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Eco-engineering for Climate Change—Floating to the Future
... Combining knowledge from different fields, ecological engineering designs and maintains ecosystems that provide desired ecological services while enhancing human well-being. Along the lines of Hadary et al. (2022), ecological engineering is an evolving discipline with the aim of building more resilient and safer coastal and marine structures for people and nature, while maximizing ecosystems, social, and economic benefits. Oceans form 71% of the earth's surface and more than 50% of the world's population lives in coastal areas, resulting in coastal hardening. ...
Climate change heightens global warming and brings about impending risks for both human society and natural systems. Climate change is the greatest threat modern humans have ever faced. Pollutant discharges involve the global atmosphere and result in the challenge of global warming that must be solved before it results in irreversible damage. Current common threats of crises need common actions among all of us: every continent, every country, every community, and every common citizen. The earlier an action, the larger its impact. This review article scrutinizes the newest developments in this paramount important research area and provides directions for future research.
... The use of modular platforms also lends to their ease of expansion and relocation with minimal impact on the seabed ecosystem (Wang and Wang, 2015). In fact, floating cities can even enhance local marine activity by providing habitats for fish and sessile organisms (Hadary et al., 2022). In light of the aforementioned advantages, the development of floating cities has therefore been recognized by the American Society of Civil Engineers (ASCE) via its Future World Vision Initiative as a crucial step towards sustainable and resilient future cities (ASCE, 2019). ...
Modular floating structures (MFS) offer a sustainable alternative over traditional land reclamation for the expansion of coastal megalopolises in the context of climate change adaptation. Yet, there are currently no guidelines for structural engineers pertaining to their analysis and design. This work presents analytical solutions readily accessible for the dynamic analysis of MFS utilizing conventional rectangular pontoons subject to regular or irregular waves. Closed-form formulations utilizing linear wave theory proved capable in capturing the response amplitude operators (RAO) for sway, heave, and roll when compared against smoothed particle hydrodynamics (SPH) simulations for a typical MFS to which appropriate damping ratios were obtained. A parametric study was subsequently implemented to examine the contribution of building slenderness and superstructure-to-pontoon mass ratios on critical accelerations induced by different sea states. It was revealed that structural configurations beneficial to static stability may result in larger dynamic effects under wave excitation thus compromising occupant comfort delineated via various international standards. Ultimately, this paper represents a significant step towards the realization of MFS for urban expansion by providing structural engineers with an accessible methodology for the dynamic analysis of floating structures as a precursor to detailed computational modeling.
Recent papers suggest that epifaunal organisms use artificial structures as stepping-stones to spread to areas that are too distant to reach in a single generation. With thousands of artificial structures present in the North Sea, we test the hypothesis that these structures are connected by water currents and act as an interconnected reef. Population genetic structure of the Blue mussel, Mytilus edulis was expected to follow a pattern predicted by a particle tracking model (PTM). Correlation between population genetic differentiation, based on microsatellite markers, and particle exchange was tested. Specimens of M. edulis were found at each location, although the PTM indicated that locations >85 km offshore were isolated from coastal sub-populations. Fixation coefficient FST correlated with the number of arrivals in the PTM. However, the number of effective migrants per generation as inferred from coalescent simulations did not show a strong correlation with the arriving particles. Isolation by distance analysis showed no increase in isolation with increasing distance and we did not find clear structure among the populations. The marine stepping-stone effect is obviously important for the distribution of M. edulis in the North Sea and it may influence ecologically comparable species in a similar way. In the absence of artificial shallow hard substrates, M. edulis would be unlikely to survive in offshore North Sea waters.
Human population growth and accelerating coastal development have been the drivers for unprecedented construction of artificial structures along shorelines globally. Construction has been recently amplified by societal responses to reduce flood and erosion risks from rising sea levels and more extreme storms resulting from climate change. Such structures, leading to highly modified shorelines, deliver societal benefits, but they also create significant socioeconomic and environmental challenges. The planning, design and deployment of these coastal structures should aim to provide multiple goals through the application of ecoengineering to shoreline development. Such developments should be designed and built with the overarching objective of reducing negative impacts on nature, using hard, soft and hybrid ecological engineering approaches. The design of ecologically sensitive shorelines should be context-dependent and combine engineering, environmental and socioeconomic considerations. The costs and benefits of ecoengineered shoreline design options should be considered across all three of these disciplinary domains when setting objectives, informing plans for their subsequent maintenance and management and ultimately monitoring and evaluating their success. To date, successful ecoengineered shoreline projects have engaged with multiple stakeholders (e.g. architects, engineers, ecologists, coastal/port managers and the general public) during their conception and construction, but few have evaluated engineering, ecological and socioeconomic outcomes in a comprehensive manner. Increasing global awareness of climate change impacts (increased frequency or magnitude of extreme weather events and sea level rise), coupled with future predictions for coastal development (due to population growth leading to urban development and renewal, land reclamation and establishment of renewable energy infrastructure in the sea) will increase the demand for adaptive techniques to protect coastlines. In this review, we present an overview of current ecoengineered shoreline design options, the drivers and constraints that influence implementation and factors to consider when evaluating the success of such ecologically engineered shorelines
Human population growth and accelerating coastal development have been the drivers for unprecedented construction of artificial structures along shorelines globally. Construction has been recently amplified by societal responses to reduce flood and erosion risks from rising sea levels and more extreme storms resulting from climate change. Such structures, leading to highly modified shorelines, deliver societal benefits, but they also create significant socioeconomic and environmental challenges. The planning, design and deployment of these coastal structures should aim to provide multiple goals through the application of ecoengineering to shoreline development. Such developments should be designed and built with the overarching objective of reducing negative impacts on nature, using hard, soft and hybrid ecological engineering approaches. The design of ecologically sensitive shorelines should be context-dependent and combine engineering, environmental and socioeconomic considerations. The costs and benefits of ecoengineered shoreline design options should be considered across all three of these disciplinary domains when setting objectives, informing plans for their subsequent maintenance and management and ultimately monitoring and evaluating their success. To date, successful ecoengineered shoreline projects have engaged with multiple stakeholders (e.g. architects, engineers, ecologists, coastal/port managers and the general public) during their conception and construction, but few have evaluated engineering, ecological and socioeconomic outcomes in a comprehensive manner. Increasing global awareness of climate change impacts (increased frequency or magnitude of extreme weather events and sea level rise), coupled with future predictions for coastal development (due to population growth leading to urban development and renewal, land reclamation and establishment of renewable energy infrastructure in the sea) will increase the demand for adaptive techniques to protect coastlines. In this review, we present an overview of current ecoengineered shoreline design options, the drivers and constraints that influence implementation and factors to consider when evaluating the success of such ecologically engineered shorelines.
Coastal squeeze caused by sea level rise threatens the size, type, and quality of intertidal habitats. Along coastlines protected by hard defenses, there is a risk that natural rocky shore habitats will be lost, with the remaining assemblages, characteristic of hard substrata, confined to sea walls and breakwaters. These assemblages are likely to be less diverse and different to those found on natural shores, as these structures lack features that provide moist refugia required by many organisms at low tide, such as pools and crevices. Engineering solutions can help mitigate the impact of sea level rise by creating habitats that retain water on existing structures. However, as experimental trials are strongly affected by local conditions and motivations, the development of new techniques and solutions are important to meet the needs of local communities and developers. Following a small-scale community project, a feasibility study retrofitted five concrete-cast artificial rock pools (“Vertipools”) on a vertical seawall on the south coast of England. After 5 years, the artificial pools increased the species richness of the sea wall and attracted mobile fauna previously absent, including fish and crabs. The Vertipools had assemblages which supported several functional groups including predators and grazers. Although disturbance of algal assemblages on the seawall from the retrofitting process was still evident after 3 years, succession to full canopy cover was underway. Collaboration between policy makers, ecologists, children and artists produced an ecologically sensitive design that delivered substantial benefits for biodiversity, which can be adapted and scaled-up to both mitigate habitat loss and enhance coastal recreational amenity.
This paper gives a discussion on the Computational Fluid Dynamics (CFD) applications in offshore engineering. Accurate hydrodynamic quantities are essential for engineering design. Offshore structures are generally subject to high Reynolds number flows. These high Reynolds number flow conditions (Re > 106) are difficult and expensive to achieve in an experimental setup. Therefore, it is attractive to use CFD to provide the essential hydrodynamic quantities for practical design. Verification and validation studies are important for determining the validity of the CFD prediction. A procedure of performing CFD simulation is shown. Different types of turbulence modelling are discussed. Three examples of high Reynolds number CFD simulations, covering flow around offshore structural components and waves past partially-submerged horizontal cylinders, are shown and discussed.
The growing number of artificial structures in estuarine, coastal and marine environments is causing “ocean sprawl”. Artificial structures do not only modify marine and coastal ecosystems at the sites of their placement, but may also produce larger-scale impacts through their alteration of ecological connectivity - the movement of organisms, materials and energy between habitat units within seascapes. Despite the growing awareness of the capacity of ocean sprawl to influence ecological connectivity, we lack a comprehensive understanding of how artificial structures modify ecological connectivity in near- and off-shore environments, and when and where their effects on connectivity are greatest. We review the mechanisms by which ocean sprawl may modify ecological connectivity, including trophic connectivity associated with the flow of nutrients and resources. We also review demonstrated, inferred and likely ecological impacts of such changes to connectivity, at scales from genes to ecosystems, and potential strategies of management for mitigating these effects. Ocean sprawl may alter connectivity by: (1) creating barriers to the movement of some organisms and resources - by adding physical barriers or by modifying and fragmenting habitats; (2) introducing new structural material that acts as a conduit for the movement of other organisms or resources across the landscape; and (3) altering trophic connectivity. Changes to connectivity may, in turn, influence the genetic structure and size of populations, the distribution of species, and community structure and ecological functioning. Two main approaches to the assessment of ecological connectivity have been taken: (1) measurement of structural connectivity - the configuration of the landscape and habitat patches and their dynamics; and (2) measurement of functional connectivity - the response of organisms or particles to the landscape. Our review reveals the paucity of studies directly addressing the effects of artificial structures on ecological connectivity in the marine environment, particularly at large spatial and temporal scales. With the ongoing development of estuarine and marine environments, there is a pressing need for additional studies that quantify the effects of ocean sprawl on ecological connectivity. Understanding the mechanisms by which structures modify connectivity is essential if marine spatial planning and eco-engineering are to be effectively utilised to minimise impacts.
Berthing pontoons, one of the most ubiquitous structures in marinas, are known to provide recruitment substrate for a variety of marine biota but little has been reported on their capacity to support epibiotic organisms in tropical marinas, and even less is known about the factors that shape their distribution in such environments. We surveyed the epibiotic assemblages on the sides of pontoons in three Singapore marinas and examined the environmental conditions that influenced their distribution. A total of 94 taxa were recorded, with each marina hosting 43–65 taxa. Assemblages among marinas were highly distinct, and, key discriminants included components of biotic (alcyonarians, hexacorallians, bivalves, and annelids), as well as abiotic (sediment, bare area and shell fragments) origin. While the assemblage variation among marinas was influenced by local environmental conditions (e.g. water motion and sedimentation rate) and pontoon material, the variation in distribution within each marina was best explained by the distance of the pontoons from the marina’s entrance (epibiotic diversity and taxa richness were lower away from the marina entrance). Knowledge on the distribution of epibiotic assemblages on pontoons is essential to identify the factors that contribute to spatial variation and encourage the design and construction of ecologically-friendly marinas. Our findings suggest that improvements to pontoon design and layout would help to augment marina biodiversity, enhance the ecology of urbanised coasts, and mitigate development impacts.
The pressures on the use of the seashore are steadily rising, not only in developed countries but worldwide. Anthropogenic activity has long impacted the marine continental shelf down to a depth of approximately -200 m. New activities are now affecting this coastal space such as renewable energies, recreational uses and aquaculture in addition to the traditional ones of navigation or fishing. This evolution raises new sources of conflict amongst users which can require state involvement in order to manage the different stakeholders and pressure groups. However, the coastal space still offers a large potential for development for two reasons. Firstly, the physical three dimensional potential of this space enables the whole water column to be used, principally to increase the fishing productivity as in Japan. Secondly, innovative synergies can be created between socio-technical and ecological uses (a "fourth dimension") such as the eco-design of wind turbine foundations in order to create fish habitat or sea grass settlement. This new vision in "4D" for the design and the management of coastal infrastructure can potentially reduce the risk of conflict as different uses of the coastal space would not necessarily exclude one another. Indeed, several forms of synergy could be developed such as fisheries with aquaculture or biological sustainability with social acceptability. Until now, limited attempts at such an approach have been done. We suggest this is likely due to the absence of a common eco-engineering vision and the lack of experience amongst biologists and engineers in the co-construction of projects. This eco-engineering, or "green" vision, also takes into account the complexity and resilience of the ecosystem in the long term, if underwater engineered infrastructures are also "eco"-designed to increase ecological gain This new conception, for development within the coastal area, provides for an increased bio-oriented complexity to engineered structure and therefore a better resistance of the ecosystem in the long term to anthropogenic pressures and a reduction in multi-user conflicts.
This paper presents results from a year-long experimental study, evaluating the performance of ecologically active concrete matrices and designs for coastal and marine construction. Results indicate that slight modifications of concrete composition and surface texture can improve the capabilities of concrete based coastal and marine infrastructure (CMI) to support enhanced marine fauna and flora, and provide valuable ecosystem services alongside with economic advantages such as elevated water quality, increased operational life span, structural stability, and absorption of hydrodynamic forces.
Many autochthonous and alien macroinvertebrates of the intertidal zone are biocalcifiers, and the present study proposes a first assessment of their calcimass and their annual calcium carbonate (CaCO3) production at a regional scale, along 500 km of the coastline of Brittany, France, which represents a wide range of the rocky-shore habitats commonly encountered in the north-eastern Atlantic region. All sites considered together gave a mean calcimass estimate of 5327 g m(-2). The corresponding mean CaCO3 gross production was 2584 g m(-2) year(-1). The net production (including dissolution) by biocalcification was 2384 g CaCO3 m(-2) year(-1). Estimations of CO2 production via both calcification and respiration were carried out in particular for the phylum Mollusca and for crustacean barnacles, dominating in terms of calcimass. Mean CO2 production obtained by summing CO2 fluxes related to net CaCO3 production and respiration for all sampled sites was 22.9 mol m(-2) year(-1). These results illustrate the significance of CO2 production during biogenic CaCO3 precipitation of intertidal invertebrates in such temperate coastal environment compared with tropical zones and the contribution of the shelves to the global CaCO3 budget.
Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential. Furthermore, we identify needs for further research and scope for improvement in this kind of scenario-based exposure analysis.
Intense shading under large piers is known to negatively affect benthic fishes. However, effects on pelagic fishes are poorly known. We employed the equivalent of acoustic video, dual frequency identification sonar (DIDSON), under a kayak to evaluate the response of pelagic fishes at a large (351 x 255 m) urban pier (Pier 40) in Hudson River. A repeated measures design (322 occupations) sampled 3 transects each across both the northern and southern open water-pier edge-under pier continuum during the day and night from June 2009 to September 2010. Over 22 000 individual fish, ranging from small schooling forage species (e. g. Anchoa mitchilli, Menidia menidia) to large predators (Morone saxatilis, Pomatomus saltatrix) were detected with DIDSON and verified with conventional sampling nets. Small (<250 mm) schooling pelagic fishes avoided areas under the pier where light is dramatically reduced during both day and night (when municipal lights illuminate the water away from the pier). Less abundant large (>250 mm) predatory fish responded somewhat differently from small schooling fish in that large predatory fish were slightly more abundant under the pier than in open water, but only from the edge extending to 5 m under the pier where there was still some light. Beyond that, abundance declined sharply. Together, these observations indicate that areas under large piers are suboptimal habitats for many of the abundant pelagic fishes, a pattern similar to that for benthic fishes.
While natural marine habitats with motion capabilities, e.g., kelps and seaweeds, have been studied alongside their associated fouling communities, little is known of the effect of motion on the communities of floating artificial habitats such as buoys, rafts, and pontoons, particularly in tropical systems. Hydrodynamic features greatly differ between floating and fixed artificial substrata, which in turn affect the structure of their associated communities. This study tested the hypothesis that floating and fixed artificial installations in a tropical reef system (Eilat, Red Sea) would support different benthic communities throughout space and time. Specifically, we examined differences in communities recruited onto settlement plates between floating and fixed installations deployed at three different sites, along a two-year monitoring period. The three sites exhibited distinct differences in species assemblages between the monitoring dates (6, 12, 18 and 24months post deployment), mainly between the first and the last two dates. The average level of dissimilarity between floating and fixed installations increased over time at all sites. Over 50% of the dissimilarity between the floating and fixed installations resulted from five taxonomic groups i.e., bryozoans, bivalves, barnacles, sponges, including the amount of bare space on the settlement plates. The contribution of these groups to the dissimilarity changed both temporally within each site, and spatially among sites. The observed differences were related to the hydrodynamic characteristics of floating and fixed habitats, interacting with biotic features such as predation, successional processes and seasonality; and abiotic features including small-scale spatial changes, light, and position in the water column.
Despite the proliferation in coastal development world-wide little is known of the biological and ecological effects of man-made submerged habitats in coastal reefal environments. Such habitats, when able to move, offer unique environmental conditions, mainly in terms of hydrodynamic aspects. The current study tested whether floating habitats would develop unique communities in comparison to identical fixed ones, due to differences in current regime between the 2 types of habitat. We found significant differences in the hydrodynamic features associated with habitats of different motion capabilities, predominantly in mass-transfer rate, current velocity and shear stress. Floating installations had greater flow velocities and shear stress compared to fixed ones. We suggest that these hydrodynamic features determine the nature of the benthic communities on floating and fixed habitats, as the former revealed greater biomass and less chlorophyll content compared to the latter, while coral settlement was greater on the fixed installations, particularly near the seabed. The motion of floating artificial habitats increased the mass-transfer rate, as reflected by higher current velocities, and elevated the shear stress felt on their surfaces. These conditions encourage massive settlement of benthic macroinvertebrates and determine the community structure of floating artificial habitats in reefal environments.
Urban structures are a conspicuous, yet poorly understood component of the marine environment along urban coastlines, Previous work has shown that different types of structures support different diversities and relative abundances of sessile marine organisms. Studies on the effects of substratum composition, age, orientation and the effects of predation have failed to explain the observed differences in assemblages that develop on different types of structures. We assessed the model that differences in epibiotic assemblages between pontoons and pilings were due to the floating nature of pontoons versus the fixed (relative to the seafloor) nature of pilings, as opposed to other structural differences (colour, shape, surface type, etc.). Two additional (non-mutually exclusive) models were also tested. These were that the presence of a 'swash zone' constantly exposed to wave action and/or attachment to the benthos could cause differences between pontoons and pilings, We hypothesized that purpose-built experimental structures that floated would develop different assemblages from structures that were held fixed relative to the seafloor, regardless of whether they were pontoons or pilings. If swash were important, then structures floating just below the surface would differ from structures floating at the surface, If attachment to the benthos were important, then pilings attached to the benthos would differ from all the other structures. Multivariate analyses supported the hypothesis that both floating and the presence of swash were important in creating a typical pontoon assemblage, while other factors (type of structure, attachment to the benthos) were not, Several taxa contributed to these differences, including the mussel Mytilus edulis, the polychaete tubeworm Hydroides sp. and several algal taxa. Differences between fixed and floating structures have implications for the interpretation of previous studies done on floating docks, More studies of this kind are needed in order to inform the managers of urban waterways about the implications of adding different types of structures to the coastal environment.
Underwater environments in ports are designed for harbour activities solely. However, by simple and cost-effective measures, suitable habitat for underwater flora and fauna can be created. This is expected to have positive effects on higher trophic levels, such as fish, and improve water quality, by enlarging filter feeder biomass. In this study we developed ‘pole hulas’ and ‘pontoon hulas’, consisting of hanging ropes of different materials. The pole hulas are made up of many 6 mm thick and 55 cm long strings just above and below the mean low water level (MLWL) around poles. The pontoon hulas resemble raft like structures with 12 mm thick and 150 cm long ropes within the open space of mooring pontoons. The first experimentation with these structures was executed in the polyhaline harbours of the port of Rotterdam. The pole hulas were rapidly colonised by a variety of organisms. Above MLWL a seaweed community dominated on the strings. Below MLWL Mytilus edulis (the Blue mussel) was found to be the dominating species after a few months. In the dense layer of M. edulis on both pole hulas and pontoon hulas many mobile soft-bottom amphipods and young ragworms occurred, which means that colonisation on these structures compensate for biodiversity loss of bottom fauna due to dredging and disturbance by propellers of ships. Settlement of the exotic Crassostrea gigas (Pacific or Japanese oyster) did not occur on the strings of the pole hulas, the ropes of the pontoon hulas and not on the poles with hulas.
Marine aliens are non-native species that have been transported across major geographi-cal barriers by human activities, involving vectors that move propagules along pathways. Species may also be newly observed in a geographical area due to range shifts, generally in association with climate change. Artificial structures are considered to be either man-made materials or natural materials shaped or displaced to serve a specific function for human activities. All types of artificial structures are currently increasing dramatically in coastal zones due to increasing human popula-tions on coastlines. Most of the significant marine vectors and pathways involve mobile artificial structures and are reviewed here. These include shipping (ballast water and hull fouling) and aqua-culture, including stock transfer and unintentional introductions, all of which can move species into new biogeographical provinces. Some types of structures frequently move long distances but have low fouling loads (e.g., commercial shipping), whereas others (e.g., barges and pontoons) can be hyperfouled due to long stationary periods such that when moved they transport mature fouling communities. We also examine the presence of alien marine species on static (immobile) artificial structures, which support different communities from those on natural hard substrata. We consider the role of these structures, such as coastal defences, artificial reefs, and offshore platforms, in the dispersal and abundance of alien species. Marinas include both mobile and immobile structures and are apparently particularly favourable habitats for many aliens. For example, in coastal North America approximately 90% of the alien species inhabiting hard substrata have been reported from docks and marinas. Detailed case studies of alien marine species (two seaweeds and four inverte-brates) are provided, with an analysis of their origin, vectors of transport, habitat in the introduced range, and potential impact. Although there are exceptions, a large majority of marine alien species seem to be associated, at least for some of the time, with artificial structures. It is clear that artificial structures can pave the way and act as stepping stones or even corridors for some marine aliens, as do urban areas, roads and riparian environments in terrestrial ecosystems. The observed acceleration of spread rates for marine invasions over the course of the last two centuries may partly be a result of the increase of artificial structures in coastal environments coupled with greater activity of vectors.
We identified different distributions of marine nonindigenous species (NIS) and native species on some artificial structures
versus natural reefs and using experimental manipulations, revealed some possible causal mechanisms. In well-established subtidal
assemblages, numbers of NIS were 1.5–2.5 times greater on pontoons or pilings than on rocky reefs, despite the local species
pool of natives being up to 2.5 times greater than that of NIS. Conversely, on reefs and seawalls, numbers of native species
were up to three times greater than numbers of NIS. Differential recruitment to different positions and types of surfaces
appeared to influence distribution patterns. NIS recruited well to most surfaces, particularly concrete surfaces near the
surface of the water, whilst natives occurred infrequently on wooden surfaces. The position of rocky reefs and seawalls close
to the shore and to the seabed appeared to make them favourable for the recruitment of natives, but this positioning alone
does not hinder the recruitment of NIS. We argue that pontoons and pilings represent beachheads (i.e. entry points for invasion)
for many nonindigenous epibiota and so enhance the spread and establishment of NIS in estuaries. Habitat creation in estuaries
may, therefore, be a serious threat to native biodiversity.
The corrosion behaviour and biofouling characteristics of structural steel coupons at three different locations in the Gulf of Mannar were studied over a period of 2 years. Oyster fouling was predominant at Tuticorin open sea, while barnacle fouling was more pronounced at Mandapam and Tuticorin harbour. Among the three locations, Tuticorin open sea showed a markedly higher biomass, particularly after 12 and 18 months. The extent of crevice corrosion caused by hard foulers was more pronounced at Tuticorin harbour when compared to that at the other two locations. The corrosion rate of the structural steel coupons for 24 months was in the order, Mandapam > Tuticorin harbor > Tuticorin open sea. The loss in tensile strength at 12 and 24 months was in the order, Tuticorin open sea > Tuticorin harbor > Mandapam. The corrosion behaviour of the structural steel coupons was strongly influenced by the variations in the biofouling assemblage at the three different coastal locations.
Overfishing is a major environmental problem in the oceans. In addition to the direct loss of the exploited species, the very act of fishing, particularly with mobile bottom gear, destroys habitat and ultimately results in the loss of biodiversity. Furthermore, overfishing can create trophic cascades in marine communities that cause similar declines in species richness. These effects are compounded by indirect effects on habitat that occur through removal of ecological or ecosystem engineers. Mass removal of species that restructure the architecture of habitat and thus increase its complexity or influence the biogeochemistry of sediments could have devastating effects on local biodiversity and important water–sediment processes. The possible overexploitation of engineering species requires more attention because the consequences extend beyond their own decline to affect the rest of the ecosystem. This is particularly problematic in the deep ocean, where oil and gas exploration and fishing pressure are likely to increase.
Urban nearshore ecosystems are built environments that differ structurally and functionally from the natural ecosystems they replace. Eco-engineering offers the ability to enhance these ecosystems by reducing the impacts of shoreline modification. Recent studies have linked shoreline armoring and pier shade—common features of modified shorelines—to lower foraging rates, altered distribution patterns, and increased predation risk for juvenile salmon. The 2017 replacement of the Elliott Bay seawall in Seattle, WA, USA incorporated novel eco-engineering design elements, including glass light penetrating surfaces (LPS) in overwater structures, an elevated seafloor, and textured substrates in the seawall face to enhance nearshore habitat for juvenile Pacific salmon (Oncorhynchus spp.) migrating from natal streams to the ocean. To examine the effectiveness of seawall eco-engineering, we used snorkel surveys to assess changes in juvenile salmon spatial distribution and foraging patterns during peak outmigration (March–August), and measured ambient light penetration before and after seawall replacement. Overall, we found that juvenile salmon were distributed more evenly across a spatial mosaic of habitats following eco-engineering. LPS enhanced ambient light penetration in nearshore under-pier habitats, and juvenile salmon use of these habitats increased concurrently. Salmon densities under piers tended to be greatest at low tides, indicating that light availability may mediate selective habitat use. Feeding rates at sites immediately adjacent to the seawall increased both between and under piers following habitat enhancement. Our findings suggest that the elevated light levels facilitated by LPS, in concert with physical enhancements that provided more complex shallow water habitat, temper the negative effects of pier shade and shoreline armoring on juvenile salmon.
Coastal zones, the world's most densely populated regions, are increasingly threatened by climate change stressors - rising and warming seas, intensifying storms and droughts, and acidifying oceans. Although coastal zones have been affected by local human activities for centuries, how local human impacts and climate change stressors may interact to jeopardize coastal ecosystems remains poorly understood. Here we provide a review on interactions between climate change and local human impacts (e.g., interactions between sea level rise and anthropogenic land subsidence, which are forcing Indonesia to relocate its capital city) in the coastal realm. We highlight how these interactions can impair and, at times, decimate a variety of coastal ecosystems, and examine how understanding and incorporating these interactions can reshape theory on climate change impacts and ecological resilience. We further discuss implications of interactions between climate change and local human impacts for coastal conservation and elucidate the context when and where local conservation is more likely to buffer the impacts of climate change, attempting to help reconcile the growing debate about whether to shift much of the investment in local conservation to global CO2 emission reductions. Our review underscores that an enhanced understanding of interactions between climate change and local human impacts is of profound importance to improving predictions of climate change impacts, devising climate-smart conservation actions, and helping enhance adaption of coastal societies to climate change in the Anthropocene.
Eco-design aims to enhance eco-engineering practices of coastal infrastructure projects in support of ecological functions before these projects are developed and implemented. The principle is to integrate eco-engineering concepts in the early phases of project design. Although ecological losses are inherent in any construction project, the goal of eco-design is to introduce environmental considerations upfront during technical design choices, and not just afterwards when evaluating the need for reduction or compensatory mitigation. It seeks to reduce the negative impacts of marine infrastructure by introducing a new reflexive civil engineering approach. It requires a valuation of nature with the aim of reducing impacts by incorporating intelligent design and habitat-centered construction. The principle advocated in this paper is to design coastal infrastructures, at micro- to macro-biological scales, using a combination of fine and large scale physical and chemical modifications to hard substrates, within the scope of civil engineering requirements. To this end, we provide a brief introduction to the factors involved in concrete-biota interactions and propose several recommendations as a basis to integrate ecology into civil engineering projects, specifically addressed to concrete.
Offshore wind is now a well-established technology in Europe with 12,631MW installed capacity from 3,589 grid connected wind turbines in 10 countries. The technology is now expanding in to new markets in North America and the Far East.
This growth is being fuelled by the reducing cost of offshore wind generation with the first subsidy free projects now in development in Europe. In these markets offshore wind will be a lower cost and more environmentally friendly means of generating electricity than gas.
This cost reduction has been driven by a number of factors but three important ones are discussed here together with a number of lessons learned from recent projects.
The wind turbines are steadily getting bigger. Larger turbines mean that fewer need to be installed for a given project size. The average size of a grid connected turbine in 2016 was 4.8MW but the future subsidy free projects will require turbines closer to 15MW. This means larger foundations and heavier turbine components need to be installed.
There is a significant degree of standardisation and repetition in the installation of offshore wind. High levels of repetition mean that a greater investment can be made on installation techniques, installation aids and procedures than would normally be seen on a one off project. This in turn places a higher demand on production and installation engineering than experienced on oil and gas projects.
The cost of project finance has come down significantly. These projects are very large and most Utilities will no longer finance them off balance sheet. Therefore the bankability of projects is critical to the developer in reaching financial close.
Based on recent successful project delivery there is a broad range of investors willing to provide finance. However, the financiers and their technical advisors set the risk levels, contracting strategy and very often the construction methodology.
Trends in offshore wind projects and lessons learned from recent projects are discussed.
Owing to a combination of increase in coastal population and processes related to global climate change, intense coastal development is inevitable. Shallow-water habitats are prone to be replaced by structures such as seawalls and breakwaters. While adding ample hard substrate to the seascape, these structures are not surrogates to natural habitats, and are often associated with nuisance and invasive species. These differences are attributed to design features including high inclination, low complexity and high homogeneity - all atypical of natural habitats. To date, coastal infrastructure has been designed with limited consideration to marine life developing on it. Consequently, its ability to provide ecosystem services similar to those offered by natural habitats has been severely compromised. This paper presents two case studies implementing ecological enhancement at the Brooklyn Bride Park waterfront. Both strategies are examples for restoring viable ecosystem services while also serving structural and societal goals. The first is an example of structural repairs of aging pier piles, by applying innovative technology of ecological concrete encasement which creates valuable habitat. The second is an example of boosting the ecological performance of a constructed riprap waterfront, by integrating precast tide-pools that add water-retaining habitat features lacking from standard coastal infrastructure.
Concrete based coastal and marine infrastructure (CMI) such as ports, piers, industrial facilities and coastal defense elements dominate coastal zones world-wide. Coastal hardening replaces natural habitats with urban/industrial waterfronts that cannot provide ecosystem services similar to those offered by undisturbed coastlines. As a result, CMI are often considered as sacrificed zones with no environmental value. Studies show that marine flora and fauna on CMI, is typically less diverse than natural assemblages, and is commonly dominated by nuisance and invasive species. Here we summarize the results of a 24 month monitoring study of a breakwater section (Haifa, Israel) composed of armor unites cast from a proprietary concrete mix with an ecological design (ECOncrete® Antifers – EA). The study compared benthic community structure (fish, invertebrates and algae), species richness, live cover, diversity and the ratio of invasive to local species, on EA to that of an adjacent breakwater section made of standard Antifers (SA) composed of Portland based concrete. The abundance, richness and diversity of invertebrates and fish were higher on and around the EA compared to SA, while the ratio of invasive to local species was considerably lower. Moreover, engineering species such as oysters, serpulid worms, bryozoans and coralline algae were more dominant on the EA than on the SA. These ecosystem engineers increase the complexity of the structure, by means of biogenic buildup, which increase the availability of food and shelter in the area, while potentially contributing to the structures stability and longevity via bioprotection. The study indicates the ability of design substrate alterations to facilitate competition for space between local and invasive species on CMI, and demonstrates the feasibility of applying environmentally sensitive technologies for enhancing the biological and ecological performance of structures like breakwaters, piers, and seawalls. Ecological enhancement of concrete based CMI increases the ecosystem services provided by the structure, without hampering its structural performance, and thus should be integrated into future coastal development projects, preferably and most efficiently from early planning stages.
Coastal defences are proliferating in response to climate change, leading to the creation of more vertical substrata. Efforts are being made to mitigate their impacts and create novel habitats to promote biodiversity. Little is known about the effect of aspect (i.e. north-south directionality) and inclination on intertidal biodiversity in artificial habitats. Artificial and natural habitats were compared to assess the role of aspect and substratum inclination in determining patterns of biodiversity at two tidal heights (high and mid). We also compared grazing activity between north-and south-facing surfaces in natural habitats to examine the potential for differential grazing pressure to affect community structure and functioning. Results were variable but some clear patterns emerged. Inclination had no effect on biodiversity or abundance. There was a general trend towards greater taxon richness and abundance on north-facing than south-facing substrata in natural and artificial habitats. On natural shores, the abundance and grazing activity of 'southern' limpets (i.e. Patella depressa) was greater on south-facing than north-facing substrata, with possible implications for further range-expansion. These results highlight the importance of incorporating shaded habitats in the construction of artificial habitats. These habitats may represent an important refuge from grazing pressure and thermal and desiccation stress in a warming climate.
Underwater cities have long been the subject of science fiction novels and movies, but the "urban sprawl" of artificial structures being developed in marine environments has widespread ecological consequences. The practice of combining ecological principles with the planning, design, and operation of marine artificial structures is gaining in popularity, and examples of successful engineering applications are accumulating. Here we use case studies to explore marine ecological engineering in practice, and introduce a conceptual framework for designing artificial structures with multiple functions. The rate of marine urbanization will almost certainly escalate as "aquatourism" drives the development of underwater accommodations. We show that current and future marine developments could be designed to reduce negative ecological impacts while promoting ecosystem services.
Rapidly growing populations and expanding development are intensifying pressures on coastal ecosystems. Sea-level rise and other predicted effects of climate change are expected to exert even greater pressures on coastal ecosystems, exacerbating erosion, degrading habitat, and accelerating shoreline retreat. Historically, society’s responses to threats from erosion and shoreline retreat have relied on armoring and other engineered coastal defenses. Despite widespread use on all types of shorelines, information about the ecological impacts of shoreline armoring is quite limited. Here we summarize existing knowledge on the effects of armoring structures on the biodiversity, productivity, structure, and function of coastal ecosystems.
As well as their destructive roles, plants, animals and microorganisms
contribute to geomorphology and ecology via direct and indirect
bioprotection, which can reduce weathering and erosion. For example,
indirect bioprotection can operate via biotic influences on microclimate
whereby physical decay processes associated with fluctuations in
temperature and moisture (salt crystallization, thermal fatigue and
wetting-drying), are limited. In the intertidal zone, the spatial
and temporal distribution of macroalgae (seaweeds) is patchy, related to
physical and ecological conditions for colonization and growth, and the
nature and frequency of natural and anthropogenic disturbance. We
examined the influence of seaweed canopies (Fucus spp.) on near-surface
microclimate and, by implication, on conditions for mechanical rock
decay and under-canopy ecology. Monitoring on hard artificial coastal
structures in South West England, UK, built from limestone and concrete
showed that both the range and maxima of daily summertime temperatures
were significantly lower, by an average of 56% and 25%, respectively, in
areas colonized by seaweed compared to experimentally cleared areas.
Short-term microclimatic variability (minutes-hours) was also
significantly reduced, by an average of 78% for temperature and 71% for
humidity, under algal canopies during low-tide events. Using seaweed as
an example, we develop a conceptual model of the relationship between
biological cover and microclimate in the intertidal zone. Disturbance
events that remove or drastically reduce seaweed cover mediate shifts
between relatively stable and unstable states with respect to mechanical
decay and ecological stress associated with heat and desiccation. In
urban coastal environments where disturbance may be frequent,
facilitating the establishment and recovery of canopy-forming species on
rocks and engineered structures could enhance the durability of
construction materials as well as support conservation, planning and
policy targets for biodiversity enhancement.
Ecological engineering, defined as the design of sustainable ecosystems that integrate human society with its natural environment for the benefit of both, has developed over the last 30 years, and rapidly over the last 10 years. Its goals include the restoration of ecosystems that have been substantially disturbed by human activities and the development of new sustainable ecosystems that have both human and ecological values. It is especially needed as conventional energy sources diminish and amplification of nature's ecosystem services is needed even more. There are now several universities developing academic programs or departments called ecological engineering, ecological restoration, or similar terms, the number of manuscripts submitted to the journal Ecological Engineering continue to increase at an rapid rate, and the U.S. National Science Foundation now has a specific research focus area called ecological engineering. There are many private firms now developing and even prospering that are now specializing in the restoration of streams, rivers, lakes, forests, grasslands, and wetlands, the rehabilitation of minelands and urban brownfields, and the creation of treatment wetlands and phytoremediation sites. It appears that the perfect synchronization of academy, publishing, research resources, and practice is beginning to develop. Yet the field still does not have a formal accreditation in engineering and receives guarded acceptance in the university system and workplace alike.
The ODAS Italia 1 oceanographic buoy is moored in the Ligurian Sea, 37 nm from Genoa, along the Genoa-Cape Corse transect (43° 48.90′ N-09° 06.80′ E), over a 1270 m deep sea bottom. The underwater portion of the buoy is 37 m long and 0.60 m in diameter, acting as a small island for colonization of fouling organisms and as a fish-aggregating device (FAD). The role of the buoy in attracting and maintaining fish assemblages was investigated by visual censuses in different seasons at depths of 0–40 m. Fish from seven families, comprising 12 species, of which three are benthic, were recorded with maximum abundance in summer. Fouling was studied from samples collected on the buoy and on immersed panels. The fouling community of the buoy consisted of 34 algae and 100 animal species, including three fish. The settlement processes of the fouling community on the panels, in particular on those exposed for over 70 months at 12 m and 33 m depth, are described based on counts of settled organisms, the covering index of each taxa and biomass assessments. On the panels, 63 species were identified. The fouling biomass, on the panel submerged for 70 months, assessed as wet weight, reached 2.8 kg/m2 at 12 m depth and 4.8 kg/m2 at 33 m depth.
Observations of benthic organisms settled directly on the buoy were made between 1988 and 1989 and when the buoy was retrieved and brought back to shore on April 15, 1991 after 52 months at sea. At this time, the fouling community along the full 37 m length of the buoy was sampled, and 91 taxa, including 83 species, were identified. Several of the species present on the buoy are shallow, coastal species, some with a very short larval period. Possible ways of colonization by such species are discussed. Despite seasonal changes, the pelagic fish community was more stable over the period of 11 years of study than the benthic community settled on the buoy (that is still developing).
Year-round observations on the condition of intertidal seaweeds growing in situ on the shore, show that the upper limits of the zones characterized by Pelvetia canaliculata (L.) Done et Thur., Fucus spiralis L. and Ascophyllum nodosum (L.) Le Jol. were periodically pruned back by environmental conditions. The uppermost plants of each species showed clear signs of tissue damage 21 to 28 days after a time when drying conditions coincided with neap tides which exposed the plant to aerial conditions for long periods. High air temperatures aggravated the damage, but neither frost nor prolonged rain had any obvious adverse effects. On spring tides the plants were wetted every day and no damage resulted regardless of the weather.These species clearly all reach up to their physiological limits on the shore investigated, but presumably Fucus vesiculosus L. and F. serratus L. do not, for they were never observed to show signs of tissue damage attributable to exposure to air. Transplant experiments did, however, prove that F. serratus cannot survive in the F. spiralis zone and nor can F. spiralis persist in the Pelvetia canaliculata zone.Laboratory experiments also demonstrated that the ability to tolerate desiccation and then to resume photosynthesis and growth when re-submerged was greatest in P. canaliculata, the species found highest on the shore, and was progressively less in species inhabiting successively lower levels.
People have caused major impacts on nearshore and intertidal habitats by building infrastructure associated with shipping, recreation, residential and commercial developments. Together with the desire or need to control erosion, these have led to increased “armouring” of intertidal shorelines, with seawalls, revetments, onshore and offshore groynes and other defence systems, piers and docks replacing natural habitats. Despite the long history of such changes, until relatively recently there had been limited research on the impacts of such alterations to shorelines, especially when compared to research into effects of urbanisation on terrestrial habitats. In addition, most research to date has focussed on the impacts of such changes on the ecological structure of assemblages, i.e. the numbers and types of organisms affected, rather than on ecological processes. With the realisation that most coastal infrastructure cannot be removed, there is now an increasing research effort into ways that infrastructure can be built to meet engineering requirements, but to also increase its value as habitat – ecological engineering. In this review, we discuss the major impacts and the experimental research that has been and is being done to build coastal infrastructure in a more biodiversity-friendly manner. Much of the review has focussed on seawalls, which is where most of the experimental work has been done to date. Finally, we raise some concerns about the types of research effort that are still needed and caution against wholesale implementation of what seem like simple remedies, without evidence that they will have the desired effect in the long term.
The world is changing rapidly, ultimately due to the pressure of human population growth driving change at global, regional and local scales. There is convincing and widely accepted evidence that the climate is changing as a result of anthropogenic forcing due to greenhouse gas emissions ([Mitchell et al., 1995], [Lee et al., 2006] and [IPCC, 2007]). Increased concentrations of one greenhouse gas — carbon dioxide is causing a reduction in the pH of the oceans ([Caldeira and Wickett, 2003], [The Royal Society, 2005] and [Doney et al., 2009]). Global trade is also leading to homogenization of floras and faunas as species are deliberately and/or accidentally transported around the world ([Mack et al., 2000], [Kolar and Lodge, 2002] and [Ruiz and Carlton, 2003]; Drake and Lodge, 2004 J.M. Drake and D.M. Lodge, Global hot spots of biological invasions: evaluating options for ballast-water management, Proc. R. Soc. B. 271 (2004), pp. 575–580. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (72)[Drake and Lodge, 2004] and [Rahel, 2007]). Overfishing is occurring globally for large pelagic species at the top of food webs ([Jackson et al., 2001], [Myers and Worm, 2003], [Worm and Myers, 2003], [Heithaus et al., 2008] and [Baum and Worm, 2009]), and at a regional scale for benthic species in most shallow seas ([Solan et al., 2004], [Steneck, 2006], [Kaiser et al., 2007] and [Genner et al., 2010]). Pollution, whilst being more regulated, especially from point sources, is all pervasive (Thompson et al., 2002) and plastic litter is a global problem (Fig. 1; [Thompson et al., 2004] and [Thompson et al., 2009]). Despite preventative efforts, oil spills can still be a major threat to the marine environment ([Southward and Southward, 1978], [Gundlach et al., 1983] and [Hawkins and Southward, 1992]), with the 2010 sinking of the Deepwater Horizon oilrig in the Gulf of Mexico representing one of the worst oil disasters in United States history. The coasts are becoming increasingly developed leading to habitat loss at local and regional scales ([Lotze et al., 2006] and [Airoldi and Beck, 2007]). Responses to rising and stormier seas will inevitably lead to intervention in coastal processes as people and infrastructure will need to be protected, leading to even more coastal habitat modification and loss (Fig. 2; [Airoldi et al., 2005], [Martin et al., 2005], [Moschella et al., 2005], [Bulleri and Chapman, 2010] and [Chapman and Underwood, 2011]).
As a peak in the global number of offshore oil rigs requiring decommissioning approaches, there is growing pressure for the implementation of a "rigs-to-reefs" program in the deep sea, whereby obsolete rigs are converted into artificial reefs. Such decommissioned rigs could enhance biological productivity, improve ecological connectivity, and facilitate conservation/restoration of deep-sea benthos (eg cold-water corals) by restricting access to fishing trawlers. Preliminary evidence indicates that decommissioned rigs in shallower waters can also help rebuild declining fish stocks. Conversely, potential negative impacts include physical damage to existing benthic habitats within the "drop zone", undesired changes in marine food webs, facilitation of the spread of invasive species, and release of contaminants as rigs corrode. We discuss key areas for future research and suggest alternatives to offset or minimize negative impacts. Overall, a rigs-to-reefs program may be a valid option for deep-sea benthic conservation.
Offshore wind farms are the subject of environmental impact assessments in which potential adverse effects are identified and quantified. Those impacts will then require to be mitigated through appropriate design, construction and operation methods. Where environmental impacts cannot be mitigated, operators would be required to compensate the environment or its users for any actual or potential damage. The present study shows that the placement of offshore wind turbines gives the potential for habitat creation, which may thus be regarded as compensation for habitat lost. Using current design criteria and construction methods, the analysis here indicates that the net amount of habitat created by the most common design of offshore wind turbine, the monopile, is up to 2.5 times the amount of area lost through the placement, thus providing a net gain even though the gained habitat may be of a different character to the one that lost. Hence, the study raises important issues for marine nature conservation managers. The study also provides suggestions for further work in order to increase the empirical evidence for the value of mitigation, compensation and habitat creation. Copyright © 2009 John Wiley & Sons, Ltd.
The growth rates of two fish species, the winter flounder Pseudopleuronectes americanus (Walbaum) (19.3 to 42.6 mm total length, TL) and the tautog Tautogaonitis (Linnaeus) (23.9 to 55.9 mm TL), were used to evaluate habitat quality under and around municipal piers in the Hudson River estuary, USA. Growth rates were measured in a series of 10 d field caging-experiments conducted at two large piers in the summers of 1996 and 1997. Cages (0.64 m2) were deployed along␣transects that stretched from underneath the piers to beyond them, encompassing the pier edge (the transitional zone between the pier interior and the outside). Growth in weight (G
w
) was determined at five locations along the transect, 40 m beneath the pier, 20 m beneath the pier, at the pier edge, 20 m beyond the pier edge, and 40 m beyond. Under piers, mean growth rates of winter flounder and tautogs were negative (x¯G
W
= −0.02 d−1), and rates were comparable to laboratory-starved control fishes (x¯G
W
= −0.02 d−1). In contrast, mean growth rates at pier edges and in open waters beyond piers were generally positive (x¯G
W
ranged from −0.001 to +0.05 d−1), with growth at pier edges often being more variable and less rapid than at open-water sites. Analyses of stomach contents upon retrieval of caged fishes revealed that dry weights of food were generally higher among fishes caged at open-water stations (x¯ range = 0.02 to 0.72 mg dry wt) than at pier-edge (x¯ range = 0.01 to 0.54 mg) or under-pier (x¯ range = 0.03 to 0.11 mg) stations, although it was apparent that benthic prey were available at all stations on the transect. Our results indicate poor feeding conditions among fishes caged under piers, and suboptimal foraging among fishes caged at pier edges. Inadequate growth rates can lead to higher rates of mortality, and, based on these and other earlier experiments, we conclude that under-pier environments are poor-quality habitats for some species of juvenile fishes.
A hydrodynamic model explaining the mechanism of contact of marine larvae in vertical flows is presented. Two hydrodynamic
factors—flow vorticity and larval self-propulsion—are the key components in the mathematical model. It is shown that flow
vorticity causes a larva to rotate and change the direction of self-thrust, thus leading to its migration across the mean
flow. The latter motion is of an oscillatory nature. Contact will be enabled only for sufficiently large amplitudes of oscillations.
Simple expressions for the probability of initial contact are obtained for two-dimensional Couette and Poiseuille flows. The
three-dimensional motion of a larva in a tube is studied using the Monte-Carlo simulations. It is shown that contact probability
depends mainly on the ratio of the characteristic flow velocity and the larva’s swimming speed. The theoretical results compare
favorably with available experimental data. Possible applications of the method and results presented here to the classical
problem of larval attachment to bodies of general geometry are briefly discussed in the concluding section.
Four species of balanomorph barnacles, Balanus crenatus
Brugire, B. balanoides (L.), Elminius modestus
Darwin and Chthamalus stellatus (Poli), were studied to assess the susceptibility of intertidal barnacle species to desiccation. Known sized samples of barnacles were exposed to controlled desiccating conditions and subsequent survival and water loss were determined. It is clear that the ability to live high on the shore is dependent on a reduction of the overall permeability to water loss. Because of greater surface area to volume ratios, small stages are particularly prone to desiccation. In normal intertidal emersion periods, small stages of B. crenatus particularly, and also of B. balanoides and E. modestus which are similar in their desiccation resistance, would be susceptible to desiccation at normal temperatures and low humidities. Large barnacles would be more prone to death from high temperatures when the tide is out. The spat of C. stellatus, although surviving much longer than spat of larger dimensions of the other species, must also be prone to prolonged emersion conditions at high shore levels.
We examined feeding success of young-of-the-year winter flounder (Pseudopleuronectes americanus Walbaum) (20–50 mm TL) around a large, municipal pier in the Hudson River estuary, USA. Replicate, 3-h feeding experiments
were conducted using benthic cages (0.64 m2) deployed under, at the edge, and outside of the pier during late spring and early summer in 1998 and 1999. Significantly
more winter flounder caged under piers had empty stomachs (
[`(x)]\bar x
=71.9%) than at the edge or in open water (
[`(x)]\bar x
=29.2% and 14.4%, respectively). Feeding intensity was significantly higher outside of the pier (
[`(x)]\bar x
=0.40%) than the edge or under the pier (
[`(x)]\bar x
=0.19% and 0.03%, respectively). Simultaneous with feeding experiments, benthic core samples were collected adjacent to cages.
Variability was high, but abundances of prey were consistently higher under the pier (
[`(x)]\bar x
=200.14±113.3 SD in 1998; 335±290.2 in 1999) than at the edge (
[`(x)]\bar x
=126.6±50.2 in 1998; 70.8±68.5 in 1999) or in open water (
[`(x)]\bar x
=53.4±16.1 in 1998; 123.8±193.9 in 1999). No significant differences in prey biomass were determined, suggesting that small,
numerous prey were available under the pier and fewer, larger taxa were present at the edge and outside. Data indicate that
feeding is suppressed among young-of-the-year winter flounder caged under piers in spite of sufficient prey available. Based
on these and other experiments we submit that areas under piers are not suitable long-term habitats for juvenile fish because
they interfere with normal feeding activities.
Worldwide demand for renewable energy is increasing rapidly because of the climate problem, and also because oil resources are limited. Wind energy appears as a clean and good solution to cope with a great part of this energy demand. As space is becoming scarce for the installation of onshore wind turbines, offshore wind energy becomes a good alternative. Renewable electricity from wind power can contribute to achieving Kyoto targets for sustainable energy development, but the green image of wind power may be jeopardized if wildlife is adversely affected. This paper deals with a brief revision of the status and development plans of offshore wind power, followed by a critical discussion about the existing challenges and attendant environmental impacts facing the offshore wind energy. Based on the discussions, suggestions are also recommended.
A 4-yr study on the motile epibionts colonizing hydroids on a floating dock in a South Carolina estuary indicated that the motile epibiotic community may impact benthic and nektonic community processes. Permanent members of the epibiotic community were preyed upon by fish, especially when the Atlantic silverside (Menidia menidia (L.)) became reproductively active and deposited eggs among the hydroids during the spring. When fish predation reduced the number of amphipods within the epibiotic community, crab megalopa colonized the hydroids. Crabs developed into juveniles and emigrated from the epibiotic community after 6–8 wk residence. The community on floating docks may be an important food source for some nekton and may recruit some benthic invertebrates.Although preferential larval settlement and fish predation are intuitive processes associated with floating dock communities, insufficient research has addressed the relationships in soft-bottom areas devoid of naturally occurring hard substrata.
Urban structures in the form of pontoons and pilings represent major coastal habitats for marine organisms and understanding the factors causing abundances of organisms to differ between these and natural habitat has been neglected in the study of coastal ecology. It has been proposed that composition of substrata explain differences previously described between subtidal assemblages of epibiota on rocky reef (sandstone) and pontoons (concrete) in Sydney Harbour, Australia. This study tested the hypothesis that differences in the composition of substratum (sandstone vs. concrete) independent of type of habitat (rocky reef vs. pontoon) affects the development of epibiotic assemblages. This was tested by experimentally providing substratum of the two types in both habitats. Epibiotic assemblages were unaffected by the composition of substratum but strongly affected by the type of habitat; demonstrating that pontoons constitute novel habitats for epibiota. This result highlights a need for determining how current ecological understanding of subtidal epibiota, which is heavily based on studies of urban structures (pilings and pontoons), relates to natural reef. Future tests of hypotheses about the nature of these differences will not only contribute to better ecological understanding of epibiota and their use of urban structures as habitats, but also to better predictions of future changes to the ecology of coastal habitats.