Marine Infrastructure Research Articles

Commercial fishing, Inuit rights, and internal colonialism in Nunavut

AbstractThis paper considers the degree to which the concept of ‘internal colonialism’ accurately describes the political economy of Nunavut’s commercial fisheries. Offshore fisheries adjacent to Nunavut were initially dominated by institutions based in southern Canada, and most economic benefits were captured by southern jurisdictions. Decades of political struggle have resulted in Nunavut establishing a role for itself in both the management of offshore resources and the operation of the offshore fishing industry. However, key decisions about fishery management are made by the federal government, and many benefits from Nunavut’s offshore fisheries continue to accrue to southern jurisdictions. The concept of internal colonialism is therefore a useful concept for understanding the historical development and contemporary conflicts over offshore fisheries. By contrast, Nunavut’s inshore fisheries were established as community development initiatives intended to promote economic well-being and stability. While inshore fisheries primarily benefit Inuit community economies, the growth of inshore fisheries has been hampered by small profit margins, inadequate marine infrastructure, and a dearth of baseline data. The federal government’s failure to support the expansion of inshore fisheries is a manifestation of internal colonialism, insofar as it reflects an unequal distribution of public infrastructure and research.

Impacts of UV-C Irradiation on Marine Biofilm Community Succession.

Marine biofilms are diverse microbial communities and important ecological habitats forming on surfaces submerged in the ocean. Biofilm communities resist environmental disturbance, making them a nuisance to some human activities ("biofouling"). Antifouling solutions rarely address the underlying stability or compositional responses of these biofilms. Using bulk measurements and molecular analyses, we examined temporal and UV-C antifouling-based shifts in marine biofilms in the coastal western North Atlantic Ocean during early fall. Over a 24-day period, bacterial communities shifted from early dominance of Gammaproteobacteria to increased proportions of Alphaproteobacteria, Bacteroidia, and Acidimicrobiia. In a network analysis based on temporal covariance, Rhodobacteraceae (Alphaproteobacteria) nodes were abundant and densely connected with generally positive correlations. In the eukaryotic community, persistent algal, protistan, and invertebrate groups were observed, although consistent temporal succession was not detected. Biofilm UV-C treatment at 13 and 20 days resulted in losses of chlorophyll a and transparent exopolymer particles, indicating biomass disruption. Bacterial community shifts suggested that UV-C treatment decreased the biofilm maturation rate and was associated with proportional shifts among diverse bacterial taxa. UV-C treatment was also associated with increased proportions of protists potentially involved in detritivory and parasitism. Older biofilm communities had increased resistance to UV-C, suggesting that early biofilms are more susceptible to UV-C-based antifouling. The results suggest that UV-C irradiation is potentially an effective antifouling method in marine environments in terms of biomass removal and in slowing maturation. However, as they mature, biofilm communities may accumulate microbial members that are tolerant or resilient under UV treatment. IMPORTANCE Marine biofilms regulate processes ranging from organic matter and pollutant turnover to eukaryotic settlement and growth. Biofilm growth and eukaryotic settlement interfering with human activities via growth on ship hulls, aquaculture operations, or other marine infrastructure are called "biofouling." There is a need to develop sustainable antifouling techniques by minimizing impacts to surrounding biota. We use the biofouling-antifouling framework to test hypotheses about marine biofilm succession and stability in response to disturbance, using a novel UV-C light-emitting diode (LED) device. We demonstrate strong bacterial biofilm successional patterns and detect taxa potentially contributing to stability under UV-C stress. Despite UV-C-associated biomass losses and varying UV susceptibility of microbial taxa, the overall bacterial community composition remained relatively stable, suggesting decoupling of disruption in biomass and community composition following UV-C irradiation. We also report microbial covariance patterns over 24 days of biofilm growth, pointing to areas for study of microbial interactions and targeted antifouling.

Geographic Factors for Managing Cruise Ship Destination Port to Attraction Passenger Transfer in the Caribbean Region

Abstract. The Cruise Line industry (CLI) is working on plans to recover from the economic impacts of COVID-19. Along with the expected benefits of a post COVID19 surge in cruise tourism, destination ports have an opportunity to mitigate potential impacts that come with the tourist economy. In this study, we expand on our previous work on four CLI destination sites (two in the Caribbean and two meso-American) to a larger regional study area in the Caribbean Sea and investigate the sustainability of destination marine infrastructure and near port transportation resilience. Twenty- Eight destinations were analyzed in the study. All the CLI destinations ports in the study are considered mature for cruise tourism and have tourist attractions of interest (including historic, natural, shopping, and other areas with sociocultural authenticity), which can be reached during a one day ship visit. An analysis of the marine traffic and geographic settings provides a more complete picture on key parameters that can potentially impact the commerce and livelihoods of local communities near destination ports. The results of the study also provide potential solutions for mitigating these impacts. As a baseline for fully operational cruise industry in the Caribbean Sea, the 2019 cruise year was analyzed since it was the last full year without impact from COVID-19. This paper offers a wider empirical view of CLI impacts on the Caribbean region once the industry resumes to full capacity following the COVID-19 pandemic, and it presents results and recommendations to build a framework for continued study of CLI sustainability.

Fineness of Coal Fly Ash for Use in Cement and Concrete

Nowadays, coal is increasingly being used as an energy source in some countries. This coal-fired generation process, however, has the disadvantage that produces large quantities of coal fly ash. Its characteristics differ depending on the combustion conditions and the coal source. Fineness will influence early compressive strength in cement-based materials. The finer the binding material, the higher the early compressive strength. They can be used to produce high-volume fly ash (HVFA) concrete, self-compacting concrete (SCC), concrete for marine infrastructures, pervious concrete, roller compacted concrete (RCC) and so on.More than seven hundred samples of coal fly ash were collected from a coal-fired power plant for a period of ten years, and their fineness were characterized by sieving. The average fineness on 45 µm, 63 µm, 90 µm and 200 µm mesh sieves were 22.5%, 15.5%, 9.1% and 2.0%, respectively. Then, most of the coal fly ash particles were lower than 45 µm, i.e., from 15 to 30% were retained on the 45 µm sieve, and from 10 to 20% by mass of coal fly ash particles were retained on a 63 µm sieve. Fineness on a 45 µm sieve is a good indirect indicator of the residues on the 63 µm, 90 µm and 200 µm mesh sieves. Accordingly, it is suggested to broaden the range from ±5% to as high as ±7% regarding the fineness variation requirement. Finally, the tested coal fly ash can be applied as cement constituent.

How and to What Degree Does Physical Structure Differ Between Natural and Artificial Habitats? A Multi-Scale Assessment in Marine Intertidal Systems

Marine infrastructures are increasing, generating a variety of impacts and introducing artificial habitats which have low ecological value and support assemblages that differ significantly from those on natural rocky coasts. While in the past there was little ecological consideration as to how artificial structures were built, now the trend is to look for “greener” designs inspired by or mimicking nature. These greening efforts have had a strong focus on enhancing physical habitat structure to support more diverse assemblages, driven by the untested assumption that artificial habitats lack the physical structure proper to natural habitats. We tested this assumption by comparing five descriptors of physical structure (inclination; exposure; roughness; abundance, and diversity of surface morphological microelements) across a combination of natural and artificial habitats of regular and irregular morphologies (seawalls = artificial regular; cliffs = natural regular; breakwaters = artificial, irregular; and boulder fields = natural irregular) in the North Adriatic Sea. Most structural descriptors were similar between artificial and natural habitats. Only inclination was consistently steeper in the artificial than in the natural habitats. Other minor differences in roughness or in the abundance of some surface microelements were related to the general morphology (regular or irregular) of the habitat rather than to its artificial or natural identity. The outcomes challenge the widespread assumption that artificial habitats lack the physical structure proper to natural habitats and stimulate renewed consideration about other structural and non-structural elements that could enhance the performance and sustainability of artificial marine structures, such as construction material, environmental setting or maintenance. They also encourage a wider reflection about what makes an artificial building surface “greener”: structural complexity is an important ecological parameter, and its deliberate increase will lead to responses in the biota, however, this may not necessarily match “more natural” conditions.

Decreasing the Weight-Size Parameters of Gas-Steam Turbine Plant by Increasing the Efficiency of Thermodynamic Processes in the Condenser

The aim of this work is decreasing the weight-size parameters of the contact gas-steam turbine plant and contact condenser elements by increasing the efficiency of thermal-gas dynamic processes of condensation through rational irrigation of countercurrent gas-steam flow. To achieve the goal the total efficiency of water-return drops ranging from 0.1 to 1 mm at different initial velocities from 5 to 35 m/s emitted by the multi-nozzle sprinkler was determined by mathematical modeling of the liquid droplet movement processes, heat and mass transfer between the liquid droplet and gas-vapor mixture, and gas-vapor mixture pressure loss. The effect of increasing the gas-steam mixture velocity from 3.3 to 6 m/s on the overall efficiency of water return was determined. The novelty of the obtained results was defined by an increase in the water return into cycle from 12 to 13% with a droplet diameter of 0.3 -- 0.4 mm and the initial velocity from the sprinkler of 5--10 m/s. The velocity of the mixture was to 6 m/s at rational correlations of the initial velocity of the droplets’ escape, which increased the total amount of heat withdrawn to 11%. The positive effect conditions of irrigation processes on thermogasdynamic and weight-size parameters of the condenser elements for the contact gas and steam turbine plant at full pressure recovery coefficients of over 0.967 were substantiated. The most significant result was the reduction of the weight-size parameters of the marine infrastructure object power plant from 8 to 19%.

Design, production, and validation of the biological and structural performance of an ecologically engineered concrete block mattress: A Nature-Inclusive Design for shoreline and offshore construction.

Over the past decade, the scientific community has studied, experimented, and published a notable body of literature on the ecological enhancement of coastal and marine infrastructure (CMI). The Nature-Inclusive Design (NID) approach refers to methods and technologies that can be integrated into the design and construction of CMI to create a suitable habitat for native species (or communities) whose natural habitat has been degraded or reduced. To examine the compliance of new environmentally sensitive technologies with structural requirements and fiscal restraints, while providing ecosystem and habitat value, this paper presents the findings of a structural-economical-biological analysis of ecologically engineered Articulated Concrete Block Mattresses (ACBMs). To evaluate the structural and biological performance of the Ecological Articulated Concrete Block Mattresses, a pilot project was deployed in April 2017 at Port Everglades, Florida, USA, and evaluated against controls of adjacent artificial structures and smooth-surface concrete blocks and monitored over a period of two years. The elements of ecological enhancement implemented in the fabrication and design of the ecologically enhanced ACBMs were comprised of bio-enhancing concrete additives and science-based designs. Based on the results of this study, these design alterations have increased the richness and diversity of sessile assemblages compared to control blocks and adjacent artificial structures and supported a higher abundance of mobile species. This ecological improvement was achieved within the operational limitations of conventional manufacturing and installation technologies, while complying with strict structural requirements for standard concrete marine construction. The results supported the working hypothesis and demonstrated that modifications of concrete composition, surface texture, and macro-design have the potential to increase the ecological value of concrete-based CMI and promote a more sustainable and adaptive approach to coastal and marine development in an era of climate resilience-building. Integr Environ Assess Manag 2022;18:148-162. © 2021 SETAC.

Numerical method for solving problems of dynamics of marine complexes and ship auxiliary mechanism

The article describes the study of methods of hydrodynamic coefficients using finite volumes, as well as numerical methods based on the study of data from the air tube experiment.The methods of converting the data of air tube experiments when working out the elements of the fixed assets of the fleet in the bases of orthogonal functions (bursts) were investigated and described. The study is based on the obtained mathematical models of processes using the methods of multi-turn engineering design, methods for constructing computer models in a structure that provides for an open process of developing and approving proposed project elements.An urgent task is to develop methods for reducing costs associated with the design and creation of marine infrastructure facilities and fixed working capital. The relevance of the tasks follows from the expensive cycles of project development, the labor costs of highly qualified specialists.

Hydrodynamics of a dual-module pontoon-net floating breakwater system: Numerical simulations and prototype tests

Floating breakwaters with a mooring system have been widely applied to protect marine infrastructures (e.g., artificial beach or island, aquaculture farm or marine vessels in harbors) from being destroyed by severe waves. In this paper, an innovative cylindrical dual pontoon-net floating breakwater was developed to enhance the wave attenuation capacity. This dual-module floating breakwater system was constructed as the prototype for on-site testing. A fully nonlinear time-domain model based on the coupled iterative solutions of the fluid integral equation and the pontoon-net dynamic equations was proposed to simulate the interactions between waves and the floating breakwater system. The flow field around the nets was simulated by introducing a porous-media model with Darcy’s law, while the deformation of the flexible nets was solved by using the lumped mass model. The instantaneous free surface was captured using the mixed Eulerian-Lagrangian (MEL) approach which employs an improved moving-grid technique based on the spring analysis to re-mesh the instantaneous water surface and the body wetted surface. On-site tests were also conducted to evaluate wave transmission performance of the floating breakwater system and to validate the numerical model. The comparisons show that the numerical solutions are in good agreement with the measured data. The effects of incident wave direction, wave period, wave height, net height, net number and net porosity on the hydrodynamic performance of the floating breakwater system were emphatically examined.

Combined Oscillating Water Column & hydrogen electrolysis for wave energy extraction and management. A case study: The Port of Motril (Spain)

This paper presents a theoretical novel approach to a marine infrastructure, which jointly uses an OWC (Oscillating Water Column) and hydrogen electrolysis as a clean source of primary conversion for energy management, capable to satisfy a continuous designed demand. A case study in the Port of Motril (Southern Spain) is proposed in order to analyze the performance of the power plant. The assessment covers the sale and management profits from the harvested energy from waves in the electricity market, and from the electrolysis of the oceanic water H2O plus dissolved salts μ into hydrogen H2, oxygen O2 and salts μ components, also known as green hydrogen.The investment analysis of the project is conducted through the dynamic financial index Net Present Value (NPV), using Monte Carlo techniques to determine the repayment period. The results are consistent, showing that the plant could supply the annual electricity demand of 356 people with a short repayment period. The amount of energy depends on peak periods Tp and wave heights Hs, which means that other locations could be found so as to improve the performance of the plant in terms of productions of energy and demand supply.

ICE REGIME IMPACT ON THE COASTAL ZONE OF THE AZOV SEA

Azov is freezing sea it means that forecast of the time of the beginning and the end of ice fields formation needs. The ice condition limited of maritime safety. Modern condition of ice regime in the Azov Sea has been considered. The navigation of the Ukrainian ports Berdjansk and Mariupol depends on ice regime, duration and ice cover thickness. For the passage of vessels along the sea approach channels and recommended courses in the winter, the use of icebreakers is required. The demolition of confining buoys by ice fields and their restoration is reflected in the economic opportunities of the ports. Purpose of the article is to establish the characteristic winter periods of the last decade, taking into account the climatic changes for the rational using of the results of the impact on the economic activity of the marine infrastructure and hydrographic services. The specific purpose of this publication is to evaluate the displacement of the means of navigation equipment – buoys in the winter, taking into account meteorological factors. The authors set the following tasks: 1) to identify periods and vectors of buoys; 2) to define wind and ice characteristics in separate periods; 3) to reveal the basic meteorological cause of the movement of the buoys. It is important to note that there are no similar publications concerning this region. It became very actual after the climate change period was marked. The reserach is based on the data of direct and remote observations, the dates of ice formation in the area of seaports of Ukraine (Berdyansk and Mariupol) the characteristics of ice, the end of freezing, the opening and clearing of ice from the water areas of ports and bays and using the information from NAVTEX warning system, the archival materials of the weather site meteo.ua. The features of the physicochemical properties of sea water during ice formation and the general circulation of the waters of the Azov Sea are examined, which is linked with the influence of fresh runoff of Don and Kuban rivers. In the period 2013–2021 the observations were made on the displacement of navigation aids (buoys) during the winter periods from the approach channels of the port of Mariupol and Berdjansk as well as noticed buoys from the Azov-Don Marine Channel (Russian Federation). The characteristic of winter periods and conditions during the last decade are considered taking into account the influence of climatic changes. It is noted that the ice regime of the Sea of Azov is closely related with the sum of average daily air tem peratures over the sea for the season and wind power. According to this criterion, winters are usually divided into three types: severe, moderate and mild. Over the past 30 years, there were only two severe winters in the Azov Sea in 2005–2006 and 2011–2012. During these winters, the Azov Sea was completely ice covered. The influence of the ice regime to the coastal zone was examined, because it is very important for the industrial and economic needs of state building. To maintain the safety of navigation and reduce economic losses, it is necessary to consider the possibility of removing buoys, which are most often displaced by ice drift. Long-term average observations indicate the beginning of ice formation in Mariupol on December 14, and in Berdyansk on December 20. The Taganrog Bay and the ice accumulation areas are cleared of ice most recently – March 20–28. Under modern climatic changes (increasing the frequency of mild winters, actual costs for the operation of ships, hydrographic, icebreakers, etc.) are expected to be an order of magnitude lower than standard indicators.

Tracking Microbial Evolution in the Subseafloor Biosphere.

ABSTRACTThe deep marine subsurface constitutes a massive biosphere that hosts a multitude of archaea, bacteria, and viruses across a diversity of habitats. These microbes play key roles in mediating global biogeochemical cycles, and the marine subsurface is thought to have been among the earliest habitats for life on Earth. Yet we have a poor understanding of what forces govern the evolution of subsurface microbes over time. Here, I outline why evolutionary trajectories in the subsurface may be different than those of microbes living on the surface of the planet and describe how we can take advantage of technological advancements to study the evolutionary dynamics of subsurface microbes and their viruses. The sequencing revolution, in tandem with marine infrastructure advancements, promises that we will soon gain a much deeper understanding of how the vast majority of the microbial biosphere changes, adapts, and evolves over time.

A multi-species assessment of artificial reefs as ecological traps

All of the marine environments have been found to be affected by anthropogenic impacts with the sprawl of marine infrastructure being one of the most extreme factors modifying habitats. Artificial reefs (ARs) are a common type of these infrastructures, that are frequently used for fisheries management, species conservation and habitat restoration. Attractiveness of ARs for some species have been demonstrated, however little is known about the fitness of individuals that occupy ARs compared to natural reefs. ARs that provide lower fitness advantages may become ecological traps. We examined individual fitness of three species (Trachinops caudimaculatus, Vincentia conspersa and Trinorfolkia clarkei) occupying three different habitat types: natural reefs, Reef Ball reefs (RBs) and custom-designed artificial reefs (CDARs) in Port Phillip Bay, Victoria, Australia, through comparing a range of condition indices (hepato-somatic, gonado-somatic and relative weight index). Additionally, we investigated mortality rates of new recruits and juveniles of T. caudimaculatus among habitat types. T. caudimaculatus exhibited nine times higher instantaneous mortality rates on RBs than the other two habitat types. Combined with known habitat preference of T. caudimaculatus for RB, this suggests that RBs may act as an ecological trap for this species. V. conspersa exhibited higher fitness on RBs, while T. clarkei fitness proxies were context dependent. Although our results indicate that responses by fishes to artificial habitats are species-, location- and habitat-specific, this is one of the first studies to demonstrate the formation of ecological traps in the marine environment due to proliferation of artificial reefs.Poorly designed or placed ARs may lead to insufficient positive outcomes or even significant negative impacts on marine communities. Combined with high costs, these effects may lead to reduced social acceptance of new placements and could impede future management and conservation efforts.

Influence of infrastructure material composition and microtopography on marine biofilm growth and photobiology

The impact of concrete composition and roughness on the formation of microalgal biofilms and their photobiology were studied on marine infrastructures presenting four different compositions combined with two degrees of roughness (rough and smooth). The structures were first inoculated with a natural microphytobenthic biofilm and immersed in sterilised seawater with a controlled photoperiod for six days. Photosynthetic activity was assessed with an imaging PAM-(Pulse Amplitude Modulated) fluorometer and microtopography was monitored in parallel with a 3-D camera. The results indicated that roughness had an impact on the biofilm biomass, its physiological status and its photosynthetic efficiency and capacity. The assessment of surface roughness indicated that negative reliefs were preferably colonised by MPB (microphytobenthic) cells with better photosynthetic performances. Moreover, MPB biofilms showed better photoacclimation in these microhabitats than on the positive and smooth reliefs. This study confirms the importance of microhabitat for biofilm formation and their photobiology.

Identifying Priorities for the Protection of Deep Mediterranean Sea Ecosystems Through an Integrated Approach

Benthic habitats of the deep Mediterranean Sea and the biodiversity they host are increasingly jeopardized by increasing human pressures, both direct and indirect, which encompass fisheries, chemical and acoustic pollution, littering, oil and gas exploration and production and marine infrastructures (i.e., cable and pipeline laying), and bioprospecting. To this, is added the pervasive and growing effects of human-induced perturbations of the climate system. International frameworks provide foundations for the protection of deep-sea ecosystems, but the lack of standardized criteria for the identification of areas deserving protection, insufficient legislative instruments and poor implementation hinder an efficient set up in practical terms. Here, we discuss the international legal frameworks and management measures in relation to the status of habitats and key species in the deep Mediterranean Basin. By comparing the results of a multi-criteria decision analysis (MCDA) and of expert evaluation (EE), we identify priority deep-sea areas for conservation and select five criteria for the designation of future protected areas in the deep Mediterranean Sea. Our results indicate that areas (1) with high ecological relevance (e.g., hosting endemic and locally endangered species and rare habitats),(2) ensuring shelf-slope connectivity (e.g., submarine canyons), and (3) subject to current and foreseeable intense anthropogenic impacts, should be prioritized for conservation. The results presented here provide an ecosystem-based conservation strategy for designating priority areas for protection in the deep Mediterranean Sea.

The usefulness of sustainable business models: Analysis from oil and gas industry

AbstractThe management of offshore platforms at the end of their production phase is a complex issue for technological, socioeconomic, ecological and safety reasons. The decommissioning or reconversion of offshore platforms in the context of a circular economy (CE) will lead to new knowledge acquisition, changing values and changing behaviours towards sustainability consistent with the ‘new’ business objectives. Multiuse platforms at sea (MUPSs) represent an interesting solution for development of marine infrastructures, including areas in which to start and develop various creative economic activities that are in harmony with the needs of environmental protection including renewable energy, sea shellfish farming, decarbonisation plants, tourism, and recreation. Particularly, the research activity focused on a deep literature review of offshore platform decommissioning and sustainable business model (SBM) in a CE context. This allowed us to access the sustainable business model canvas (SBMC), a conceptual tool that represents a holistic view of the different managerial multiuse options and their social and environmental impacts. Besides, to test the SBMC, we adopt an empirical analysis by semi‐structured questionnaires given to a sample of stakeholders in the decommissioning industry. The methodology was enriched by interviews with key informants to better investigate the business ecosystem and the feasibility of decommissioning applied to the case of an Italian offshore platform located in the Adriatic Sea. This article aims to contribute to supporting SBMs development following a holistic approach in relationship with all stakeholders and propose a multi‐criteria decision‐making analysis for evaluating and comparing alternative decommissioning options.

FRP interlocking multi-spiral reinforced square concrete columns: A promising compression application for marine engineering

The hybrid utilization of seawater sea-sand concrete (SWSSC) and fiber-reinforced polymer (FRP) composites to create innovative structures show promising application prospects in marine infrastructure construction, as it achieves steel corrosion elimination and use of available local materials. A potential combination of SWSSC and FRP is FRP-reinforced SWSSC columns. The rectangular or square stirrups provide inefficient confinement to the in-filled concrete compared to circular spirals, which limits practical applications of FRP-reinforced SWSSC square columns. The interlocking multi-spiral configuration may be a viable option, including a large circular spiral interlocking with four small spirals at column corners. In this study, the axial compressive performance of square SWSSC columns reinforced with glass FRP interlocking multi-spirals is investigated. Main variables are FRP transverse reinforcement configurations, spacings, and corner spiral sizes of interlocking multi-spirals. Test results confirmed that corner spirals provided additional confinement to the central spiral and longitudinal reinforcement, and decreases in spacings and corner spiral sizes effectively improved the post-peak compressive behavior. Moreover, comparisons between FRP transverse reinforcements indicated that interlocking multi-spirals enabled columns to exhibit better deformability than stirrups with identical amounts. A modified theoretical model was developed based on section analyses, which provided reasonably accurate predictions of test results.

Eco-Engineering of Seawalls—An Opportunity for Enhanced Climate Resilience From Increased Topographic Complexity

In the context of “green” approaches to coastal engineering, the term “eco-engineering” has emerged in recent years to describe the incorporation of ecological concepts (including artificially water-filled depressions and surface textured tiles on seawalls and drilled holes in sea structures) into the conventional design process for marine infrastructures. Limited studies have evaluated the potential increase in wave energy dissipation resulting from the increased hydraulic roughness of ecologically modified sea defences which could reduce wave overtopping and consequent coastal flood risks, while increasing biodiversity. This paper presents results of small-scale laboratory investigations of wave overtopping on artificially roughened seawalls. Impulsive and non-impulsive wave conditions with two deep-water wave steepness values (=0.015 and 0.06) are evaluated to simulate both swell and storm conditions in a two-dimensional wave flume with an impermeable 1:20 foreshore slope. Measurements from a plain vertical seawall are taken as the reference case. The seawall was subsequently modified to include 10 further test configurations where hydraulic effects, reflective of “eco-engineering” interventions, were simulated by progressively increasing seawall roughness with surface protrusions across three length scales and three surface densities. Measurements at the plain vertical seawall compared favorably to empirical predictions from the EurOtop II Design Manual and served as a validation of the experimental approach. Results from physical model experiments showed that increasing the length and/or density of surface protrusions reduced overtopping on seawalls. Benchmarking of test results from experiments with modified seawalls to reference conditions showed that the mean overtopping rate was reduced by up to 100% (test case where protrusion density and length were maximum) under impulsive wave conditions. Results of this study highlight the potential for eco-engineering interventions on seawalls to mitigate extreme wave overtopping hazards by dissipating additional wave energy through increased surface roughness on the structure.

The study of long-term durability and bio-colonization of concrete in marine environment

The purpose of this paper is to study the long-term durability and bio-colonization of concrete in marine environment. In this work, concrete formulations were developed and optimised by varying the type of cement (CEMII and CEMV) and introducing shellfish by-products (Oyster Shells) into their composition (by substituting 20% by weight of 4/10 aggregates). Four concrete formulations were thus studied. The durability of these materials upon bio-colonization were tested after 90 days, 180 and 360 days of immersion in natural seawater. The monitoring of the photosynthetic activity of biofilms and the biomass on the materials surface showed a better acclimatisation of the microphytobenthos in CEMII 20% Shells concrete than in other concretes despite a lower colonization on this concrete. It was also noticed that the chlorophyll biomass was the highest in concrete CEMV 20% Shells after 360 days. During immersion, the mechanical strengths of CEMII 0% Shells, CEMII 20% Shells and CEMV 20% Shells increased. At long term of immersion, the chloride ions diffusion was more reduced, in natural seawater, for CEMII 0% Shells, CEMII 20% Shells and CEMV 20% Shells concretes than for concrete CEMV 0% Shells. these results lead to the assumption that the accumulation of biofilm plays a role as protective barrier against the action of chloride ions. Finally, it appears that the concrete CEMII 20% Shells is the most suitable concrete mix design for marine infrastructure amongst the tested designs.

Background of the Bathymetric Cartography of Mexico

At present the Mexican oceans are important for economic, social, and climatic reasons; Mexico’s privileged geographic location, between two oceans, largely explains the enormous biological and environmental diversity that it brings together, in addition to its wide range of marine resources and ecosystems. A determining factor that influences marine life is undoubtedly the relief that is submerged in the oceans, since different ecosystems originate in it where diversity of species is concentrated. Likewise, a great diversity of metals and hydrocarbons are concentrated in the relief, which currently constitute another wealth for Mexico. Given this, the National Institute of Statistics and Geography (INEGI, by its acronym in spanish)) has been given the task of providing data and geographic information of the undersea relief of Mexico through bathymetric cartography to represent the seabed to assist in decision-making in the areas economic, political, social, and technical, as well as for the planning and development of marine infrastructure and, where appropriate, for disaster prevention and response.