Abstract
A series of surveys were carried out to characterize the physical and biological parameters of the Millennium Atoll lagoon during a research expedition in April of 2009. Millennium is a remote coral atoll in the Central Pacific belonging to the Republic of Kiribati, and a member of the Southern Line Islands chain. The atoll is among the few remaining coral reef ecosystems that are relatively pristine. The lagoon is highly enclosed, and was characterized by reticulate patch and line reefs throughout the center of the lagoon as well as perimeter reefs around the rim of the atoll. The depth reached a maximum of 33.3 m in the central region of the lagoon, and averaged between 8.8 and 13.7 m in most of the pools. The deepest areas were found to harbor large platforms of Favia matthaii, which presumably provided a base upon which the dominant corals (Acropora spp.) grew to form the reticulate reef structure. The benthic algal communities consisted mainly of crustose coralline algae (CCA), microfilamentous turf algae and isolated patches of Halimeda spp. and Caulerpa spp. Fish species richness in the lagoon was half of that observed on the adjacent fore reef. The lagoon is likely an important nursery habitat for a number of important fisheries species including the blacktip reef shark and Napoleon wrasse, which are heavily exploited elsewhere around the world but were common in the lagoon at Millennium. The lagoon also supports an abundance of giant clams (Tridacna maxima). Millennium lagoon provides an excellent reference of a relatively undisturbed coral atoll. As with most coral reefs around the world, the lagoon communities of Millennium may be threatened by climate change and associated warming, acidification and sea level rise, as well as sporadic local resource exploitation which is difficult to monitor and enforce because of the atoll's remote location. While the remote nature of Millennium has allowed it to remain one of the few nearly pristine coral reef ecosystems in the world, it is imperative that this ecosystem receives protection so that it may survive for future generations.
Highlights
Millennium is among the most remote coral atolls on earth, and is home to some of the most pristine coral reefs
Rising only 3 m above sea level, the land area of Millennium is under the highest level of threat to sea level rise according to the United Nations [3]
The higher abundance of microbes in deep areas of the lagoon is likely due to the absence of filter feeders at these depths, the hydrodynamics and amount of mixing within the lagoon is currently unknown and likely has an affect on microbial and plankton uptake by the benthos and the abundance of these organism in the lagoon [25]. This is the first time that the microbial abundance from Millennium lagoon has been quantified, and provides a valuable reference for microbial abundance in this relatively pristine lagoon. This is the first comprehensive survey of the lagoon at Millennium Atoll, which contains some of the few remaining coral reefs that are relatively unaltered by human activity
Summary
Millennium is among the most remote coral atolls on earth, and is home to some of the most pristine coral reefs. Millennium spans approximately 10 km from north to south and about 2 km east to west. A large central lagoon accounts for the majority of the center of the atoll, measuring about 6 km by 0.5 km, and the shallow perimeter reef supports most of the approximately 39 islets. The three largest islets are Nake Islet, Long Islet, and South Islet, which comprise the majority of the land area. Rising only 3 m above sea level, the land area of Millennium is under the highest level of threat to sea level rise according to the United Nations [3]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
