Although many riparian and semi-aquatic plant species disperse via water currents, little is known about how this process interacts with the landscape matrix. In mangroves, the dense aerial root network could act as a strong dispersal barrier for the morphologically diverse propagules found in these trees. In this study, we combined field and laboratory experiments to test the effect of root density, propagule morphology and hydrodynamic variables on retention rates and trajectories of the propagules of 4 common species. Overall, flume experiments showed that larger propagules were more frequently retained than smaller ones. For the larger propa gules, retention rates increased with increasing obstacle density in the landscape matrix. In elongated propagules, intraspecific variation was linked to floating orientation. Experimental wave action and increased water flow velocity reduced retention. Dispersal in the field was constrained by major tidal currents and experiments confirmed less retention of smaller propagules, which moved farther than larger ones. Overall, our results reveal that the pronounced morphological variation in mangrove propagules interacts with the landscape matrix, contributing to strong differences in dispersal capacity among species and morphotypes. These results may help to explain observed mangrove distribution patterns, including zonation at local, regional and global scales. Additionally, given that many mangrove biotopes are currently strongly threatened by human pressure and fragmentation, this information is important as an input variable for dispersal models that aim to predict dispersal patterns at multiple scales and species responses to environmental change.

To complete their life cycle waterbirds rely on patchily distributed and often ephemeral wetlands along their migration route in a vast unsuitable matrix. However, further loss and degradation of remaining wetland habitats might lead to a configuration and size of stopovers that is no longer sufficient to ensure long-term survival of waterbird populations. By identifying optimal conservation targets to maintain overall habitat availability en route, we can accommodate an as yet absent functional connectivity component in larger management frameworks for migratory waterbirds, such as the Ramsar Convention and the EU Natura 2000 Network. Using a graph-based habitat availability metric (Equivalent Connected Area) we determine the functional connectivity of wetland networks for seven migratory waterbirds with divergent habitat requirements. Analyses are performed at two spatial extents both spanning the Mediterranean Sea and centered around Greece (Balkan-Cyrenaica and Greece-Cyrenaica). We create species-specific suitable habitat maps and account for human disturbance by species-specific disturbance buffers, based on expert estimates of Flight Initiation Distances. At both spatial extents we quantitatively determine the habitat networks’ overall functional connectivity and identify wetland sites that are crucial for maintaining a well-connected network. We show that the wetland networks for both spatial extents are relatively well connected and identify several wetland sites in Greece and Libya as important for maintaining connectivity. The application of disturbance buffers results in wetland site-specific reduction of suitable habitat area (0.90–7.36%) and an overall decrease of the network’s connectivity (0.65–6.82%). In addition, we show that the habitat networks of a limited set of species can be combined into a single network which accounts for their autoecological requirements. We conclude that targeted management in few but specific wetland complexes could benefit migratory waterbird populations. Deterioration of these vital wetland sites in Greece and Libya will have disproportionate consequences to the waterbird populations they support.

Assessing the quality of wetlands as refuelling areas for migrating waterbirds based on resource distribution patterns is challenging. Resources in wetlands can vary both horizontally and vertically and may be differentially available to different bird species at different times of the year. Therefore, the extent to which wetland quality can be generalised across seasons and for a diversity of birds remains unresolved. Spatiotemporal variation in abundance and quality of macrobenthos as food for migrating waders was studied in a set of wetland areas near a Mediterranean migration bottleneck in the Balkan peninsula, during both spring and autumn migration. Samples were subdivided into different depth layers to differentiate between parts of the sediment that are accessible to different groups of wader species. To quantify food availability and the resulting refuelling capacity in different wetland habitat types, abundance, wet weight, and lipid and protein content of invertebrate taxa were determined for each sample. Invertebrate food availability and quality were markedly higher in spring than in autumn. Given the higher abundance and protein and lipid content of prey in spring, the total energy that could be harvested in spring (3.81 ± 0.79 kJ/m2) was about 7 times higher than in autumn (0.56 ± 0.12 kJ/m2). Most prey were found in the top layer of the sediment (0–22 mm depth), but about a third of the total energy was present in the deepest soil layer that only longer‐billed species could reach (55–200 mm depth). Higher quality prey items such as larger‐bodied and heavier polychaetes and bivalves were found in the deeper sediment layers. For other taxa, there was no evident vertical pattern of increasing individual body size. Prey abundance differed between certain habitat types but, overall, food availability could not be linked to distinct habitats. In spring, redox potential tended to be higher, while pH, vegetation cover, conductivity, and temperature were lower than in autumn. Different wetland habitat classes used in a conservation framework may provide similar food resources for waders. As a result, linking food availability to habitat classifications is not straightforward. Furthermore, seasonal variation in wetland quality requires a re‐evaluation of the importance of wetland areas during spring and autumn migration. Finally, nutritional analyses are essential for determining the capacity of wetlands to support refuelling by migratory waterbirds.

Aim Waterbirds that travel seasonally between Europe and Africa use wetlands along four major Palearctic‐Afrotropical flyways. However, it is unknown to what extent the overall connectivity of these flyways may be threatened by ongoing habitat loss and degradation. Here, we contrasted the wetland connectivity along these four flyways, applying graph‐theoretic connectivity metrics on an intercontinental scale. We also explored for which flyway connectivity is most at risk. We then identified the most important wetlands by their contribution to connectivity in each flyway. Location Western Palearctic, Afrotropics. Methods Based on high‐resolution wetland maps, we calculated directional probabilistic connectivity metrics. Estimates of overall connectivity of each flyway were obtained, as well as the relative importance of wetlands, for birds with different migration strategies: short‐distance hoppers and long‐distance jumpers. Results The East‐Atlantic flyway and Eastern Mediterranean flyway had higher overall functional connectivity than the two central routes, reflecting the larger barrier represented by the Mediterranean Sea and Sahara Desert. Fewer than 5% of all wetlands supported more than 70% of the total connectivity of the network in each flyway, regardless of the considered migration strategy. These wetlands were either large, strategically positioned or both. Removing non‐protected wetlands from the analysis showed that the connectivity of some flyways could be jeopardized and that the East‐Atlantic and Eastern Mediterranean flyway may be most vulnerable to additional habitat loss. Main conclusions Our results illustrate (i) the major contribution of unprotected wetlands to flyway connectivity, (ii) the importance of integrating migration ecology into site‐based connectivity analyses and (iii) the utility of graph‐based connectivity metrics to inform conservation prioritization under present and future scenarios.

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