Sea Channel Research Articles

日本海東縁海底下に分布する砂層の孔隙特性と年代 : MD179航海

In 2010 the MD179 project was undertaken aiming at recovery of deep seated gas hydrate, methane induced carbonate, and deep sediments older than 300 ka. Sediment samples were obtained in the Umitaka Spur, Joetsu Channel, Toyama Trough, Japan Basin, Nishi Tsugaru and Okushiri Ridge areas. Small amounts of sandy sediment have been retrieved as thin intercalations in Pleistocene and Holocene muddy layers, where trace fossils and strong bioturbations are commonly observed.Those sandy sediments consist of very fine- to fine-grained sand grains, and are sometimes tuffaceous. Pore-size distribution measurements and thin-section observations of these sands were undertaken, which indicated that porosities of muddy sediments are around 50 % but those of arenites range from 42 to 52%. Mean pore sizes and permeabilities of those arenites are larger than those of mudstones. While the presence of gas hydrate in intergranular pores of sands has not been confirmed, the soupy occurrence in recovered sediments may strongly indicate the presence of hydrate filling the intergranular pore system of sands. Such arenites have been recognized till now in the Mallik, NW Territory Canada, as well as in the Nankai Trough areas, which are expected common even in the subsurface sandy sediments at the eastern margin of Japan Sea. Concentration of gas hydrate may need primary intergranular pores large enough for gas hydrate to occur within host sediments likely deposited in the sedimentary environment such as deep sea channels. Small amounts of sandy sediment were retrieved as thin intercalations in Pleistocene silty layers, because supplying sediments may not be abundant due to sea level fluctuation during Pleistocene ice age. As time of deposition of coarse-grained sediments can be recognized by the thermoluminescence (TL) dating method, sandy sediments are usually tuffaceous and contain a small amount of quartz grains, and TL dating has been completed only for seven samples, which indicate 48 to 980 ka in age. This study was performed as a part of the MH21 Research Consortium.

Pleistocene Rhine-Thames landscapes - a geological background for hominin occupation patterns in the southern North Sea

The relatively shallow southern North Sea is one of the most productive Pleistocene fossils bearing localities. Perhaps the most spectacular find thus far is a fragment of a Neanderthal skull. Unfortunately, it lacked a stratigraphical context and that applies to most of the finds retrieved. The North Sea Neanderthal project was therefore started with the aim to provide a better stratigraphical context for archaeological and palaeontological finds. Northwestern Europe was at the edge of the living range of hominins during major parts of the Pleistocene and establishing the pattern of hominin absence/presence is crucial to understand range shifts. We constructed a litho-morphogenetic framework explaining the stratigraphy and the spatial and temporal distribution of the Pleistocene deposits in the southern North Sea. This poster focuses on the largescale palaeogeographical changes in the drainage network that occurred during the Pleistocene. These changes result in a threefold division of the Pleistocene: 1.before the breaching of the Chalk bridge (pre-Anglian/Elsterian), the English Channel and the North Sea were separated; 2.After the Anglian/Elsterian and before MIS 6, the waters of the North Sea and English Channel were still separated, now by a smaller landbridge consisting of massive Paleogene clays, separating the Thames from the Rhine. It is hypothesised that breaching of the land bridge formed by the massive Paleogene clays occurred during MIS 6; 3.From MIS 5 to present, the final situation evolved with a highstand sea strait and a lowstand gorge in the Dover Strait. Besides directly impacting migration routes of animals and hominins, the changes also resulted in a larger availability of raw flint material (breach of Strait of Dover), but also in favourable conditions for extensive loess accumulation in northern France and Belgium which enabled preservation of Middle Palaeolithic sites, in contrast to Britain where thick loess blankets are rare.

Invasion of the North American wedge clam Rangia cuneata (G.B. Sowerby I, 1831) (Bivalvia: Mactridae) in the Vistula Lagoon of the Baltic Sea

North American brackish water bivalve Rangia cuneata (G.B. Sowerby I, 1831) was recorded for the first time in the Vistula Lagoon of the Baltic Sea in September 2010. On the basis of features of its biology, we assume that the invasion of this species into the Vistula Lagoon took place at least 2–3 years earlier, in 2007–2008. In 2010–2011, R. cuneata colonized and inhabited a large area of the bay. The maximum abundance (up to 4040 ind./m2) was observed in the areas adjacent to the Kaliningrad sea channel. Most likely, the invasion of R. cuneata into the Vistula Lagoon is related to the ballast waters of ships, including dredging ships, which came from areas where the clams are already naturalized. The naturalization of R. cuneata poses a threat of new serious transformations in the ecosystem of the Vistula Lagoon. The invasion requires increased monitoring of the state of its benthic communities.

The Transmission Waveform of Active Acoustic Homing Torpedo and ODN

There are Various torpedo transmission waveform. Classical theory of detection and parametric estimation indicates: the optimum homing receiver is related to not only sea channel but also the homing transmission waveform. Based on the relationship between the torpedo transmission waveform and ODN the paper illuminates that the transmission waveform have a great impact on the anti-reverberation effect of ODN, and the narrower pulse spectrum, the better anti-reverberation effect. At last the paper verifies the conclusion by analysing and comparing the rectanglar envelope pulse, trapezoidal envelope pulse and cosine envelope pulse.

Ensuring representative economic data: survey data-collection methods in France for implementing the Common Fisheries Policy

Abstract Van Iseghem, S., Quillérou, E., Brigaudeau, C., Macher, C., Guyader, O., and Daurès, F. 2011. Ensuring representative economic data: survey data-collection methods in France for implementing the Common Fisheries Policy. – ICES Journal of Marine Science, 68: 1792–1799. Since 2001, Ifremer has implemented an economic data collection programme (EDCP) within the Data Collection Framework of the EU. It aims to obtain economic data from a sample of vessels representative of the entire French fishing fleet. This paper presents the strategies used for vessel sampling selection in the French EDCP and its implementation over several consecutive years. The approach is illustrated by the sampling plan for the fleet in the North Sea Channel Atlantic region. We show that the EDCP allows precise economic indicators such as gross revenue or fuel costs to be estimated for the whole fishing fleet, including small vessels (<10 m), and consequently, it facilitates sound scientific advice regarding the Common Fisheries Policy. The apparent underestimation of landings by small vessels in official statistics is highlighted.

Regional patterns of continental shelf polychaete diversity: examples for the North Sea, English Channel, Irish Sea and Outer Bristol Channel areas

Polychaetes are a well-represented group in most marine and estuarine environments, both in terms of number of individuals and species; they typically constitute a significant percentage of the total macrofaunal diversity. The aim of our analyses was to characterise the biodiversity and regional distribution patterns of polychaete assemblages from the continental shelf (0–200 m) of the North Sea, English Channel and Irish Sea. Variations in depth and local distribution of sediment types, amongst other environmental factors, are the main factors affecting the pattern of distribution of benthic polychaetes. Here we applied and compared different approaches to draw the diversity pattern of this marine invertebrate group on a regional biogeographical scale, and to identify the main factors structuring these patterns.

Iskandar Malaysia

Since 2006, the Federal Malaysian government has developed the South-Johor Economic Region as a major corridor for economic development. A vision, known as Iskandar Malaysia, has been facilitated through a Comprehensive Development Plan underpinning strategies to boost the physical and economic development of the Johor Bahru metropolitan area. The latter borders Singapore; the two cities, separated by a one km. sea channel, are linked by two bridges. Thousands of people cross the Johor Straits to enjoy better wages (in Singapore) and cheap goods (in Malaysia). The paper provides an analysis of the Iskandar Malaysia Vision. A key message is the need for future plans to consider both cities, Johor Bahru and Singapore, as part of an emerging transnational urban region.

Characteristics of shallow thermally driven flow in the complex topography of the south-eastern Adriatic

Abstract. Characteristics of thermally induced flow, namely the sea breeze, are investigated along the south-eastern Adriatic. The chosen period 24–25 April 2006 favoured sea breeze development and simultaneously allowed a comparison of the large-scale wind influence (north-westerly wind versus south-easterly wind) and the complex terrain on the local circulations. Particular attention is paid to the small-scale formation of the wind field, convergence zones (CZs), channelling flows and small scale eddies, especially in the vicinity of two airports in the central part of south-eastern Adriatic. The results are based on wind measurements (from meteorological surface stations, radiosoundings, satellite data and sodar data) and further supplemented by model data at fine grid spacing. This study shows the formation of numerous irregular daytime and nighttime CZs, which occurred along the coastline in the lee of mountains and over the larger, elongated islands. The results show that the above mentioned airports are surrounded by daytime CZ formations within the lowermost 1000 m and associated updrafts of 1 m s−1, especially if CZs are maintained by the north-westerly large-scale winds. Whereas the daytime CZ was generated due to merged sea breezes, the weaker and shallower nighttime CZs were formed by wind convergence of the seaward breezes, and significantly modified by the large-scale flow of the topography (e.g., accelerated flow in the sea channels and substantial swirled flows around the islands). The passes between the coastal mountain peaks changed the inflow penetration, provoking the increase in wind speed of the channelled flow. The strongest sea breeze channelling was observed above the valley of the Neretva River, where the onshore flow reached 40 km inland with a strength of 8 m s−1, and the highly asymmetric offshore part was confined within the sea channel.

Phylogeography and conservation of the endemic Hispaniolan Palm-Tanagers (Aves: Phaenicophilus)

The Gray-crowned Palm-Tanager (Phaenicophilus poliocephalus), sometimes considered conspecific with its more widespread congener P. palmarum, is restricted to Haiti’s Tiburon Peninsula, a biodiversity hotspot threatened by extensive habitat loss. We used a multilocus phylogeographic approach to identify evolutionarily distinct populations of Phaenicophilus. Mitochondrial haplotypes formed two reciprocally monophyletic groups separated by 5% uncorrected divergence. Genealogical patterns of differentiation at nuclear intron alleles were congruent with those of mtDNA, and the two species also differed in body size and shape. An ancient sea channel between the Tiburon Peninsula and mainland Haiti was likely a dispersal barrier that led to allopatric divergence, a hypothesis supported by our estimates of divergence times. Our results support the recognition of two Palm-Tanager species, confirming P. poliocephalus as Haiti’s only endemic bird species and underscoring the need to protect the Tiburon Peninsula’s single primary forest reserve.

Satyrinae butterflies from Sardinia and Corsica show a kaleidoscopic intraspecific biogeography (Lepidoptera, Nymphlidae)

The Mediterranean islands of Sardinia and Corsica are known for their multitude of endemics. Butterflies in particular have received much attention. However, no comprehensive studies aiming to compare populations of butterflies from Sardinia and Corsica with those from the neighbouring mainland and Sicily have been carried out. In the present study, the eleven Satyrinae species inhabiting Sardinia and Corsica islands were examined and compared with continental and Sicilian populations by means of geometric morphometrics of male genitalia. Relative warp computation, discriminant analyses, hierarchical clustering, and cross-validation tests were used to identify coherent distributional patterns including both islands and mainland populations. The eleven species showed multifaceted distributional patterns, although three main conclusions can be drawn: (1) populations from North Africa and Spain are generally different from those belonging to the Italian Peninsula; (2) populations from Sardinia and Sicily often resemble the North Africa/Spain ones; Corsica shows transitional populations similar to those from France; and (3) sea barriers represent filters to dispersal, although their efficacy appears to be unrelated to their extension. Indeed, the short sea straits between Sardinia and Corsica and between Sicily and the Italian Peninsula revealed a strong effectiveness with respect to preventing faunal exchanges; populations giving onto sea channels between Corsica and Northern Italy and between Sicily and Tunisia showed a higher similarity. A comparison of island and mainland distributions of the eleven taxa have helped to unravel the complex co-occurrence of historical factors, refugial dynamics, and recent (post-glacial) dispersal with respect to shaping the populations of Mediterranean island butterflies. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 195–212.

Under‐ice salinity and stable isotope distribution of Saroma‐ko Lagoon, Hokkaido, northern Japan

AbstractIn winter, lakes and lagoons at high altitudes or high latitudes have interesting hydrological cycles that differ from those in other seasons or in other regions, because water surfaces are covered with ice. Hydrological balances of lakes and lagoons are complex dynamic systems, and to elucidate them, isotopic tracers of water have been used as effective tools along with observations of precipitation, evaporation, inflows, and outflows. Here, to understand hydrological processes during freezing periods in the brackish Saroma‐ko Lagoon, Hokkaido, northern Japan, we examined horizontal and vertical distributions of salinity and isotope compositions of lagoon water and ice in 2005 and 2006. Horizontal and vertical gradients of salinity and isotope compositions were observed from the river mouth to the sea channel, and factors determining these distributions were considered. The mixing of freshwater and seawater and a freezing effect were presumed to be factors in relationships between salinity and isotopes and in relationships between surface waters and ice just above the water. A simple box model for water balance was constructed based on these putative factors to reproduce the distributions of salinity and isotope compositions of surface waters and ice. An evaluation of the model revealed that this hydrological system is controlled primarily by horizontal advection of the epilimnion, freshwater influx, and the ice growth rate. Copyright © 2009 John Wiley & Sons, Ltd.

Species composition and distribution patterns of the family Corycaeidae Dana, 1852 (Copepoda: Cyclopoida) in the middle Adriatic Sea

In 1999 copepods of the family Corycaeidae were studied in channel and offshore waters of the middle Adriatic Sea. Among 12 identified taxa, Ditrichocorycaeus minimus indicus was recorded for the first time and related to the ingression of the Levantine water into the Adriatic Sea. Analysis of the corycaeid vertical distribution identified the group inhabiting the upper epipelagic zone, the second group preferring below 50 m depths and the third group occupying the whole water column. Temperature was identified as the main abiotic control of this distribution pattern. Species from the second group occurred at the shallower channel waters at the time of winter isothermia. Based on the size distribution of adult corycaeids recorded in the area, the necessity of <200 µm mesh for adequate sampling of small corycaeids is stated.

Seismic stratigraphy of the Qiongdongnan deep sea channel system, northwest South China Sea

Based on more than 4000 km 2D seismic data and seismic stratigraphic analysis, we discussed the extent and formation mechanism of the Qiongdongnan deep sea channel. The Qiongdongnan deep sea channel is a large incised channel which extends from the east boundary of the Yinggehai Basin, through the whole Qiongdongnan and the Xisha trough, and terminates in the western part of the northwest subbasin of South China Sea. It is more than 570 km long and 4-8 km wide. The chaotic (or continuous) middle (or high) amplitude, middle (or high) continuity seismic facies of the channel reflect the different lithological distribution of the channel. The channel formed as a complex result of global sea level drop during early Pliocene, large scale of sediment supply to the Yinggehai Basin, inversion event of the Red River strike-slip fault, and tilted direction of the Qiongdongnan Basin. The large scale of sediment supply from Red River caused the shelf break of the Yinggehai Basin to move torwards the S and SE direction and developed large scale of prograding wedge from the Miocene, and the inversion of the Red River strike-slip fault induced the sediment slump which formed the Qiongdongnan deep sea channel.

Narrow sea crossings present major obstacles to migrating Griffon Vultures Gyps fulvus

The flight behaviour of Griffon Vultures Gyps fulvus was studied at a major migration bottleneck, the Strait of Gibraltar in southernmost Spain, during the autumns of 2004 to 2007. The 14‐km‐wide sea channel significantly impeded the southern migration of the species into Africa, with many birds attempting repeated passage for weeks before crossing, and others not crossing at all and overwintering in Southern Spain. Water‐crossing attempts were restricted to times between 11:00 and 14:00 h on days with light or variable winds, or on days with strong winds from the north or west. No crossing attempts were made on days with strong winds from the south or east. Vultures attempted to cross the Strait in large flocks and never attempted to do so alone. Although 29% of the birds soared during crossing attempts, at least until they flew beyond visible range of approximately 4 km, most engaged in considerable flapping flight when attempting to cross. Overall, birds flying over water flapped more than 10 times as frequently as those flying over land prior to crossing attempts. Vultures did not flap continuously, but intermittently in brief bouts of flapping interspersed with periods of gliding or soaring flight. The number of flaps per bout over water was significantly greater than the number of flaps per bout over land. Vultures flying over water that flapped at rates of 20 flaps or more per minute typically aborted attempted crossings and returned to Spain in intermittent flapping and gliding flight. There are numerous reports of Vultures falling into the Strait and drowning while attempting to cross, as well as reports of returning Vultures collapsing on the beach having reached Spain in spring (Barrios Partida 2006). Our observations indicate that passage of Griffon Vultures at the Strait of Gibraltar is limited by the species’ over‐water flapping‐flight abilities, including its inability to flap continuously for even short periods of time. We suggest that even relatively short sea crossings represent significant obstacles to migrating Vultures and discuss the implications of this limitation on the distribution and abundance of the species.

A Water Management Support System for Amman Zarqa Basin in Jordan

A Water Management Support System for Amman Zarqa Basin in Jordan has been developed. The water management support system employs the Water Evaluation and Planning system (WEAP). The water resources and demands in the basin were modeled as a network of supply and demand nodes connected by links. The model was calibrated for the year 2005 data and then validated for the year 2006 data. Validation results showed good agreement between calculated and measured inflows to wastewater treatment plants in the basin. The model was run for the year 2005 data as well as for four scenarios for the year 2025 which are Business As Usual (BAU) scenario, Advanced Wastewater Treatment (AWWT) scenario, the Red Sea, Dead Sea Channel (RSDSC) scenario and the optimistic scenario. The BAU scenario assumes that water use trends for the year 2025 follows predictable trends, the implementation of the disi project and the Wehda dam are main components of the BAU scenario. The AWWT scenario assumes that the effluent of As Samra wastewater treatment plant is treated to a level where it can be used for unrestricted irrigation within the basin and in the highlands. The main component of the RSDSC scenario is the implementation of the RSDSC project. The optimistic scenario combines both the AWWT scenario and the RSDSC scenario. The AWWT scenario, the RSDSC scenario, and the optimistic scenario are child scenarios of the BAU scenario. The results showed that neither domestic demand nor agricultural demand is met for the year 2005. The results also showed that domestic and industrial demands can be satisfied for all the considered scenarios by proper management of the available resources. However, agricultural demand can’t be satisfied for the business as usual scenario.

Water input requirements of the rapidly shrinking Dead Sea

The deepest point on Earth, the Dead Sea level, has been dropping alarmingly since 1978 by 0.7 m/a on average due to the accelerating water consumption in the Jordan catchment and stood in 2008 at 420 m below sea level. In this study, a terrain model of the surface area and water volume of the Dead Sea was developed from the Shuttle Radar Topography Mission data using ArcGIS. The model shows that the lake shrinks on average by 4 km(2)/a in area and by 0.47 km(3)/a in volume, amounting to a cumulative loss of 14 km(3) in the last 30 years. The receding level leaves almost annually erosional terraces, recorded here for the first time by Differential Global Positioning System field surveys. The terrace altitudes were correlated among the different profiles and dated to specific years of the lake level regression, illustrating the tight correlation between the morphology of the terrace sequence and the receding lake level. Our volume-level model described here and previous work on groundwater inflow suggest that the projected Dead Sea-Red Sea channel or the Mediterranean-Dead Sea channel must have a carrying capacity of >0.9 km(3)/a in order to slowly re-fill the lake to its former level and to create a sustainable system of electricity generation and freshwater production by desalinization. Moreover, such a channel will maintain tourism and potash industry on both sides of the Dead Sea and reduce the natural hazard caused by the recession.

Petroleum system in deepwater basins of the northern South China Sea

The northern South China Sea margin has experienced a rifting stage and a post-rifting stage during the Cenozoic. In the rifting stage, the margin received lacustrine and shallow marine facies sediments. In the post-rifting thermal subsidence, the margin accumulated shallow marine facies and hemipelagic deposits, and the deepwater basins formed. Petroleum systems of deepwater setting have been imaged from seismic data and drill wells. Two kinds of source rocks including Paleogene lacustrine black shale and Oligocene-Early Miocene mudstone were developed in the deepwater basin of the South China Sea. The deepwater reservoirs are characterized by the deep sea channel fill, mass flow complexes and drowned reef carbonate platform. Profitable capping rocks on the top are mudstones with huge thickness in the post-rifting stage. Meanwhile, the faults developed during the rifting stage provide a migration path favourable for the formation of reservoirs. The analysis of seismic and drilling data suggests that the joint structural and stratigraphic traps could form giant hydrocarbon fields and hydrocarbon reservoirs including syn-rifting graben subaqueous delta, deepwater submarine fan sandstone and reef carbonate reservoirs.

Shallow-Water Acoustic Tomography Performed From a Double-Beamforming Algorithm: Simulation Results

Recent shallow-water experiments in sea channels have been performed using two vertical coplanar densely sampled source and receive arrays. Applying a double-beamforming algorithm on the two arrays both on synthetic numerical simulations and on experimental data sets, we extract efficiently source and receive angles as well as travel times for a large number of acoustic rays that propagate and bounce in the shallow-water waveguide. We then investigate how well sound-speed variations in the waveguide are reconstructed using a ray time-delay tomography based on a Bayesian inversion formulation. We introduce both data and model covariance matrices and we discuss on the synthetic numerical example how to choose the a priori information on the sound-speed covariance matrix. We attribute the partial sound-speed reconstruction to the ray-based tomography and we suggest that finite-frequency effects should be considered as the vertical and horizontal size of the Fresnel zone significantly spreads in the waveguide. Finally, the contribution of a different set of ray angles for tomography goal is also presented.

Macrogeographic genetic variation in broad‐snouted caiman (Caiman latirostris)

Broad-snouted caiman's (Caiman latirostris) geographic distribution comprises one of the widest latitudinal ranges among all crocodilians. In this study we analyzed the relationship between geographic distance (along the species latitudinal range) and genetic differentiation using DNA microsatellite loci developed for C. latirostris and Alligator mississippiensis. The results suggest that there is a consistent relationship between geographic distance and genetic differentiation; however, other biogeographical factors seem to be relevant. The Atlantic Chain (Serra do Mar) seems to be an effective geographic barrier, as well as the relatively narrow (< or =1.5 km) sea channel between Cardoso Island and the continent. In addition, coastal populations seem to have been well connected in recent geological time (Pleistocene 16,000 years ago) all along the eastern Brazilian coast. Further studies should focus on the São Francisco River drainage, which is still poorly known for this species.

The Canaries: an important biogeographical meeting place

The Canaries: an important biogeographical meeting place