The Importance of Marine Predators in the Provisioning of Ecosystem Services by Coastal Plant Communities

Reorganization of seagrass communities in a changing climate

Although climate change projections indicate significant threats to terrestrial biodiversity, the effects are much more profound and striking in the marine environment. Here we explore how different facets of locally distinctive α- and β-diversity (changes in spatial composition) of seagrasses will respond to future climate change scenarios across the globe and compare their coverage with the existing network of marine protected areas. By using species distribution modelling and a dated phylogeny, we predict widespread reductions in species' range sizes that will result in increases in seagrass weighted and phylogenetic endemism. These projected increases of endemism will result in divergent shifts in the spatial composition of β-diversity leading to differentiation in some areas and the homogenization of seagrass communities in other regions. Regardless of the climate scenario, the potential hotspots of these projected shifts in seagrass α- and β-diversity are predicted to occur outside the current network of marine protected areas, providing new priority areas for future conservation planning that incorporate seagrasses. Our findings report responses of species to future climate for a group that is currently under represented in climate change assessments yet crucial in maintaining marine food chains and providing habitat for a wide range of marine biodiversity.

Role of extracellular polymeric substances in metal sequestration during mangrove restoration

Extracellular polymeric substances (EPS) are widely observed in aquatic ecosystems, however the potential function of EPS on metal sequestration in mangrove wetlands is unclear. Thus, an ecological restoration area (including Sonneratia apetala, Kandelia obovata and unvegetated mudflat) was employed to assess the effect of mangrove reforestation on metal sequestration and the underlying roles played by EPS. The results showed that mangrove restoration directly promoted metal accumulation (e.g., Cr, Cu, Ni, Pb, and Zn) in sediments. However, alleviated metal bioavailability was detected after mangrove reforestation. The changes in metal accumulation and bioavailability were highly correlated with EPS and microbial composition. Mangrove restoration (especially for K. obovata reforestation) also significantly promoted EPS production, in which multiple metal-chelating functional groups (e.g., hydroxyl, carboxyl, and imino) were identified by Fourier infrared spectra. Moreover, the contents of EPS were positively correlated with metal accumulation but negatively correlated with metal bioavailability. The present data further illustrated that the enhancements of Gammaproteobacteria, Bacteroidia, Desulfobulbia, and Desulfobacteria might be important for EPS production. In summary, this is the first study to reveal that the presence of artificial mangroves might act as an efficient barrier in metal sequestration and immobilization by enhancing inherent microbial EPS.

Mangrove restoration promotes the anti-scouribility of the sediments by modifying inherent microbial community and extracellular polymeric substance

Coastal erosion will aggravate the loss of shorelines and threaten the safety of coastal engineering facilities. Mangrove is often considered as an efficient coastal guard; however the mechanisms involved in anti-scouribility ascribed to mangrove are still poorly understood. Thus, two artificial mangrove forests (including exotic Sonneratia apetala and native Kandelia obovata) and an unvegetated mudflat control were selected to explore the potential function of microbial extracellular polymeric substance (EPS) on the anti-scouribility of the sediments. A cohesive strength meter was used for the analysis of anti-scouribility, while a sequential extraction and 16S high-throughput sequencing were employed to evaluate the changes in EPS and microbial community driven by mangrove restoration. Principal component, redundancy, and two-matrix correlation heatmap analyses were performed for the analyses of the correlations among shear stress, EPS, microbes, and soil properties. The results showed an obvious enhancement of anti-scouribility after mangrove restoration. Compared to those of unvegetated mudflat, shear stress increased from 1.94 N/m² to 3.26 and 4.93 N/m² in the sediments of S. apetala and K. obovata stands, respectively. Mangrove restoration also promoted EPS content in the sediments, irrespective of EPS components and sub-fractions. Both extracellular protein and polysaccharide were found to be positively correlated with anti-scouribility. Coinciding with increased anti-scouribility and EPS, increased bacterial abundances were also detected in the sediments after mangrove restoration (especially K. obovata), whereas Proteobacteria and Bacteroides may be important and influential for EPS secretion and anti-scouribility promotion. Nevertheless, increased total organic carbon, total nitrogen and total phosphorus induced by mangrove restoration may also partially contribute to improvement of anti-scouribility. In conclusion, this is the first study to provide evidence for a link between mangrove restoration and increased EPS which improve resistance to scouring. The present study provides a novel perspective on the revealing of the function of mangrove on erosion mitigation.

Demographic analysis of an Israeli Carpobrotus population

Carpobrotus species are harmful invaders to coastal areas throughout the world, particularly in Mediterranean habitats. Demographic models are ideally suited to identify and understand population processes and stages in the life cycle of the species that could be most effectively targeted with management. However, parameterizing these models has been limited by the difficulty in accessing the cliff-side locations where its populations are typically found, as well as accurately measuring the growth and spread of individuals, which form large, dense mats. This study uses small unmanned aerial vehicles (drones) to collect demographic data and parameterize an Integral Projection Model of an Israeli Carpobrotus population. We validated our data set with ground targets of known size. Through the analysis of asymptotic growth rates and population sensitivities and elasticities, we demonstrate that the population at the study site is demographically stable, and that reducing the survival and growth of the largest individuals would have the greatest effect on reducing overall population growth rate. Our results provide a first evaluation of the demography of Carpobrotus, a species of conservation and economic concern, and provide the first structured population model of a representative of the Aizoaceae family, thus contributing to our global knowledge on plant population dynamics. In addition, we demonstrate the advantages of using drones for collecting demographic data in understudied habitats such as coastal ecosystems.

Imperfect detection alters the outcome of management strategies for protected areas

Designing protected area configurations to maximise biodiversity is a critical conservation goal. The configuration of protected areas can significantly impact the richness and identity of the species found there; one large patch supports larger populations but can facilitate competitive exclusion. Conversely, many small habitats spreads risk but may exclude predators that typically require large home ranges. Identifying how best to design protected areas is further complicated by monitoring programs failing to detect species. Here we test the consequences of different protected area configurations using multi-trophic level experimental microcosms. We demonstrate that for a given total size, many small patches generate higher species richness, are more likely to contain predators, and have fewer extinctions compared to single large patches. However, the relationship between the size, number of patches, and species richness was greatly affected by insufficient monitoring, and could lead to incorrect conservation decisions, especially for higher trophic levels.