The influence of swash infiltration–exfiltration on beach face sediment transport: onshore or offshore?

Measurements were obtained from the swash-zone of a high-energy macrotidal dissipative beach of pore-pressure at four levels below the bed, and cross-shore velocity at a single height above the bed. Time-series from relatively high (H_s≈2.0 m) energy conditions were chosen for analysis from the mid-swash-zone at high tide. Calculation of upwards-directed pore-pressure gradients shows that, in this case, fluidisation of the upper layer of sediment, leading to enhanced backwash transport, is unlikely. An apparent conflict exists in the literature regarding the net effect of infiltration–exfiltration on the sediment transport, through the combined effects of stabilisation–destabilisation and boundary layer modification. This is examined for the data collected using a modified Shields parameter. Inferred instantaneous transport rates integrated over a single swash cycle show a decrease in uprush transport of 10.5% and an increase in backwash transport of 4.5%. Sensitivity tests suggest that there is a critical grain size at which the influence of infiltration–exfiltration changes from offshore to onshore. The exact value of this grain size is highly sensitive to the method used to estimate the friction factor.     

Circulations east of Taiwan and in East China Sea and east of Ryukyu Islands during early summer 1985

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The joint long-term distribution of design environmental factors for offshore structures Multivariate probabilities and simulating method

With the development of ocean engineering, it is one of the most important factors which determine the structural safety, cost and suitable forms of engineerings to select the ocean environmental design criteria. Owing to the complexity , variation and randomness of ocean environmental conditions, the commonly used methods for determining design criteria cannot consider the joint occurring probabilities of several environmental factors ,therefore, lead to overestimate design criteria of them and result in an unnecessary overspend invest in engineering. On the basis of the measured and hindcasting data and the multi-demension joint probability theory, this paper presented the study of the joint loads of wind , wave and current on the offshore structures and its responsible joint probability level with the application of random simulation techniques, and presented the joint design criteria of environmental loads for the realistic design of engineerings.     

The use of GPS for marine positioning in Germany—requirements,experience, and concepts

Abstract

While beginning to establish a German Civil GPS Information and Observation Service in 1990, the actual and (near) future GPS market in Germany was analyzed. In addition, the feasibility of using GPS for water authority tasks has been studied during past years. Typical capabilities in this area are real‐time positioning for hydrographic surveying (kinematic application) and precise transfer of levels to tide gauges and verification at offshore positions.

The article describes the user interests, the requirements, some of the test campaigns, and the derived concepts for future applications.     

Abundance of total bacteria, ATP and manganese-oxidating bacteria in the sediments and manganese nodules of the Northwestern Pacific Ocean

In the seawater and sediments of the ocean, there exist huge quantities of bacteria whose living activities cause various chemical reaction processes. It is demonstrated that microorganisms play a fundamental role on chemical changes of the sediments and diageneses. Over the last twenty years, great interest has been increased about the role of deep-sea bacteria in the ferromanganese sedimentary process. Much work has been done on this aspect in the Atlantic Ocean, the Baltic Sea and the Pacific O-     

Distribution of molluscan remains in the sediment of the Chukchi Sea and its vicinity, the Arctic

INTRODUCTIONInordertostudythemarinesedimentationoftheChukchiSeaandBeringSeaandgathertheinformationofpaleoceanographyandpaleoenvironment,theFirstChineseNationalArcticResearchExpeditionTeamcollectedbenthonicmolluscansamplesintheChukchiSea ,BeaufortSeaandBeringSeafromJuly 1sttoSeptember 9th ,1 999byicebreakerXuelong .ItwasnotonlythefirstsamplingthatChinesescientistscollectedmolluscaremainsinabove mentionedar eas,butalsooneofinvestigationsinasinglecruisewithhighersamplingrateandalotofb…     

The influence of organic sources and environments on source rock deposition during the periods of Cretaceous–Eocene and Oligocene–Miocene,northern Kalimantan

The sedimentary system of Kalimantan has undergone significant development since the Oligocene. Previous research have largely ignored the capacity of the Cretaceous–Eocene sediments to produce hydrocarbons,focusing instead primarily on the Oligocene–Miocene coal as the principal source rocks. Shales and coals from the outcrops in the northern margin of Kalimantan were analyzed with palynological and geochemical methods to characterize the palaeoenvironmental and palaeoecological differences bet...     

Observations of boundary layer parameters and suspended sediment transport over the intertidal flats of northern Jiangsu, China

A current-turbidity monitoring system (CTMS) was deployed on the intertidal flat at Wanggang, northern Jiangsu during October 16-17, 2000, to measure the tidal current speeds and seawater turbidities at 5 levels above the seabed. Based upon the logarithmic-prof‘de equation, the boundary layer parameters, i.e., u*, Z0 and C60, were obtained for 247 tidal flow velocity prof‘des. Around 90% of the profiles were logarithmic according to the critical correlation coefficient. Internal consistency analysis shows that these parameters derived by different methods are consistent with each other. In addition, the height of the bedforms observed is close to the seabed roughness lengths calculated from the velocity prof‘des, indicating that the boundary layer parameters obtained can reveal the conditions at the sedimentwater interface on the intertidal flats. Suspended sediment concentrations were obtained from the 5 CTMS turbidity meters using laboratory and in-situ calibrations. The results show that the in-situ calibrated SSCs have a much higher accuracy than the laboratory calibrated ones. Calculation of suspended sediment fluxes on the intertidal flats, with a magnitude of 104 kg/m per spring tidal cycle, indicates that suspended sediment moves towards the northwest, which is reversal to the transport pattern controlled by the southward Northern Jiangsu Coastal Current in the sub-tidal zone and adjacent shallow waters.     

The sediment types in the northeastern part of the South Cnina Sea—A discussion on regularity of the sedimentary types

Based on the comprehensive analysis of the types of sedimentary grain size in the studied region and the characteristics of organism, mineral and chemical compositions of the sediments, from the view-point of origin of the sediments, the sediments in the studied region are classified into four sedimentary types, namely, terrigenous detritus, biogenic-terri-genous, authigenous-terrigenous and volcanic-terrigenous (Fig. 1). Their characteristics, distributions and sedimentary regularities are approached in this paper.     

The concentration of total dissolved CO2 in surface water in ENSO event——The results of investigation during TOGA expeditions

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Cheats in a cooperative behaviour? Behavioural differences and breakdown of cooperative behaviour in aggregating,intertidal littorinids (Mollusca)

Cooperative behaviours result in the evolution of cheats: individuals that benefit from the behaviour without sharing the costs required to generate the behaviour. Normally the proportion of cheats is small, as large numbers of cheats will result in the breakdown of the behaviour. Using empirical and simulation‐derived results we demonstrate a cooperative behaviour (aggregation between two species of intertidal snails that provides a benefit by reducing desiccation stress) that shows many characteristics similar to those of a cooperative system with cheats present. In this system, the high rocky shore littorinid Echinolittorina malaccana forages for longer after high water than Echinolittorina radiata, which stops foraging and begins to form aggregations earlier. Nevertheless, E. malaccana, the ‘cheat’ in this system, still occupies an equal proportion of the most beneficial places in aggregations. Computer simulations demonstrate that up to 65% of individual snails can show the behaviour of E. malaccana before the breakdown of this aggregation behaviour begins to occur through aggregations becoming smaller, and hence less effective against desiccation. The high proportion of ‘cheats’ possible in this cooperative behaviour implies that different selective pressures may act on individuals of different species in multi‐species cooperative behaviours to those acting on individuals engaging in single species cooperative behaviours. Social symbiosis appears to be occurring between the species, but it appears that both mutualistic and parasitic symbioses are occurring.     

Distribution,abundance and population structure of Hexaplex trunculus and Bolinus brandaris (Gastropoda: Muricidae) in offshore areas of the Gulf of Gabès,southern Tunisia

The banded murex Hexaplex trunculus and purple dye murex Bolinus brandaris are frequently caught as bycatch by bottom trawlers operating in the Gulf of Gabès, southern Tunisia. Although these muricid gastropods might importantly constitute an additional source of income for fishermen as well as help to diversify local shellfish production, information on their catches is relatively scarce. Hence, the present study aimed to assess the status of local populations of H. trunculus and B. brandaris, including data on their spatial and depth distributions, abundance, biomass, population structure and mortality. Fishing surveys using bottom trawls were performed between May 2006 and June 2007 in offshore areas of the Gulf of Gabès. In total, 198 fishing hauls were analysed, corresponding to a total fishing duration of 333.3 hours and a total prospecting area of 1 534 ha at depths of 20–86 m. Altogether, 3 026 H. trunculus and 3 599 B. brandaris of a broad size range (22.9?91.1 and 22.4?97.0 mm shell length, respectively) were sampled during the study period. GIS-produced maps were employed to determine the species’ spatial and bathymetric distributions by extrapolating their estimated fishing yield (bycatch per unit effort), abundance, biomass and mortality in relation to the total area surveyed in the gulf. The results provide valuable baseline information that may be applied to management proposals for regulating this untargeted resource, ultimately assisting sustainable exploitation and long-term preservation of this alternative fishing resource in the offshore areas of the Gulf of Gabès.     

The influence of neoliberalization on the success and failure of fishing cooperatives in contemporary small-scale fishing communities: A case study from Yucatán,Mexico

This paper examines the effects of neoliberalization on the opportunities and constraints that fishing cooperatives face in Yucatán, Mexico. Cooperatives have the potential to enhance small-scale fishing livelihoods and participate in sustainable resource governance. However, promoting cooperatives’ success entails developing a realistic understanding of the political and economic contexts in which they operate. Drawing on interview and census data, the analysis employs the theory of club goods to examine how the neoliberalization of Mexican fisheries policies in the 1980s and 1990s has affected cooperatives’ ability to provide members with collective benefits, and thus the success and failure of fishing cooperatives in the region. In general, neoliberalization has reduced support to fishing cooperatives and generated greater challenges for their success in Yucatán. The results of this study are likely relevant to many other small-scale fisheries in the South that have undergone similar processes of neoliberalization.     

The point of no return and pectoral angle of Japanese anchovy(Engraulis japonicus) larvae during growth and starvation

At a temperature of 23.0~24.8℃,the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted.The point of no return(PNR) was reached on the 6th day after hatching.On the 4th day after hatching,the pectoral angle appeared in both fed and unfed anchovy larvae although it was more evident and sharper in the starved and the PNR stage larvae than in the fed ones.According to observations of larvae collected in the sea,the pectoral angles were evident not only in the larvae of 3.62~7.44 mm in standard length,but also in the larvae of 2.70 mm in standard length with remnants of yolk.The pectoral angles became diffuse when the larvae reached 7.84 mm and vanished at 9.86 mm.The pectoral angle cannot be used as a criterion to distinguish healthy from starving larvae.     

The size-fractionated chlorophyll a and primary productivity in the Bering Sea during the summer of 2003

1Introduction Thephytoplanktonistheprimaryproducerofor- ganicsubstancesintheoceanandplaysanimportant roleinthesubstancecycleandenergyconversionof marineecosystem.Chlorophyllaconcentration(Chla) isanimportantindexmanifestingthelightenergy-au- totrophicbiomassinthesea.Primaryproductivityre- flectstheabilitytoconvertinorganiccarbonintoor- ganiccarbonbythephytoplanktonintheocean.Both Chlaandprimaryproductivityaretheimportantcon-tentsbeingstudiedinthemarineecosystemaswellas theimportantfoundationa…     

The Kuroshio east of Taiwan and the currents east of the Ryūkūy-guntō during October of 1995

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Crucial physical characteristics of sea ice in the Arctic section of 143°–180°W during August and early September 2008

Sea-ice physical characteristics were investigated in the Arctic section of 143°-180°W during August and early September 2008. Ship-based observations show that both the sea-ice thickness and concentration recorded during southward navigation from 30 August to 6 September were remarkably less than those recorded during northward navigation from 3 to 30 August, especially at low latitudes. Accordingly, the marginal ice zone moved from about 74.0°N to about 79.5°N from mid-August to early September. Melt-pond coverage increased with increasing latitude, peaking at 84.4°N, where about 27% of ice was covered by melt ponds. Above this latitude, melt-pond coverage decreased evidently as the ice at high latitudes experienced a relatively short melt season and commenced its growth stage by the end of August. Regional mean ice thickness increased from 0.8 (±0.5) m at 75.0°N to 1.5 (±0.4) m at 85.0°N along the northward navigation while it decreased rapidly to 0.6 (±0.3) m at 78.0°N along the southward navigation. Because of relatively low ice concentration and thin ice in the investigated Arctic sector, both the short-term ice stations and ice camp could only be set up over multiyear sea ice. Observations of ice properties based on ice cores collected at the short-term ice stations and the ice camp show that all investigated floes were essentially isothermal with high temperature and porosity, and low density and salinity. Most ices had salinity below 2 and mean density of 800-860 kg/m~3 . Significant ice loss in the investigated Arctic sector during the last 15 a can be identified by comparison with the previous observations.     

The Study of Fish Eggs, Larvae and Juveniles of the Estuary at Beitang

The fish eggs, larvae and juveniles were collected during 25 cruises from April to No-vember 1980 and 1981 respectively. They were represented by 40 species, 36 genera, 19families and 9 orders. According to their habit, the fish eggs, larvae and juveniles couldbe referred to three types: (1) shallow sea and estuary type; (2) migration type of outersea; (3) fresh water type. The shallow sea and estuary species were 29 in number, occu-pying 72.5% of the total; the migration species were 3 in number, occupying 7.5% of thetotal; the fresh water species were 8 in number occupying 20% of the total.