Dust transport to the tropical/subtropical northwestern Pacific over the past 600 kyr was investigated using radiogenic isotopes ( 87 Sr/ 86 Sr and ε Nd ), together with the clay mineral composition, of eolian dust preserved in a sediment core obtained from the Philippine Sea (12°30′N, 134°60′E). These data revealed the influence of two prevailing dust sources, namely, the Asian deserts and nearby volcanic arcs (e.g., the Luzon Arc), with average contributions of around 70% and 30%, respectively, from each. The clay mineral composition of the core resembled dust from the central Asian deserts (CADs; e.g., the Taklimakan Desert) as in the north-central Pacific, but published aerosol data collected near the study site during winter/spring have the mineralogical signature of dust originating from the East Asian deserts (EADs). These data indicate that the relative contribution of EAD dust increases with the northeasterly surface winds associated with the East Asian Winter Monsoon (EAWM) during winter/spring, but the Prevailing Westerlies and Trade Winds that carry dust from the CADs is the dominant transport agent in the overall dust budget of the study site. The results of this study contradict the prevailing view that direct dust transport by the EAWM winds in spring dominates the annual flux of eolian dust in the northwest Pacific.
Although coral reefs are facing severe challenges from a variety of natural and anthropogenic stresses, there is anecdotal evidence that the high-latitude coral species Alveopora japonica Eguchi, 1968, has increased its population over the past two decades around Jeju Island, off the southern coast of Korea. The present study provides the first ecological data on this species. Alveopora japonica is opportunistically occupying the empty space left vacant following the recent kelp-forest decline. Colony abundance, age- and size-frequency distributions, lifespan, growth rates and biological characteristics such as surface area, weight and volume of two A. japonica populations in Jeju Island were investigated. Alveopora japonica around Jeju Island is characterised by a mean colony size of 30cm2, a slow growth rate (4.8mm year–1), and a short lifespan of 12–13 years, as determined by X-radiographic measurements. Alveopora japonica presented a dense population of 120 colonies m–2 on average. Population-age and -size structures at both sites reflected a healthy status and indicated a local stability, with a stationary size structure allowing population maintenance over time. The present study provided data to develop population-dynamics models to predict the potential outcomes of A. japonica populations to alternative management scenarios in Jeju Island.
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