Barcodes of marine invertebrates from north Iberian ports: Native diversity and resistance to biological invasions.

Ports are gateways for many marine organisms transported by ships worldwide, especially non-indigenous species (NIS). In this study carried out in North Iberian ports (Cantabrian Sea, Bay of Biscay) we have observed 38% of exotic macroinvertebrates. Four species, namely the barnacle Austrominius modestus, the tubeworm Ficopomatus enigmaticus, the Pacific oyster Crassostrea gigas and the pygmy mussel Xenostrobus securis, exhibited clear signs of invasiveness. A total of 671 barcode (cytochrome oxidase subunit I or 18S rRNA) genes were obtained and confirmed the species status of some cryptic NIS. Negative and significant correlation between diversity estimators of native biota and proportion of NIS suggests biotic resistance in ports. This could be applied to management of port biota for contributing to prevent the settlement of biopollutants in these areas which are very sensitive to biological invasions.

Response of top shell assemblages to cyclogenesis disturbances. A case study in the Bay of Biscay.

Cyclones and other climate disturbances profoundly affect coastal ecosystems, promoting changes in the benthic communities that require time, sometimes even years, for a complete recovery. In this study we have analysed the morphological and genetic changes occurred in top shell (Gibbula umbilicalis and Phorcus lineatus) assemblages from the Bay of Biscay following explosive cyclogenesis events in 2014. Comparison with previous samples at short (three years before the cyclogenesis) and long (Upper Pleistocene) temporal scales served to better evaluate the extent of change induced by these disturbances in a more global dimension. A significant increase in mean size after the cyclogenesis was found for the two species, suggesting selective sweeping of small individuals weakly adhered to substrata. Loss of haplotype variants at the cytochrome oxidase subunit I gene suggests a population bottleneck, although it was not intense enough to produce significant changes in haplotype frequencies. The high population connectivity and metapopulation structuring of the two species in the area likely help the populations to recover from disturbances. At a wider temporal scale, cyclogenesis effects seemed to compensate the apparent decreasing trends in size for P. lineatus occurred after the Pleistocene-Holocene transition. Considering disturbance regimes for population baselines is recommended when the long-term effects of climate and anthropogenic pressures are evaluated.