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Phytoplankton are known as important harbingers of climate change in aquatic ecosystems. Here, the influence of the oceanographic settings on the phytoplankton community structure in the western South China Sea (SCS) was investigated during two seasons, i.e., the winter (December 2006) and summer (August–September, 2007). The phytoplankton community was mainly composed of diatoms (192 taxa), dinoflagellates (109 taxa), and cyanobacteria (4 taxa). The chain-forming diatoms and cyanobacteria Trichodesmium were the dominants throughout the study period. The phytoplankton community structure displayed distinct variation between two seasons, shifting from a diatom-dominated regime in winter to a cyanobacteria-dominated system in summer. The increased abundance of overall phytoplankton and cyanobacteria in the water column during the summer signifies the impact of nutrient advection due to upwelling and enriched eddy activity. That the symbiotic cyanobacteria–diatom (Rhizosolenia–Richelia) association was abundant during the winter signifies the influence of cool temperature. On the contrary, Trichodesmium dominance during the summer implies its tolerance to increased temperature. Overall, the two seasonal variations within the local phytoplankton community in the western SCS could simulate their community shift over the forthcoming climatic conditions.

The spatial location relations between service-providing areas and service-demand areas determine the effective provision level of ecosystem services. Some scholars use the term ecological service flow to conceptualize the transmission path, transmission characteristics, and service benefits of the provision-oriented service type between service-providing areas and service-demand areas. A few scholars have characterized the transmission range and spatial unit characteristics of single or several ecosystem service types, such as production services and regulation services between the providing area and demand area based on landscape, region and global scale. The current literature lacks quantitative studies on the spatial location relations between providing areas and demand areas of ecosystem services and the actual level of ecosystem service provision at the municipal scale based on the demand for ecosystem services faced by cities. This study takes Jinan, China, as the research area, quantifies the providing areas, connecting areas and demand areas of seven services—namely, the air purification service, climate regulation service, flood prevention service, water pollution prevention service, water supply service, soil erosion prevention service, and habitat supply service—and analyzes the spatial relation characteristics of each element. On this basis, the Hellwig model is used to quantitatively analyze the impact of service-providing area and service-connecting area on regional overall ecosystem service assessment. The results prove that service-providing areas and service-connecting areas are the key units that affect the level of regional ecosystem service provision. The evaluation of regional ecosystem service provision level is inseparable from the identification of service-providing areas and service-connecting areas and the study of their attributes, characteristics, and spatial relations. Service-providing areas and service-connecting areas should be differentiated when developing strategies to optimize and improve the level of regional ecosystem service provision. Different optimization measures should be formulated according to the differences in unit attributes and service barriers in different areas. The results provide guidance for the optimization of ecosystem services to ensure the efficient and sustainable provision of regional ecosystem services and improve the actual benefits of service-demand groups or service-demand areas.

Urbanization leads to the continuous expansion of urban built-up areas and the erosion of green space in urban fringe areas, leading to the continuous decline of biodiversity. Urban planners and managers need corresponding decision support tools to coordinate the contradiction between the utilization and protection of green space, ensure the maintenance capacity of biodiversity in green space, and realize the sustainable development of regional economy, society and ecology. Therefore, based on the Hellwig Method, this study designed a decision-making method of green space utilization and protection in urban fringe areas and applied the method to the decision simulation of single or multiple green space utilization and protection modes. In the decision simulation of a green space utilization mode, we evaluated the Hk values of one or several green space sample units, respectively. The smaller the Hk value, the smaller the influence of the green space unit on the biodiversity maintenance function of the whole green space in the region, so the green space unit can be selected first when making green space utilization planning decisions in the urban fringe. In the decision simulation of green space protection mode, the higher the Hk value of single green space sample unit combination or multiple green space sample unit combination, the greater the influence of the green space unit in the combination on the maintenance function of the overall green space biodiversity in the region. Then, when planning the green space protection in the urban fringe, the combination of such green space sample units should be given priority as the key protection and control objects. As a decision support tool for optimal scheme of green space utilization and protection in urban fringe areas, the method is practical, instructive, reasonable, operable, flexible, and universal.

Diatoms are a successful group of marine phytoplankton that often thrives under adverse environmental stress conditions. Members of the Skeletonema genus are ecologically important which may subsist during silicate stress and form a dense bloom following higher silicate concentration. However, our understanding of diatoms&rsquo, underlying molecular mechanism involved in these intracellular silicate stress-responses are limited. Here an iTRAQ-based proteomic method was coupled with multiple physiological techniques to explore distinct cellular responses associated with oxidative stress in the diatom Skeletonema dohrnii to the silicate limitation. In total, 1768 proteins were detected, 594 proteins were identified as differentially expressed (greater than a two-fold change, p &lt, 0.05). In Si-limited cells, downregulated proteins were mainly related to photosynthesis metabolism, light-harvesting complex, and oxidative phosphorylation, corresponding to inducing oxidative stress, and ROS accumulation. None of these responses were identified in Si-limited cells, in comparing with other literature, Si-stress cells showed that ATP-limited diatoms are unable to rely on photosynthesis, which will break down and reshuffle carbon metabolism to compensate for photosynthetic carbon fixation losses. Our findings have a good correlation with earlier reports and provides a new molecular level insight into the systematic intracellular responses employed by diatoms in response to silicate stress in the marine environment.