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with the proliferation of coastal defences. This is an adaptation option (sensu IPCC 2014) that has been adopted worldwide to protect the growing coastal population and its property, transport infrastructure, industry and commerce, as well as valuable amenity and recreational areas (for review, see chapters in Burcharth et al. 2007, Zanuttigh et al. 2014). In this review, we discuss current evidence and thinking on biodiversity and ecosystem responses to global drivers of change, with a focus on recent rapid climate change and its interaction with regional and local impacts due to 'ocean sprawl'-the proliferation of artificial structures in the sea. We consider how efforts to combat climate change, such as mitigation via offshore renewables ('green' energies to reduce CO 2 emissions), and adaptation via sea defences are leading to a proliferation of artificial structures, resulting in changes in the proportion of hard versus soft coastal habitats, the distribution of species, assemblage composition, and community structure. We also discuss the role of coastal development, including ports and other transport infrastructure as well as offshore structures (e.g., oil and gas platforms), in altering coastal and marine ecosystem structure and functioning. Finally, we undertake a critical review of the current 'state of the art' in the emerging field of 'green engineering', which combines environmentally conscious attitudes, values, and principles with science, technology, and engineering practice, all directed towards improving local and global environmental quality. Our scope is the global coastline extending vertically to the uppermost extent of tidal influence, with particular emphasis on open coasts and offshore structures that have seen the most research. This is in contrast to the freshwater tidal reaches of estuaries, which have received little attention (but see Francis & Hoggart 2008, 2009, Hoggart et al. 2012). Many of the case studies and examples are drawn from temperate systems in developed countries, reflecting the experience of the authors and the distribution of published research. Two themes permeate our review: firstly, how ecosystem services are at risk from modification of the coast by artificial structures; secondly, the interaction between the provision of new 'hard' substratum as a societal adaptation response, resulting in altered habitat connectivity and changes in the distribution of species and composition of assemblages. We conclude by identifying current knowledge gaps and future research needs. Burgeoning coastal human populations The diversity of coastal habitats includes rocky shores, sandy and muddy beaches, barriers, spits and sand dunes, estuaries and lagoons, deltas, wetlands, and coral reefs. These individually and K27072_C004.indd 190 6/15/16 12:57 PM 191 OCEAN SPRAWL collectively provide a disproportionately greater number of ecosystem services (see Millennium Ecosystem Assessment [MEA] 2005 for a discussion of provisioning, regulating, supporting, and cultural services) to human ...

Abstract1. Along urbanised coastlines, urban infrastructure is increasingly becoming the dominant habitat. These structures are often poor surrogates for natural habitats, and a diversity of eco-engineering approaches have been trialled to enhance their biodiversity, with varying success.2. We undertook a quantitative meta-analysis and qualitative review of 109 studies to compare the efficacy of common eco-engineering approaches (e.g. increasing texture, crevices, pits, holes, elevations and habitat-forming taxa) in enhancing the biodiversity of key functional groups of organisms, across a variety of habitat settings and spatial scales.3. All interventions, with one exception, increased the abundance or number of species of one or more of the functional groups considered. Nevertheless, the magnitude of effect varied markedly among groups and habitat settings. In the intertidal, interventions that provided moisture and shade had the greatest effect on the richness of sessile and mobile organisms, while water-retaining features had the greatest effect on the richness of fish. In contrast, in the subtidal, small-scale depressions which provide refuge to new recruits from predators and other environmental stressors such as waves, had higher abundances of sessile organisms while elevated structures had higher numbers and abundances of fish. The taxa that responded most positively to eco-engineering in the intertidal were those whose body size most closely matched the dimensions of the resulting intervention. Synthesis and applications. The efficacy of eco-engineering interventions variesamong habitat settings and functional groups. This indicates the importance of developing site-specific approaches that match the target taxa and dominant stressors. Furthermore, because different types of intervention are effective at enhancing different groups of organisms, ideally a range of approaches should be applied simultaneously to maximise niche diversity. K E Y W O R D Sartificial structure, crevice, depression, eco-engineering interventions, habitat-forming species, microhabitat, protrusion, rockpool, seeding, urban infrastructure

Firth, L. B., Thompson, R. C., Bohn, K., Abbiati, M., Airoldi, L., Bouma, T. J., Bozzeda, F., Ceccherelli, V. U., Colangelo, M. A., Evans, A., Ferrario, F., Hanely, M. E., Hinz, H., Hoggart, S. P. G., Jackson, J. E., Moore, P., Morgan, E. H., Perkol-Finkel, S., Skov, M. W., Strain, E. M., van Belzen, J., Hawkins, S. J. (2014). Between a rock and a hard place: Environmental and engineering considerations when designing coastal defence structures. Coastal Engineering, 87, 122-135Coastal defence structures are proliferating as a result of rising sea levels and stormier seas. With the realisation that most coastal infrastructure cannot be lost or removed, research is required into ways that coastal defence structures can be built to meet engineering requirements, whilst also providing relevant ecosystem services so-called ecological engineering. This approach requires an understanding of the types of assemblages and their functional roles that are desirable and feasible in these novel ecosystems. We review the major impacts coastal defence structures have on surrounding environments and recent experiments informing building coastal defences in a more ecologically sustainable manner. We summarise research carried out during the THESEUS project (2009-2014) which optimised the design of coastal defence structures with the aim to conserve or restore native species diversity. Native biodiversity could be manipulated on defence structures through various interventions: we created artificial rock pools, pits and crevices on breakwaters; we deployed a precast habitat enhancement unit in a coastal defence scheme; we tested the use of a mixture of stone sizes in gabion baskets; and we gardened native habitat-forming species, such as threatened canopy-forming algae on coastal defence structures. Finally, we outline guidelines and recommendations to provide multiple ecosystem services while maintaining engineering efficacy. This work demonstrated that simple enhancement methods can be cost-effective measures to manage local biodiversity. Care is required, however, in the wholesale implementation of these recommendations without full consideration of the desired effects and overall management goals. (C) 2013 Elsevier B.V. All rights reserved.authorsversionPeer reviewe

Aim Artificial coastal defence structures are proliferating in response to rising and stormier seas. These structures provide habitat for many species but generally support lower biodiversity than natural habitats. This is primarily due to the absence of environmental heterogeneity and water-retaining features on artificial structures. We compared the epibiotic communities associated with artificial coastal defence structures and natural habitats to ask the following questions: (1) is species richness on emergent substrata greater in natural than artificial habitats and is the magnitude of this difference greater at mid than upper tidal levels; (2) is species richness greater in rock pools than emergent substrata and is the magnitude of this difference greater in artificial than natural habitats; and (3) in artificial habitats, is species richness in rock pools greater at mid than upper tidal levels?Location British Isles.Methods Standard non-destructive random sampling compared the effect of habitat type and tidal height on epibiota on natural rocky shores and artificial coastal defence structures.Results Natural emergent substrata supported greater species richness than artificial substrata. Species richness was greater at mid than upper tidal levels, particularly in artificial habitats. Rock pools supported greater species richness than emergent substrata, and this difference was more pronounced in artificial than natural habitats. Rock pools in artificial habitats supported greater species richness at mid than upper tidal levels.Main conclusions Artificial structures support lower biodiversity than natural habitats. This is primarily due to the lack of habitat heterogeneity in artificial habitats. Artificial structures can be modified to provide rock pools that promote biodiversity. The effect of rock pool creation will be more pronounced at mid than upper tidal levels. The challenge now is to establish at what tidal height the effect of pools becomes negligible and to determine the rock pool dimensions for optimum habitat enhancement.

Coastal defences are proliferating in response to anticipated climate change and there is increasing need for ecologically sensitive design in their construction. Typically, these structures support lower biodiversity than natural rocky shores. Although several studies have tested habitat enhancement interventions that incorporate novel water-retaining features into coastal defences, there remains a need for additional long-term, fully replicated trials to identify alternative cost-effective designs. We created artificial rock pools of two depths (12cm, 5cm) by drill-coring into a shore-parallel intertidal granite breakwater, to investigate their potential as an intervention for delivering ecological enhancement. After 18 months the artificial rock pools supported greater species richness than adjacent granite rock surfaces on the breakwater, and similar species richness to natural rock pools on nearby rocky shores. Community composition was, however, different between artificial and natural pools. The depth of artificial rock pools did not affect richness or community structure. Although the novel habitats did not support the same communities as natural rock pools, they clearly provided important habitat for several species that were otherwise absent at mid-shore height on the breakwater. These findings reveal the potential of drill-cored rock pools as an affordable and easily replicated means of enhancing biodiversity on a variety of coastal defence structures, both at the design stage and retrospectively.

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Biogenic reefs are important for habitat provision and coastal protection. Long-term datasets on the distribution and abundance of Sabellaria alveolata (L.) are available from Britain. The aim of this study was to combine historical records and contemporary data to (1) describe spatiotemporal variation in winter temperatures, (2) document short-term and long-term changes in the distribution and abundance of S. alveolata and discuss these changes in relation to extreme weather events and recent warming, and (3) assess the potential for artificial coastal defense structures to function as habitat for S. alveolata. A semi-quantitative abundance scale (ACFOR) was used to compare broadscale, long-term and interannual abundance of S. alveolata near its range edge in NW Britain. S. alveolata disappeared from the North Wales and Wirral coastlines where it had been abundant prior to the cold winter of 1962/1963. Population declines were also observed following the recent cold winters of 2009/2010 and 2010/2011. Extensive surveys in 2004 and 2012 revealed that S. alveolata had recolonized locations from which it had previously disappeared. Furthermore, it had increased in abundance at many locations, possibly in response to recent warming. S. alveolata was recorded on the majority of artificial coastal defense structures surveyed, suggesting that the proliferation of artificial coastal defense structures along this stretch of coastline may have enabled S. alveolata to spread across stretches of unsuitable natural habitat. Long-term and broadscale contextual monitoring is essential for monitoring responses of organisms to climate change. Historical data and gray literature can be invaluable sources of information. Our results support the theory that Lusitanian species are responding positively to climate warming but also that short-term extreme weather events can have potentially devastating widespread and lasting effects on organisms. Furthermore, the proliferation of coastal defense structures has implications for phylogeography, population genetics, and connectivity of coastal populations.