Beware of oysters. Rapid advance of non-native species in tropical Pacific islands.

Non-indigenous species can become a problem for the ecosystem health, especially when their distribution grows to the detriment of native species. In this moment, they can become invasive species. In marine ecosystems, the maritime transport is the principal gate and corridor for the movement of alien species. The genetic identification, using barcoding tools, of different oyster species in ports of the remote French Polynesia islands and atolls, showed a significant increase of exotic versus native oyster species between 2011 and 2018. This supports the spread of exotic species with the maritime traffic as the main cause. Moreover, the 11% of inaccurate identification at species level obtained in this study shows the need to complete the genetic databases.

DNA barcodes of Antipode marine invertebrates in Bay of Biscay and Gulf of Lion ports suggest new biofouling challenges.

Marine biological invasions threaten global biodiversity nowadays. In this article, we have studied fouling communities from 10 port areas of south Bay of Biscay (Atlantic Ocean) and Gulf of Lion (Mediterranean Sea). A total of 834 individuals were genetically barcoded and corresponded to 95 different species. A total of 76 native species 8 genera and 1 family were identified, 58 from the Bay of Biscay and 23 from the Gulf of Lion. Furthermore, 19 species were identified as non-indigenous or cryptogenic (18 from the Bay of Biscay and 4 from the Gulf of Lion). We found a high proportion of Antipode non-indigenous species (NIS) that represented the 19.3% of all sampled individuals and the 54.21% of NIS specimens of this study. A framework for inference of donor regions based on a phylogenetic screening of genetic sequences was proposed as a proof of concept and tested, as well as models for the relationship between NIS introductions, maritime imports and distance to NIS native range and inferred donor areas. Consistent generalized linear models (GLM) with positive association between NIS genetic diversity and distance, not with maritime growth weight imports, strongly suggest that distant NIS could pose higher invasion risk than closer species. Selection for wider tolerance ranges during the long travel -direct or stepwise, as well as environmental similarity between donor and receiving regions, may explain these results.

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.