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761.
《China Geology》2019,2(3):315-324
The sedimentary environment and ecological system in the South Yellow Sea (SYS) changed dramatically due to sea level change caused by glacial-interglacial cycles. The authors report the use of marine biomarkers (brassicasterol, dinosterol and C37 alkenones) and terrigenous biomarkers (C28+C30+C32 n-alkanols) in core DLC70-3 from the SYS to reconstruct the variation in the phytoplankton productivity and community structure and possible mechanisms during the middle Pleistocene. The results show that the primary productivity and that of single algae presented a consistent trend for the whole core during the middle Pleistocene, which was high during interglacial periods and low during glacial periods, with the highest being in marine isotope stage (MIS) 5–9 and MIS 19–21. The main reason is that the Yellow Sea Warm Current (YSWC) carried much of high temperature, high salinity water into the SYS, causing upwelling and vertical mixing and stirring, which increased the nutrient supply in the photosynthetic layer. The phytoplankton community structure mainly showed an increase in the relative content of haptophytes in MIS 5–9 and MIS 19–21, while the relative content of diatoms and dinoflagellates decreased; there was no evidence for a haptophyte content in other stages. The results reveal a shift from a coccolitho-phorid-dominated community during MIS 5 –9 and MIS 19 –21 to a diatom-dominated community during the other stages, mainly as a result of surface salinity variation, attributed to the invasion of the YSWC during high sea level periods. 相似文献
762.
Bermuda is a reef atoll along the northern edge of Caribbean coral province. Although investigated by seismic and some shallow drilling, the Pleistocene marine depositional geohistory is poorly constrained. Islands along the southern rim are built by tropical calcareous aeolianites that range in age from Holocene to early Pleistocene (ca 880 kyr). These dunes are composed of particles that were derived from adjacent Pleistocene marine environments at the time of formation. Thus, the aeolianites should contain a record of marine deposition through the Early to Late Pleistocene. Carbonate grains from all aeolian deposits can, via Ward cluster analysis, be separated into two distinct groups: (i) a Halimeda‐rich group; and (ii) a crustose coralline‐rich group. Distribution of these two groups is interpreted to broadly reflect low‐energy (lagoonal) and high‐energy marginal reef (coralline algae and cup‐reef) environments, respectively. Unlike the beach sources, coral particles are perplexingly absent in the aeolianites. This conundrum is interpreted to partly reflect the domal nature of Bermudan corals, which are not incorporated into aeolian deposits due to their relatively large size. Aeolianites from Marine Isotope Stages 7, 9 and 11 record sediments produced in adjacent shallow marine settings that were similar to those present today. The spatially consistent sediment trends are not, however, present in aeolianites from Marine Isotope Stage 5E, where the aeolian bioclastic components are uniformly rich in Halimeda along both southern and northern shores. Such a distribution, where coralline‐rich sediments would be expected, suggests an extrinsic oceanographic control, interpreted herein to be elevated seawater temperature brought in by the Gulf Stream. This interpretation is consistent with palaeozoological studies of Bermuda, as well as North America, the Mediterranean, Japan and Western Australia. 相似文献
763.
Datangpo-type sedimentary manganese deposits, which are located in northeastern Guizhou province and its adjacent areas, are Mn carbonate-type deposits hosted in black carbonaceous shale that represent a series of medium to large deposits containing a huge tonnage of reserves. PAAS-normalized rare earth element distribution patterns of manganese ores record “hat-shaped” REY (REE + Y) plots characterized by pronounced middle rare earth element enrichment, evident positive Ce anomalies, weak to strong positive Eu anomalies and negligible negative Y anomalies. These REY geochemical characteristics are different from those of country rocks and record the processes and features of sedimentation and diagenesis. Manganese was precipitated as Mn-oxyhydroxide particles in oxidized water columns with the sorption of a certain amount of rare earth elements, subsequently transforming from Mn-oxyhydroxides to rhodochrosite and redistributing REY in reducing alkaline pore-water during early diagenesis. A number of similarities can be observed through a comparison of Datangpo-type manganese ores and modern marine ferromanganese oxyhydroxide precipitates based on their rare earth elements. The precipitation of Datangpo-type manganese ores is similar to that of hydrogenetic crusts and nodules based on their positive Ce anomalies and relatively higher total REY concentrations. However, several differences also exist. Compared to hydrogenetic crusts and nodules, Datangpo-type manganese ores record smaller positive Ce anomalies, lower total REY concentrations, unobvious fractionation between Y and Ho, and weak to strong positive Eu anomalies. These were caused by quicker sedimentary rates in the oxic water columns of the shallower basin, after which pore water became strongly reducing and alkaline due to the degradation of organic matter in the early diagenetic stage. In addition, compared to typical deposits in the world, Datangpo-type manganese ores are similar to hydrogenetic deposits and different than hydrothermal deposits. All of these characteristics of manganese ores indicate that Datangpo-type manganese ores, the principal metallogenic factors of which include oxidation conditions during deposition and reducing conditions during early diagenetic stages, represent hydrogenetic deposits. 相似文献
764.
765.
《Marine Policy》2017
Some scholars have thought the United Nations Convention on the Law of the Sea would transform marine politics and policy by incorporating social values of equity and justice via the Common Heritage of Mankind and authentic conservation of an essential part of the biosphere, displacing the dominant commodification of the ocean. Likewise, the United Nations Food and Agricultural Organization has claimed that the “productivity paradigm” of growth in fishery catch has been replaced by balanced norms of sustainability. This article tests these claims by asking “What is the ‘generative grammar’, or value-based blueprints, of governance for the World Ocean?” using a quantitative content analysis of all extant State of the World Fisheries and Aquaculture (SOFIA) reports (1995–2016). Not only does the analysis disprove the FAO’s assertions, this research reveals an otherwise invisible, non-codified economistic regime governing the World Ocean that is guided by the norms of sheer volume production, named here simply the “World Ocean Regime.” This partially explains why the marine world is experiencing structural ecological changes, including massive biodiversity loss partly driven by overfishing. The analysis finds that overfishing, ecological life support, moral aesthetic values, social equity, and science are very minor concerns for the World Ocean Regime. Governance is the second-most important set of discourses, but this governance is clearly driven by economic values and norms. The World Ocean Regime has critical implications not only for the sustainability of the World Ocean, but the planetary system that depends on the World Ocean. 相似文献
766.
《Marine Policy》2017
A generic framework (FW) for the monitoring and evaluation of spatially managed areas (here defined as marine areas subject to a planning and management regime) was developed and tested in nine marine areas of 13 European countries under the EU funded project MESMA (Monitoring and Evaluation of Spatially Managed Areas). This paper describes the lessons learned in the use of the FW and draws conclusions for its future use and development. The selected case studies represented diverse spatial scales, management status and complexity, ranging from sub-national areas to entire national coastlines, and large offshore regions. The application of the FW consisted of seven steps: starting with (i) context setting and (ii) gathering of relevant ecosystem information, human activities and management goals; it continues with (iii) indicator selection and (iv) risk assessment; and the final steps considers the (v) analysis of findings and (vi) the evaluation of management effectiveness, to end up with (vii) the revision and proposal of adaptation to current management. The lessons learnt through the application of the FW in the case studies have proved the value of the FW. However, difficulties rose due to the diversity of the nature and the different stages of development in planning and management in the case study areas; as well as, limited knowledge on ecosystem functioning needed for its implementation. As a conclusion the FW allowed for a flexible and creative application and provided important gap analyses. 相似文献
767.
《Marine Policy》2017
In the North-east Atlantic Ocean there are 550 inshore and offshore MPAs established to accomplish a high diversity of objectives, which can be classified into 24 different types of MPA designations. Only 153 of these MPAs have a management plan (MgP) --the basic tool required for an effective management. Amongst these, only 66 are actually managed, i.e. they have the staff and resources required to operate the plan. A common characteristic of these MPAs is the lack of standardized indicators of their performance. In order to address this issue, an alternative approach was developed based on the assessment of management performance using the expert knowledge and perceptions of managers operating MPAs, a universal source of information that could allow overcoming the usual gaps due to the restrictions in coverage of scientific monitoring and assessments. MgPs showed differences among countries but were homogeneous within each country, reflecting the usual top-down approach in the establishment of MPAs. Compliance with the qualitative objectives present in MgPs was higher than compliance with quantitative ones (87% versus 50%), and the MPAs that most successfully achieved their objectives were those with regular monitoring. This analysis also shows that beyond these objectives, the establishment of an MPA and the activities developed as a consequence of its creation have a positive socio-economic impact on the local human community. 相似文献
768.
《Marine Policy》2017
Biodiversity offsetting is used in diverse policy contexts to reduce, halt or reverse losses of biodiversity arising from development or other uses of the natural environment. Despite increasing interest in the concept of biodiversity offsetting, relatively little attention has been devoted to investigating its use in marine environments. This paper presents a systematic review of documents evidencing the application or inclusion of biodiversity offset principles in policy frameworks concerning the marine environment, and in marine development projects. Biodiversity offsetting policies applicable to marine environments were found to exist in six countries (US, Canada, Australia, France, Germany, Colombia) and have been actively considered in at least 27 others. Outside of these, a wide range of other approaches promoting uptake of biodiversity offsetting principles in a marine context were identified. These range from preliminary studies to identify habitat, to nascent biodiversity markets, and project-level application of corporate standards of no net loss. Evidence suggests that where offsetting policy is developed for specific marine application, the preferred approach is to pool financial contributions from developers into funds for strategic action for biodiversity benefit. 相似文献
769.
《Marine Policy》2017
Our global oceans are threatened by climate change, overfishing, pollution and a growing list of other impacts that demonstrate an urgent global need for sustainable ocean management. Whilst marine conservation initiatives and protected ocean spaces have increased over recent years, ocean management still lags behind the terrestrial sectors in incorporating and involving communities in its development. ‘Social licence to operate’ is used broadly across the terrestrial literature, but its understanding and application within the marine has been limited to date. This review sought to collate and synthesise instances of social licence in the marine realm as documented in the literature, aiming to create an understanding that may inform future research and development of social licence. Its results determine that social licence is yet an emergent concept in the marine sector but there may be great potential for its application in the marine context. Social licence has become an important theme for development in marine industry and resource use, particularly towards exploring communication and stakeholder engagement. This paper identifies future themes and areas requiring investigation and application in this domain. 相似文献
770.
《Marine Policy》2017
Dudley et al. [9] commented on our paper [11], arguing that the current IUCN objective-based categorization of protected areas, which is also used in marine protected areas (MPAs), should not be abandoned and replaced by the new regulation-based classification system [11]. Here we clarify that we do not advocate replacing the current IUCN categories, but highlight the benefits of using both the objective-based IUCN categories and the new regulation-based classification when applied to MPAs. With an increasing number of MPA types being implemented, most of them multiple-use areas zoned for various purposes, assessing ecological and socioeconomic benefits is key for advancing conservation targets and policy objectives. Although the IUCN categories can be used both in terrestrial and marine systems, they were not designed to follow a gradient of impacts and there is often a mismatch between stated objectives and implemented regulations. The new regulation-based classification system addresses these problems by linking impacts of activities in marine systems with MPA and zone classes in a simple and globally applicable way. Applying both the IUCN categories and the regulation-based classes will increase transparency when assessing marine conservation goals. 相似文献