Sea surface temperature (SST) is an important oceanic parameter which can be accessed easily and vastly by satellite remote sensing. Recent hydrographic observations suggested that the water temperature near Dongsha Atoll were affected by internal waves of South China Sea (SCS). This study hypothesizes that the SST variations near Dongsha Atoll and continental shelf cab be observed by satellite data. To test the hypothesis, MODIS SST data during January 2005 to December 2009 were collected and analyzed using harmonic and EOF analyses. The results show that there can be a 1 ¢XC temperature drop, near Dongsha Atoll during the passage of internal waves, based on a longitudinal section cut for a typical SST image. The SST patterns in northern SCS are distributed lower in the east and higher in the west. The temperature showed an average of 0.5¢XC lower near Dongsha Atoll. Especially, the pattern of lower temperature near Dongsha is significant during neap tide in summer season. EOF analysis showed that the spatial distribution of SST aligned well with the bottom topography of the continental shelf. This result suggests that internal tide may be important to the vertical mixing in this region. The total variation of mode 1 in EOF accounted for 97.7% and is dominated by seasonal changes. For the long term and large area SST statistics, the internal wave induced variation is insignificant, as comparing the Dongsha region with shelf region and Kuroshio region.

This study focuses on the relationship between hydrological and nutrient conditions in seawater surrounded by Dongsha Atoll. Dongsha Atoll is located in the northern South China Sea (NSCS), the water properties should be in coherence with the NSCS water masses. However, due to the semi-enclosed topography the water inside Dongsha Atoll is largely affected by local insolation and rainfall. Significant relationships between SiO2 or PO43- and salinity indicate that rainfall could be a major source of these nutrients. Insignificant relationship between N+N and salinity indicates that rainfall and nitrogen fixation both might affect the distribution of N+N. Temporal variations of temperature and chlorophyll a were alike, except for which occurred in July, 2011. It was probably caused by photo inhibition on phytoplankton growth. The inventory of chlorophyll a was positively correlated with both N+N and SiO2 but not with of PO43-, indicating that phytoplankton growth in Dongsha Atoll was mainly affected by N+N and SiO2. Phytoplankton growth maybe limited by N+N but not by SiO2, as the concentration of SiO2 was mostly beyond the limitation concentration for phytoplankton. According to close relationships between chlorophyll a and TSM, POC and PN, the particulate matter maybe mainly derived from biological origins. The inventory of chlorophyll a was positively correlated with both dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), manifesting the importance of biological origins for DOC and DON concentration. The ratios of DOC/DON, DON/DOP and DOC/DOP within the atoll were in ranges of 7.34-303 (mean: 30.4), 3.00-142 (mean: 22.7) and 104-2546 (mean: 421), respectively. The ratios are higher than those values in NSCS and East China Sea, implying the excretion of carbon-enriched DOM by phytoplankton. The concentration of chlorophyll a, DOC and POC were higher in the Small Lagoon than in the Atoll Lagoon, implying a relatively high productivity in the Small Lagoon. The fluxes of carbonate in the atoll was more than 30 times of the flux in the NSCS, due to its unique characteristics in the coral reef habitat. The organic matter of settling particulates was mainly derived from biological sources. The metal of enrichment factor of settling particulates reveals that Fe and Al are mainly derived from crustal sources, while Cu, Zn and Pb are likely influenced by anthropogenic sources.

The Dongsha Islands, a group of remote islands under Taiwan's jurisdiction, consist of Dongsha Atoll (the only atoll in Taiwan) and North Vereker Bank and South Vereker Bank (two coral reef groups). Dongsha Island is the only terrestrial portion of the islands. Owing to its location in the northern part of the South China Sea, the physical and chemical conditions fostered the formerly abundant marine and coastal biota of this region. This area is one of Taiwan's traditional fishing grounds. The islands are also located near the major sea route connecting the Pacific and Indian Oceans. However, due to improper fishing practices and the development of fishing facilities, the marine biota and habitats have been depleted in recent decades to the point of being threatened with extinction. These improper and excessive human activities/uses within the waters of the Dongsha Islands are threatening its ecosystems and resources through unsustainable exploitation and depletion. The current situation of the Dongsha Islands illustrates the difficulties of protecting the marine ecosystems of remote islands where the presence of law enforcement is not particularly in evidence. Even if the Kaohsiung City Government were to designate the Dongsha Islands a ¡§no-fishing zone¡¨, further steps, i.e., the planning and management of marine protected areas for example, would still require in-depth considerations and discussion. This study focuses on several aspects, including the planning process of developing the management plan, the legal and administrative framework of the management plan and associated action plans, and a model outline for developing the management plan and action plans. Following the results/guidelines are suggestions for further study.

The subject of this study was to investigate the species composition and spatial distribution pastern of iving (Rose Bengal stained) benthic foraminifera in sediment surface samples (0-1 cm) off the Southwestern Taiwan and Dongsha Atoll. The main objectives of this study was to document the living benthic foraminiferal assemblages off the Southwestern Taiwan and Dongsha Atoll and to examine their distribution in relation to environmental parameters. Four benthic foraminiferal biofacies were recognized within the substrate type in Dongsha Atoll: A1 (Fine-grained) is represented by Pseudomassilina spp. - Quinqueloculina parkeri, A2 (Fine-grained) is represented by Hauerina spp. - Pseudomassilina spp., B1 (Coarse-grained) is characterised by Calcarina spp. - Quinqueloculina spp., B2 (Coarse-grained) is characterised by Amphistegina spp. - Quinqueloculina spp. Sediment surface samples off the Southwestern Taiwan during May 2009 led to the identification of four assemblages. Assemblage A is characterised by Ammonia spp. - Bolivina spp., Assemblage B between is characterized by Asterorotalia spp. - Globobulimina spp., Assemblage C is represented by Cibicides spp. - Nummulites spp., Assemblage D is represented by Ammonia spp. - Cibicides spp. Sediment surface samples off the Southwestern Taiwan during Nov. 2009 led to the identification of three assemblages. Assemblage A is dominated by Ammonia spp. - Cibicides spp., Assemblage B is characterised by Ammonia spp. - Bolivina spp., Assemblage C is characterised by Asterorotalia spp. - Bolivina spp. Stained benthic foraminifera form Dongsha Atoll correlated with current wave, collected site, coarse fraction and TOC contents. Living benthic foraminifera off the Southwestern Taiwan seems not to be related with TOC contents and coarse fraction, the assemblages were found to be more related to tidal energy and lateral transport.

The northern margin of South China Sea contains several favorable areas for occurrence of gas hydrate. In this study, we collected pore water samples in two piston cores (X-01 and D-01) from Xisha Trough and Dongsha area, respectively, and the concentrations of sulfate and carbon isotopic compositions of dissolved inorganic carbon (DIC) were measured. The results showed different geochemical characteristics in these two sites. The X-01 core shows relatively constant δ13C-DIC values and sulfate concentrations, which suggest that anaerobic methane oxidation (AMO) processes did not occur in this site. In contrast, very large variation in δ13C-DIC values and sulfate concentrations are revealed in D-01 core, and good linear correlations for sulfate gradients and δ13C-DIC values are observed. The calculated sulfate-methane interface (SMI) depth is 9.6 mbsf. These data indicate that an AMO process occurred in sediments with large methane flux from depth in the Dongsha area, which are comparable to other gas hydrate locations in the world oceans such as the Blake Ridge. We suggest that the Dongsha area is one of the most favorable targets for future gas hydrate exploration.