Effects of COVID-19 lockdown on the observed density of coral reef fish along coastal habitats of Moorea, French Polynesia.

During the first COVID-19 lockdown in 2020, levels of coastal activities such as subsistence fishing and marine tourism declined rapidly throughout French Polynesia. Here, we examined whether the reduction in coastal use led to changes in fish density around the island of Moorea. Two natural coastal marine habitats (bare sand and mangrove) and one type of man-made coastal structure (embankment) were monitored on the west coast of the island before and after the first COVID-19 lockdown. At the end of the lockdown (May 2020), significantly higher apparent densities of juvenile and adult fish, including many harvested species, were recorded compared to levels documented in 2019 at the same period (April 2019). Fish densities subsequently declined as coastal activities recovered; however, 2 months after the end of the lockdown (July 2020), densities were still higher than they were in July 2019 with significant family-specific variation across habitats. This study highlights that short-term reductions in human activity can have a positive impact on coastal fish communities and may encourage future management policy that minimizes human impacts on coastline habitats. Supplementary Information: The online version contains supplementary material available at 10.1007/s10113-022-02011-0.

Marine biodiversity of a pristine coral reef in French Polynesia

Understanding the natural state of coral reefs is paramount to evaluate the response of these ecosystems to local and global human impacts as well as management and conservation strategies. In French Polynesia, some islands are still pristine or uninhabited, such as Tupai atoll. Tupai has been uninhabited, with access to the lagoon prohibited since 2010. However, fishers from nearby islands often take from the outer reef slope at Tupai. Our marine biodiversity survey (coral, macro-invertebrates, and fish) conducted in 2019 highlighted a low density of commercial fish species and top-predators on the outer slope in comparison to the lagoon, where the top-predators represented 16% (of the density) of functional trophic groups. Our surveys also showed a high living coral cover (46%) on the outer slope of Tupai, perhaps due to the absence of both touristic sub-aquatic activities and local pollution from private and commercial activities. Overall, this initial scientific assessment of Tupai has granted an understanding of the spatial patterns of coral, macro-invertebrates, and fish assemblages in the absence of human impacts (i.e., in the lagoon), representing an ecological baseline that could inform conservation management strategies to ensure the preservation of coral reef ecosystem.