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Background During a LIFE research project aiming at the implementation of the conservation of the habitats and restoration of coastal wetland areas of Praia da Vitória (Terceira, Azores, Portugal), there was the opportunity undertake a systematic record of several groups of arthropods in three wetland areas: Paul da Praia da Vitória (PPV), Paul do Belo Jardim (PBJ) and Paul da Pedreira do Cabo da Praia (PPCP). The objective of the study was to perform a rapid biodiversity assessment, comparing the three sites in two different years, before and after the implementation of several conservation measures. This project also contributed to improve the knowledge of Azorean arthropod diversity at both local and regional scales, including new taxa for Terceira island and new records for Azores. Taking into consideration those aims, a set of standardised sampling methods were performed, inspired by the COBRA protocol originally developed for spiders. New information A total of 15,810 specimens belonging to 216 arthropod species and subspecies were collected. Beetles (Insecta, Coleoptera) and spiders (Araneae) dominated, with 81 and 51 taxa, respectively. Two beetle families dominated, Staphylinidae and Curculionidae with, respectively, 22 and 17 species and subspecies. Exotic species were also dominant (132 species and subspecies), the Azorean endemics being restricted to only eight taxa. The remaining 76 species and subspecies are native non-endemic. Two rare endemic species were found with relatively sustainable populations, the Azores Cone-head Conocephalus chavesi (Orthoptera, Tettigoniidae) and the true weevil Drouetius oceanicus oceanicus (Coleoptera, Curculionidae). A total of six species are novel for the Azores, five exotic ( Bledius unicornis, Carpelimus zealandicus, Oenopia doublieri, Sitona hispidulus, Trichiusa immigrata) and one possibly native (Pyrrhocoris apterus). An additional 15 taxa are novel for Terceira island, ten exotic (Cheiracanthium mildei, Cylindroiulus latestriatus, Eumodicogryllus bordigalensis, Nemobius sylvestris, Pissodes castaneus, Psyllipsocus ramburi, Trachyzelotes lyonneti, Trigonnidium cicindeloides, Tychius cuprifer, Zelotes tenuis ) and five native (Aegialia arenaria, Oxypoda lurida, Platycleis sabulosa, Plinthisus brevipennis, Tachyura diabrachys). [ABSTRACT FROM AUTHOR]

Habitat destruction is the leading cause of species extinctions. However, there is typically a time-lag between the reduction in habitat area and the eventual disappearance of the remnant populations. These “surviving but ultimately doomed” species represent an extinction debt. Calculating the magnitude of such future extinction events has been hampered by potentially inaccurate assumptions about the slope of species–area relationships, which are habitat- and taxon-specific. We overcome this challenge by applying a method that uses the historical sequence of deforestation in the Azorean Islands, to calculate realistic and ecologically-adjusted species–area relationships. The results reveal dramatic and hitherto unrecognized levels of extinction debt, as a result of the extensive destruction of the native forest:>95%, in<600 yr. Our estimations suggest that more than half of the extant forest arthropod species, which have evolved in and are dependent on the native forest, might eventually be driven to extinction. Data on species abundances from Graciosa Island, where only a very small patch of secondary native vegetation still exists, as well as the number of species that have not been found in the last 45 yr, despite the extensive sampling effort, offer support to the predictions made. We argue that immediate action to restore and expand native forest habitat is required to avert the loss of numerous endemic species in the near future. [ABSTRACT FROM AUTHOR]