In Central Pacific atolls (e.g., Tuvalu, Kiribati, Marshall Islands), shells of large benthic foraminifera are the primary components of sand-sized sediments (Collen and Garton 2004; Yamano et al. 2005). Thus, corals and foraminifera are two major sand producers. Coral reefs on the ocean side act as a natural breakwater and provide bioclastic see more materials.

If a coral reef is healthy without receiving adverse impacts such as rising acidity of seawater, it has an upward growth potential of as much as 400 mm/100 years, which matches the median predicted value of sea-level rise. Thus, a healthy coral reef has the potential to keep up with rising sea level (Kayanne et al. 2005). Recent studies have suggested that reef islands and adjacent coral reefs located near densely populated areas are being affected by wastewater discharge and waste disposal (Abraham et al. 2004; Richmond et al. 2002; Vieux et al. 2004). The main islands of atoll nations are densely populated (e.g., 8,300 people/km2 on Fongafale, Tuvalu; 2,558 people/km2 on South Tarawa, Kiribati and 11,724 people/km2 on Majuro, Marshall

Aloxistatin order Islands) (Secretariat of the Pacific Community 2005, 2007; Economic Policy, Planning and Statistics Office 2007) owing to limited habitable areas. Concentrations of nutrients were high in reef-flat seawater near densely populated islands, resulting in both direct and indirect negative effects on foraminifera through habitat changes and/or the

collapse of algal symbiosis (Osawa et al. 2010). Such reduced water quality on coral reefs caused changes in benthic foraminiferal communities (Hallock et al. 2003; Uthicke and Nobes 2008; Carilli and Walsh 2012). Large benthic foraminifera were rare or absent in the ocean reef flat of Majuro Atoll (Fujita et al. 2009), in lagoons and ocean reef flats of the south Tarawa Atoll (Ebrahim 2000) and in the vicinity of wastewater outfalls on Enewetak Atoll (Hirshfield et al. 1968). The decrease in sediment supply has the potential to contribute to increased coastal erosion (Collen and Garton 2004); however, the mechanisms causing such high nutrient Astemizole concentrations are as yet unknown. Reef islands and their populations are considered vulnerable to a range of climatic changes including sea-level rise and similar extreme occurrences (Mimura et al. 2007). The most anticipated physical impacts of sea-level rise on reef islands are shoreline erosion, inundation, flooding, salinity intrusion and reduced resilience of the coastal ecosystem (Khan et al. 2002; Leatherman 1997; Mimura 1999; Yamano et al. 2007). If the atoll nations disappear, there will be no islands left and nothing to inhabit (Connell 2004). Considering the above studies, a degradation of coral reefs and a decline in large benthic foraminifera, caused by anthropogenic impacts, will accelerate the onset of serious problems that may be caused by future sea-level rise.