Building blue infrastructure: Assessing the key environmental issues and priority areas for ecological engineering initiatives in Australia's metropolitan embayments

Current extent and future opportunities for living shorelines in Australia

Living shorelines aim to enhance the resilience of coastlines to hazards while simultaneously delivering co-benefits such as carbon sequestration. Despite the potential ecological and socio-economic benefits of living shorelines over conventional engineered coastal protection structures, application is limited globally. Australia has a long and diverse coastline that provides prime opportunities for living shorelines using beaches and dunes, vegetation, and biogenic reefs, which may be either natural ('soft' approach) or with an engineered structural component ('hybrid' approach). Published scientific studies, however, have indicated limited use of living shorelines for coastal protection in Australia. In response, we combined a national survey and interviews of coastal practitioners and a grey and peer-reviewed literature search to (1) identify barriers to living shoreline implementation; and (2) create a database of living shoreline projects in Australia based on sources other than scientific literature. Projects included were those that had either a primary or secondary goal of protection of coastal assets from erosion and/or flooding. We identified 138 living shoreline projects in Australia through the means sampled starting in 1970; with the number of projects increasing through time particularly since 2000. Over half of the total projects (59 %) were considered to be successful according to their initial stated objective (i.e., reducing hazard risk) and 18 % of projects could not be assessed for their success based on the information available. Seventy percent of projects received formal or informal monitoring. Even in the absence of peer-reviewed support for living shoreline construction in Australia, we discovered local and regional increases in their use. This suggests that coastal practitioners are learning on-the-ground, however more generally it was stated that few examples of living shorelines are being made available, suggesting a barrier in information sharing among agencies at a broader scale. A database of living shoreline projects can increase knowledge among practitioners globally to develop best practice that informs technical guidelines for different approaches and helps focus attention on areas for further research.

The influence of environmental context on community composition in artificial rockpools associated with seawalls

Artificial structures have become widespread features of coastal marine environments, and will likely proliferate further over the coming decades. These constitute new hard substrata in the marine environment which provide a fundamentally different habitat than natural shores. Eco-engineering solutions aim to ameliorate these differences by combining ecological knowledge and engineering criteria in the construction and modification of artificial substrata. Vertipools™ are artificial bolt-on rockpools intended for deployment on seawalls, where they have been shown to provide biodiversity benefits. In this study, a total of 32 Vertipools were retrofitted on eight seawalls in different environmental contexts (estuarine vs marine and urban vs rural) along the Irish Sea coastline, and were exposed to the environment for a period of two years. After two years, there were no differences in species richness, species-abundance distributions, diversity, or community composition between the specific environmental contexts examined here. Site-level variation was significant, and communities on Vertipools deployed in marine contexts were more variable in general than those in estuarine contexts. Community composition differed significantly between structural sections of the Vertipools, indicating that different sections provide specific microhabitats for colonisation. This study indicates that Vertipools provide biodiversity benefits in a variety of environmental contexts, and therefore are broadly viable as an eco-engineering solution.

Metrics matter: Multiple diversity metrics at different spatial scales are needed to understand species diversity in urban environments

Worldwide, natural habitats are being replaced by artificial structures due to urbanisation. Planning of such modifications should strive for environmental net gain that benefits biodiversity and ecosystems. Alpha (α) and gamma (γ) diversity are often used to assess 'impact' but are insensitive metrics. We test several diversity measures across two spatial scales to compare species diversity in natural and artificial habitats. We show γ-diversity indicates equivalency in biodiversity between natural and artificial habitats, but natural habitats support greater taxon (α) and functional richness. Within-site β-diversity was also greater in natural habitats, but among-site β-diversity was greater in artificial habitats, contradicting the commonly held view that urban ecosystems are more biologically homogenous than natural ecosystems. This study suggests artificial habitats may in fact provide novel habitat for biodiversity, challenges the applicability of the urban homogenisation concept and highlights a significant limitation of using just α-diversity (i.e., multiple metrics are needed and recommended) for assessing environmental net gain and attaining biodiversity conservation goals.

Alternative stable state and its evaluation in wetland reconstruction based on landscape design

An alternative stable state is closely related to the health and sustainable development of ecosystems; however, knowledge of the alternative stable state and its quantitative evaluation in wetland reconstruction remains incomplete. In this study, we used landscape design to reconstruct an optimized ecological polder wetland and a lake wetland in the Yunmeng Marsh area, China, and the alternative stable states of the two wetland ecosystems were assessed from an ecosystem perspective via emergy/eco-exergy and fractal dimensions. The emergy densities for the optimized ecological polder wetland and the lake wetland were 2.35E+13 sej yr^-1 m^-3 and 2.18E+13 sej m^-3, and the emergy sustainability index (ESI) values were 216.57 and 193.31, respectively, indicating that the reconstructed wetland ecosystems were dominated by renewable energy flows and were highly sustainable. The eco-exergy density and emergy/eco-exergy ratio results showed that natural selection self-organized the reconstructed wetland ecosystems to tolerate environmental stresses and changes. In addition, the fractal dimensions of the morphology and contour of the polder wetland, which reflect the space occupation capacity of geometric and physical constraints in the wetland, were 1.57 and 1.75, and those of the lake wetland were 1.03 and 1.47, respectively. The synthetic evaluation results showed that the alternative stable states of both the optimized ecological polder wetland ecosystem and the lake wetland ecosystem were ecofriendly modes of wetland reconstruction, which can be implemented together to create a "lake-polder" ecosystem. Our study on the alternative stable states of wetland ecosystems is helpful for exploring the synergistic symbiosis between traditional culture and the ecological environment in China and other wetland-rich regions and countries with severe disturbances.

Analysis of Blue Infrastructure Network Pattern in the Hanjiang Ecological Economic Zone in China

As a crucial part of urban development, blue infrastructure (BI) provides multiecosystem services. Using the Hanjiang Ecological Economic Zone as the study area, the potential benefits of a BI network were constructed using morphological spatial pattern analysis (MSPA) and minimum cumulative resistance model (MCR) for three periods in order to assess network structure. The main conclusions are: (1) The total BI area of the study location increased at first and then decreased from 2010 to 2020, during which the area of the core and loop was continually rising while the islet and bridge were gradually dropping. These results reveal that landscape fragmentation was well controlled; (2) Both the Integral Index of Connectivity(IIC) and Probability of Connectivity(PC) of the landscape showed an increasing trend, but the integral connectivity level was still low; (3) The comprehensive resistance value decreased gradually from west to east. The potential corridors were concentrated in the middle and lower reaches of the Hanjiang and extended upstream. The amount decreased first and then increased. (4) The structure of the BI network was simple first and then complex, which is in line with changes in the number of BI sources. Thus, changes in the BI network pattern are closely linked to the changes in the study area and the number of BI sources.

Emerging Solutions to Return Nature to the Urban Ocean

Urban and periurban ocean developments impact 1.5% of the global exclusive economic zones, and the demand for ocean space and resources is increasing. As we strive for a more sustainable future, it is imperative that we better design, manage, and conserve urban ocean spaces for both humans and nature. We identify three key objectives for more sustainable urban oceans: reduction of urban pressures, protection and restoration of ocean ecosystems, and support of critical ecosystem services. We describe an array of emerging evidence-based approaches, including greening grayinfrastructure, restoring habitats, and developing biotechnologies. We then explore new economic instruments and incentives for supporting these new approaches and evaluate their feasibility in delivering these objectives. Several of these tools have the potential to help bring nature back to the urban ocean while also addressing some of the critical needs of urban societies, such as climate adaptation, seafood production, clean water, and recreation, providing both human and environmental benefits in some of our most impacted ocean spaces.

Loss of coastal ecosystem spatial connectivity and services by urbanization: Natural-to-urban integration for bay management

Urbanization has negative consequences for the integrity of ecosystems and services they provide, by reducing their extent and quality in both aquatic and terrestrial environments. Few studies have explored how urban infrastructure expansion affects the spatial connectivity of coastal ecosystems by provoking their fragmentation and loss. Here we explore changes in the spatial connectivity of coastal ecosystems due to urbanization, analyzing ecosystem extent and concatenation with urban infrastructures (shared perimeter) in four bays of the Coquimbo region of northern Chile (from 29°S to 32°S) as model systems. Increase in natural-to-urban concatenation patterns were observed in most urbanized bays; sandy beaches and wetlands were the habitats most connected with urban infrastructures like roads and coastal artificial defenses. Availability of ecosystem services is compromised by progressive loss of natural connectivity and poor governance structure, which seems to confer high vulnerability to urbanized bays with future urban expansion. Complementary actions are proposed to reduce the vulnerability of coastal urban systems, considering 1) investment in nature-based infrastructures for coastal defenses, 2) restoration-rehabilitation of natural (remnant) urban ecosystems and eco-engineering of current artificial infrastructures, focusing on reestablishment of biodiversity patterns and habitat connectivity, and 3) limitation of coastal town and village expansion. Management strategies can improve coastal adaptation to natural hazards, stabilizing changes in the natural-urban concatenation mosaic present in coastal urban systems like bays.

Occurrence and assemblage composition of intertidal non-native species may be influenced by shipping patterns and artificial structures

Habitat modification coupled with the spread of non-native species (NNS) are among the top threats to marine biodiversity globally. Species are known to be transported to new locations via international shipping and secondarily spread via regional vessels and artificial structures. Rapid Assessment Surveys (RAS) combining quantitative and semi-quantitative methods compared NNS richness and assemblage composition on intertidal natural rocky shores and artificial structures in harbours in different regions along the south coast of England. Quantitative data showed that artificial habitats supported higher richness than natural habitats, while semi-quantitative data found no difference in richness among habitat types. This result was attributed to additional species found in rock pools during searches of complex microhabitats in natural habitats. Assemblages on artificial structures differed among regions, with regions and harbours with greater numbers of vessels supporting greater richness. Results highlight the importance of shipping and artificial structures for NNS introduction and spread.

The concept of a participatory approach to water management on a reservoir in response to wicked problems

Integrated Water Resources Management (IWRM) in the social, economic and environmental aspect is widely accepted although still represents a big challenge for its implementation in global, regional and local scales. This is particularly important in the situation of new investments. In the case of already existing hydro-technical facilities, which were built at the end of the nineties of the last century, water management takes into account only the ecological awareness for their design and social participation is limited to acceptance of the local community. The Mściwojów retention reservoir analysed in the article is an example of an object whose project included ecological solutions aimed at ensuring high water quality, and its construction was approved and supported by the local community. At present, the reservoir does not function in accordance with the adopted assumptions, and water management requires the implementation of system solutions that take into account contradicting expectations of users and stakeholders of the reservoir. The current situation can be categorized as a wicked problem. The article presents a proposal to solve the situation on the basis of a participatory approach involving stakeholders through social learning as a part of the reservoir management system. The system approach was developed based on the principles of Soft Systems Methodology (SSM) and 10 Steps Planning Processing by Wilhite while using the causal loop diagrams (CLD). The result is an organizational model of the reservoir management structure and framework methodology for building solution scenarios. The key assumption of the proposed approach is the cyclicality of activities as part of the management process taking into account changes in the reservoir system and its settings in the social, economic and environmental aspects.

Urban blue: A global analysis of the factors shaping people's perceptions of the marine environment and ecological engineering in harbours

Marine harbours are the focus of a diverse range of activities and subject to multiple anthropogenically induced pressures. Support for environmental management options aimed at improving degraded harbours depends on understanding the factors which influence people's perceptions of harbour environments. We used an online survey, across 12 harbours, to assess sources of variation people's perceptions of harbour health and ecological engineering. We tested the hypotheses: 1) people living near impacted harbours would consider their environment to be more unhealthy and degraded, be more concerned about the environment and supportive of and willing to pay for ecological engineering relative to those living by less impacted harbours, and 2) people with greater connectedness to the harbour would be more concerned about and have greater perceived knowledge of the environment, and be more supportive of, knowledgeable about and willing to pay for ecological engineering, than those with less connectedness. Across twelve locations, the levels of degradation and modification by artificial structures were lower and the concern and knowledge about the environment and ecological engineering were greater in the six Australasian and American than the six European and Asian harbours surveyed. We found that people's perception of harbours as healthy or degraded, but not their concern for the environment, reflected the degree to which harbours were impacted. There was a positive relationship between the percentage of shoreline modified and the extent of support for and people's willingness to pay indirect costs for ecological engineering. At the individual level, measures of connectedness to the harbour environment were good predictors of concern for and perceived knowledge about the environment but not support for and perceived knowledge about ecological engineering. To make informed decisions, it is important that people are empowered with sufficient knowledge of the environmental issues facing their harbour and ecological engineering options.