Intertidal artificial habitats are proliferating, but are generally simpler in structure and host lower biodiversity than natural rocky reefs. Eco-engineering aims to enhance the biodiversity of coastal infrastructure, often through physical structural modifications that mimic topographic properties of natural shores. Relationships between biotic assemblages and structural properties of natural and artificial reefs have been extensively studied at sampling scales of up to 1 m2. But evidence that quantified local structural variation has an appreciable influence on biotic assemblages, at a shore-wide scale across regional environmental gradients, is lacking. Here we addressed this knowledge gap with an observational study at 32 natural and artificial intertidal reef sites in Wales, UK. We used multivariate community analysis and permutation tests to examine associations between local physical structure, regional environmental variables and sessile biotic assemblages. A potential influence of local habitat structure on assemblage composition was evident across regional-scale environmental gradients. Compared to natural sites, artificial reefs had lower taxonomic richness, distinct and more variable assemblage composition, and different physical structure. After removing the effect of habitat (natural or artificial), canonical correspondence analysis showed that environmental variables (wave exposure, sea surface temperature and salinity variation), along with two metrics of physical structure (standard deviation in log-transformed detrended roughness and skewness of surface verticality, both at 0.5 m scale), explained 40 % of the variation in assemblage composition among sites. The two structural metrics independently explained 14.5 % of the variation. Associations identified between individual taxa and environmental variables indicated that sites with a higher proportion of horizontal surfaces hosted more canopy macroalgae, which in turn support other algae and invertebrates. Our findings provide evidence to inform scaling-up of structural eco-engineering interventions from experimental contexts to enhance the biodiversity of coastal infrastructure across regional extents.
Political discourse around coastal wetland restoration and blue carbon management strategies has increased in the past decade, yet carbon storage has neither been a reason for restoration, nor a criterion to measure the success of current saltmarsh restoration schemes in the UK. To maximise climate change mitigation through saltmarsh restoration, knowledge on the key drivers of carbon stock variability is required. We use restored saltmarshes of similar age, paired with adjacent natural marshes as references, to identify drivers of carbon stocks following managed realignment within an estuary in southeastern England. From surficial soil cores (top 30 cm), we measured carbon stock alongside environmental characteristics. Carbon stock between natural and restored sites were similar after ~ 30 years when restored sites were above mean high water neap (MHWN) tidal levels. Elevated marsh platforms likely provide suitable conditions for the development of mature plant communities associated with greater capture and production of organic carbon. The restored site at Tollesbury (Essex, UK) had a 2-fold lower carbon stock than other restored sites in the estuary. We attribute this to the site’s low position in the tidal frame, below MHWN tidal levels, coupled with low sediment supply and the dominance of pioneer plant communities. As blue carbon is anticipated to become an important facet of saltmarsh restoration, we recommend that sites above MHWN tidal levels are selected for managed realignment or that preference is given to coastlines with a high sediment supply that may rapidly elevate realignment sites above MHWN. Alternatively, elevation could be artificially raised prior to realignment. Restoration schemes aiming to maximise climate change mitigation should also encourage the establishment of key plant species (e.g., Atriplex portulacoides in our study) to enhance carbon stocks. However, the overall goal of restoration ought to be carefully considered as trade-offs in ecosystem services may ensue if restoration for climate change mitigation alone is pursued.
The epidemiology and severity of ash dieback (ADB), the disease caused by the ascomycete fungus Hymenoscyphus fraxineus , has been linked to a variety of site conditions; however, there has been a lack of analysis at an individual tree scale. Symptoms of ADB were scored on ca. 400 trees of Fraxinus excelsior (ash) in permanent sample plots during two successive years in a UK natural woodland reserve. Using comprehensive plot records maintained since 1945, and detailed spatial records updated since 1977, we assembled an array of potential explanatory variables, including site environment factors, ash tree density, previous and present tree condition and near neighbourhood summary statistics (NNSS), such as species mingling and size dominance. Their impact on the severity of ADB of focal ash trees was tested with generalised linear mixed effects models (GLMM). The severity of ADB was much greater in the lower slope parts of the site with moister soils and least in a managed area subject to tree thinning in the previous 35 years. Severity of ADB had a negative association with focal ash tree prior relative growth rate over a period of a decade immediately before the disease was detected at the site. Greater ADB severity was also significantly associated with smaller diameter at breast height of ash trees. Additionally, ADB was significantly positively associated with a greater proportion of heterospecific trees amongst the six nearest neighbours of the focal tree. Synthesis. The relationship of the severity of ADB disease with site environment, tree condition and neighbourhood is complex but nevertheless important in the progression of the disease. The findings suggest some silvicultural interventions, such as thinning to increase the vigour of retained ash trees, might reduce the impact of ADB.
Increasing attention is being paid to the carbon sequestration and storage services provided by coastal blue carbon ecosystems such as saltmarshes. Sites restored by managed realignment, where existing sea walls are breached to reinstate tidal inundation to the land behind, have considerable potential to accumulate carbon through deposition of sediment brought in by the tide and burial of vegetation in the site. While this potential has been recognised, it is not yet a common motivating factor for saltmarsh restoration, partly due to uncertainties about the rate of carbon accumulation and how this balances against the greenhouse gases emitted during site construction. We use a combination of field measurements over four years and remote sensing to quantify carbon accumulation at a large managed realignment site, Steart Marshes, UK. Sediment accumulated rapidly at Steart Marshes (mean of 75 mm yr-1) and had a high carbon content (4.4% total carbon, 2.2% total organic carbon), resulting in carbon accumulation of 36.6 t ha-1 yr-1 total carbon (19.4 t ha-1 yr-1 total organic carbon). This rate of carbon accumulation is an order of magnitude higher than reported in many other restored saltmarshes, and is somewhat higher than values previously reported from another hypertidal system (Bay of Fundy, Canada). The estimated carbon emissions associated with the construction of the site were ~2-4% of the observed carbon accumulation during the study period, supporting the view that managed realignment projects in such settings may have significant carbon accumulation benefits. However, uncertainties such as the origin of carbon (allochthonous or autochthonous) and changes in gas fluxes need to be resolved to move towards a full carbon budget for saltmarsh restoration.
Sediment data from Steart Marshes described in Mossman et al. "Rapid carbon accumulation at a saltmarsh restored by managed realignment exceeded carbon emitted in direct site construction". Data are provided as a .xlsx file (Data package.xlsx) with four tabs. Tab 1 has column heading descriptions. Tab 2 has total carbon samples. Tab 3 has total organic carbon samples. Tab 4 has bulk density samples. Each tab is also provided as a seperate csv file.
1. Spatial heterogeneity of species (beta diversity) is an important attribute of ecological communities, but is less frequently considered when assessing restoration success than other aspects of diversity (gamma and alpha). Differences in beta diversity between restored and natural sites may arise due to differences in environmental heterogeneity. 2. We used a nested sampling design to survey plant communities and environmental conditions (elevation, redox potential and metrics of topography) on four pairs of restored and natural saltmarshes. We assessed whether there were differences in both alpha and beta diversity between natural and restored sites and analysed their environmental drivers. 3. Topography
Coastal salt marshes provide important habitat for fishes and crustaceans, including species of commercial value that feed or take refuge in the marsh. Yet population abundances vary considerably between sites, often without clear explanation. We hypothesised that faunal abundance and mean size would be positively related to 2 physical properties that govern marsh accessibility to water-dependent species, as has been found on the southeastern coast of the USA: (1) the volume of water exchanged by tidal flooding, which gives access to the marsh, and (2) edge amount, the length of the water-vegetation borderline per unit area where species can take refuge and feed. Digital terrain models and tidal information were used to select 5 marshes in Wales, UK, that differed in edge amount and water exchange (52°N, 4°W). Fishes and crustaceans were sampled using baited traps, fyke nets and seine nets. In total, 15 species were caught, including commercially valuable brown shrimp, European eel and sea bass. We found water exchange volume, but not edge amount, boosted fish and crustacean abundances. Crab and sea bass sizes were both negatively affected by water exchange, while shrimp and fish sizes were unaffected. Our findings show how the mechanisms that drive fish and crustacean abundances and sizes vary between geographical regions. Feasibly, fisheries associations with marsh hydrogeomorphology might operate differently as well.
Ocean sprawl is a growing threat to marine and coastal ecosystems globally, with wide-ranging consequences for natural habitats and species. Artificial structures built in the marine environment often support less diverse communities than natural rocky marine habitats because of low topographic complexity. Some structures can be eco-engineered to increase their complexity and promote biodiversity. Tried-and-tested eco-engineering approaches include building-in habitat designs to mimic features of natural reef topography that are important for biodiversity. Most designs mimic discrete microhabitat features like crevices or holes and are geometrically-simplified. Here we propose that directly replicating the full fingerprint of natural reef topography in habitat designs makes a novel addition to the growing toolkit of eco-engineering options. We developed a five-step process for designing natural topography-based eco-engineering interventions for marine artificial structures. Given that topography is highly spatially variable in rocky reef habitats, our targeted approach seeks to identify and replicate the ‘best’ types of reef topography to satisfy specific eco-engineering objectives. We demonstrate and evaluate the process by designing three natural topography-based habitat units for intertidal structures, each targeting one of three hypothetical eco-engineering objectives. The process described can be adapted and applied according to user-specific priorities. Expanding the toolkit for eco-engineering marine structures is crucial to enable ecologically-informed designs that maximise biodiversity benefits from burgeoning ocean sprawl.
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.
Background Coral reefs are rapidly changing in response to local and global stressors. Research to better understand and inform the management of these stressors is burgeoning. However, in situ studies of coral reef ecology are constrained by complex logistics and limited resources. Many reef studies are also hampered by the scale-dependent nature of ecological patterns, and inferences made on causal relationships within coral reef systems are limited by the scales of observation. This is because most socio-ecological studies are conducted at scales relevant to the phenomenon of interest. However, management often occurs across a significantly broader, often geopolitical, range of scales. While there is a critical need for incisive coral reef management actions at relevant spatial and temporal scales, it remains unclear to what extent the scales of empirical study overlap with the scales at which management inferences and recommendations are made. This systematic map protocol will evaluate this potential scale mismatch with the goal of raising awareness about the significance of effectively addressing and reporting the scales at which researchers collect data and make assumptions. Methods We will use the Collaboration for Environmental Evidence (CEE) systematic mapping guidelines to identify relevant studies using a framework-based synthesis to summarise the spatial and temporal scales of coral reef fish ecology research and the scales at which management inferences or recommendations are made. Using tested predefined terms, we will search for relevant published academic and grey literature, including bibliographic databases, web-based search engines, and organisational websites. Inclusion criteria for the evidence map are empirical studies that focus on coral reef fish ecological organisation and processes, those informing management interventions and policy decisions, and management documents that cite coral reef research for management decision-making. Study results will be displayed graphically using data matrices and heat maps. This is the first attempt to systematically assess and compare the scales of socio-ecological research conducted on coral reef systems with their management.
Coastal ecosystems are threatened by habitat loss and anthropogenic “smoothing” as hard engineering approaches to sea defence, such as sea-walls, rock armouring, and offshore reefs, become common place. These artificial structures use homogenous materials (e.g. concrete or quarried rock) and as a result, lack the surface heterogeneity of natural rocky shoreline known to play a key role in niche creation and higher species diversity. Despite significant investment and research into soft engineering and ecologically sensitive approaches to coastal development, there are still knowledge gaps, particularly in relation to how patterns that are observed in nature can be utilised to improve artificial shores. Given the technical improvements and significant reductions in cost within the portable remote sensing field (structure from motion and laser scanning), we are now able to plug gaps in our understanding of how habitat heterogeneity can influence overall site diversity. These improvements represent an excellent opportunity to improve our understanding of the spatial scales and complexity of habitats that species occur within and ultimately improve the ecological design of engineered structures in areas experiencing “smoothing” and habitat loss. In this talk, I will highlight how advances in remote sensing techniques can be applied to context-specific ecological problems, such as low diversity and loss of rare species within marine infrastructure. I will describe our approach to combining large-scale ecological, 3D geophysical and engineering research to design statistically-derived ecologically-inspired solutions to smooth artificial surfaces. We created experimental concrete enhancement units and deployed them at a number of coastal locations. I will present preliminary ecological results, provide a workflow of unit development and statistical approaches, and finally discuss how these advances may improve future ecological intervention and design options.
This review represents a comprehensive analysis on pollutants in elasmobranchs including meta-analysis on the most studied pollutants: mercury, cadmium, PCBs and DDTs, in muscle and liver tissue. Elasmobranchs are particularly vulnerable to pollutant exposure which may pose a risk to the organism as well as humans that consume elasmobranch products. The highest concentrations of pollutants were found in sharks occupying top trophic levels (Carcharhiniformes and Lamniformes). A human health risk assessment identified that children and adults consuming shark once a week are exposed to over three times more mercury than is recommended by the US EPA. This poses a risk to local fishing communities and international consumers of shark-based products, as well as those subject to the widespread mislabelling of elasmobranch products. Wider screening studies are recommended to determine the risk to elasmobranchs from emerging pollutants and more robust studies are recommended to assess the risks to human health.
Mahmood, Rezaul; Pielke, Roger A. Sr.; Hubbard, Kenneth G.; Niyogi, Dev; Bonan, Gordon; Lawrence, Peter; McNider, Richard; McAlpine, Clive; Etter, Andres; Gameda, Samuel; Qian, Budong; Carleton, Andrew; Beltran-Przekurat, Adriana; Chase, Thomas; Quintanar, Arturo I.; Adegoke, Jimmy O.; Vezhapparambu, Sajith; Connor, Glen; Asefi, Salvi; Sertel, Elif; Legates, David R.; Wu, Yuling; Hale, Robert; Frauenfeld, Oliver W.; Watts, Anthony; Shepherd, Marshall; Mitra, Chandana; Anantharaj, Valentine G.; Fall, Souleymane; Lund, Robert; Treviño, Anna; Blanken, Peter D.; Du, Jinyang; Chang, Hsin-I; Leeper, Ronnie; Nair, Udaysankar S.; Dobler, Scott; Deo, Ravinesh; and Syktus, Jozef, "Impacts of Land Use/Land Cover Change on Climate and Future Research Priorities" (2010). Papers in Natural Resources. 395. https://digitalcommons.unl.edu/natrespapers/395
List of key featuresBulbous nasal tipFull cheeks and lipsSlightly everted lower lipComplex focal seizuresDevelopmental delayStereotypic movementsIntroductionThe CASPR2 deficiency syndrome (MIM #610042) is an ultra-rare autosomal recessive condition characterized by moderate-to-severe intellectual di
Saltmarshes can be created to compensate for lost habitat by a process known as managed realignment (MR), where sea defences are deliberately breached to flood low-lying agricultural land. However, the vegetation that develops on MR sites is not equivalent to natural habitat. In natural sites, surface topography and creek networks are drivers of vegetation diversity, but their development on restored sites has not been well studied. We investigate the topographic characteristics of 19 MR areas, and compare these to nearby natural saltmarshes (representing desired conditions) and to coastal agricultural landscapes (representing conditions prior to MR). From high-resolution LiDAR data, we extracted values of elevation, six measures of surface topography (although two were later excluded due to collinearity), and three measures of creek density. MR and natural marshes differed significantly in all surface topographic indices, with MR sites having lower rugosity and more concave features, with greater potential for water accumulation. MR sites also had significantly lower creek density. MRs and coastal agricultural landscapes were more similar, differing in only one topographic measure. Importantly, there was no relationship between age since restoration and any of the topographic variables, indicating that restored sites are not on a trajectory to become topographically similar to natural marshes. MR schemes need to consider actively constructing topographic heterogeneity; better mirroring natural sites in this way is likely to benefit the development of saltmarsh vegetation, and will also have implications for a range of ecosystem functions.