Small- and large-scale processes including anthropogenic pressures as drivers of gastropod communities in the NE Atlantic coast: A citizen science based approach.

Rocky-shores are among the most threatened coastal habitats, particularly under human pressures. While rocky-shore communities have been increasingly used to evaluate local anthropogenic perturbations such as water eutrophication for instance, large-scale variability in relation to both natural and anthropogenic pressures is still overlooked. Here, using citizen science-based data, we applied a Random Forest modelling approach to assess the relative impact of both small-and large-scale processes (including natural and some anthropogenic pressures) on intertidal gastropod communities as well as taxa-specific gastropod abundances over more than 1000 km of the North-East Atlantic coast. Our model results demonstrate that small-scale conditions (i.e. within shore) are determinant in shaping gastropod communities. However, community responses are mainly driven by taxon-specific effects. Among large-scale predictors, high concentrations of inorganic nutrients and total suspended matter, as found in large river plumes, are the main drivers impacting the gastropod communities by depleting both taxon abundances and richness. According to models, the decline in abundance of the yet most prevalent taxa (Steromphala umbilicalis, Patella spp., S. pennanti and Phorcus lineatus) is expected to be between 65% and 85%, while Littorina littorea was the only taxon which may be favoured by high concentrations of inorganic nutrients and total suspended matter. Such results provide relevant insights in the context of ever-increasing needs for bioindicators of coastal ecosystems. Finally, this work sheds light on the value of a citizen science program resulting from a consultation between professional and citizen volunteers as a useful and efficient tool to investigate large-scale processes.

Passive rewilding may (also) restore phylogenetically rich and functionally resilient forest plant communities.

Passive rewilding is increasingly seen as a promising tool to counterbalance biodiversity losses and recover native forest ecosystems. One key question, crucial to understanding assembly processes and conservation issues underlying land-use change, is the extent to which functional and phylogenetic diversity may recover in spontaneous recent woodlands. Here, we compared understorey plant communities of recent woodlands (which result from afforestation on agricultural lands during the 20th century) with those of ancient forests (uninterrupted for several centuries) in a hotspot of farmland abandonment in western Europe. We combined taxonomic, functional, and phylogenetic diversity metrics to detect potential differences in community composition, structure (richness, divergence), conservation importance (functional originality and specialization, evolutionary distinctiveness) and resilience (functional redundancy, response diversity). The recent and ancient forests harbored clearly distinct compositions, especially regarding the taxonomic and phylogenetic facets. Recent woodlands had higher taxonomic, functional and phylogenetic richness and a higher evolutionary distinctiveness, whereas functional divergence and phylogenetic divergence were higher in ancient forests. On another hand, we did not find any significant differences in functional specialization, originality, redundancy, or response diversity between recent and ancient forests. Our study constitutes one of the first empirical pieces of evidence that recent woodlands may spontaneously regain plant communities phylogenetically rich and functionally resilient, at least as much as those of ancient relict forests. As passive rewilding is the cheapest restoration method, we suggest that it should be a very useful tool to restore and conserve native forest biodiversity and functions, especially when forest areas are restricted and fragmented.

Validation of Eustiromastix guianae (Caporiacco, 1954) (Araneae, Salticidae) with a first description of the female, and additions to the salticid fauna of French Guiana.

In this paper, we validate the doubtful species status of E. guianae, with redescriptions of (supposedly lost) type and holotype males, and a first description of the female. Both sexes are measured and illustrated by pictures of habitus and copulatory organs. Seventeen new salticid species for French Guiana are also reported and a detailed catalogue of all salticid species from the Trinité National Nature Reserve is provided.