Types Of Artificial Structures Research Articles

Influence of habitat features on the colonisation of native and non-indigenous species

Marine artificial structures provide substrates on which organisms can settle and grow. These structures facilitate establishment and spread of non-indigenous species, in part due to their distinct physical features (substrate material, movement, orientation) compared to natural habitat analogues such as rocky shores, and because following construction, they have abundant resources (space) for species to colonise. Despite the perceived importance of these habitat features, few studies have directly compared distributions of native and non-indigenous species or considered how functional identity and associated environmental preferences drive associations. We undertook a meta-analysis to investigate whether colonisation of native and non-indigenous species varies between artificial structures with features most closely resembling natural habitats (natural substrates, fixed structures, surfaces oriented upwards) and those least resembling natural habitats (artificial materials, floating structures, downfacing or vertical surfaces), or whether functional identity is the primary driver of differences. Analyses were done at global and more local (SE Australia) scales to investigate if patterns held regardless of scale. Our results suggest that functional group (i.e., algae, ascidians. barnacles, bryozoans, polychaetes) rather than species classification (i.e., native or non-indigenous) are the main drivers of differences in communities between different types of artificial structures. Specifically, there were differences in the abundance of ascidians, barnacles, and polychaetes between (1) upfacing and downfacing/vertical surfaces, and (2) floating and fixed substrates. When differences were detected, taxa were most abundant on features least resembling natural habitats. Results varied between global and SE Australian analyses, potentially due to reduced variability across studies in the SE Australian dataset. Thus, the functional group and associated preferences of the highest threat NIS in the area should be considered in design strategies (e.g., ecological engineering) to limit their establishment on newly built infrastructure.

Application of DNA molecules in nature- inspired technologies: a mini review

The DNA molecule is considered as an object of nature-like technologies, with the focus on the special electromagnetic properties of DNA-like helices. This is the difference from the traditional approach to the DNA molecule as the repository of genetic information. DNA-like helices are regarded as artificial micro-resonators, or “meta-atoms,” exhibiting both dielectric and magnetic properties, that are equally pronounced. The article presents methods for creating spatial structures directly from DNA molecules, as well as from DNA-like helices. It is shown that the design of metamaterials and metasurfaces should be carried out considering the special electromagnetic properties of DNA-like helices. This will make it possible to obtain the required properties of metamaterials and metasurfaces and achieve advantages over other types of artificial structures.

Nonlinear vibration analysis of a pyramid lattice sandwich plate in subsonic airflow

The lattice sandwich structure is a new type of artificial structure developed in recent years. It is light in weight and rigid in stiffness, which is naturally suitable for the aviation engineering. This article deals with the subsonic aerodynamic stability and nonlinear forced vibration properties of this particular structure, which exactly describes the application of this structure as the outer surfaces of the aircraft. In this article, the coupled equation of motion of the lattice sandwich plate interacting with subsonic external airflow is established based on the nonlinear plate theory and the linear potential flow theory. The stability of the system is analyzed by monitoring the variations of the natural frequencies of the system with different flow velocities. The steady state responses of the structure are analyzed by using the incremental harmonic balance method. The effects of the design parameters of the lattice sandwich plate on the nonlinear responses of the system are discussed. Based on the theoretical and numerical analysis, some suggestions for the optimal design of the lattice sandwich plate in aerodynamic environment are proposed.

Coastal armouring affects intertidal biodiversity across the Alboran Sea (Western Mediterranean Sea)

Intertidal ecosystems are key habitats that are being replaced by artificial hard substrates due to the increment of human activities in coastal areas. These new substrates host generally less biodiversity mainly due to differences in complexity and composition. This is a global phenomenon and has led to the development of strategies in the framework of eco-engineering. However, mitigating measures, such as new eco-designs, must cope with the high spatial variability of the region where they are applied. Therefore, in order to assess if differences in biodiversity detected at local scales in previous studies could be scaled up to predict patterns at a wider scale, we studied taxa richness and taxonomic structure of intertidal communities across the Alboran Sea (western Mediterranean Sea). We compared four different types of artificial substrates (cubes, rip-raps, seawalls and tetrapods) to assess which produces less impact. Overall, artificial substrates host low benthic biodiversity, specially on seawalls, whereas boulder-like artificial structures such as rip-raps were more similar to natural ones. Nevertheless, the effect of a particular type of artificial structure at a regional scale seems unpredictable, highlighting the challenge that eco-engineering measures face in order to establish global protocols for biodiversity enhancement and the importance of local scale in management programmes.

Artificial shorelines lack natural structural complexity across scales.

From microbes to humans, habitat structural complexity plays a direct role in the provision of physical living space, and increased complexity supports higher biodiversity and ecosystem functioning across biomes. Coastal development and the construction of artificial shorelines are altering natural landscapes as humans seek socio-economic benefits and protection from coastal storms, flooding and erosion. In this study, we evaluate how much structural complexity is missing on artificial coastal structures compared to natural rocky shorelines, across a range of spatial scales from 1 mm to 10 s of m, using three remote sensing platforms (handheld camera, terrestrial laser scanner and uncrewed aerial vehicles). Natural shorelines were typically more structurally complex than artificial ones and offered greater variation between locations. However, our results varied depending on the type of artificial structure and the scale at which complexity was measured. Seawalls were deficient at all scales (approx. 20–40% less complex than natural shores), whereas rock armour was deficient at the smallest and largest scales (approx. 20–50%). Our findings reinforce concerns that hardening shorelines with artificial structures simplifies coastlines at organism-relevant scales. Furthermore, we offer much-needed insight into how structures might be modified to more closely capture the complexity of natural rocky shores that support biodiversity.

Invasive ascidians: How predators reduce their dominance in artificial structures in cold temperate areas

Artificial structures can provide suitable space for invasive species through a colonisable surface and refuge against predators. Besides several physical factors, invasive species can present different colonization success and dominance on structures that are connected to the sea floor (i.e. fixed) compared to structures that are suspended, depending on the differential predation pressure that affect both structures. Benthic and nektonic predators can reach fouling communities on fixed structures, while only nektonic predators can affect communities growing on suspended structures, depending on the distance to the sea floor. Only few studies tested both communities of predators at the same time in different artificial structures. In this study, we evaluated the effect of benthic and nektonic predators on the cover, composition and diversity on fouling communities and on the dominance of invasive ascidians on these communities, in two different types of artificial structures. We performed an experiment in the port area of Puerto Madryn (Southwestern Atlantic, Argentina) to compare the fouling community development between fixed and suspended structures and among different predator exclusion treatments. Results showed that benthic predators exerted a higher predation pressure than nektonic predators on the cover, composition and diversity of the fouling communities. In the absence of benthic predators, and even where nektonic predators were not excluded, communities were greatly dominated by two invasive ascidians, Ascidiella aspersa (Müller, 1776) and Ciona robusta Hoshino and Tokioka, 1967. Our results suggest that in this type of cold temperate ports, fouling organisms find refuge from benthic predators growing on suspended structures, where nektonic predators exert low predation pressure. We propose that, since benthic predators in temperate latitudes have an essential role decreasing invasive ascidians dominance and the cover of fouling communities, future studies should consider both predator communities, i.e. nektonic and benthic, in experimental designs performed to test biotic resistance and predation pressure.

Do artificial structures affect the diet of the limpet Patella caerulea Linnaeus, 1758?

The current scenario of global change and the increase of human population in coastal areas is leading to the introduction of numerous man-made structures into the coastal environment. Those artificial structures provide different services at the expenses of habitat loss and a range of widely documented ecological impacts. Limpets are keystone species that are worldwide established in these artificial habitats. However, little is known about the impact of artificial coastal defence structures on the diet of limpets. Therefore, the aim of this study was to evaluate if different kinds of artificial structures (cubes, rip-raps, seawalls and tetrapods) across a geographical gradient (western to eastern Alboran Sea), could affect the food consumption of the limpet Patella caerulea by using carbon and nitrogen isotopes analysis. Our results suggested that for certain localities, there was a shift in the trophic niche of P. caerulea inhabiting artificial substrates in comparison with the nearest natural rocky shore. However, patterns were not consistent for all localities and different types of artificial structures, which reinforces the importance of considering local scales for conservation and management purposes. Finally, δ15N ratio in P. caerulea is a good indicator of eutrophication at regional scales, by showing a gradient of enrichment in the limpet tissues from oligotrophic to eutrophic waters within the Alboran Sea.

The microbiome and biodiversity hypothesis of health

Artificial structures are agents of change in marine ecosystems. They add novel habitat for hard-substrate organisms and modify the surrounding environment. Most research to date has focused on the communities living directly on artificial structures, and more research is needed on the potential impacts these structures have on nearby communities and the surrounding environment. We compared the sedimentary habitat surrounding two types of artificial structures (pilings and seawalls) to sediments adjacent to rocky reefs using a combination of traditional sediment analyses, stable isotope analysis, and environmental DNA. Artificial and natural shore sediments were best differentiated by sediment variables strongly associated with flow speed. Pilings sediments had significantly finer grain size, higher organic content, and generally lower C:N ratios than sediments adjacent to the other habitat types, suggesting flow is reduced by pilings. Sedimentary assemblages near pilings were also consistent with those predicted under low-flow conditions, with elevated bacterial colonization and increased relative abundances of small deposit feeders compared with other habitat types. Additionally, lumbrinerid polychaetes in pilings sediments had reduced δ15N values, suggesting different detrital resources and fewer trophic linkages compared with lumbrinerids in other habitats. Woody detritus was greater adjacent to seawalls than to natural rocky shores or pilings. Our findings suggest that artificial structures have the potential to influence adjacent soft sediments through changes to sediment properties that affect infaunal and microbial communities, as well as trophic linkages for some consumers. We hypothesize that this is due to a combination of altered flow, differing detrital subsidies, and differing adjacent land-use among habitat types. Managers should consider the potential for changed sediment properties and ecology when deciding where to build different types of artificial structures. Further manipulative experiments are needed to understand mechanisms of change and help manage the impacts of artificial structures on the seafloor.

Not all artificial structures are created equal: Pilings linked to greater ecological and environmental change in sediment communities than seawalls

Artificial structures are agents of change in marine ecosystems. They add novel habitat for hard-substrate organisms and modify the surrounding environment. Most research to date has focused on the communities living directly on artificial structures, and more research is needed on the potential impacts these structures have on nearby communities and the surrounding environment. We compared the sedimentary habitat surrounding two types of artificial structures (pilings and seawalls) to sediments adjacent to rocky reefs using a combination of traditional sediment analyses, stable isotope analysis, and environmental DNA. Artificial and natural shore sediments were best differentiated by sediment variables strongly associated with flow speed. Pilings sediments had significantly finer grain size, higher organic content, and generally lower C:N ratios than sediments adjacent to the other habitat types, suggesting flow is reduced by pilings. Sedimentary assemblages near pilings were also consistent with those predicted under low-flow conditions, with elevated bacterial colonization and increased relative abundances of small deposit feeders compared with other habitat types. Additionally, lumbrinerid polychaetes in pilings sediments had reduced δ15N values, suggesting different detrital resources and fewer trophic linkages compared with lumbrinerids in other habitats. Woody detritus was greater adjacent to seawalls than to natural rocky shores or pilings. Our findings suggest that artificial structures have the potential to influence adjacent soft sediments through changes to sediment properties that affect infaunal and microbial communities, as well as trophic linkages for some consumers. We hypothesize that this is due to a combination of altered flow, differing detrital subsidies, and differing adjacent land-use among habitat types. Managers should consider the potential for changed sediment properties and ecology when deciding where to build different types of artificial structures. Further manipulative experiments are needed to understand mechanisms of change and help manage the impacts of artificial structures on the seafloor.

Benthic assemblages, biodiversity and invasiveness in marinas and commercial harbours: an investigation using a bioindicator group

Fouling communities on artificial marine structures are generally different from benthic communities in natural rocky habitats. However, they may also differ among different types of artificial structures. Two artificial structures in direct contact with arriving vessels were compared: floating pontoons within recreational marinas, and sea-walls within commercial harbours. Natural rocky habitats were used as a reference, and the genus Eudendrium (Cnidaria, Hydrozoa) was chosen as a bioindicator. The assemblages were different among the three types of habitat studied, with different species characterising each habitat. The probability of finding an invasive Eudendrium species was significantly higher on pontoons. Diversity was the lowest on pontoons, but it was not significantly different between sea-walls and natural rocks. In general, a barrier to the spread of exotic species exists between harbours and natural rocky habitats. Floating pontoons seem to be a less suitable habitat for native fauna and a key element in marine biological invasions.

Land, Sea and Skyscape: Two Case Studies of Man-made Structures in the Azores Islands

The exploration of the Mediterranean seascape goes back to the foragers of the early Holocene period around the ninth millennium BCE. Two case studies in the Azores islands show possible integration of elements of landscape, seascape and skyscape in the way two different types of artificial structures were aligned. The major axes of the Maroiço structures from Pico Island may have been aligned on the summit of Pico Mountain and, reciprocally, on the setting sun at the summer solstice over the neighbouring Faial Island. The artificial caves near the sea excavated in Monte Brasil, Terceira Island, may have integrated solar calendrical marks, especially for the Equinox sunset over the distant S. Jorge Island.

Artificial Petal Effect on Nanofibrillar Parylene™ Surface

The hierarchical structure on a rose petal surface achieves a large contact angle with high contact angle hysteresis. Inspired by the petal effect, two types of artificial structures, fibril mesh and fibril microhills, were fabricated and compared with the rose petal surface. The fibril mesh, composed of Parylene™ nanofibrils and underneath capillary structures was fabricated using template-assisted deposition. The fibril microhills were formed by peeling the fibril mesh off. The contact angle and contact angle hysteresis on these two surfaces treated by various surface modifications for enhancing the hydrophobicity were measured. The fabricated surface showed similar wetting behavior to the rose petal which is hydrophobic and sticky to water droplets. The relation between the contact angle and the contact angle hysteresis on the various artificial surfaces and the rose petal were discussed. The qualitative estimations of the contact angle hysteresis for the various artificial surfaces were presented.

Land, Sea and Skyscape: Two Case Studies of Man-made Structures in the Azores Islands

Two case studies in the Azores islands show possible integration of elements of landscape, seascape and skyscape in the way two different types of artificial structures were aligned. The major axes of the Maroiço structures from Pico Island may have been aligned on the summit of Pico Mountain and, reciprocally, on the setting sun at summer solstice over the neighbouring Faial Island. The artificial caves near the sea excavated in Monte Brasil, Terceira Island, may have integrated solar calendrical marks, especially for the Equinox sunset over the distant S. Jorge Island.

Mussel beds on different types of structures support different macroinvertebrate assemblages

Abstract Artificial structures, such as seawalls, pilings and pontoons, are common features of urban estuaries. They replace natural structures or add to the amount of hard substratum in an area and provide habitats for many fish and invertebrates. Previous work has concentrated on fish or on the invertebrates that occupy the primary substratum of artificial structures. Mussels often grow on different types of structures (pontoons, pilings, seawalls and natural reefs) and provide a secondary substratum for other organisms to inhabit. Counting and identifying organisms associated with mussel beds is traditionally done to species level, which is very time‐consuming. To save time, organisms in this study were identified to coarse levels of taxonomic resolution (a mix of taxa, such as class, order, family and genus), which showed similar patterns to those when particularly speciose and abundant groups were identified to species. This study tests hypotheses that the distribution and abundance of mobile and sessile organisms that inhabit mussel beds will differ among natural and various types of artificial structures. When the associated assemblages of mussel beds from different types of structures and from different locations were examined, assemblages varied according to the type of structure they inhabited and its location. Assemblages associated with mussels on pontoons differed consistently from those on other types of structures. Patterns in the assemblages were also consistent through time. These data show that the types and amounts of artificial structures added to an environment can affect the types, distribution and abundances of organisms living in biogenic habitats.

Assemblages of animals around urban structures: testing hypotheses of patterns in sediments under boat-mooring pontoons

Assemblages of animals in soft-sediments were studied in relation to pontoons for mooring private boats in two estuaries near Sydney, Australia. Based on previously observed patterns around other types of artificial structures, it was predicted that assemblages of animals under pontoons would be different from those in similar areas away from pontoons. Hypotheses about overall differences in average abundance and composition between sites with and without pontoons were tested, as were hypotheses about variable differences among and within estuaries. Analyses revealed that there were fewer crustaceans under pontoons in one estuary. The most conspicuous patterns related to pontoons were, however, differences in variability among sites with pontoons compared to sites without pontoons. Differences in spatial variability were found for the overall multivariate structure using Bray–Curtis dissimilarities and for abundances of most major taxa. Total abundance was approximately 60 times more variable among sites without pontoons and number of taxa were seven times more variable among sites with pontoons. Such patterns indicate that impacts of pontoons occur at some sites but not at others. This may be explained by intrinsic differences among sites or by differences in practices for maintenance. Predictions from these two contrasting models need to be tested in order to achieve efficient management of this type of structure.