This literature review encompasses more than one-hundred and sixty worldwide studies on artificial reefs (ARs) in terms of their design, application, performance and management. Over the past three decades, research on ARs has increased remarkably, suggesting an increase in social and economic aspects of ARs. The scope of AR research has largely expanded from early AR design and deployment to improve fisheries to various additional purposes. In particular, recent research on ARs has had a tendency to focus on variations in the community structure or composition of ARs, suggesting that the purpose of AR research has shifted from improving fisheries as a resource to rehabilitation of marine ecosystems. Most countries are expected to make active use of AR functions, even if the objective of deployment might be different for each case. Consequently, AR research will most likely expand and evolve to span multiple purposes in the future.
The coastline of Qatar is a rich mosaic of productive and diverse ecosystems including mangrove forests, intertidal mudflats (sabkha), seagrass beds, and coral reefs. These ecologically interconnected ecosystems contain a substantial proportion of Qatar's total biodiversity, and support an estimated 97% of the >US$ 67 million in annual commercial fisheries, the highest value resource sector after petroleum. The extreme environmental conditions that characterize Qatar has led to fauna that are robust compared with other regions, but makes them highly sensitive to further pressure from anthropogenic stress. These vulnerable ecosystems have come under increasing pressure in recent decades as a result of dramatic expansion of coastal development, and threats to these ecosystems are likely to accelerate in the coming years as Qatar's economy and population continue to grow. Although environmental regulation had historically lagged behind the rapid pace of development, in recent years Qatar's leadership has aggressively expanded environmental management as a result of the growing awareness of the importance of coastal ecosystems. While these improvements are encouraging, management remains challenged by its current sectorial, project-driven focus. Ecosystem-based management (EBM) offers an opportunity to overcome these challenges by integrating impacts from across all major activities in multiple sectors and considering their cumulative effects on ecosystem services and products. While an EBM approach would require modest reprioritizing of existing processes and attention to addressing deficiencies in data needed to support decision making, it has the potential to greatly enhance the efficiency and effectiveness of coastal zone management. The article closes by summarizing a recently initiated research project on coral reefs and seagrass beds in Qatar which can serve as a model for development of the EBM approach for other coastal ecosystems in Qatar.
Coastal shoreline hardening is intensifying due to human population growth and sea level rise. Prior studies have emphasized shoreline-hardening effects on faunal abundance and diversity; few have examined effects on faunal biomass and size structure or described effects specific to different functional groups. We evaluated the biomass and size structure of mobile fish and crustacean assemblages within two nearshore zones (waters extending 3 and 16 m from shore) adjacent to natural (native wetland; beach) and hardened (bulkhead; riprap) shorelines. Within 3 m from shore, the total fish/crustacean biomass was greatest at hardened shorelines, driven by greater water depth that facilitated access to planktivore (e.g., bay anchovy) and benthivore-piscivore (e.g., white perch) species. Small-bodied littoral-demersal species (e.g., Fundulus spp.) had greatest biomass at wetlands. By contrast, total biomass was comparable among shoreline types within 16 m from shore, suggesting the effect of shoreline hardening on fish biomass is largely within extreme nearshore areas immediately at the land/water interface. Shoreline type utilization was mediated by body size across all functional groups: small individuals (≤60 mm) were most abundant at wetlands and beaches, while large individuals (>100 mm) were most abundant at hardened shorelines. Taxonomic diversity analysis indicated natural shoreline types had more diverse assemblages, especially within 3 m from shore, although relationships with shoreline type were weak and sensitive to the inclusion/exclusion of crustaceans. Our study illustrates how shoreline hardening effects on fish/crustacean assemblages are mediated by functional group, body size, and distance from shore, with important applications for management.
Coastal reclamation is the gain of land from the sea or coastal wetlands for agricultural purposes, industrial use or port expansions. Large-scale coastal land reclamation can have adverse effects on the coastal environment, including loss of marine habitats and deterioration of coastal water quality. In recent decades, coastal land reclamation has occurred extensively to meet the increasing needs of rapid economic development and urbanization in China. The overall objective of this study is to understand the coastal reclamation status of China from 1979 to 2014 and analyzed its driving factors for mitigating negative ecological effects. The data of coastal reclamation were done with the ERDAS Imagine V9.2 platform and ArcGIS software based on remote images including Landsat, SPOT, ZY-2 and ZY-3. Potential driving factors for sea reclamation were selected based on statistics bulletins and the knowledge of experts in coastal management. In order to understand the relationships among possible impact factors and coastal reclamation, the Partial Least-Squares Regression models was constructed. The analysis results indicated that the total area of reclamation was 11162.89 km2 based on remote sensing images between 1979 and 2014. Shandong Province is the largest reclamation area, reaching 2736.54 km2, and the reclamation is mainly concentrated in Zhejiang, Jiangsu and Liaoning, where the reclamation areas were all more than 1000 km2. According to the remote sensing images, there are three coastal reclamation hotspot regions including Bohai bay (in which is located Liaoning, Tianjin and Hebei), Jiangsu province coastal area and Hangzhou bay (in Zhejiang province). A large scale land reclamation plan of more than 5880 km2 has been made by local government and 2469 km2 has approved by the State Council. From the analyzed results, there is a significant collinearity between these indicators, and no significant correlation between the area of reclamation and selected indicators. Economic development and employees in marine industries have weak positive correlation and correspondingly, the area of cultivated land (ACL) had a negative correlation. Because of the weak correlation, there is an assumption that economic development, outcome of coastal reclamation and population growth were not only was the direct driving factor, but also the outcome of coastal reclamation and population growth was not the direct driving indicator. Construction land quota and huge economic returns to local government may be the direct driving factors according to our field investigation. To resolve the contradiction between the need for land and coastal wetland conservation, it is recommended that China should establish a special management agency and coordination mechanisms, reconsidered the implementation of the reclamation plans and projects that have been approved, enhance law enforcement and increase penalties and strengthen public participation in reclamation management.
Coastal zones are exposed to natural hazards in the context of global change and the concentration of human activities, which justifies the interest in assessing at-risk territories. This paper proposes a reproducible method to identify the erosion risk territories on the basis of an exposure index creation. An assessment of the building exposure to shoreline retreat is conducted along 350 km of the Atlantic French coast (Pays de la Loire regional administrative division) including rocky coasts, coastal barriers and sand spits, estuaries, bays, and coasts with protection structures. The segmentation of a 100-m landward strip is carried out with 30*100 m boxes. Three geoindicators are computed within each box: (i) the shortest shoreline-building distance (ii) the building footprint of the first row (iii) the coastal erosion along sandy coasts. The aggregation of these geoindicators within each box leads to the creation of an exposure index. Thus, this spatial framework provides a reproducible method to improve the synthetic knowledge of the erosion risk in the Pays de la Loire Region. The whole of the risk situation is detected at 1/5000 scale, which is original and significant progress. The accuracy of this study is due to the generic data used and the 30*100 m segmentation. This spatial resolution leads to finer results than previous studies. This new method can detect all the exposures in order to anticipate crises management through the deployment of a real operational alert system.
Nearshore ecosystems are increasingly recognized as critical habitats for fish of cultural, ecological and economic significance. These ecosystems are often densely inhabited by juvenile fish, highly productive and refuges from predation, leading ecologists to characterize them as nurseries. However, nearshore ecosystems are being transformed globally to support demands of growing coastal populations. Many shorelines are modified by armouring (e.g. seawalls, riprap) that minimizes erosion, and overwater structures (e.g. piers, docks) that facilitate waterfront use. These modifications affect the ecology of nearshore systems by restructuring, eliminating and shading shallow waters.
Here, we review literature examining effects of armouring and overwater structures on coastal and estuarine fishes, and discuss how research and management can coordinate to minimize negative effects.
Along armoured shorelines, fish assemblages differed from unarmoured sites, fish consumed less epibenthic and terrestrial prey, beach spawning was less successful and fish were larger. Under large overwater structures, visually oriented fish were less abundant and they fed less. Shade from overwater structures also interrupted localized movements of migratory fish. Thus, shoreline modifications impaired habitats by limiting feeding, reproduction, ontogenetic habitat shifts from shallow to deeper waters and connectivity.
Research suggests that restoring shallow waters and substrate complexity, and minimizing shading underneath overwater structures, can rehabilitate habitats compromised by shoreline modifications.
Synthesis and applications. Shoreline armouring and overwater structures often compromise fish habitats. These threats to nearshore fish habitats will become more severe as growing coastal populations and rising sea levels increase demands for shoreline infrastructure. Our ability to assess and rehabilitate nearshore fish habitats along modified shorelines will be enhanced by: focusing research attention on metrics that directly indicate fish habitat quality; implementing and evaluating shoreline features that repair compromised habitat functions within human-use constraints; collating natural history knowledge of nearshore ecosystems; and embracing the socio-ecological nature of habitat improvements by educating the public about conservation efforts and fostering appreciation of local nearshore ecosystems. Actions to reduce impacts of shoreline modifications on fish are particularly feasible when they align with societal goals, such as improving flood protection and providing spaces that facilitate recreation, education, and connections between people and nature.
Artificial reefs now form part of an integrated approach to enhance fisheries around the world. A responsible approach to artificial reef deployment calls for clear, well defined goals prior to any reef being placed in the field, followed by subsequent monitoring to assess whether these goals are being achieved. In this study, to evaluate if an artificial reef off Sydney was meeting its goal of providing quality fishing opportunities through the establishment of a complex fish assemblage, a 4-year monitoring program was designed. This program examined the response of reef-associated and pelagic fishes to the deployment of a purpose built offshore reef, relative to control reefs. Fish were observed immediately following deployment, but the artificial reef fish assemblage remained distinct from the three natural control reefs throughout the monitoring period. Also, the artificial reef displayed inter-annual variability associated with successional processes, which was not evident on the natural reefs. Fish length data indicated that the artificial reef was providing resources for both juvenile and adults of a number of species. This study demonstrates artificial reefs can provide habitats for a diverse group of fish, but the assemblages are unlikely to mimic those on natural reefs. We have also shown that longer term monitoring periods, covering multiple years are required to gain a robust understanding of the response of fish to reef deployment. This information can be used to understand the benefits and limitations of future artificial reef deployments.
Urbanisation in terrestrial systems has driven architects, planners, ecologists and engineers to collaborate on the design and creation of more sustainable structures. Examples include the development of ‘green infrastructure’ and the introduction of wildlife corridors that mitigate urban stressors and provide positive ecological outcomes. In contrast, efforts to minimise the impacts of urban developments in marine environments have been far more restricted in their extent and scope, and have often overlooked the ecological role of the built environment as potential habitat. Urban foreshore developments, i.e. those built on the interface of intertidal and/or subtidal zones, have the potential to incorporate clear multi-functional outcomes, by supporting novel ecosystems. We present a step-by-step eco-engineering framework for ‘building blue’ that will allow coastal managers to facilitate planning and construction of sustainable foreshore developments. Adopting such an approach will incorporate ecological principles, thereby mitigating some of the environmental impacts, creating more resilient urban infrastructure and environments, and maximising benefits to the multiple stakeholders and users of marine urban waterfronts.
Shoreline armoring can impact a variety of ecosystem functions, goods and services provided by beaches. Shoreline managers struggle to balance genuine need for armoring to protect infrastructure versus unacceptable losses of ecosystem functions––whether these be in beaches, sand dunes, or marshes. We use our recent research effort in the Salish Sea, Washington, as a case study to illustrate how highlighting the negative consequences of shoreline armoring to publicly important ecosystem functions may help to strengthen implementation of policy and prioritize restoration actions. We focus on two distinct mechanisms of armoring impact that link strongly to key beach functions, and recommend: (1) where armoring is clearly necessary, place or move it as high on the beach as possible. Armoring emplaced relatively low on the shore is more likely to affect a variety of ecosystem functions from forage fish spawning to beach recreation; (2) prioritize protection or restoration (armor removal) of feeder bluffs that are critical for sediment supply to the beach; this sediment is essential to the maintenance of beach functions. In addition, we recommend that nature-based alternatives to armoring be given preferential regulatory consideration and that outreach efforts clarify the advantages of these engineering methods.
Land-Ocean-Human (L-O-H) interactions in intensively developing coastal zones are demonstrated using four case studies in the western Bohai Sea, China. Three aspects of L-O-H interactions are discussed: 1. Coastlines are the result of Land-Ocean (L-O) interactions, but human activities have changed many coastlines from natural to artificial. In recent years, sea reclamation projects have moved the land and its coastline towards the sea, leading to hydrodynamic changes and affecting both the topography and sediment-erosion dynamics in western Bohai Bay (case study 1). 2. Estuaries are key areas for L-O interactions; river sediments, together with ocean power, shape the topography of the estuarine delta, while river nutrients impact offshore biological productivity. However, due to irrigation and reservoir construction up-stream, runoff and sediments have decreased resulting in increased coastal erosion in the Yellow River Delta (case study 2). Rivers carry industrial and agricultural point and non-point source pollution into the sea, causing marine pollution in Jinzhou Bay (case study 3). 4. Sea-level rise caused by global climate change enhances the role of the ocean. At a local scale, in Binhai New Area, sea-level change is also influenced by vertical land movement along with some land subsidence caused by over-exploitation of groundwater. Rising sea levels exacerbate storm surges and floods, and increase the risk of socio-economic and ecological impacts (case study 4). Because of rapid economic growth in Chinese coastal areas, L-O-H interactions have become the most significant factors changing natural and artificial environments. If the coastal zone is to be developed sustainably, human activities must be regulated.