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This study comprehensively explores the intricate hydrodynamic and geomorphological processes that affect the Sulina Channel and bar area. It employs advanced hydrodynamic, wave, and sediment transport models to simulate the influence of marine currents, waves, and shipping traffic on sediment transport and deposition patterns, providing valuable insights for maintaining navigable conditions in the Sulina Channel. It is shown that sediment deposition is highly dynamic, particularly in the Sulina bar area, where rapid sediment recolonization occurs within one to two months after dredging. The simulation indicates that vessels with drafts of 11.5 m cause notable erosion. In comparison, drafts of 7 m have a minimal impact on sediment transport, emphasizing the importance of managing vessel drafts to mitigate sediment disturbances. This research highlights and quantifies the siltation phenomenon from the Black Sea to the mouth of the Sulina Channel, effectively addressing the challenges posed by natural and anthropogenic factors to ensure the Channel's sustainability and operational efficiency. [ABSTRACT FROM AUTHOR]

Surface and subsurface currents are two of the Essential Climate Variables (ECVs) defined by the Global Climate Observing System (GCOS). In situ current measurements can be made by Eulerian methods with instruments on moorings fixed in space. These methods require the determination of two metrological quantities: the speed and the direction of the motion. Their measurement and calibration require the determination of reference velocities and the measure of the angular movement of seawater in relation to the measuring device, as well as of the measuring device in relation to a reference direction given by the magnetic North. This reference direction is determined by electronic compasses integrated into current meters and current profilers. Compasses are sensitive to their magnetic environment, and, therefore, to the objects and instruments that surround them. This publication describes experiments conducted with current meters and current profilers to measure the influence of different devices on the accuracy of their compass measurements. It gives some explanations about the origin of measurement errors and proposes solutions to correct or attenuate the defaults in direction measurements and the measured deviations. Correction formulas are given that can be applied to measured data. They allow the reduction of errors of several tens of degrees for data to be within the instrument’s specifications.

Background: Long-distance rafting on anthropogenic marine debris (AMD) is thought to have a significant impact on global marine biogeography and the dispersal of non-indigenous species. Therefore, early identification of arrival sites of AMD and its epibionts is crucial for the prioritization of preventive measures. As accumulation patterns along global coastlines are largely unstudied, we tested if existing oceanographic models and knowledge about upstream sources of litter and epibionts can be used as a simple and cost-efficient approach for predicting probable arrival sites of AMD-rafting biota in coastal zones. Methods: Using the Southeast Pacific as a model system, we studied daily accumulation rates, composition, and minimum floating times of AMD with and without epibionts on seven sandy beaches, covering the oceanic environment (Rapa Nui/Easter Island) and three regions (south, centre, north) along the Chilean continental coast, over a minimum of 10 consecutive days, and we contrast our results with predictions from published models. Results: Total AMD accumulation rates varied from 56 ± 36 (mean ± standard deviation) to 388 ± 433 items km-1 d-1 and differed strongly between regions, in accordance with local geomorphology and socioeconomic conditions (presence of larger cities and rivers upstream, main economic activities, etc.). Daily accumulation of items with pelagic epibionts (indicators of a pelagic trajectory) ranged from 46 ± 29 (Rapa Nui) to 0.0 items km-1 d-1 (northern continental region). Minimum floating times of rafts, as estimated from the size of pelagic epibionts, were longest in the South Pacific Subtropical Gyre's (SPSG) centre region, followed by the high-latitude continental region under the influence of the onshore West Wind Drift, and decreased along the continental alongshore upwelling current, towards lower latitudes. Apart from pelagic rafters, a wide range of benthic epibionts, including invasive and cryptogenic species, was found on rafts at the continental beaches. Similarly, we present another record of local benthic corals Pocillopora sp., on Rapa Nui rafts. Discussion: Our results agree with the predictions made by recent models based on the prevailing wind and surface current regimes, with high frequencies of long-distance rafting in the oceanic SPSG centre and very low frequencies along the continental coast. These findings confirm the suitability of such models in predicting arrival hotspots of AMD and rafting species. Moreover, storm surges as well as site-related factors seem to influence AMD arrival patterns along the Chilean continental coast and might cause the observed high variability between sampling sites and days. Our results highlight the possible importance of rafting as a vector of along-shore dispersal and range expansions along the SE Pacific continental coast and add to the discussion about its role in benthic species dispersal between South Pacific oceanic islands. [ABSTRACT FROM AUTHOR]

Background Long-distance rafting on anthropogenic marine debris (AMD) is thought to have a significant impact on global marine biogeography and the dispersal of non-indigenous species. Therefore, early identification of arrival sites of AMD and its epibionts is crucial for the prioritization of preventive measures. As accumulation patterns along global coastlines are largely unstudied, we tested if existing oceanographic models and knowledge about upstream sources of litter and epibionts can be used as a simple and cost-efficient approach for predicting probable arrival sites of AMD-rafting biota in coastal zones. Methods Using the Southeast Pacific as a model system, we studied daily accumulation rates, composition, and minimum floating times of AMD with and without epibionts on seven sandy beaches, covering the oceanic environment (Rapa Nui/Easter Island) and three regions (south, centre, north) along the Chilean continental coast, over a minimum of 10 consecutive days, and we contrast our results with predictions from published models. Results Total AMD accumulation rates varied from 56 ± 36 (mean ± standard deviation) to 388 ± 433 items km−1 d−1 and differed strongly between regions, in accordance with local geomorphology and socioeconomic conditions (presence of larger cities and rivers upstream, main economic activities, etc.). Daily accumulation of items with pelagic epibionts (indicators of a pelagic trajectory) ranged from 46 ± 29 (Rapa Nui) to 0.0 items km−1 d−1 (northern continental region). Minimum floating times of rafts, as estimated from the size of pelagic epibionts, were longest in the South Pacific Subtropical Gyre’s (SPSG) centre region, followed by the high-latitude continental region under the influence of the onshore West Wind Drift, and decreased along the continental alongshore upwelling current, towards lower latitudes. Apart from pelagic rafters, a wide range of benthic epibionts, including invasive and cryptogenic species, was found on rafts at the continental beaches. Similarly, we present another record of local benthic corals Pocillopora sp., on Rapa Nui rafts. Discussion Our results agree with the predictions made by recent models based on the prevailing wind and surface current regimes, with high frequencies of long-distance rafting in the oceanic SPSG centre and very low frequencies along the continental coast. These findings confirm the suitability of such models in predicting arrival hotspots of AMD and rafting species. Moreover, storm surges as well as site-related factors seem to influence AMD arrival patterns along the Chilean continental coast and might cause the observed high variability between sampling sites and days. Our results highlight the possible importance of rafting as a vector of along-shore dispersal and range expansions along the SE Pacific continental coast and add to the discussion about its role in benthic species dispersal between South Pacific oceanic islands.

The evolution of tidal stream turbines is increasing the feasibility of future tidal plants in shallow depth areas with mid-tidal ranges (<5 m). However, extreme events such as changes in bathymetry due to the access channel deepening of coastal ports and sea level rise modify hydrodynamics and might affect the infrastructure and energy production of tidal energy converters. This research focused on Buenaventura Bay to analyze the effect of these extreme events on marine currents through calibrated-validated numerical modeling. Several monitored points were analyzed, and the results highlighted that the bay has potential for implementing tidal stream turbines because of the reported velocities between 0.25 and 2 m/s. The sea level rise increased 11.39% and access channel deepening reduced by 17.12% the velocity currents of the bay, respectively. These findings convert Buenaventura Bay to a candidate for implementing third generation tidal stream turbines and motivate future research for implementing tidal power systems in crucial areas such as the Colombian Pacific, where communities face restrictions in accessing affordable and clean energy. [ABSTRACT FROM AUTHOR]

The evolution of tidal stream turbines is increasing the feasibility of future tidal plants in shallow depth areas with mid-tidal ranges (

The aim of this work is to analyse the marine currents distribution within Constanta port and its vicinity areas, in order to evaluate the impacts on port operations and coastal system as well. The currents propagation into the port basin and adjacent areas were the subject of ADCP measurements in relation with the incident waves and sea level variations. Certain experiments and special conditions were considered such as storm surges, storm induced currents, seiches propagation into the port basin, specific marine currents around the port jetties, and the influence of vertical water movements. [ABSTRACT FROM AUTHOR]

An east-west correlation profile through the upper Neogene succession north of Antwerp, based on cone penetration tests, reveals the architecture of the lower Pliocene Kattendijk Formation. It shows a basal incision of the Kattendijk Formation down to 20 m in Miocene sands and locally even Lower Oligocene clays. The incision is part of a much larger gully system in the region at the base of the Kattendijk Formation. The strongest gully incision is observed along the western profile, and coincides with increases in the thickness of the Kattendijk Formation from its typical four to six meters thickness in the east towards a maximum of 15 m in the west. Correlations show that this additional thickness represents a separate sequence of the Kattendijk Formation that first filled the deepest part of the gully prior to being transgressed and covered by the second sequence deposited in a larger gully system. Both sequences of the Kattendijk Formation have basal transgressive layers, and are lithologically identical. Initial, deep incision at the base of the Kattendijk Formation might have been the result of the constriction of early Pliocene tidal currents that invaded and expanded fluvial or estuarine gullies that had developed during the latest Miocene sea-level low. A similar mechanism had been proposed for the development of late Miocene gully system at the base of the Diest Formation further southeast in northern Belgium. As the wider area was transgressed and covered by the second sequence of the Kattendijk Formation, flow constriction ended, currents weakened and gully incisions were reduced in size. [ABSTRACT FROM AUTHOR]

Copyright of EMERG: Energy. Environment. Efficiency. Resources. Globalization is the property of Romanian National Committee of World Energy Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Information on the genetic population structure of economic species is important for understanding their evolutionary processes and for management programmes. In this study, the genetic structure of 12 P. trituberculatus populations along the China seas and Japan was analysed. A fragment of mitochondrial control region was sequenced as a genetic marker in swimming crabs sampled from the Bohai Sea, Yellow Sea, East China Sea, South China Sea and Japan, with dense sampling in the Bohai Sea. These populations showed an intermediate and significant genetic population structure, with an overall Φst value of 0.054 (P < 0.01). Based on a hierarchical AMOVA, they could be divided into two groups, the South China Sea population and all the other populations. The distribution of the haplotypes and the pairwise Φst values between populations indicated a high level of gene flow among most populations in the Bohai Sea, Yellow Sea, East China Sea and Japan. However, low but significant genetic differentiation (P < 0.05) was also detected among several populations in these areas. Many details of the genetic structure were revealed, especially for the populations in the semi-enclosed Bohai Sea, and the inconsistency with previous studies was discussed. The structure patterns indicate that sea-level changes during the glacial period of the Pleistocene and oceanographic factors are important in shaping the genetic population structure of swimming crabs. Finally, the implications for fishery are suggested. [ABSTRACT FROM AUTHOR]

Summary:   Motivated by segmentation issues in studies of sea current circulation, we describe a hidden Markov random field for the analysis of spatial cylindrical data, i.e. bivariate spatial series of angles and intensities. The model is based on a mixture of cylindrical densities, whose parameters vary across space according to a latent Markov field. It enables segmentation of the data within a finite number of latent classes that represent the conditional distributions of the data under specific environmental conditions, simultaneously accounting for unobserved heterogeneity and spatial auto‐correlation. Further, it parsimoniously accommodates specific features of environmental cylindrical data, such as circular–linear correlation, multimodality and skewness. Because of the numerical intractability of the likelihood function, estimation of the parameters is based on composite likelihood methods and essentially reduces to a computationally efficient expectation–maximization algorithm that iteratively alternates the maximization of a weighted composite likelihood function with weights updating. These methods are tested on simulations and exploited to segment the sea surface of the Gulf of Naples by means of meaningful circulation regimes. [ABSTRACT FROM AUTHOR]

Copyright of Geominas is the property of FUNDA-GEOMINAS. (Fundacion de Egresados d Amigos de la Escuela de Ingenieria Geologica y de Minas) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The work involves assessing of the marine current regime in the north west of the Black Sea, Midia Cape-Constanta area. The area of interest is chosen due its existing features, using marine currents data (direction and speed) within the CFD to determine the distribution of velocities and pressures. The study on the distribution of velocities and pressures, according to local hydro-meteorological characteristic elements, can be used for identifying the risk areas for navigation and existing hydro-technical construction industry. Modelling results using the CFD analysis shows the currents velocity values, pressures and turbulences of the investigated marine region. The model can be used in the analysis and the coastline changes as well as in risk assessment for hydraulic structures. Additional parameters into the model, such as the sea wave characteristics, aim to provide an indication of the potential hydro-dynamic power that is available at a determined location of interest. [ABSTRACT FROM AUTHOR]

Renewable energies play a fundamental role within the current political and social framework for minimizing the impacts of climate change. The ocean has a vast potential for generating energy and therefore, the marine renewable energies are included in the Sustainable Development Goals (SDGs). These energies include wave, tidal, marine currents, ocean thermal, and osmotic. Moreover, it can also be included wind, solar, geothermal and biomass powers, which their main use is onshore, but in the near future their use at sea may be considered. The manuscript starts with a state-of-the-art review of the abovementioned marine renewable energy resources worldwide. The paper continues with a case study focused on the Spanish coast, divided into six regions: (I) Cantabrian, (II) Galician, (III) South Atlantic, (IV) Canary Islands, (V) Southern Mediterranean, and (VI) Northern Mediterranean. The results show that: (1) areas I and II are suitable for offshore wind, wave and biomass; (2) areas III and V are suitable for offshore wind, marine current and offshore solar; area IV is suitable for offshore wind, ocean wave and offshore solar; (3) and area VI is suitable for offshore wind, osmotic and offshore solar. This analysis can help politicians and technicians to plan the use of these resources in Spain.

This study is investigating about marine currents provided electrical energy through the numerical model. The objective of this study is to know the power available distributions in the Manado Bay, North Sulawesi, Indonesia. The Manado Bay was width 2200 m with 79 m of depth. In computation, we are made grids in x and y horizontal were 7 m respectively, also for z vertical of four layers. The results shown that the power available distributions in the Manado Bay at 0.1 Sv were 0.00-20.00 kW/m² when low tide currents and when high tide currents were 0.00-105 kW/m². The values will enable for marine currents power plant in the Manado Bay to future. [ABSTRACT FROM AUTHOR]

The exploitation of technologies with which to harness the energy from ocean currents will have considerable possibilities in the future thanks to their enormous potential for electricity production and their high predictability. In this respect, the development of methodologies for the economic viability of these technologies is fundamental to the attainment of a consistent quantification of their costs and the discovery of their economic viability, while simultaneously attracting investment in these technologies. This paper presents a methodology with which to determine the economic viability of tidal energy projects, which includes a technical study of the life-cycle costs into which the development of a tidal farm can be decomposed: concept and definition, design and development, manufacturing, installation, operation and maintenance and dismantling. These cost structures are additionally subdivided by considering their sub-costs and bearing in mind the main components of the tidal farm: the nacelle, the supporting tidal energy converter structure and the export power system. Furthermore, a technical study is developed in order to obtain an estimation of the annual energy produced (and, consequently, the incomes generated if the electric tariff is known) by considering its principal attributes: the characteristics of the current, the ability of the device to capture energy and its ability to convert and export the energy. The methodology has been applied (together with a sensibility analysis) to the particular case of a farm composed of first generation tidal energy converters in one of the Channel Island Races, the Alderney Race, in the U.K., and the results have been attained by means of the computation of engineering indexes, such as the net present value, the internal rate of return, the discounted payback period and the levelized cost of energy, which indicate that the proposed project is economically viable for all the case studies. [ABSTRACT FROM AUTHOR]

The potential of generating electricity from marine tidal currents is enormous. Tidal energy is a renewable source that has an additional value in a future energy market with regard to other renewable energy sources thanks to its high predictability. Moreover, tidal energy technologies are characterized by CO 2 emission-free power, thus enabling energy security and contributing to economic growth and job creation in coastal and remote areas. Substantial progress is currently being made by the European Union as regards the reduction of greenhouse gas emissions, renewable energy and energy efficiency, in order to fulfil the target of an installed capacity of 3.6 GW of ocean energy by 2020, and to achieve a future installed capacity of 188 GW of ocean energy in 2050. This paper presents a comprehensive review of the current status of tidal energy conversion technologies and describes the costs incurred in the development of tidal energy projects so as to study their economic viability. The study also identifies the principal current risks and the role of each of the stakeholders involved in the successful development of tidal energy projects. Finally, future challenges in tidal technologies that will influence the increase in their current potential are briefly presented along with the current developments of our research group in the field of tidal energy converters design. [ABSTRACT FROM AUTHOR]

In a recent contribution to this journal, Wilmé et al. (2016) proposed that the giant tortoises of the islands of the Western Indian Ocean ( WIO: Aldabra, the Mascarenes, and the Granitic Seychelles) might have originated from translocation by early Austronesian sailors. Prompted by this paper we review recent literature and show that natural overseas dispersal was remarkably widespread in the colonization history of terrestrial reptiles in the WIO region. Almost 90% of the successful colonization events are supported by prevailing marine surface currents. However, these currents may change over geological (and evolutionary) time-scales, and eddies and counter-currents may facilitate transport against the main current direction. We review the cases of the extant and extinct WIO giant tortoises and suggest that the current distribution of all lineages can be convincingly explained by overseas dispersal. [ABSTRACT FROM AUTHOR]

Tidal flows around the Channel Islands contain a significant energy resource that if harnessed could provide electrical power to the Channel Islands, the UK and France. We have developed a new 2D hydrodynamic model of the English Channel which gives an improvement to the temporal and spatial resolution of the ambient flow in comparison with previous regional scale resource assessments. The ambient flow was characterised to identify suitable sites, resulting in a reduction in total development area of up to 80% compared with previous studies. Estimates for upper bound energy extraction confirm that Alderney Race contains the majority of the Channel Islands resource, giving a maximum potential of 5.1 GW, which exceeds a previous estimate for the Pentland Firth by 35%. This is followed by Casquets (0.47 GW) and then Big Roussel (0.24 GW). Our work shows that energy extraction at Alderney Race has a constructive impact on the resource at Casquets, and that the sensitivity to added drag at each site with respect to energy extraction is highly dependent on bathymetry and the proximity of coastlines. These results have implications for the overall resource development within the Channel Islands, where regulation is needed to account for site-site interaction. [ABSTRACT FROM AUTHOR]

Paleobotanical evidence for the climate-forming significance of marine currents in the Early Paleogene of the Arctic is reported. It is based on the analysis of mega- and microfossil plant assemblages derived from the outcrops located along the Arctic coastline of Eurasia and on the islands within the Arctic shelf. The occurrence of warm marine water masses is inferred from findings of Lower Paleogene microplankton and megafossils and palynomorphs of higher plants including Lauraceae, Magnoliaceae, Araliaceae, Loranthaceae, Palmaceae, and members of other thermophilic groups along the Arctic coast. The Early Paleogene climate in this realm was milder and was influenced by currents washing the continent and by marine heat transfer via the Trans-Siberian strait together with the atmospheric heat transfer. [ABSTRACT FROM AUTHOR]

The Beagle Channel (BC) is a subantarctic passage connecting the Pacific and Atlantic oceans at latitude ∼55°S. Along its tortuous path, the channel defines particular environments of prominent ecological value that are under study from a variety of scientific fields, while the main physical features that form the basis for these ecosystems are still critically understudied. In this work, historical data series of currents measured with surface drifters and moored current meters as well as sea-level data measured by gauge stations and pressure transducers, are analyzed. These are used to describe the propagation of the tidal wave and the general water motion along the BC. Astronomical amplitudes and phases of the main tidal components, computed from historical and recent sea-level data series obtained at the BC and gathered from global numerical models, are integrally analyzed to describe the propagation of a single, progressive tidal wave in the channel and in the surrounding ocean area, in contrast with previous assumptions that considered two tidal waves advancing in opposite directions. The relative narrowness of the channel, which is roughly oriented in a west-east direction, favors currents with a dominant zonal component. Such fact is exacerbated at and near topographic constrictions such as Mackinlay Strait, where a substantial acceleration of the flow is also observed. Superimposed on the mixed semidiurnal tidal regime, there is a remarkably persistent residual surface flow in an eastwards direction along the BC, likely contributing to the regional transport of water and properties from the Pacific Ocean to the Atlantic Patagonian Shelf. The existence of a semi-permanent sea-level tilt between the Pacific and Atlantic sides of the BC, is proposed as the main driver for that along-channel current. However, inversions of the residual current (i.e., westwards flow) do occur below the depths of major topographic constrictions, likely promoting recirculation and high residence times in the middle BC west of Mackinlay Strait. • A single progressive tidal wave moves along BC from west to East. • Mixed semidiurnal tides are a prominent contributor to observed currents. • Surface residual flow is eastwards, forced by sea-level tilt between the Pacific and Atlantic oceans. • Flow accelerates at and east of Mackinlay Strait due to a decrease in water depth. • Current reversals of the residual flow take place at deeper areas below sills. [ABSTRACT FROM AUTHOR]

A new hidden Markov random field model is proposed for the analysis of cylindrical spatial series, i.e. bivariate spatial series of intensities and angles. It allows us to segment cylindrical spatial series according to a finite number of latent classes that represent the conditional distributions of the data under specific environmental conditions. The model parsimoniously accommodates circular–linear correlation, multimodality, skewness and spatial autocorrelation. A numerically tractable expectation–maximization algorithm is provided to compute parameter estimates by exploiting a mean-field approximation of the complete-data log-likelihood function. These methods are illustrated on a case study of marine currents in the Adriatic sea. [ABSTRACT FROM AUTHOR]

One of the current biggest hurdles to harnessing renewable energy resources is their intermittent nature. Hybrid energy conversion minimizes intermittency by diversifying energy production. This work presents a conceptual design of a hybrid energy conversion system for ocean currents and waves on a shared platform: TIWAG (Tidal-Waves Generator). The power converter consists of two turbines and a float, each connected to a Doubly-Fed Induction Generator. We use a detailed bond graph methodology to develop the mechanical and electrical systems' dynamical modeling and apply a rotation control strategy for the hydrokinetic turbines and float. The system's operational feasibility is analyzed numerically for different tidal current speeds and wave heights – in loco data collected in São Marcos Bay, on the coast of the state of Maranhão, Brazil. Due to the addition of the float device to the structure with two turbines, the system goes from producing 209.2 kW to 300.7 kW without an increase in the occupied area, converting 32.6% of the available energy in the ocean currents and waves into electrical power. The different energy sources in the system complement one another to reduce intermittency, increasing the stability in energy production by 20%–30%. • Concept design of a new hybrid tidal-waves energy conversion system. • Dynamic modeling and robust system control based on in-loco data. • Increase of 20%–30% in energy production stability due to hybridization. [ABSTRACT FROM AUTHOR]

In this study, we report for the first time the presence of magnetotactic bacteria (MTB) on the Northeastern Atlantic coast. Microscopy observations indicated a heterogeneous population of MTB morphotypes. The analysis of the 16S rDNA by pyrosequencing technology revealed four operational taxonomic sequence units affiliated within the Magnetococcales order, class Alphaproteobacteria. One of them was closely related to sequences of MTB from the Tunisian coast, central Mediterranean Sea. This work offers information on anew environmental context and on biogeography of MTB, highlights the putative impact that marine currents may have on MTB distribution on Earth, and underlines the role that pristine or polluted areas may play on the structure of the MTB communites. [ABSTRACT FROM AUTHOR]

Understanding the factors that contribute to population genetic divergence across a species' range is a long-standing goal in evolutionary biology and ecological genetics. We examined the relative importance of historical and ecological features in shaping the present-day spatial patterns of genetic structure in two related plant species, Beta vulgaris subsp. maritima and Beta macrocarpa. Using nuclear and mitochondrial markers, we surveyed 93 populations from Brittany ( France) to Morocco - the southern limit of their species' range distribution. Whereas B. macrocarpa showed a genotypic structure and a high level of genetic differentiation indicative of selfing, the population genetic structure of B. vulgaris subsp. maritima was consistent with an outcrossing mating system. We further showed (1) a strong geographic clustering in coastal B. vulgaris subsp. maritima populations that highlighted the influence of marine currents in shaping different lineages and (2) a peculiar genetic structure of inland B. vulgaris subsp. maritima populations that could indicate the admixture of distinct evolutionary lineages and recent expansions associated with anthropogenic disturbances. Spatial patterns of nuclear diversity and differentiation also supported a stepwise recolonization of Europe from Atlantic-Mediterranean refugia after the last glacial period, with leading-edge expansions. However, cytoplasmic diversity was not impacted by postglacial recolonization: stochastic long-distance seed dispersal mediated by major oceanic currents may mitigate the common patterns of reduced cytoplasmic diversity observed for edge populations. Overall, the patterns we documented here challenge the general view of reduced genetic diversity at the edge of a species' range distribution and provide clues for understanding how life-history and major geographic features interact to shape the distribution of genetic diversity. [ABSTRACT FROM AUTHOR]

Abstract: Ocean energy has many forms, encompassing tides, surface waves, ocean circulation, salinity and thermal gradients. This paper will considers two of these, namely those found in the kinetic energy resource in tidal streams or marine currents, driven by gravitational effects, and the resources in wind-driven waves, derived ultimately from solar energy. There is growing interest around the world in the utilisation of wave energy and marine currents (tidal stream) for the generation of electrical power. Marine currents are predictable and could be utilised without the need for barrages and the impounding of water, whilst wave energy is inherently less predictable, being a consequence of wind energy. The conversion of these resources into sustainable electrical power offers immense opportunities to nations endowed with such resources and this work is partially aimed at addressing such prospects. The research presented conveys the current status of wave and marine current energy conversion technologies addressing issues related to their infancy (only a handful being at the commercial prototype stage) as compared to others such offshore wind. The work establishes a step-by-step approach that could be used in technology and project development, depicting results based on experimental and field observations on device fundamentals, modelling approaches, project development issues. It includes analysis of the various pathways and approaches needed for technology and device or converter deployment issues. As most technology developments are currently UK based, the paper also discusses the UK''s financial mechanisms available to support this area of renewable energy, highlighting the needed economic approaches in technology development phases. Examination of future prospects for wave and marine current ocean energy technologies are also discussed. [Copyright &y& Elsevier]