Assessment of ecological status of the lagoon of Bora-Bora Island (French Polynesia)

Abstract

In the South Pacific, an important island has been forgotten and neglected from monitoring and research programs on marine biodiversity: Bora-Bora, often called the ‘Pearl of the Pacific’. To fill this gap in our knowledge, we have analyzed the only two datasets available to date on the biodiversity of Bora-Bora’s reefs: Reef Checks’ program, conducted on 18 sites inside the lagoon in 2006 and 2018; and Biodiversity’s monitoring program, conducted on 31 lagoon sites in 2019. Both monitoring programs showed that the corals in Bora-Bora lagoon are in good health. The living coral cover has been stable on all recorded geomorphological zones between 2006 and 2019. In contrast, there was a strong decrease in the density of all macro-invertebrate species recorded (i.e. giant clams, sea-urchins, sea-cucumbers, sea-snails). For giant clams, three human-related causes of extraction were identified: collecting activities of tourists, local inhabitants and occasional major predation by large groups of people visiting from other islands for local festivities. Lastly, both monitoring programs showed that all commercial families (i.e. Acanthuridae, Scaridae, Serranidae) increased in density over time. This may be because the larval recruitment of fish seems to be sufficient to offset the loss of adults from local fishing. Overall, our monitoring programs, conducted on coral, macro-invertebrates and fish, suggest that the luxury tourism industry developed at Bora-Bora contributed to the maximization of the economic and social benefits of coral reefs while preserving Bora-Bora’s natural sites, ecosystems and the socio-cultural balance.