Nonlinear features in wave-resolving microwave radar observationsof ocean waves

Transformation of sea-surface Doppler microwave backscatter observations from the space-time domain to the wavenumber-frequency domain separates linear wave energy from nonlinear effects. Here observations and modeling are used to investigate the sources of these nonlinearities. Wave breaking and electromagnetic shadowing are examined with emphasis on their relative effects both inside and outside the region of the wavenumber-frequency spectrum associated with the linear dispersion equation. Shadowing significantly reduces the variance levels within the linear spectral region. In addition, shadowing is less directly related to changes in variance outside this region, i.e., that region associated with nonlinearity in the wave field. Wave breaking has less of an effect on the variance within the linear region than shadowing. However, the modeled wave breaking does have a greater tendency to increase variance levels at frequencies less than that of the linear wave field, for any given wavenumber. Aliasing and emphasis of crest backscatter are also explored to explain features seen in some wavenumber-frequency intensity images. Two-dimensional data allow the linear wave spectrum to be separated from nonlinear effects. This results in improved wave height spectrum estimation     

Rights-based management in Canada: Lessons from two coasts and a centre

Canada has had experience with a number of different rights-based management programs for fish harvesting for more than thirty years. These programs have spanned both coasts, as well as been applied to fisheries in the central region. This paper sets the institutional context within which these programs operate, reviews selected programs for instances of successes and/or failures, and presents some lessons learned.     

普里兹湾区水团和环流时空变化的若干问题

自50年代后期以来国际上对普里兹湾区海洋过程的调査研究不断加强(Zverev,1959,1963; Izvekov,1959),尤其是进入80年代后,由于在现场考察中采用了CTD系统和浮标测流系统,人们对该区海洋过程的认识有了长足的进步。但由于该海区的热盐结构有非常显著的时空变化(Kornilov,1971; Smith et al.,1984; Middleton and Hamphries,1989;乐肯堂等,1996,1997),因而对该海区水团和环流中的若干重要问题,例如环流子午向分布向题,底层水形成问题,热盐结构时空变化间题等,仍缺乏足够的了解。 在乐肯堂等(1996,1997)的文章中,我们主要根据中国第六次(CNARE-Ⅵ,1989-1990)和第七次(CNARE-Ⅶ,1990-1991)南极考察中的海洋调查资料,分析了普里兹湾区的热盐结构、环流性质和混合过程。在本文中,我们将着重分析中国第八次(CNARE-Ⅷ,1991-1992)和第九次(CNARE-Ⅸ,1992-1993)南极考察中的CTD资料,并结合CNARE-Ⅵ,Ⅶ的资料,对该区的水团和环流的时空变化问题进行初步探讨。 关于CNARE-Ⅵ和 CNARE-Ⅶ的资料概况可见乐肯堂等(1996),不再重述。CNARE-Ⅷ的CTD断面设置与 CNARE-Ⅶ相同[参见乐肯堂等(1996)];但观测工作分为两个阶段:第一阶段从1991年12月31日至1992年1月5日,完成了从78°E至108°E共6个断面的测站;第二阶段,从1992年1月23日至25日,完成了68°E和73°E两个断面的测站。CNARE-Ⅸ的CTD断面如图1所示;观测工作也分两个阶段:第一阶段从1993年1月11日至1月15日,完成了I、Ⅱ、Ⅲ3个断面的测站;第二阶段从1993年1月29日至2月5日,进行了IV、V、Ⅵ3个断面的观测。这两次考察的CTD观测,每次均分为两个航次,而两个航次之间又都相隔二十余天,因而资料的同步性受到一定的影响。     

Moving beyond a top-down fisheries management approach in the northwestern Mediterranean: Some lessons from the Philippines

The management of fisheries resources in the northwestern Mediterranean is traditionally centralized and developed within the framework of coastal states and European Union common policies. In general, it has not been sufficiently effective in reversing the declining situation of fisheries resources and fishers in this region. This paper discusses the feasibility of moving away from a top-down approach in fisheries management towards a more participative and convergent mode of governance in the region. More specifically, the study focuses on MPAs as a fisheries management tool and evaluates their current establishment and management system in the French Mediterranean as a case study for the region. A brief review of the experiences on fisheries and MPA management in the Philippines is also presented to obtain insights on bottom-up and collaborative management approaches. Finally, possible opportunities for adopting a more decentralized and coordinated approach in fisheries management within the French socio-political system, and possibly in the northwestern Mediterranean region, are discussed. These include the existence of fishing community organizations in the region, such as the prud'homies in France and cofradias in Spain, starting with management strategies that are simpler to enforce and more acceptable to direct users, e.g., fishery reserves, and exploring co-management arrangements to manage fisheries at ecologically meaningful but operationally manageable scales as has been proposed by some development organizations. However, effective changes in the system would require major national policy and institutional reforms, social preparation and organizational strengthening which would take time and resources.     

Distribution of chlorophyll a and some ecological factors in the Daya Bay

The marine environment, productivity and potential biotic resources in the waters of the Daya Bay were investigated by South China Sea Institute of Oceanology, Academia Sinica from 1984 to 1986. The present paper deals mainly with the annual variation and distribution characteristics in chlorophyll a and with some of the ecological factors involved in chlorophyll distribution within the bay. Correlation models are established and discussed. The results could be helpful for further probing into ecosystem and for the exploitation-utilization of aquatic resources in this region.     

Styles of compressional neotectonics in the eastern Alboran Sea

The preliminary interpretation of new high-resolution seismic reflection profiles from the eastern Alboran Sea indicates strong geological similarities between this region and southeastern Spain. The principal neotectonic elements, which result from roughly north-south compression, are defined by northeast-southwest oriented wrenches separated by intervening north-south and west-northwest-east-southeast strike-slip faults. Variations in direction of principal stress axes have permitted faulting to alternate between these two systems, and for reverse faulting to occur within some wrench zones during periods when there was a component of compression perpendicular to them.     

Regional geochemistry of sediments from the Hellenic volcanic arc in regard to submarine hydrothermal activity

Some 600 surface sediment samples from the Hellenic Volcanic Arc region have been analyzed by bulk and HCl selective leach geochemical techniques. Geostatisti‐cal analysis, followed by further selective leaches on a number of samples, has been used in order to identify any regional hydrothermal influence on the sediments and/or any local hydrothermal metal enrichments. The two main sediment components affecting the geochemical variability in the region are biogenic carbonate and volcaniclastic/terrigenous detritus. Proximity to islands appears to be the primary factor controlling the variability in these components. Sediments from deeper water, to the south of the Hellenic Volcanic Arc and in the Anydros Basin, exhibit some elevated levels of Mn, Co, and Cu, probably of hydrogenous origin. No widespread hydrothermal influence to the sediments in the region is recognized, although this could in part be due to the high sedimentation rates in the region. Localized hydrothermal inputs to sediments are, however, recognized proximal to Santorini, in particular within the northern part of the central caldera. These are predominantly of Fe and associated adsorbed/coprecipitated elements along with some Mn enrichment. Several samples proximal to Milos, just off the coast in the northern part of the central Milos embayment, also show enrichments of commonly hydrothermally associated elements, including Mn, Cu, Zn, and Pb. Data suggest that these enrichments could, in part, be due to weathering of “on‐land”; mineralization as well as hydrothermal inputs.     

Maritime clusters: What can be learnt from the South West of England

The South West of England is a very extensive region, with constraints in terms of its transport network. It is imperative if the region is to optimise its economic development for transport services to fully utilise all transport modes, not least, short sea shipping. To achieve this objective will require, inter alia, investment in the region’s port infrastructure. The result of this study suggests that each South West port provides a hub to develop a small maritime cluster which provides some sort of platform for marine and maritime related activities or businesses to co-ordinate and communicate. In addition, the region is well placed geographically in relation to a number of other European Union countries, with which to develop seaborne trade links. If this can be supported both by the development of coastal shipping links between regional ports and the incremental capability of rail and road transport within the region, then substantial increased economic activity for the region could result. Moreover, it would be beneficial if the region’s ports could act as a maritime cluster, optimising the contribution each port can make. This in no way would preclude healthy competition between the ports.     

Compressive tectonism along the eastern margin of Malaita Island (Solomon Islands)

New bathymetric and geophysical data were collected in the region east of the island of Malaita during the SOPACMAPS II cruise of the French research vessel L'ATALANTE. This region, part of the Malaita Anticlinorium was interpreted as a piece of oceanic crust from the Ontong Java Plateau obducted over the old Solomon Islands arc during collision between the Pacific and Australian plates. It has been generally accepted that convergent motion between the Australia and Pacific plates since the Late Miocene was absorbed exclusively along the San Cristobal trench, southwest of the Solomon Islands Arc.Bathymetry, imagery, and geophysical data (magnetism, gravity, seismic) acquired during the SOPACMAPS II survey allow us to classify the successive parallel ridges mapped within the region as being recent volcanic, oceanic crust, or deformed sedimentary ridges.Seismic profiling provides evidence of successive compressive events along the Malaita margin caused by the relative motion between the Solomon Islands and the Pacific plate. The main phase of convergence probably occurred during Oligocene-early Miocene time, but some relative motion between the two domains are still being absorbed along the East Malaita boundary. The existence of active faulting in the sedimentary cover throughout the region and the present-day deformation of the outer sedimentary ridge is a good illustration of this phenomenon.     

Structural evolution of Malay Basin,its link to Sunda Block tectonics

The Malay Basin is located offshore West Malaysia in the South China Sea, within north central region of 1st order Sunda Block. The basin developed partly as a result of tectonic collisions and strike-slip shear of the Southeast Asia continental slabs, as the Indian Plate collided into Eurasia, and subsequent extrusion of lithospheric blocks towards Indochina. The Sunda Block epicontinental earliest rift margins were manifested by the Palaeogene W–E rift valleys, which formed during NW–SE sinistral shear of the region. Later Eocene NW–SE dextral shear of (2nd order) Indochina Block against East Malaya Block rifted open a 3rd order Malay Basin. Developed within it is a series of 4th order N–S en-echelon ridges and grabens. The grabens and some ridges, sequentially, host W–E trending 5th order folds of later compressional episodes. The Malay Basin Ridge and Graben Model explains the multi-phased structural deformation which started with, the a) Pre-Rift Palaeo/Mesozoic crystalline/metamorphic Basement, b) Synrift phase during Paleogene, c) Fast Subsidence from Late Oligocene to Middle Miocene, d) Compressional inversion of first Sunda fold during Late Miocene, and e) Basin Sag during Plio-Pleistocene with mild compressional episodes. The subsequent Mio-Pliocene folding history of Malay Basin is connected to the collision of Sunda Block against subducting Indian–Australian Plate. This Neogene Sunda tectonics, to some degree after the cessation of South China Sea spreading, is due to the diachronous collision along the 1st order plate margins between SE Asia and Australia.     

Community structure of infaunal macrobenthos around vestimentiferan thickets at the San Clemente cold seep,NE Pacific

The San Clemente cold seep lies within 100–200 km of other reducing habitats in the NE Pacific, offering an opportunity to compare diversity and species overlap among reducing habitats (i.e. whale‐, kelp‐, and wood‐falls) at similar depths within a single region. Video observations from the research submersible Alvin at the San Clemente seep (1800 m depth) indicated clumps (‘thickets’) of vestimentiferans distributed as meter‐scale patches interspersed with vesicomyid clam beds and black sediments. Sediment‐core samples were collected at distances of 0 to 80–200 m along randomly oriented transects radiating outward from vestimentiferan thickets to evaluate changes in macrofaunal community structure from thickets into the background community. Macrofaunal abundance was elevated at distances of 0–1 m compared to 80–200 m (i.e. the ‘background’ community). The tube‐building frenulate worms Siboglinum spp., along with peracarid crustaceans, dominated sediments within 1 m of vestimentiferan thickets. Species diversity was depressed within 1 m of thickets but with high rates of species accumulation, suggesting that seep sites greatly increase sediment heterogeneity and facilitate colonization by non‐background macrofaunal species. Stable isotope data indicate chemosynthetic nutrition for some dominant macrofaunal species within 1 m of tubeworm thickets. The macrofaunal community near vestimentiferan thickets in San Clemente seep contains intermediate levels of species richness and diversity compared to other deep‐sea seep areas in the northeast Pacific. There was low species overlap between the San Clemente seep macrofauna and communities in reducing habitats near wood‐, whale‐, and kelp‐falls at similar depths within the region, suggesting that seeps harbor a distinct infaunal community.     

Trends of the Galician upwelling in the context of climate change

Coastal upwelling is a phenomenon of great importance both for the study of ocean dynamics and for the development of fish production in some coastal regions. Our study region, the Galician coast, lies at the northern end of the Canary–Iberian Peninsula upwelling system. Knowing the changes provoked by climate change on this upwelling system is particularly relevant for the future of this area taking into account the social and economic importance of fishing activities in this region. In this paper we study the trends in the intensity and frequency of upwelling in the Galician coast and the expected changes in this phenomenon for the next decades using three regional models implemented within the European project ENSEMBLES. As a main result, we observe that the models show a positive trend in both the intensity and frequency of upwelling phenomenon for the future, particularly significant in spring and summer which are the seasons favorable for upwelling. In autumn and winter there are no significant changes.     

A review of sustainable sea-transport for Oceania: Providing context for renewable energy shipping for the Pacific

This paper summarises research and options for sustainable sea transport in Oceania with a focus on domestic shipping. This debate is situated initially within the context of the current Pacific domestic shipping scenario, a region of minute economies connected by some of the longest sea transport routes in the world. All current options are fossil fuel powered and increasingly uneconomic and unsustainable. Many routes are marginal or unviable and a vicious cycle of old ships replaced with old ships prevails. Although a central and essential issue of many Pacific communities, the option of pursuing sustainable sea transport is currently invisible within the policy space at all levels. Various renewable energy options are possible and increasingly available. Recent research finds that these have strong potential for providing benefits across multiple wellbeings. The barriers to pursing this agenda are complex and poorly understood but are perceptual and institutional more than technological. A small number of critical experiments during the last oil crisis provide critical lessons and direction.     

北部湾海域球形棕囊藻遗传多样性分析

南海北部湾海域近年来连年暴发球形棕囊藻赤潮,严重威胁近海生态安全,亟待探明赤潮成因。球形棕囊藻是一种广泛分布于温带至热带海域的有害藻华微藻,具有明显的种下遗传分化。为了解北部湾海域球形棕囊藻的遗传多样性及其对赤潮藻种来源的指示意义,本研究针对分离于北部湾海域赤潮发生期间的4株棕囊藻,以核糖体28S大亚基rRNA基因（28S rDNA）D1-D2区和转录间隔区（ITS区）为靶区构建克隆文库,通过测序分析了北部湾海域球形棕囊藻的遗传多样性。结果表明,从北部湾分离的4株棕囊藻均为球形棕囊藻,但不同年份分离的球形棕囊藻藻株之间存在明显的遗传差异。部分球形棕囊藻藻株（PG2015和PG2017）的不同克隆间也存在遗传差异,这种遗传差异在由单一藻细胞建立的克隆培养系中仍存在,表明遗传差异是来自细胞内多拷贝的基因序列,可能源自不同地理种群球形棕囊藻之间的基因交流。与ITS区相比,28S rDNA D1-D2区能更好地反映球形棕囊藻遗传多样性状况,具有作为分子标记指示球形棕囊藻地理种群的潜力,但仍需深入研究。研究结果深化了对北部湾球形棕囊藻遗传多样性的认识,有望为进一步解析北部湾海域球形棕囊藻赤潮原因种来源提供判据。     

The US Southern Ocean Joint Global Ocean Flux Study: an introduction to AESOPS

The United States Southern Ocean Joint Global Ocean Flux Study (JGOFS), also known as AESOPS (Antarctic Environment and Southern Ocean Process Study), focused on two distinct regions. The first was the Ross-Sea continental shelf, where a series of six cruises collected a variety of data from October 1996 through February 1998. The second area was the southwest Pacific sector of the Southern Ocean, spanning the Antarctic Circumpolar Current (ACC) at 170°W. Data were collected within this region during five cruises from September 1996 through March 1998, as well as during selected transits between New Zealand and the Ross Sea. The first results of these cruses are described in this issue. The Ross-Sea investigation extensively sampled the area along 76°30′S to elucidate the temporal patterns and processes that contribute to making this one of the Antarctic's most productive seas. Hydrographic distributions confirm that stratification is initiated early in October within the polynya, generating an environment that is favorable for phytoplankton growth. Significant spatial variations in mixed-layer depths, the timing of the onset of stratification, and the strength of the stratification existed throughout the growing season. Nutrient concentrations reflected phytoplankton uptake, and reached their seasonal minimal in early February. Chlorophyll concentrations were maximal in early January, whereas productivity was maximal in late November, which reflects the temporal uncoupling between growth and biomass accumulation in the region. Independent estimates of biogenic export suggest that majority of the flux occurred in late summer and was strongly uncoupled from phytoplankton growth. The ACC region exhibited seasonal changes that in some cases were greater than those observed in the Ross Sea. Sea ice covered much of the region south of the Polar Front in winter, and retreated rapidly in late spring and early summer. Mixed layers throughout the region shoaled in summer due to surface heating, while the addition of freshwater from melting sea ice enhanced stratification in the Seasonal Ice Zone, creating conditions favorable for phytoplankton growth. For example, silicic acid concentrations decreased from initial values as high as 65 to less than 2 μM within approximately 100 km (from 65.7 to 64.8°S). Fluorescence values, however, showed less than a two-fold variation over the same distance. The vertical flux of carbon in the Polar Front area is substantial, and marked variations in the composition of exported material exited over the region. The results provide a means whereby the controls of phytoplankton growth and organic matter flux and remineralization can be analyzed in great detail. Additional results of the AESOPS project are discussed.     

Distributions and behaviour of dissolved Cu,Zn and Mn in the Tamar estuary

Concentrations of dissolved Cu, Zn and Mn have been recorded together with salinity, suspended particulate load, dissolved oxygen and pH, in twenty-two transects of the Tamar Estuary carried out between 1976 and 1985.The axial profiles of dissolved Mn accord with the results of previous studies. These showed persistent minima indicating varying degrees of removal within the low salinity, high turbidity region. Mid-estuarine maxima were also recorded. These were variable in magnitude and location within the salinity range 3–15‰. The pattern of Zn distributions was similar to that of Mn. Removal of Zn occurred in the same low salinity region but was generally less accentuated. The mid-estuarine Zn maxima fell within the salinity range 3–20‰. Cu was also removed within the low salinity region but the mid-estuarine maxima were confined to the 1–8‰ salinity range.The characteristics of removal within the low salinity zone for all three metals are compatible with rapid adsorption onto suspended particles forming the estuarine turbidity maximum. A comparison of metal distributions throughout the rest of the estuary using a statistical technique indicates that while direct pore water infusions contribute to the observed mid-estuarine maxima of dissolved Cu and Zn, desorption from tidally resuspended sediment particles also plays a significant role. Desorption from seaward fluxing particles of immediate riverine origin is probably largely confined to the very low salinity region where its effect is more than counterbalanced by the sorptive uptake process.It is concluded that the pronounced dissolved metal reactivity within this estuary is attributable to an enhancement of particle-water interactions by highly dynamic internal sediment mobility driven by high tidal energy inputs.     

Entrainment of Antarctic euphausiids across the Antarctic Polar Front by a cold eddy

An unusual region of high meso-scale turbulence has been identified in the Indian Ocean sector of the Southern Ocean. It has been shown that this is the result of eddy shedding from the Antarctic Polar Front. These eddies may dramatically affect the local distribution of marine organisms. To investigate this, the euphausiid community structure and species composition in the region of a cold eddy within the Antarctic Polar Frontal Zone (APFZ) was investigated during April 2005. Water masses within the core of the eddy were typically Antarctic, showing they had come from south of the Antarctic Polar Front. Results of numerical analyses indicate that the euphausiid community within the survey area consisted of three distinct groups: those in APFZ waters, those at the edge of the eddy and those in the core of the eddy. These results indicate that eddies generated by the interaction of the Antarctic Circumpolar Current with the South-West Indian Ridge play an important role in transporting Antarctic euphausiid species equatorward, thus contributing to the spatial heterogeneity of the zooplankton community within the region.     

The regional approach to management of marine pollution in the South Pacific

Marine pollution does not recognise maritime boundaries. Consequently, protection of the marine environment from pollution must involve an international cooperative effort, with near neighbours, in particular, working together to protect coastal and ocean areas close to their political boundaries. This paper describes a regional approach adopted from 1988 to 1994 in the South Pacific Region to address marine pollution problems. Some 25 countries and territories lie within the region. Apart from Australia, New Zealand and Papua New Guinea, the countries of the region consist basically of a large number of small islands separated by substantial stretches of ocean. Growing populations and demands for better living standards are exerting increasing pressures on coastal and marine resources, leading in some cases to significant marine pollution. The Region has limited financial and technical resources to address such problems and countries have therefore determined to assess and control them through a concerted regional approach. This paper reviews aspects of this effort, outlining the methods adopted, describing the outcomes and discussing the problems and lessons learned.     

The spatial,temporal and volumetric analysis of a large mud volcano province within the Eastern Mediterranean

This paper documents and describes through the use of 3D seismic data a prolific mud volcano province within the Eastern Mediterranean. As many as 386 mud volcanoes were mapped within the post-salt succession of the western slope of the Nile Cone, offshore Egypt, using high resolution 3D seismic data. The mud volcanoes within this field display significant geometrical variability in diameter (c. 550 m to c. 5660 m), height (c. 25 m to c. 510 m) and volume (c. 0.1 km³ to c. 3.3 km³) and lie at depths ranging from c. > 6000 m subsea to c. 3100 m at the seafloor. A close spatial relationship between mud volcanoes and base-salt depressions and regions of anomalous thinning within the immediate pre-salt succession, combined with documented core samples taken from mud volcanoes within this region present a powerful argument for a pre-salt source of mud. 3D seismic interpretation and volumetric analysis of these mud volcanoes and their source region permit the definition and quantification of their depletion zones. A conceptual model for a dynamic liquefaction and sediment withdrawal process is proposed whereby mud is fed into a central conduit as the depletion zone propagates radially and episodically outwards resulting in a the formation of a concentric depletion zones. Prolonged mud volcanism within this region over the last ∼5.3 Ma implies the potential for long lived pre-salt overpressure and continued mud volcanism following the catastrophic hydrodynamic impact of the Messinian Salinity Crisis. It is suggested that the scale of mud volcanism means that this region should be considered as among the largest mud volcano provinces in the world.     

Depth-stratified community zonation patterns on Gulf of Alaska rocky shores

Vertical zonation patterns have been considered ubiquitous in intertidal ecosystems but questions remain about their generality for individual taxonomic groups and over broad spatial scales, and whether they continue into adjacent shallow subtidal habitats. Taxon richness, invertebrate abundance, and macroalgal biomass were examined in the summer of 2003 along a vertical gradient in the rocky intertidal and shallow subtidal habitats around Kodiak Island, Kachemak Bay, and Prince William Sound, all within the Gulf of Alaska. Replicate samples of benthic organisms were taken in the high (～ 7 m), mid (～ 4 m) and low (～ 0 m) intertidal (relative to MLLW), and at 1, 5, 10 and 15 m water depths at three sites in each region, and identified to the lowest possible taxonomic level. Our primary goals were to assess (1) how estimates of taxon richness, invertebrate abundance, and macroalgal biomass vary among intertidal heights and subtidal depths and (2) how general these patterns are when considered across the Gulf of Alaska. Our results show that when all invertebrates were considered together, most of the variation in taxon richness was accounted for by differences among depths (i.e. intertidal heights and subtidal depths) (～ 51%), and among replicate samples within each depth (～ 26%). Little to none of the variation was accounted for by differences among sites within each region (～ 1%) or among regions themselves (～ 0%). When considered across the Gulf of Alaska, total taxon richness and organism abundance were greatest in the low intertidal/shallow subtidal and decreased with increasing height/depth. When separated by phylum and examined together with macroalgae, variation in abundance and/or biomass among depths was significant and accounted for most of the variability. Differences among regions and sites within each region were not significant and accounted for little to none of the variance. Because the pattern of zonation varied among sites within each region, it reduced the generality of a single zonation pattern for the Gulf of Alaska. Likewise, when community composition was compared among depths, geographic regions and sites within each region using multivariate analyses, vertical zonation patterns were evident at a regional scale, but high variability in these patterns among sites within each region reduced the generality of these patterns.