A strategy for detecting derelict fishing gear at sea

Derelict fishing gear (DFG) is a highly persistent form of marine pollution known to cause environmental and economic damage. At-sea detection of DFG would support pelagic removal of this gear to prevent and minimize impacts on marine environments and species. In 2008, experts in marine debris, oceanography, remote sensing, and marine policy outlined a strategy to develop the capability to detect and ultimately remove DFG from the open ocean. The strategy includes three interrelated components: understanding the characteristics of the targeted DFG, indirectly detecting DFG by modeling likely locations, and directly detecting pelagic DFG using remote sensing. Together, these components aim to refine the search area, increase the likelihood of detection, and decrease mitigation response time, thereby providing guidance for removal operations. Here, we present this at-sea detection strategy, relate it to relevant extant research and technology, and identify gaps that currently prevent successful at-sea detection and removal of DFG.     

Marine resources,biophysical processes,and environmental management of a tropical shelf seaway: Torres Strait,Australia–Introduction to the special issue

This special issue of Continental Shelf Research contains 20 papers giving research results produced as part of Australia's Torres Strait Co-operative Research Centre (CRC) Program, which was funded over a three-year period during 2003–2006. Marine biophysical, fisheries, socioeconomic-cultural and extension research in the Torres Strait region of northeastern Australia was carried out to meet three aims: 1) support the sustainable development of marine resources and minimize impacts of resource use in Torres Strait; 2) enhance the conservation of the marine environment and the social, cultural and economic well being of all stakeholders, particularly the Torres Strait peoples; and 3) contribute to effective policy formulation and management decision making. Subjects covered, including commercial and traditional fisheries management, impacts of anthropogenic sediment inputs on seagrass meadows and communication of science results to local communities, have broad applications to other similar environments.     

Mass distribution and mass transport in the Earth system

Melting of continental ice sheets and glaciers, changes in ocean circulation pattern and in sea level, variations of surface and ground water levels and river discharge, glacial-isostatic adjustment, mantle convection and tectonics, all this causes transport and (re-) distribution of mass inside the Earth and at its surface. Equipped with precise sensor systems, gravity field and altimeter satellites observe these mass-transport processes. During 2006–2012, the German Research Association DFG had established the SPP 1257, ‘Mass distribution and Mass Transport in the Earth System’ as a coordinated research programme to facilitate integrated analysis of these data, to improve our knowledge about several transport processes within the Earth system and to investigate their interactions. This special issue reports about the findings of the first 4 years within the programme.     

Marine,seabed, and land seismic equipment for broadband acquisition: a review

The broadband capabilities of marine, seabed, and land seismic equipment are reviewed with respect to both the source and the receiver sides. In marine acquisition, the main issue at both ends of the spectrum relates to ghosts occurring at the sea surface. Broadband deghosting requires towing at variable depth to introduce notch diversity or using new equipment like multi‐component and/or low‐noise streamers. As a result, a doubling of the bandwidth from about three to six octaves (2.5–200 Hz) has been achieved. Such improvement is not yet observed for seabed surveys in spite of deghosting being a standard process on the receiver side. One issue may be related to the coupling of the particle motion sensor, particularly at high frequencies. For land acquisition, progress came from the vibrators. New shakers and control electronics using broadband sweeps made it possible to add two more octaves to the low‐frequency signal (from 8 to 2 Hz). Whereas conventional 10 Hz geophones are still able to record such low frequencies, 5 Hz high gain geophones or digital accelerometers enhance them to keep the signal above the noise floor. On the high end of the bandwidth, progress is not limited by equipment specifications. Here, the issue is related to a low signal‐to‐noise ratio due to the strong absorption that occurs during signal propagation. To succeed in enlarging the bandwidth, these improved equipment and sweeps must be complemented by a denser spatial sampling of the wavefield by point–source and point–receiver acquisition.     

Relative role and extent of marine and groundwater inundation on a dune‐dominated barrier island under sea‐level rise scenarios

Climate change and sea‐level rise will have severe impacts on coastal water resources around the world. However, whereas the influence of marine inundation is well documented in the literature, the impact of groundwater inundation on coastal communities is not well known. Here, core analysis, groundwater monitoring, and ground penetrating radar are utilized to assess the groundwater regime of the surficial aquifer on Bogue Banks Barrier Island (USA). Then, geospatial techniques are used to assess the relative roles and extents of groundwater and marine inundation on the dune‐dominated barrier island under sea‐level rise scenarios of 0.2, 0.5, and 1.0 m above current conditions by 2100. Additionally, the effects of rising water tables on onsite wastewater treatment systems (OWTS) are modelled using the projected sea‐level rise scenarios. The results indicate that the surficial aquifer comprising fine to medium sands responds quickly to precipitation. Water‐level measurements reveal varying thicknesses of the vadose zone (>3 to 0 m) and several groundwater mounds with radial flow patterns. Results from projected sea‐level rise scenarios suggest that owing to aquifer properties and morphology of the island, groundwater inundation may occur at the same rate as marine inundation. Furthermore, the area inundated by groundwater may be as significant as that affected by marine inundation. The results also show that the proportion of land in the study area where OWTS may be perpetually compromised by rising water tables under worst case scenarios may range from ~43 to ~54% over an 86‐year‐period. Copyright © 2014 John Wiley & Sons, Ltd.     

Dealing with contaminated dredged materials with reference to the Oslo Convention 1972 and the new Paris Convention 1992

Protection of the sea has received much political attention—for example, at successive North Sea Conferences environmental ministers have formulated a stringent policy with the aim of reducing pollution in the north-east Atlantic. In the past this area received many substances from many sources, but gradually intergovernmental action since 1972 in the Oslo and Paris Conventions has succeeded in tracing the major sources and understanding the effects of these inputs on the marine environment. After long discussion, many dumpings and discharges have been ended because they were considered harmful to the marine environment. Dredging activities were included in the discussions but they may be regarded as being a special case compared with many other disposals.

In general, clean dredged material for sea disposal offers no problems, although restrictions may be caused by physical impacts, mainly to habitats for living organisms. However, this material also has positive, often even beneficial uses. In contrast, contaminated material disposal is restricted and the internationally accepted rule is that the material should not create hazards to human health, harm living resources and marine life or damage amenities or interfere with other legitimate uses of the sea. There are in principle three options for dealing with polluted sediments: doing nothing, remedial action in situ, removal of the contaminated material; occasionally treatment is a possibility. The distinction has been made between the disposal of industrial waste, sewage sludge or dredged material. Industrial waste disposal is now prohibited; sewage sludge may be dumped until 31 December 1998, although dredged material may still be stored at sea under certain conditions. The Oslo Convention 1972 decided with regard to dredged material: that pollution has to be tackled at the source; dumping at sea is forbidden, although dredged materials may be excluded from this; land disposal prevails, although in several countries there is a growing resistance to disposal on land; there should be a precautionary approach against marine disposal; a stand-still principle should be followed where the quantities disposed in a certain year should not be exceeded nor should the quality of the receiving water be reduced; marine disposal should be phased out and, where appropriate, time-limits set; and the polluter pays.

Dredged material is regarded as polluted and as a consequence may in general not be disposed of at sea when it contains substances listed in the Annexes of the Convention. Exceptions to this are indicated by the terms ‘a trace contaminant’, ‘rapidly rendered harmless’ or ‘significant amounts’. Therefore, to achieve uniformity in the application of the Convention, guidelines have been prepared by a joint London Dumping Convention/Oslo Commission working group of experts on dredged material. Several characteristics must be considered when choosing a site for marine disposal and interests such as beach recreation, sport and commercial fishing, nature, cultural or historical interests, navigation, military interests and cables and pipelines should be taken into account. Also the capacity of the area to assimilate disposed matter per time unit must not be exceeded, especially in low energy areas. It is considered that in discussions of the environmental aspects of dredging it is important that associations such as PIANC argue for safe and economic navigation.     

Microplastics in the marine environment

This review discusses the mechanisms of generation and potential impacts of microplastics in the ocean environment. Weathering degradation of plastics on the beaches results in their surface embrittlement and microcracking, yielding microparticles that are carried into water by wind or wave action. Unlike inorganic fines present in sea water, microplastics concentrate persistent organic pollutants (POPs) by partition. The relevant distribution coefficients for common POPs are several orders of magnitude in favour of the plastic medium. Consequently, the microparticles laden with high levels of POPs can be ingested by marine biota. Bioavailability and the efficiency of transfer of the ingested POPs across trophic levels are not known and the potential damage posed by these to the marine ecosystem has yet to be quantified and modelled. Given the increasing levels of plastic pollution of the oceans it is important to better understand the impact of microplastics in the ocean food web.     

Wildfire and earth surface processes

Wildfire is a landscape-scale disturbance that changes the rate and magnitude of many earth surface processes. The impacts of fire on earth surface processes can vary substantially from place to place depending on a variety of site-specific conditions, including topography, fire severity, regional climate, vegetation type, and soil type. This variation makes it critical to bring together scientists studying fire and earth surface processes from different perspectives and in different parts of the world. This special issue pulls together studies that present cutting-edge research addressing the geomorphic and hydrologic impacts of wildfire across a range of spatial and temporal scales, including advances in managing some of the negative, short-term effects of wildfire. Contributions to this collection cover the following themes: insights from field measurements, sediment and carbon redistribution, insights from process-based modeling, post-fire debris flows, and post-fire mitigation. The work presented in this special issue will help to advance the capabilities of scientists and land managers to observe, simulate, and anticipate changes to earth surface processes following fire.     

最小二乘反演迭代算法在压制海上变深度缆采集数据虚反射中的应用

海水面的虚反射(鬼波)引起海上拖缆采集数据陷波,导致地震记录频带变窄,而近年发展的变深度缆采集技术,具有多样的陷波特征,通过专门的去虚反射处理方法可获得宽频数据.本文基于已有研究成果,将最小二乘反演迭代压制虚反射算法应用于某海上变深度缆宽频处理.基于频率波数域镜像记录生成方法获得镜像炮集记录,并采用最小二乘解从变深度缆原始和镜像炮集记录中提取上行波.针对镜像炮集记录生成受初始速度模型精度的影响,使得某深度缆接收的上行波和下行波之间的实际延迟时间存在误差,采用最小二乘反演迭代算法最优化计算下行波与上行波之间的平均延迟时间和上行波记录,并采用时空数据窗口滑动克服延迟时间随炮检距和目的层深度变化问题.合成数据及某海上实际变深度缆数据处理测试结果表明,该方法能较好地压制变深度缆由海水面产生的虚反射,能达到拓宽地震记录频带目的.     

South China Sea

The South China Sea is poorly understood in terms of its marine biota, ecology and the human impacts upon it. What is known is most often contained in reports and workshop and conference documents that are not available to the wider scientific community. The South China Sea has an area of some 3.3 million km² and depths range from the shallowest coastal fringe to 5377 m in the Manila Trench. It is also studded with numerous islets, atolls and reefs many of which are just awash at low tide. It is largely confined within the Tropic of Cancer and, therefore, experiences a monsoonal climate being influenced by the Southwest Monsoon in summer and the Northeast Monsoon in winter. The South China Sea is a marginal sea and, therefore, largely surrounded by land. Countries that have a major influence on and claims to the sea include China, Malaysia, the Philippines and Vietnam, although Thailand, Indonesia and Taiwan have some too. The coastal fringes of the South China Sea are home to about 270 million people that have had some of the fastest developing and most vibrant economies on the globe. Consequently, anthropogenic impacts, such as over-exploitation of resources and pollution, are anticipated to be huge although, in reality, relatively little is known about them. The Indo-West Pacific biogeographic province, at the centre of which the South China Sea lies, is probably the world's most diverse shallow-water marine area. Of three major nearshore habitat types, i.e., coral reefs, mangroves and seagrasses, 45 mangrove species out of a global total of 51, most of the currently recognised 70 coral genera and 20 of 50 known seagrass species have been recorded from the South China Sea. The island groups of the South China Sea are all disputed and sovereignty is claimed over them by a number of countries. Conflicts have in recent decades arisen over them because of perceived national rights. It is perhaps because of this that so little research has been undertaken on the South China Sea. What data are available, however, and if Hong Kong is used, as it is herein, as an indicator of what the perturbations of other regional cities upon the South China Sea are like, then it is impacted grossly and an ecological disaster has probably already, but unknowingly, happened.     

A Comprehensive Dynamic Threshold Algorithm for Daytime Sea Fog Retrieval over the Chinese Adjacent Seas

Sea fog influences human activities over oceans. It is somewhat difficult to separate sea fog from marine boundary stratus (low stratus and stratocumulus) by satellites due to their microphysical similarities and shared spectral features. For the purpose of improving sea fog detection over the Chinese adjacent seas where fog is common during the spring–summer seasons, the vertical structures of fog and stratus were analyzed using ground-based soundings, resulting in the observation of very explicit discrepancies between them, in terms of TAT ? SST (TAT, the temperature at tops of fog or stratus; SST, the sea surface temperature). Based on these discrepancies and on previous related studies, we suggest a comprehensive dynamic threshold algorithm. The method combines real-time brightness temperature from Moderate Resolution Imaging Spectroradiometer channel 31 (~11 μm) with climatological monthly mean SSTs to produce a threshold that is monthly-dependent. The retrieved results are generally consistent with the observations from meteorological stations near the coast, on islands and from ships, and the scores of validation by conventional methods are promising. The distribution patterns of the retrieved sea fog frequency in May and June from 2006 to 2010 are both compatible with that from ship-based observations and exhibit more details that are consistent with our understanding of sea fog characteristics. This study is helpful for marine weather service and the improvement of models for sea fog forecasting.     

Marine litter distribution and composition in the North Sea

Following the development of marine litter surveillance methodologies for use on beaches, this study shows the feasibility of similar surveys at sea. The results indicate widespread distribution of marine litter in the surface waters of the North Sea, especially plastics. Not only does this draw attention to the need for the implementation of Annexe V of the MARPOL Convention, but serious consideration should be given now to the designation of the North Sea as a ‘special area’ such that the dumping of all garbage from ships, except food wastes, should be prohibited.     

我国海洋地学编图现状、计划与主要进展

我国海洋地质地球物理工作起步晚,整体调查程度较低,进一步加强我国海洋地学编图显得十分必要.我国实施的"海洋地质保障工程",将分"中国海陆"、"中国海及邻域"和"中国各海区"三个层次来进行地学编图.第一层次编制了空间重力异常图、布格重力异常图、磁力异常图、地震层析成像图、莫霍面深度图、地质图、大地构造格架图和大地构造格架演化图等8种图件.编图反映出中国海陆重力异常是"线性异常带纵横交错,块状异常区坐落其间"、重力梯级带主要为块体结合带;陆地磁力异常大致正负磁异常相间分布,海域北部为沟-弧-盆相关异常、南部磁条带异常;莫霍面总体特征为"东西分带,南北分块";地震层析成像反映出中国东部和西部岩石层厚度的差异以及上地幔软流层的分布特点;大地构造格架和演化图再现了块体体制向板块体制的转换过程.本次编图强调地球深部结构的变化对表层构造的关联,重视地球物理资料与地质构造的结合,以深-浅层结合来划分中国大地构造格架.已有成果表明,中国海陆大地构造格局可以用"块体构造学说"来描述.     

Public awareness and attitudes towards naval sonar mitigation for cetacean conservation: a preliminary case study in Fairfax County, Virginia. (the DC Metro area)

The potential impacts of naval sonar on cetaceans has led to a series of court cases and statements of concern by international organizations. However, there has been no research conducted on attitudes of the general public with respect to this issue. To investigate this, a preliminary public survey was conducted in Fairfax, Virginia (the Washington, DC Metro region). The majority of the public sampled believed that naval sonar impacted marine mammals (51.3%), that the US Navy should not be exempt from environmental regulations in time of peace (75.2%), and that sonar use should be moderated if it impacts cetaceans (75.8%). Individuals who were conservative, Republican, and have served in the military were more likely to believe the Navy should be exempt from marine mammal protection regulations. In addition, expert interviews were conducted to gain opinions on the potential ramifications of the recent US Supreme Court case on naval sonar mitigation.     

Special issue: Marine and river bedforms dynamics,MARID VI

Marine and river bedforms are rhythmic features driven by unidirectional or reversing currents and waves. They are ubiquitous on the floors of rivers, estuaries, coastal and marine settings. Despite a considerable history of dedicated studies, many aspects of their origin, development and dynamics are still the subject of scientific debate in various disciplines. The MARID conferences series hosts experts from geosciences, physics, engineering and other disciplines to provide a platform for the interdisciplinary exchange of fundamental and applied knowledge of marine and river dune dynamics. MARID VI took place in April 2019 in Bremen, Germany. Related scientific contributions are presented in this special issue of Earth Surface Processes and Landforms. An overview of the conference series and the specifics of MARID VI, as well as considerations in the context of equity, diversity and inclusion, are given. This introduction highlights the progress made with the papers published in the special issue.     

Geodynamics of the Gibraltar Arc and the Alboran Sea region

Located at the Westernmost tip of the Mediterranean sea, the Gibraltar Arc is a very complex zone. The Betics in Spain and the Rif belt in Morocco surround the Alboran sea characterized by a thinned continental crust. The geodynamic evolution of this region results from the convergence of African and Iberian margins since the Late Cretaceous. It is controlled both by plate convergence and mantle dynamics, which significantly impact on morphology, sedimentary environments, tectonics, metamorphism and magmatism. We present here the contents of the special issue on the Gibraltar Arc and nearby regions, following the workshop organized at the University Abdelmalek Essaadi of Tetouan in Morocco from 27 to 28 October, 2011. The goal of this international workshop was to have an overview of the actual advance in research concerning the Rif and Betics chains, the Alboran basin, and their influence on the Iberian and African forelands.     

Determining the impact of the Holocene highstand at the coastal‐fluvial interface,Shoalhaven River,south‐eastern Australia

With enhanced rates of sea‐level rise predicted for the next century, the upstream extent of sea‐level influence across coastal plains is a topic of public importance. Australian coastal rivers provide a testing ground for exploring this issue because the area is tectonically stable, was not glaciated, and experienced a Holocene highstand between 7.4 and 2 ka of up to 1.5 m above Australian Height Datum (AHD). In the Shoalhaven River of New South Wales, investigation of a confined bedrock reach at Wogamia, 32 km inland, has identified a unit of dark, cohesive silt and sand with marine diatoms, shell fragments, and enhanced pyrite content, interpreted as estuarine. The unit is up to 13 m thick, thickens downstream, and is overlain by fluvial channel and floodplain deposits. The estuarine unit on‐laps a remnant Pleistocene terrace and extends to approximately +2.2 m AHD. Optically stimulated luminescence (OSL) and radiocarbon ages suggest that estuarine deposition commenced prior to 7.8 ka cal bp , predating the highstand by ~ 500 years, and that marine influence in the area continued to 5.3 ± 0.7 ka. During this period, a delta probably persisted at Wogamia, where a narrow upstream reach opens out, and subsequently advanced to fill the broad Shoalhaven coastal embayment. Although the effect of sea‐level rise depends on many factors, the results suggest that, during a highstand at or above present sea level, a strong marine influence may extend for tens of kilometres inland and penetrate confined bedrock reaches landward of coastal embayments. Copyright © 2013 John Wiley & Sons, Ltd.     

Sensitivity of sea ice and ocean simulations to sea ice salinity in a coupled global climate model

The impacts of the spatiotemporal variations of sea ice salinity on sea ice and ocean characteristics have not been studied in detail, as the existing climate models neglect or misrepresent this process. To address this issue, this paper formulated a parameterization with more realistic sea ice salinity budget, and examined the sensitivity of sea ice and ocean simulations to the ice salinity variations and associated salt flux into the ocean using a coupled global climate model. Results show that the inclus...     

Effect of sea cucumber (Australostichopus mollis) grazing on coastal sediments impacted by mussel farm deposition

Deposit-feeding holothurians are important processors of surface sediments in many coastal marine systems. The present study examined the effect of grazing by the sea cucumber Australostichopus mollis on sediment impacted by green-lipped mussel biodeposits (faeces and pseudofaeces) from coastal aquaculture activities. Grazing effects were investigated in a series of tank-based feeding experiments conducted over 1, 2, 4 and 8 week periods. Sediment quality indicators routinely applied to determine the impacts of coastal aquaculture were used to evaluate sediment health from grazed and ungrazed sediments. Sea cucumber grazing resulted in reductions in total organic carbon, chlorophyll a and phaeopigment, as well as chlorophyll a/phaeopigment ratio of impacted sediments. These results demonstrate that sea cucumber grazing significantly reduces the accumulation of both organic carbon and phytopigments associated with biodeposition from mussel farms. Sea cucumber grazing offers a means of constraining or reversing the pollutive impacts of coastal bivalve aquaculture.     

High CO₂ and marine animal behaviour: potential mechanisms and ecological consequences

Exposure to pollution and environmental change can alter the behaviour of aquatic animals and here we review recent evidence that exposure to elevated CO? and reduced sea water pH alters the behaviour of tropical reef fish and hermit crabs. Three main routes through which behaviour might be altered are discussed; elevated metabolic load, 'info-disruption' and avoidance behaviour away from polluted locations. There is clear experimental evidence that exposure to high CO? disrupts the ability to find settlement sites and shelters, the ability to detect predators and the ability to detect prey and food. In marine vertebrates and marine crustaceans behavioural change appears to occur via info-disruption. In hermit crabs and other crustaceans impairment of performance capacities might also play a role. We discuss the implications for such behavioural changes in terms of potential impacts at the levels of population health and ecosystem services, and consider future directions for research.