Open AccessArticle
Sediment Transport into the Swinomish Navigation Channel, Puget Sound—Habitat Restoration versus Navigation Maintenance Needs
J. Mar. Sci. Eng. 2017, 5(2), 19; doi:10.3390/jmse5020019 -
Abstract
The 11 mile (1.6 km) Swinomish Federal Navigation Channel provides a safe and short passage to fishing and recreational craft in and out of Northern Puget Sound by connecting Skagit and Padilla Bays, US State abbrev., USA. A network of dikes and jetties
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The 11 mile (1.6 km) Swinomish Federal Navigation Channel provides a safe and short passage to fishing and recreational craft in and out of Northern Puget Sound by connecting Skagit and Padilla Bays, US State abbrev., USA. A network of dikes and jetties were constructed through the Swinomish corridor between 1893 and 1936 to improve navigation functionality. Over the years, these river training dikes and jetties designed to minimize sedimentation in the channel have deteriorated, resulting in reduced protection of the channel. The need to repair or modify dikes/jetties for channel maintenance, however, may conflict with salmon habitat restoration goals aimed at improving access, connectivity and brackish water habitat. Several restoration projects have been proposed in the Skagit delta involving breaching, lowering, or removal of dikes. To assess relative merits of the available alternatives, a hydrodynamic model of the Skagit River estuary was developed using the Finite Volume Community Ocean Model (FVCOM). In this paper, we present the refinement and calibration of the model using oceanographic data collected from the years 2006 and 2009 with a focus on the sediment and brackish water transport from the river and Skagit Bay tide flats to the Swinomish Channel. The model was applied to assess the feasibility of achieving the desired dual outcome of (a) reducing sedimentation and shoaling in the Swinomish Channel and (b) providing a direct migration pathway and improved conveyance of freshwater into the Swinomish Channel. The potential reduction in shoaling through site-specific structure repairs is evaluated. Similarly, the potential to significantly improve of brackish water habitat through dike breach restoration actions using the McGlinn Causeway project example, along with its impacts on sediment deposition in the Swinomish Navigation Channel, is examined. Full article
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Open AccessArticle
Coastal Ecosystem Effects of Increased Summer Temperature and Contamination by the Flame Retardant HBCDD
J. Mar. Sci. Eng. 2017, 5(2), 18; doi:10.3390/jmse5020018 -
Abstract
The combined effects of ocean warming and contaminants on marine ecosystems are poorly understood. In this study, we exposed model ecosystems comprising typical shallow coastal Baltic Sea communities to elevated temperature (+5 °C) and the flame retardant hexabromocyclododecane (HBCDD), both singly and in
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The combined effects of ocean warming and contaminants on marine ecosystems are poorly understood. In this study, we exposed model ecosystems comprising typical shallow coastal Baltic Sea communities to elevated temperature (+5 °C) and the flame retardant hexabromocyclododecane (HBCDD), both singly and in combination, for 13 days. Higher temperatures caused the release of PO4 from the sediment, which in turn stimulated the growth of the cyanobacteria Dolichospermum sp. This in turn led to an increase in the copepod Acartia bifilosa and other indirect effects in the plankton, interpreted as being caused by changes in predation, grazing, and competition. Elevated temperatures also stimulated benthic primary production and increased production of benthic mollusk larvae. Although increased temperature was the dominant driver of effects in these systems, HBCDD also appeared to have some effects, mainly in the zooplankton (both direct and indirect effects) and benthic meiofauna (an interactive effect with temperature). Although the study used model ecosystems, which are an approximation of field conditions, it highlights that interactive ecosystem effects between two stressors are possible and demonstrates the ecological and temporal complexity of such responses. Such unpredictable responses to warming and contaminants are a major challenge for ecosystem management to deal with multistressor situations in the Baltic Sea. Full article
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Open AccessErratum
Erratum: Garzon, J.L.; Ferreira, C.M. Storm Surge Modeling in Large Estuaries: Sensitivity Analyses to Parameters and Physical Processes in the Chesapeake Bay. J. Mar. Sci. Eng. 2016, 4, 45
J. Mar. Sci. Eng. 2017, 5(2), 17; doi:10.3390/jmse5020017 -
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Open AccessBrief Report
Short-Term Nitrogen and Phosphorus Release during the Disturbance of Surface Sediments: A Case Study in an Urbanised Estuarine System (Gold Coast Broadwater, Australia)
J. Mar. Sci. Eng. 2017, 5(2), 16; doi:10.3390/jmse5020016 -
Abstract
Understanding the effects of sediment disturbances on nutrient loadings is important for the management of estuarine settings. This study investigated the initial influence of sediment disturbance on water column nutrient concentrations in a shallow estuarine setting within the Gold Coast Broadwater, using a
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Understanding the effects of sediment disturbances on nutrient loadings is important for the management of estuarine settings. This study investigated the initial influence of sediment disturbance on water column nutrient concentrations in a shallow estuarine setting within the Gold Coast Broadwater, using a laboratory-based approach. Undisturbed sediment cores (200 mm Ø × 330 mm length, plexiglass) were incubated before and after being subjected to a disturbance event, to investigate the effect on the immediate and subsequent short-term water column nutrient concentrations. Sediment NH4+bio and PO43−bio concentrations ranged from 150 to 478 and 1.50 to 8.56 nmol g−1 dry wt, respectively. Water column NH4+ concentrations underwent the greatest increase (>1000% or approx. 14 times greater) immediately following disturbance, with mean effluxes increasing by >300%. Thereafter, water column NH4+ concentrations and efflux rates declined to near initial pre-disturbance concentrations. Water column NH4+ concentrations accounted for 0.58%–5.50% of the depth-integrated sediment NH4+bio concentration, indicating mobilization of the sediment bound exchangeable NH4+. The observed changes in PO43− concentrations and fluxes were much lower in comparison to those observed for N-species. Following disturbance, increases in the water column PO43− concentration accounted for 7.16%–8.22% depth-integrated sediment bioavailable PO43− at +1 and +2 hours, and 5.65% at +7 hours, respectively. These results provide important insight into the potential implications of disturbance events, such as vessel activities and dredging operations, within the case study region, providing information for potential management options and relevant water quality concerns. Full article
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Open AccessArticle
Offshore Deployments of Wave Energy Converters by Seabased Industry AB
J. Mar. Sci. Eng. 2017, 5(2), 15; doi:10.3390/jmse5020015 -
Abstract
Since 2008, Seabased Industry AB (SIAB) has manufactured and deployed several units of wave energy converters (WECs) of different design. The WECs are linear generators with point absorber buoy systems that are placed on the seabed, mounted on a gravitation concrete foundation. These
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Since 2008, Seabased Industry AB (SIAB) has manufactured and deployed several units of wave energy converters (WECs) of different design. The WECs are linear generators with point absorber buoy systems that are placed on the seabed, mounted on a gravitation concrete foundation. These deployments have taken place in different areas, using different deployment vessels. Offshore deployments of WECs and underwater substations have so far been complicated procedures, that were both expensive and time-consuming. The focus of this paper is to discuss these deployments in terms of economy and time efficiency, as well as safety. Because seven vessels have been used to facilitate the deployments, an evaluation on the above basis is carried out for them. The main conclusions and certain solutions are presented for the various problems encountered during these deployments and the vessel choice is discussed. It is found that the offshore deployment process can be optimized in terms of cost, time efficiency and safety with a careful vessel choice, use of the latest available technologies and detailed planning and organizing. Full article
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Open AccessArticle
Application of State of the Art Modeling Techniques to Predict Flooding and Waves for a Coastal Area within a Protected Bay
J. Mar. Sci. Eng. 2017, 5(1), 14; doi:10.3390/jmse5010014 -
Abstract
Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure from storm surge sand associated waves in the coastal zone. The maps are used by state agencies and
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Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure from storm surge sand associated waves in the coastal zone. The maps are used by state agencies and municipalities to help guide coastal planning and establish the minimum elevation and construction standards for new or substantially improved structures. A summary of the methods used and a comparison with the results of 2013 FIRM mapping are presented for Warwick, Rhode Island (RI), a coastal community located within Narragansett Bay. Because of its location, Warwick is protected from significant coastal erosion and wave attacks, but is subject to surge amplification. Concerns surrounding the FEMA methods used in the 2013 FIRM analysis are put in context with the National Research Council’s (NRC) 2009 review of the FEMA coastal mapping program. New mapping is then performed using state of the art, fully coupled surge and wave modeling, and data analysis methods, to address the NRC concerns. The new maps and methodologies are in compliance with FEMA regulations and guidelines. This new approach makes extensive use of the numerical modeling results from the recent US Army Corp of Engineers, North Atlantic Coast Comprehensive Study (NACCS, 2015). Revised flooding maps are presented and compared to the 2013 FIRM maps, to provide insight into the differences. The new maps highlight the importance of developing better estimates of surge dynamics and the advancement in nearshore mapping of waves in flood inundated areas by the use of state of the art, two-dimensional, wave transformation models. Full article
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Open AccessReview
Inspection-Class Remotely Operated Vehicles—A Review
J. Mar. Sci. Eng. 2017, 5(1), 13; doi:10.3390/jmse5010013 -
Abstract
This paper presents a review of inspection-class Remotely Operated Vehicles (ROVs). The review divides the classification of inspection-class ROVs; categorising the vehicles in order of size and capability. A state of the art technology review is undertaken, discussing various common subsystems of the
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This paper presents a review of inspection-class Remotely Operated Vehicles (ROVs). The review divides the classification of inspection-class ROVs; categorising the vehicles in order of size and capability. A state of the art technology review is undertaken, discussing various common subsystems of the ROV. Standard and novel ROV shapes and designs are reviewed, with emphasis on buoyancy, frame materials and hydrodynamics. Several power considerations and designs are discussed, accounting for battery fed and mains fed systems. ROV telemetry is split into a discussion on the various transmission hardware systems and the communication protocols that are most widely used in industry and research today. A range of thruster technologies is then introduced with consideration taken of the various thruster architectures available. Finally, the navigation and positioning sensors employed for ROV navigation and control are reviewed. The author has also created a number of comparison tables throughout the review; tables include comparison of wired data transmission technology, comparison of common ROV communication protocols and comparisons of various inertial navigation systems. By the end of the review the reader will have clearer understanding on the fundamentals of inspection-class ROV technologies and can use this as an introduction to further paper investigation. Full article
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Open AccessArticle
Wind-Wave Characterization in a Wind-Jet Region: The Ebro Delta Case
J. Mar. Sci. Eng. 2017, 5(1), 12; doi:10.3390/jmse5010012 -
Abstract
This manuscript describes the wind-wave generation, development and fading in a complex area: a wind-jet region. The study region is the offshore Ebro Delta (NW Mediterranean Sea) where strong cross-shelf winds occur due to a topographic channelization. This leads to relatively short-fetch conditions,
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This manuscript describes the wind-wave generation, development and fading in a complex area: a wind-jet region. The study region is the offshore Ebro Delta (NW Mediterranean Sea) where strong cross-shelf winds occur due to a topographic channelization. This leads to relatively short-fetch conditions, which interact with the swell component. The third-generation wave model Simulating WAves Nearshore (SWAN) is implemented and fed by high-resolution wind fields. A combination of buoy and High Frequency (HF) radar data is used for model validation, resulting in a reasonable level of agreement. The numerical results characterize the wind-wave evolution during a wind jet. A bimodal spectrum is observed due to the interaction of swell and sea systems. The wave directional spreading exhibits lower values at the wind-jet axis. Finally, a reliability analysis of the wave data from an HF radar deployed at the region is carried out. Full article
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Open AccessArticle
Scheduling of Maintenance Tasks and Routing of a Joint Vessel Fleet for Multiple Offshore Wind Farms
J. Mar. Sci. Eng. 2017, 5(1), 11; doi:10.3390/jmse5010011 -
Abstract
Maintenance costs related to offshore wind farms are severely limiting their potential for being profitable. This paper proposes a new mathematical model that considers how maintenance tasks should be scheduled and performed by technicians transported using a fleet of dedicated vessels. The model
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Maintenance costs related to offshore wind farms are severely limiting their potential for being profitable. This paper proposes a new mathematical model that considers how maintenance tasks should be scheduled and performed by technicians transported using a fleet of dedicated vessels. The model is novel in its combination of modelling several work shifts and including vessels that can stay offshore for several shifts, while handling large maintenance tasks and accurate calculation of downtime costs. Simulation is used to evaluate the performance of the model in its pure form, as well as when solved heuristically using a rolling horizon heuristic. The results indicate that the end-of-horizon effects of the mathematical formulation are handled effectively. Computational experiments also illustrate how the mathematical model coupled with simulation can be used to evaluate strategic decisions regarding the composition of a vessel fleet used to execute maintenance tasks. Full article
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Open AccessArticle
Application of State of Art Modeling Techniques to Predict Flooding and Waves for an Exposed Coastal Area
J. Mar. Sci. Eng. 2017, 5(1), 10; doi:10.3390/jmse5010010 -
Abstract
Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure in the coastal zone from storm surge and coincidental waves. The maps are used by state agencies and
[...] Read more.
Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure in the coastal zone from storm surge and coincidental waves. The maps are used by state agencies and municipalities to help guide coastal planning and establish the minimum elevation standard for new or substantially improved structures. A summary of the methods used and results of 2012 FIRM mapping are presented for Charlestown, RI; a coastal community located along the exposed, southern shoreline of the state. Concerns with the methods used in the 2012 analysis are put in context with the National Research Council’s (NRC) 2009 review of the FEMA coastal mapping program. New mapping is then performed using state of the art, fully coupled surge and wave modeling and data analysis methods to address the concerns in the NRC review. The new maps and methodologies are in compliance with FEMA regulations and guidelines. The approach makes extensive use of the numerical modeling results from the recent US Army Corp of Engineers (USACE), North Atlantic Coast Comprehensive Study (NACCS 2015). Revised flood maps are presented and compared with the 2012 FIRM map to provide insight into the differences. The new maps highlight the importance of developing better estimates of offshore surge dynamics and its coupling to waves, dune erosion based on local observations, and the advancement in nearshore mapping of waves in flood inundated areas by the use of state of the art, two-dimensional wave transformation models. Full article
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Open AccessFeature PaperArticle
Energy Balance of Biogas Production from Microalgae: Effect of Harvesting Method, Multiple Raceways, Scale of Plant and Combined Heat and Power Generation
J. Mar. Sci. Eng. 2017, 5(1), 9; doi:10.3390/jmse5010009 -
Abstract
A previously-developed mechanistic energy balance model for production of biogas from the anaerobic digestion of microalgal biomass grown in open raceway systems was used to consider the energetic viability of a number of scenarios, and to explore some of the most critical parameters
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A previously-developed mechanistic energy balance model for production of biogas from the anaerobic digestion of microalgal biomass grown in open raceway systems was used to consider the energetic viability of a number of scenarios, and to explore some of the most critical parameters affecting net energy production. The output demonstrated that no single harvesting method of those considered (centrifugation, settlement or flocculation) produced an energy output sufficiently greater than operational energy inputs to make microalgal biogas production energetically viable. Combinations of harvesting methods could produce energy outputs 2.3–3.4 times greater than the operational energy inputs. Electrical energy to power pumps, mixers and harvesting systems was 5–8 times greater than the heating energy requirement. If the energy to power the plant is generated locally in a combined heat and power unit, a considerable amount of “low grade” heat will be available that is not required by the process, and for the system to show a net operational energy return this must be exploited. It is concluded that the production of microalgal biogas may be energetically viable, but it is dependent on the effective use of the heat generated by the combustion of biogas in combined heat and power units to show an operational energy return. Full article
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Open AccessArticle
Characterization of the New Status of Nador Lagoon (Morocco) after the Implementation of the Management Plan
J. Mar. Sci. Eng. 2017, 5(1), 7; doi:10.3390/jmse5010007 -
Abstract
The present study was carried out in 2011 with the aims of (1) evaluating the changes in sedimentary distribution that occurred in Nador lagoon seabed (Morocco) after the implementation of the lagoon management plan in 2009; and (2) characterizing its new sedimentary status
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The present study was carried out in 2011 with the aims of (1) evaluating the changes in sedimentary distribution that occurred in Nador lagoon seabed (Morocco) after the implementation of the lagoon management plan in 2009; and (2) characterizing its new sedimentary status in 2011. Due to the lack of a baseline, we used the 1992 sedimentary status for comparison. The seabed surface sediment distribution showed a great change between 1992 and 2011. We found the same four sediment facies, which were present in 1992, namely: mud, sandy mud, muddy sand, and fine sand. However, in 2011, mud covered more than 54% of the lagoon seabed surface, mostly located in the middle part of the seabed, whereas in 1992, more than 80% of the lagoon seabed was covered by sandy mud. The sediments’ characteristics showed moderately to poorly sorted facies (S0), ranging between platykurtic and leptokurtic (SK) and with various symmetry indices (SG). The organic matter content in sediment has strongly decreased, from values higher than 20% in most areas in 1992 to a mean value of 3.9% in 2011, ranging from 0.2% to 10.4%, thus confirming that the management actions implemented in 2009 were likely effective in reducing the organic pollution. Full article
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Open AccessArticle
Towards the Development of an Operational Forecast System for the Florida Coast
J. Mar. Sci. Eng. 2017, 5(1), 8; doi:10.3390/jmse5010008 -
Abstract
A nowcasting and forecasting system for storm surge, inundation, waves, and baroclinic flow for the Florida coast has been developed. The system is based on dynamically coupled CH3D and SWAN models and can use a variety of modules to provide different input forcing,
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A nowcasting and forecasting system for storm surge, inundation, waves, and baroclinic flow for the Florida coast has been developed. The system is based on dynamically coupled CH3D and SWAN models and can use a variety of modules to provide different input forcing, boundary and initial conditions. The system is completely automated and operates unattended at pre-scheduled intervals as well as in event-triggered mode in response to Atlantic-basin tropical cyclone advisories issued by the National Hurricane Center. The system provides up to 72-h forecasts forward depending on the input dataset duration. Spatially, the system spans the entire Florida coastline by employing four high-resolution domains with resolutions as fine as 10–30 m in the near-shore and overland to allow the system to resolve fine estuarine details such as in the Intracoastal Waterway and minor tributaries. The system has been validated in both hindcast and nowcast/forecast modes using water level and salinity data from a variety of sources and has been found to run robustly during the test periods. Low level products (e.g., raw output datasets) are disseminated using THREDDS while a custom defined web-based graphical user interface (GUI) was developed for high level access. Full article
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Open AccessArticle
Thermal Recirculation Modeling for Power Plants in an Estuarine Environment
J. Mar. Sci. Eng. 2017, 5(1), 5; doi:10.3390/jmse5010005 -
Abstract
Many power plants require large quantities of water for cooling purposes. The water taken from the source water body (e.g., lakes, estuaries, bays and rivers) circulates through the plant and returns to the source through outfall with a higher temperature. For optimal performance
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Many power plants require large quantities of water for cooling purposes. The water taken from the source water body (e.g., lakes, estuaries, bays and rivers) circulates through the plant and returns to the source through outfall with a higher temperature. For optimal performance of the power plant, the intake inlet and discharge outlet should be meticulously placed so that the heated water will not recirculate back into the power plant. In this study, the Flow module of the Delft3D software is employed to simulate the temperature transport within the study area in three-dimensional and nested format. Model results are used to optimize the location of intake inlets, outfall outlets and diffuser port orientations. The physical processes used in the study are tidal fluctuations, winds, river discharges, salinity and temperature. The subject power plant (power plant parameters presented in this paper are realistic; however, they do not target any specific power plant within the study area) has a nominal capacity of 2600 MW and is planned to be located in Delaware Bay, USA. Existing field measurements are used to calibrate the model in a coupled two-staged fashion for main tidal constituents, currents and water temperature. The sensitivity of the model against various input parameters is tested, and conservative values are selected. The location of the intake is fixed, and the location of the outfall is changed until the thermal impact to the intake is less than 1 °C. Analysis of the results shows that there is a linear logarithmic relation between the excess temperatures at the intake inlet and horizontal eddy diffusivity. The k-ϵ turbulence closure results in higher excess temperature and a more conservative design. Extending the outfall location to the deeper portion of the estuary combined with port orientations reduces the impact by keeping the thermal plume away from the intake inlet and meeting the established criteria. It is concluded that an approximate distance of 1300 m is the optimal location for the power plant outfall outlets. In addition, the diffuser ports should not discharge the heated water toward the intake and have to be oriented away from the line connecting outfall to the intake. Full article
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Open AccessEditorial
Acknowledgement to Reviewers of JMSE in 2016
J. Mar. Sci. Eng. 2017, 5(1), 6; doi:10.3390/jmse5010006 -
Abstract
The editors of JMSE would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016. We greatly appreciate the contribution of expert reviewers, which is crucial to the journal’s editorial process. We aim to recognize reviewer contributions through
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The editors of JMSE would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016. We greatly appreciate the contribution of expert reviewers, which is crucial to the journal’s editorial process. We aim to recognize reviewer contributions through several mechanisms, of which the annual publication of reviewer names is one. Reviewers receive a voucher entitling them to a discount on their next MDPI publication and can download a certificate of recognition directly from our submission system. Additionally, reviewers can sign up to the service Publons (https://publons.com) to receive recognition. Of course, in these initiatives we are careful not to compromise reviewer confidentiality. Many reviewers see their work as a voluntary and often unseen part of their role as researchers. We are grateful to the time reviewers donate to our journals and the contribution they make. Full article
Open AccessArticle
Information Theoretic Source Seeking Strategies for Multiagent Plume Tracking in Turbulent Fields
J. Mar. Sci. Eng. 2017, 5(1), 3; doi:10.3390/jmse5010003 -
Abstract
We present information theoretic search strategies for single and multi-robot teams to localize the source of biochemical contaminants in turbulent flows. The robots synthesize the information provided by sporadic and intermittent sensor readings to optimize their exploration strategy. By leveraging the spatio-temporal sensing
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We present information theoretic search strategies for single and multi-robot teams to localize the source of biochemical contaminants in turbulent flows. The robots synthesize the information provided by sporadic and intermittent sensor readings to optimize their exploration strategy. By leveraging the spatio-temporal sensing capabilities of a mobile sensing network, our strategies result in control actions that maximize the information gained by the team while minimizing the time spent localizing the biochemical source. By leveraging the team’s ability to obtain simultaneous measurements at different locations, we show how a multi-robot team is able to speed up the search process resulting in a collaborative information theoretic search strategy. We validate our proposed strategies in both simulations and experiments. Full article
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Open AccessArticle
Evaluating the Reliability of Counting Bacteria Using Epifluorescence Microscopy
J. Mar. Sci. Eng. 2017, 5(1), 4; doi:10.3390/jmse5010004 -
Abstract
The common practice of counting bacteria using epifluorescence microscopy involves selecting 5–30 random fields of view on a glass slide to calculate the arithmetic mean which is then used to estimate the total bacterial abundance. However, not much is known about the accuracy
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The common practice of counting bacteria using epifluorescence microscopy involves selecting 5–30 random fields of view on a glass slide to calculate the arithmetic mean which is then used to estimate the total bacterial abundance. However, not much is known about the accuracy of the arithmetic mean when it is calculated by selecting random fields of view and its effect on the overall abundance. The aim of this study is to evaluate the accuracy and reliability of the arithmetic mean by estimating total bacterial abundance and to calculate its variance using a bootstrapping technique. Three fixed suspensions obtained from a three-week-old marine biofilm were stained and dispersed on glass slides. Bacterial cells were counted from a total of 13,924 fields of view on each slide. Total bacterial count data obtained were used for calculating the arithmetic mean and associated variance and bias for sample field sizes of 5, 10, 15, 20, 25, 30, 35 and 40. The study revealed a non-uniform distribution of bacterial cells on the glass slide. A minimum of 20 random fields of view or a minimum of 350 bacterial cells need to be counted to obtain a reliable value of the arithmetic mean to estimate the total bacterial abundance for a marine biofilm sample dispersed on a glass slide. Full article
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Open AccessArticle
Multi-Layered Stratification in the Baltic Sea: Insight from a Modeling Study with Reference to Environmental Conditions
J. Mar. Sci. Eng. 2017, 5(1), 2; doi:10.3390/jmse5010002 -
Abstract
The hydrodynamic and transport characteristics of the Baltic Sea in the period 2000–2009 were studied using a fully calibrated and validated 3D hydrodynamic model with a horizontal resolution of 4.8 km. This study provided new insight into the type and dynamics of vertical
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The hydrodynamic and transport characteristics of the Baltic Sea in the period 2000–2009 were studied using a fully calibrated and validated 3D hydrodynamic model with a horizontal resolution of 4.8 km. This study provided new insight into the type and dynamics of vertical structure in the Baltic Sea, not considered in previous studies. Thermal and salinity stratification are both addressed, with a focus on the structural properties of the layers. The detection of cooler regions (dicothermal) within the layer structure is an important finding. The detailed investigation of thermal stratification for a 10-year period (i.e., 2000–2009) revealed some new features. A multilayered structure that contains several thermocline and dicothermal layers was identified from this study. Statistical analysis of the simulation results made it possible to derive the mean thermal stratification properties, expressed as mean temperatures and the normalized layer thicknesses. The three-layered model proposed by previous investigators appears to be valid only during the winter periods; for other periods, a multi-layered structure with more than five layers has been identified during this investigation. This study provides detailed insight into thermal and salinity stratification in the Baltic Sea during a recent decade that can be used as a basis for diverse environmental assessments. It extends previous studies on stratification in the Baltic Sea regarding both the extent and the nature of stratification. Full article
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Open AccessFeature PaperArticle
Role of Beach Morphology in Wave Overtopping Hazard Assessment
J. Mar. Sci. Eng. 2017, 5(1), 1; doi:10.3390/jmse5010001 -
Abstract
Understanding the role of beach morphology in controlling wave overtopping volume will further minimise uncertainties in flood risk assessments at coastal locations defended by engineered structures worldwide. XBeach is used to model wave overtopping volume for a 1:200 year joint probability distribution of
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Understanding the role of beach morphology in controlling wave overtopping volume will further minimise uncertainties in flood risk assessments at coastal locations defended by engineered structures worldwide. XBeach is used to model wave overtopping volume for a 1:200 year joint probability distribution of waves and water levels with measured, pre- and post-storm beach profiles. The simulation with measured bathymetry is repeated with and without morphological evolution enabled during the modelled storm event. This research assesses the role of morphology in controlling wave overtopping volumes for hazardous events that meet the typical design level of coastal defence structures. Results show that disabling storm-driven morphology under-represents modelled wave overtopping volumes by up to 39% under high Hs conditions and has a greater impact on the wave overtopping rate than the variability applied within the boundary conditions due to the range of wave-water level combinations that meet the 1:200 year joint probability criterion. Accounting for morphology in flood modelling is therefore critical for accurately predicting wave overtopping volumes and the resulting flood hazard and to assess economic losses. Full article
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Open AccessArticle
Variations in the Wave Climate and Sediment Transport Due to Climate Change along the Coast of Vietnam
J. Mar. Sci. Eng. 2016, 4(4), 86; doi:10.3390/jmse4040086 -
Abstract
This study quantifies the climate change (CC)-driven variations in wave characteristics and the resulting variations in potential longshore sediment transport rate along the ~2000 km mainland coast of Vietnam. Wind fields derived from global circulation models (GCM) for current and future (2041–2060 and
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This study quantifies the climate change (CC)-driven variations in wave characteristics and the resulting variations in potential longshore sediment transport rate along the ~2000 km mainland coast of Vietnam. Wind fields derived from global circulation models (GCM) for current and future (2041–2060 and 2081–2100) climate conditions are used to force a numerical wave model (MIKE21 SW) to derive the deep water wave climate. The offshore wave climate is translated to nearshore wave conditions using another numerical model (Simulating WAves Nearshore—SWAN) and finally, a sediment transport model (GENEralized model for Simulating Shoreline Change—GENESIS) is used to estimate potential sediment transport for current and future climate conditions. Results indicate that CC effects are substantially different in the northern, central and southern parts of the coast of Vietnam. The 2081–2100 mean significant wave height along the northern coast is estimated to be up to 8 cm lower (relative to 1981–2000), while projections for central and southern coasts of Vietnam indicate slightly higher (increases of up to 5 cm and 7 cm respectively). Wave direction along the northern coast of Vietnam is projected to shift by up to 4° towards the south (clockwise) by 2081–2100 (relative to 1981–2000), up to 6° clockwise along the central coast and by up to 8° anti-clockwise (to the north) along the southern coast. The projected potential longshore sediment transport rates show very substantial and spatially variable future changes in net transport rates along the coast of Vietnam, with increases of up to 0.5 million m3/year at some locations (by 2081–2100 relative to 1981–2000), implying major changes in future coastline position and/or orientation. The vicinity of the highly developed city of Da Nang is likely to be particularly subject to coastline changes, with potentially an additional 875,000 m3 of sand being transported away from the area per year by the turn of the 21st century. Full article
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