridge and the plains that run between the islands. Secondly, the inside of the Laguna is littered with small spot riffs, often connected by deep corals that form a reticular system with "line reef" constructions and columns of corals, battlements and bogeys.
Two or more of these line riffs in the south part of the atoll run entirely across the Laguna from north to south and are at low tide. At least two of these line riffs run from north to south. A third large biotope within the Laguna is the bottom of the Laguna, which is mostly coated with very thin carbonated sandy and rigid substrates of old corals and Relic corals.
Line coral predominated the lineages, with an mean occultation of 62.09 (±9.4.1 SE; Fig. 2A.3A-B) ranging from close to 100% to zero. The CCA were by far the most frequent groups of seaweed functions at the spot riffs (19.9%±6.5), followed by lawnweed (.09%±2.6; Fig. 2A).
The macroalgae coverage was very low and mainly comprised Halimeda and Caulerpa spp (mean coverage 0.85%±0.6; Figure 2A). Coverage of corals differed according to location (Figure 2B) and was strongest in areas with higher flows within the Laguna (e.g. along the east parts of the Laguna and at columns and line riffs bordering canals and open areas).
It was least covered where the river was more limited, e.g. at the west (leeward) side of the Laguna and at the north side of the islands and in "closed ponds" where the line riffs had risen to the sea level, which limited the refl ect. of the reef. Shell T. maxa was quite frequent, accounting for 2. 65% of benthic species (±1. 5, SE; Figure 2A).
Illustration 2. and A) Covering of line riffs in the millenium lagoon with a mean default error±1. B ) Percentage coverage of line riffs by area. A) The number of corals per colony and percentage of area. Illustration 3. Prestigious pictures of ordinary marine life. Acropora sp. The fall of the settlements along the edges of the shore is obvious.
B ) Example of Acropora ppp. dominating the entire area. This is a collection of large pelagic rocks at the top of a canyon. D ) Blacktipriffhai. Acropora predominated the freshwater corals in the Laguna (about 90% by area and number of settlements, Figure 2C), followed by Montipora, Fungia, Pavona and Leptastrea.
Altogether 32 types were watched in the Lagune (table 1). The acropora types are small pillows in other habitats, but in the tranquil water of the lake they are growing in very long hands alongside each other, the external 10-15 cm being lively. Acroporids were dominant in the sizes 20-40 cm and 40-80 cm (Figure 2D).
At the densest overgrown cliffs there were also >3.2 meters of population. A large number of small settlements were found (50 cm TL) and adolescents (