The biodiversity audit approach challenges regional priorities and identifies a mismatch in conservation

1. Despite a strong uptake of evidence-based approaches, conservation often proceeds from a grossly incomplete understanding of species priorities. To optimize conservation impact within a biogeographical region, quantitative knowledge is needed of the species present, which should be prioritized, and the management interventions these require. The next challenge is to avoid a proliferation of competing species plans, or conversely, a lack of detail within generic habitat-based approaches. 2. We present a methodology for biodiversity auditing. We quantified regional biodiversity by systematically collating available species records, allowing objective prioritization. We collated autecological information to integrate multiple species into management guilds with shared requirements, providing evidence-based guidance for regional conservation. 3. For two regions of Eastern England, Breckland (2300 km^2 ) and The Broads (2000 km^2 ), we collated 083 and 15-million records, respectively. Numbers of species (12 845 and 11 067) and priority species (rare, threatened, designated or regionally restricted: 2097 and 1519, respectively) were orders of magnitude greater than previously recognized. Regional specialists, with a UK range largely or entirely restricted to the region, were poorly recognized posing a risk of regional homogenization. 4. A large body of autecological information existed for priority species and collating this allowed us to define cross-taxa management guilds. Numbers of priority species requiring different combinations of ecological processes and conditions were not matched by current conservation practice in Breckland. For example, the current agri-environment agreements for designated grass heaths potentially catered for only 15% of the 542 priority species and 21% of 47 regional specialists that could potentially benefit from evidence-based management. A focus on vegetation composition rather than the ecological requirements of priority species underpinned this failure. 5. Synthesis and applications. The biodiversity audit approach provides an objective model for prioritization and cost-effective conservation, applicable to regions of Europe where biodiversity has been well characterized. By using this approach to collate available information, management guilds with similar requirements can be defined across taxa, providing evidence-based guidance for regional conservatio

Implications of climate change for coastal and inter-tidal habitats in the UK

Coastal habitats are diverse and vary in the extent to which they are shaped by physiographic processes, such as wave action, wind, tides and sediment availability, and the relative influence of terrestrial and marine environments, e.g. tidal inundation versus groundwater levels. Coastal systems usually comprise mosaics of habitats that are functionally interdependent: for instance, saltmarsh may form behind a barrier island or shingle ridge that itself may also support a dune system; or estuaries may include a range of habitats that ultimately depend on sediment supply from the catchment and the mixing of fresh and saline waters. Coastal grazing marsh is a man-made, largely freshwater habitat, occurring landward of intertidal and coastal habitats and protected from them by natural or man-made structures. Whilst grazing marsh and other coastal habitats are not strictly functionally interdependent, there are significant conflicts between protecting grazing marsh and allowing landward movement of coastal habitats

Biodiversity climate change impacts report card technical paper:10. Implications of climate change for coastal and inter-tidal habitats in the UK

Executive summary - Coastal habitats are complex, dynamic and interdependent. They are important in providing sea defences, areas for recreation, biodiversity and a range of other ecosystem services. - Increased air- and sea-surface temperatures have resulted in changes in the distribution of marine and coastal species. Both warmer- and colder-water species are shifting northwards. However, warmer-water species are shifting northwards faster than colder-water species are retreating, resulting in changes in community composition. Changes in the abundance of keystone taxa can cause a cascade of responses, further altering community composition. - Changes in the phenology of coastal species have been observed, with the rates of change in marine species being considerably greater than those in terrestrial and freshwater systems. Recent advances in the phenology of species have not all occurred at the same rate, in some cases resulting in mismatches of timing of annual cycles of animals and their food organisms. - Changes in precipitation are likely to affect coastal habitats, but the projected increase in winter rainfall and decrease in summer rainfall will tend to have opposing effects; the net result of these is not known. High winter rainfall and milder winter temperatures may extend the growing season and lead to faster succession and dominance by taller competitive plant species. This will be exacerbated by anthropogenic nutrient enrichment. However, increasing frequency and severity of summer droughts may counteract the effects of nutrient enrichment and winter precipitation. Increased drought will have impacts on habitats that are highly dependent on the maintenance of hydrological regimes, such as machair lochs and dune slacks. - Rising sea levels have been associated with the loss of coastal habitats. Predicted future rises will have significant impacts on coastal and intertidal habitats, including changing geomorphological processes, further habitat loss and increasing the vulnerability of infrastructure. However, coastal systems are dynamic and have the potential to adapt to rising sea levels, but only if there is an adequate supply of sediment to allow accretion and if there is landward space for the coast to roll-back into. Sea defences and other coastal management interrupt the movement of sediment between systems and prevent natural coastal realignment. - Managed coastal realignment is beneficial because it offers the potential to create habitat and provide flood defence benefits. Inevitably, there will be conflict between the need to maintain intertidal and other coastal habitats (e.g. saltmarsh, mud flat and sand dune) by realignment, and the need to protect valuable inland coastal habitats, such as grazing marsh and saline lagoons. - Future changes in coastal habitats are hard to predict because it is difficult to separate the impacts of rising sea levels from those of coastal management, including sea defences. Coastal zone management and adaptation, and the interactions with other climate drivers, nutrient deposition and habitat management, will have significant influence on the quantity, quality and location of future coastal habitats

Restored saltmarshes have low beta diversity due to limited topographic variation, but this can be countered by management

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 was an important driver of plant alpha diversity and beta diversity on saltmarshes. The effects of topography were partly indirect, mediated though changes in redox potential, but topography also influenced plant communities independently of both elevation and redox. 4. Restored saltmarshes were less heterogeneous in topography than natural marshes. This reduced topography was reflected in lower beta diversity; plant communities 1 m apart in natural marshes were as dissimilar as those found 20 m apart in restored marshes. 5. Large-scale topographic manipulation carried out at one site a decade after initial restoration successfully increased topographic heterogeneity and increased beta diversity when surveyed 3 years after manipulation. These changes were still evident when resurveyed after a further 2 years. 6. Synthesis and applications. Increasing environmental heterogeneity can improve restoration outcomes by increasing beta diversity on restored sites. The effect of environmental heterogeneity is likely to be particularly strong within intertidal habitats such as saltmarshes, where small changes in topography can determine whether a species can occur at a given location. Topographic manipulation is a feasible post-restoration technique that can be applied to ensure restored saltmarshes better meet policy targets of biological, physical and functional equivalence with natural marshes

Diversity of vibrissal follicle anatomy in cetaceans

Most cetaceans are born with vibrissae but they can be lost or reduced in adulthood, especially in odontocetes. Despite this, some species of odontocetes have been found to have functioning vibrissal follicles (including the follicle itself and any remaining vibrissal hair shaft) that play a role in mechanoreception, proprioception and electroreception. This reveals a greater diversity of vibrissal function in odontocetes than in any other mammalian group. However, we know very little about vibrissal follicle form and function across the Cetacea. Here, we qualitatively describe the gross vibrissal follicle anatomy of fetuses of three species of cetaceans, including two odontocetes: Atlantic white-sided dolphin (Lagenorhynchus acutus), harbour porpoise (Phocoena phocoena), and one mysticete: minke whale (Balaenoptera acutorostrata), and compared our findings to previous anatomical descriptions. All three species had few, short vibrissae contained within a relatively simple, single-part follicle, lacking in muscles. However, we observed differences in vibrissal number, follicle size and shape, and innervation distribution between the species. While all three species had nerve fibers around the follicles, the vibrissal follicles of Balaenoptera acutorostrata were innervated by a deep vibrissal nerve, and the nerve fibers of the odontocetes studied were looser and more branched. For example, in Lagenorhynchus acutus, branches of nerve fibers travelled parallel to the follicle, and innervated more superficial areas, rather than just the base. Our anatomical descriptions lend support to the observation that vibrissal morphology is diverse in cetaceans, and is worth further investigation to fully explore links between form and function

Invited perspectives: Managed realignment as a solution to mitigate coastal flood risks – optimizing success through knowledge co-production

Nature-based solutions are increasingly suggested for mitigating coastal flood risks in the face of climate change. Managed realignment (MR), a coastal adaptation strategy that entails the landward realignment of coastal defences to restore coastal habitats (often salt marshes), plays a pivotal role in implementing nature-based solutions in the coastal zone. Across Europe, more than 130 sites have been implemented so far, often to harness their potential to mitigate coastal flood risks while restoring coastal habitats (ABPmer, 2021). However, local communities often oppose MR projects, not only because they are seen as returning hard-won land to the sea but also because their coastal protection function is less trusted than traditional hard engineering techniques. This scepticism has foundation. The proclaimed coastal protection function of MRs is based on a broad body of literature on the protective function of natural salt marshes. However, contrary to natural salt marshes, MRs are often semi-enclosed tidal basins with narrow breaches to the open sea/estuary. Recent studies indicate that MR-internal hydrodynamics may significantly reduce their coastal protection, depending on their engineering design. To successfully implement MR, a much-improved scientific knowledge base is needed, as well as a process for addressing community concerns and genuinely engaging stakeholders in decision-making beyond the usual obligatory consultancy approach. Here, we propose the co-production of scientific knowledge with local communities and stakeholders to optimize the success of coastal nature-based solutions and promote community acceptance

Species interactions modulate the response of saltmarsh plants to flooding

Background and aims The vegetation that grows on coastal wetlands is important for ecosystem functioning, a role mediated by plant traits. These traits can be affected by environmental stressors and by the competitive environment the plant experiences. The relative importance of these influences on different traits is poorly understood and, despite theoretical expectations for how factors may interact, empirical data are conflicting. Our aims are to determine the effect of flooding, species composition and their interaction on plant functional traits, and assess the role of biodiversity and species composition in driving community-level responses to flooding. Methods We conducted a factorial glasshouse experiment assessing the effects of species composition (all combinations of three saltmarsh species, Aster tripolium, Plantagomaritima and Triglochin maritima) and flooding (immersion of roots) on a suite of functional traits. We also related biomass in mixed species pots to that expected from monocultures to assess how species interactions affect community-level biomass. Key results Species composition frequently interacted with flooding to influence functional traits and community level properties. However, there was also considerable intraspecific variability in traits within each treatment. Generally, effects of flooding were more pronounced for belowground than aboveground biomass, while composition affected aboveground biomass more than belowground biomass. We found both negative and positive interactions between species (indicated by differences in above and belowground biomass from expectations under monoculture), meaning that composition was an important determinate of community function. Conclusions While the effect of flooding alone on traits was relatively weak, it interacted with species composition to modify the response of both individual plants and communities. Our results suggest that responses to increased flooding will be complex and depend on neighbourhood species interactions. Furthermore, intraspecific trait variability is a potential resource that may dampen the effects of changes in flooding regime

A prioritization metric and modelling framework for fragmented saltmarsh patches restoration

Saltmarsh is a coastal ecosystem providing crucial ecosystem services, and its continued degradation and fragmentation has drawn increasing attention. However, how to effectively restore the connectivity between fragmented saltmarsh patches remains an open challenge. In this study, we developed a metric and modelling framework that prioritised saltmarsh patches for restoration. To demonstrate our approach, we simulated spatially explicit restoration schedules for Suaeda salsa patches at the Yellow River Delta National Nature Reserve, China, using three strategies: increasing-patch-area, increasing-number-of-patches and a benchmark unrestrictive prioritization strategy. We prioritised patches for restoration based on a number of widely used graph-theoretic landscape connectivity and metapopulation capacity metrics. Our simulation results suggested the rank connectivity-importance of extant patches was correlated within the group of graph-theoretic connectivity metrics or metapopulation capacity metrics, but unrelated across group. The unrestrictive prioritization strategy clearly outperformed the strategies of increasing-patch-area and increasing-number-of-patches which returned comparable connectivity restoration outcomes. For the more effective unrestrictive prioritization strategy, there were substantial differences in the simulated priority patches between metrics that considered stepping stone effects and those did not. While the former resulted in corridor-building priority patches that led to a more connected landscape throughout the region, the latter led to local clustering. We recommend use of the total probability of connectivity (PC) among the metrics we tested due to similarity of results to other metrics and its simulation efficiency. The proposed framework is readily applicable to prioritise areas for connectivity conservation and restoration in any monospecific ecosystem at the regional scale

Rapid carbon accumulation at a saltmarsh restored by managed realignment exceeded carbon emitted in direct site construction

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

Limited Vegetation Development on a Created Salt Marsh Associated with Over-Consolidated Sediments and Lack of Topographic Heterogeneity

Restored salt marshes frequently lack the full range of plant communities present on reference marshes, with upper marsh species underrepresented. This often results from sites being too low in the tidal frame and/or poorly drained with anoxic sediments. A managed coastal realignment scheme at Abbotts Hall, Essex, UK, has oxic sediments at elevations at which upper marsh communities would be expected. But 7 years after flooding, it continued to be dominated by pioneer communities, with substantial proportions of bare ground, so other factors must hinder vegetation development at these elevations. The poorly vegetated areas had high sediment shear strength, low water and organic carbon content and very flat topography. These characteristics occur frequently on the upper parts of created marshes. Experimental work is required to establish causal links with the ecological differences, but other studies have also reported that reduced plant β-diversity and lower usage by fish are associated with topographic uniformity. Uniformity also leads to very different visual appearance from natural marshes. On the upper intertidal, sediment deposition rate are slow, water velocities are low and erosive forces are weak. So, topographic heterogeneity cannot develop naturally, even if creeks have been excavated. Without active management, these conditions will persist indefinitely