Design options, Implementation Issues and Evaluating Success of 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 shoreline

Little evidence that lowering the pH of concrete supports greater biodiversity on tropical and temperate seawalls

Concrete is one of the most commonly used materials in the construction of coastal and marine infrastructure despite the well known environmental impacts which include a high carbon footprint and high alkalinity (~pH 13). There is an ongoing discussion regarding the potential positive effects of lowered concrete pH on benthic biodiversity, but this has not been investigated rigorously. Here, we designed a manipulative field experiment to test whether carbonated (lowered pH) concrete substrates support greater species richness and abundance, and/or alter community composition, in both temperate and tropical intertidal habitats. We constructed 192 experimental concrete tiles, half of which were carbonated to a lower surface pH of 7-8 (vs. control pH of &gt;9), and affixed them to seawalls in the United Kingdom and Singapore. There were 2 sites per country, and 6 replicate tiles of each treatment were collected at 4 time points over a year. Overall, we found no significant effect of lowered pH on the abundance, richness, or community assemblage in both countries. Separate site- and month-specific generalised linear models (GLMs) showed only sporadic effects: i.e. lowered pH tiles had a small positive effect on early benthic colonisation in the tropics but this was later succeeded by similar species assemblages regardless of treatment. Thus, while it is worth considering the modification of concrete from an environmental/emissions standpoint, lowered pH may not be a suitable technique for enhancing biodiversity in the marine built environment.</jats:p

Coastal greening of grey infrastructure: an update on the state-of-the-art

\ua9 2023 Emerald Publishing Limited: All rights reserved.In the marine environment, greening of grey infrastructure (GGI) is a rapidly growing field that attempts to encourage native marine life to colonize marine artificial structures to enhance biodiversity, thereby promoting ecosystem functioning and hence service provision. By designing multifunctional sea defences, breakwaters, port complexes and off-shore renewable energy installations, these structures can yield myriad environmental benefits, in particular, addressing UN SDG 14: Life below water. Whilst GGI has shown great promise and there is a growing evidence base, there remain many criticisms and knowledge gaps, and some feel that there is scope for GGI to be abused by developers to facilitate harmful development. Given the surge of research in this field in recent years, it is timely to review the literature to provide an update update on the state-of-the-art of the field in relation to the many criticisms and identify remaining knowledge gaps. Despite the rapid and significant advances made in this field, there is currently a lack of science and practice outside of academic sectors in the developed world, and there is a collective need for schemes that encourage intersectoral and transsectoral research, knowledge exchange, and capacity building to optimize GGI in the pursuit of contributing to sustainable development

Evaluating seaweed farming as an eco-engineering strategy for ‘blue’ shoreline infrastructure

Ecological Engineerin

Modelling surface temperature of granite seawalls in Singapore

10.1016/j.csite.2019.100395Case Studies in Thermal Engineering13100395-10039

Current and projected global extent of marine built structures

The sprawl of marine construction is one of the most extreme human modifications to global seascapes. Nevertheless, its global extent remains largely unquantified compared to that on land. We synthesized disparate information from a diversity of sources to provide a global assessment of the extent of existing and projected marine construction and its effects on the seascape. Here we estimated that the physical footprint of built structures was at least 32,000 km2 worldwide as of 2018, and is expected to cover 39,400 km2 by 2028. The area of seascape modified around structures was 1.0–3.4 × 106 km2 in 2018 and was projected to increase by 50–70% for power and aquaculture infrastructure, cables and tunnels by 2028. In 2018, marine construction affected 1.5% (0.7–2.4%) of global Exclusive Economic Zones, comparable to the global extent of urban land estimated at 0.02–1.7%. This study provides a critical baseline for tracking future marine human development

Identifying the consequences of ocean sprawl for sedimentary habitats

Extensive development and construction in marine and coastal systems is driving a phenomenon known as “ocean sprawl”. Ocean sprawl removes or transforms marine habitats through the addition of artificial structures and some of the most significant impacts are occurring in sedimentary environments. Marine sediments have substantial social, ecological, and economic value, as they are rich in biodiversity, crucial to fisheries productivity, and major sites of nutrient transformation. Yet the impact of ocean sprawl on sedimentary environments has largely been ignored. Here we review current knowledge of the impacts to sedimentary ecosystems arising from artificial structures. Artificial structures alter the composition and abundance of a wide variety of sediment-dependent taxa, including microbes, invertebrates, and benthic-feeding fishes. The effects vary by structure design and configuration, as well as the physical, chemical, and biological characteristics of the environment in which structures are placed. The mechanisms driving effects from artificial structures include placement loss, habitat degradation, modification of sound and light conditions, hydrodynamic changes, organic enrichment and material fluxes, contamination, and altered biotic interactions. Most studies have inferred mechanism based on descriptive work, comparing biological and physical processes at various distances from structures. Further experimental studies are needed to identify the relative importance of multiple mechanisms and to demonstrate causal relationships. Additionally, past studies have focused on impacts at a relatively small scale, and independently of other development that is occurring. There is need to quantify large-scale and cumulative effects on sedimentary ecosystems as artificial structures proliferate. We highlight the importance for comprehensive monitoring using robust survey designs and outline research strategies needed to understand, value, and protect marine sedimentary ecosystems in the face of a rapidly changing environment

ESTABLISHED AND EMERGING TECHNIQUES FOR CHARACTERISING THE FORMATION, STRUCTURE AND PERFORMANCE OF CALCIFIED STRUCTURES UNDER OCEAN ACIDIFICATION

Ocean acidification (OA) is the decline in seawater pH and saturation levels of calcium carbonate (CaCO3) minerals that has led to concerns for calcifying organisms such as corals, oysters and mussels because of the adverse effects of OA on their biomineralisation, shells and skeletons. A range of cellular biology, geochemistry and materials science approaches have been used to explore biomineralisation. These techniques have revealed that responses to seawater acidification can be highly variable among species, yet the underlying mechanisms remain largely unresolved. To assess the impacts of global OA, researchers will need to apply a range of tools developed across disciplines, many of which are emerging and have not yet been used in this context. This review outlines techniques that could be applied to study OA-induced alterations in the mechanisms of biomineralisation and their ultimate effects on shells and skeletons. We illustrate how to characterise, quantify and monitor the process of biomineralisation in the context of global climate change and OA. We highlight the basic principles, as well as the advantages and disadvantages, of established, emerging and future techniques for OA researchers. A combination of these techniques will enable a holistic approach and better understanding of the potential impact of OA on biomineralisation and its consequences for marine calcifiers and associated ecosystems