Rapid expansion and ecosystem health risk of invasive biopollutants dispersed by maritime traffic in French Polynesia

The introduction of biopollutant species challenge ecosystem health and economy in remote islands. Here we checked the advance of invasive fouling species in five French Polynesian islands. Expansion of invasive species (Acantophora spicifera, Bugula neritina, Chthamalus proteus, Dendostrea frons) was detected using individual barcoding (COI for animals, RBLC for algae), and metabarcoding on biofouling (COI and 18S sequences). They were especially abundant in Port Phaeton (Tahiti), Bora Bora and Rangiroa atoll. Chthamalus proteus is a vector of bacterial diseases and may harm native French Polynesian mollusks. Dendostrea frons is a vector of Perkinsus, a parasite to which black pearl oysters, the mainstay of the Polynesian economy, are susceptible. High ecological and epidemiological risks were estimated for C. proteus and D. frons, and ecological risks also for A. spicifera and especially for B. neritina. Strengthening marine biosecurity measures is highly recommended to conserve these unique ecosystems and their associated services.

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.