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Research about Micronesia

Source-linked reports with geographic coverage including Micronesia.

7 recordsLinked to original sources
USGS2022

A comprehensive assessment of mangrove species and carbon stock on Pohnpei, Micronesia

Mangrove forests are the most important ecosystems on Pohnpei Island, Federated States of Micronesia, as the island communities of the central Pacific rely on the forests for many essential services including protection from sea-level rise that is occurring at a greater pace than the global average. As part of a multi-component assessment to evaluate vulnerabilities of mangrove forests on Pohnpei, mangrove forests were mapped at two points in time: 1983 and 2018. In 2018, the island had 6,426 ha of mangrove forest. Change analysis indicated a slight (0.76%) increase of mangrove area between 1983 and 2018, contrasting with global mangrove area declines. Forest structure and aboveground carbon (AGC) stocks were inventoried using a systematic sampling of field survey plots and extrapolated to the island using k-nearest neighbor and random forest species models. A gridded or wall to wall approach is suggested when possible for defining carbon stocks of a large area due to high variability seen in our data. The k-nearest neighbor model performed better than random forest models to map species dominance in these forests. Mean AGC was 167 ± 11 MgC ha -1 , which is greater than the global average of mangroves (115 ± 7 MgC ha -1 ) but within their global range (37–255 MgC ha -1 ) Kauffman et al. (2020). In 2018, Pohnpei mangroves contained over 1.07 million MgC in AGC pools. By assigning the mean AGC stock per species per area to the map, carbon stock distributions were visualized spatially, allowing future conservation efforts to be directed to carbon dense stands.

Pohnpei Island↗
USGS2012

The unexpected discovery of blind snakes (Serpentes: Typhlopidae) in Micronesia: Two new species of Ramphotyphlops from the Caroline Islands

Two new blind snakes in the genus Ramphotyphlops are described from Ulithi ( R. hatmaliyeb sp. nov. ) and Ant Atoll ( R. adocetus sp. nov. ) in the Caroline Islands, the first blind snake species known from Micronesia east of Palau (excluding Ramphotyphlops braminus ). Both species are unusual in being known only from small, low-lying atolls. They can be distinguished from other Ramphotyphlops by the combination of 22 scale rows over the length of the body; a wedge-shaped snout, without a keratinized keel; and a broad, pyriform ( R. adocetus ) or ovate ( R. hatmaliyeb ) rostral scale.

Caroline Islands↗
USGS2011

Spatial and temporal characteristics of grouper spawning aggregations in marine protected areas in Palau, western Micronesia

In Palau, Ngerumekaol and Ebiil Channels are spawning aggregation sites that have been protected from fishing since 1976 and 2000, respectively. Groupers and other targeted fisheries species were monitored monthly over a 1.5 year period at these two spawning aggregations and two nearby exploited reference sites where grouper formerly aggregated to spawn. At the protected aggregation sites, three grouper species ( Plectropomus areolatus , Epinephelus polyphekadion , and Epinephelus fuscoguttatus ) accounted for 78% of the abundance and 85% of the biomass of all resource species surveyed but comprised <1% of the total abundance and biomass at reference sites not protected from fishing that formally harbored spawning aggregations. Abundance and biomass of grouper species pooled were 54% and 72% higher, respectively, at Ngerumekaol compared to Ebiil. Comparisons with data from the same locations in 1995–1996 showed order of magnitude declines in abundance of E. polyphekadion at both locations. The lower numbers of E. fuscoguttatus and the near absence of E. polyphekadion at Ebiil may reflect the effects of previous and current overexploitation.

Palau↗
USGS2001

Effect of the 1997-1998 ENSO-related drought on hydrology and salinity in a Micronesian wetland complex

The potential effects of global climate change on coastal ecosystems have attracted considerable attention, but the impacts of shorter-term climate perturbations such as ENSO (El Niño-Southern Oscillation) are lesser known. In this study, we determined the effects of the 1997–1998 ENSO-related drought on the hydrology and salinity of a Micronesian mangrove ecosystem and an adjacent freshwater swamp. A network of 9 piezometer clusters installed at the study site served as sampling points for continuous and manual measurements of salinity and water level. During the drought period from January through April 1998, mean water table levels in the mangroves and freshwater swamp were approximately 12 and 54 cm lower, respectively, than during May through December when precipitation returned to near normal levels. At the peak of the drought (February 1998), the most dramatic result was a reversal in groundwater flow that sent groundwater from the mangroves upstream toward the freshwater swamp. Flow nets constructed for this period and immediately after illustrate the strong hydrological linkage between the two systems. This linkage was also illustrated by measurements of groundwater salinity in the piezometer network. Ninety-six percent of the salinity measurements taken in the mangroves during the study were at least 10‰ less than the salinity of sea water, indicating that the mangroves were consistently receiving freshwater flows. An analysis of variance of groundwater salinity measurements during and after the drought showed that salinity levels in the 0.5 and 1.0 m depth piezometers were greater during than after the drought. In a comparison of salinity values in 0.5-m wells during low tide, mean salinity was approximately twice as high during the drought than after (14.7‰ versus 6.2‰, respectively). This study demonstrates that short-term climate perturbations such as ENSO can disrupt important coastal processes. Over repeated drought cycles, such perturbations have the potential to affect the structure and function of mangrove forests and upstream ecosystems.

Kosrae↗
USGS1996

Geology and water-resources reconnaissance of Lenger Island, State of Pohnpei, Federated States of Micronesia, 1991

Lenger is a small (less than 0.2 square miles) volcanic island located within the lagoon of Pohnpei Island. Ground water on Lenger moves as shallow subsurface flow through weathered bedrock slopes into low-lying areas near the coast before discharging into the surrounding lagoon. Estimated ground-water recharge to the island from rainfall is 506,000 gallons per day on the basis of a mean annual rainfall of 140 inches. The basal part of Lenger is composed of a relatively low- permeability post-shield-building lava flow. This flow is overlain by a more permeable conglomerate of stream deposits which is in turn overlain by a relatively low-permeability columnar-jointed lava flow. The limited land mass and relatively low-permeability lava flows that form the bedrock of Lenger are not favorable to the formation of well-defined drainage basins or large basal ground-water bodies. Numerous springs and seeps discharge shallow subsurface flow at the contact between water-bearing weathered bedrock and underlying less-permeable bedrock. Because the amount of water stored in these shallow subsurface ground-water bodies is limited, springflow and seepflow rates are directly related to rainfall. Barbosa Pond, the largest surface-water body on Lenger, contained 162,000 gallons of water on June 19, 1991. On June 20, 1991, springflow into the pond increased from 0.6 gallons per minute during base-flow conditions to 21 gallons per minute during a 4-hour period of rain that totaled 0.74 inches. The water from Barbosa Pond contains iron and manganese in concentrations that may cause problems in a water-supply system. Small-scale development of ground water, such as was done at Barbosa Pond by the Japanese, is possible by tapping water stored in colluvial talus deposits that flank the base of Mosher hill. The source of water in these deposits is from seeps and springs that have low base flows; however, additional quantities of water could be obtained from these deposits by widening or deepening the capture area of wells used to develop these deposits. If sufficient storage facilities are built, water from these deposits would be available during drought conditions.

Water-Resources Investigations Report↗