Marine Flora of French Polynesia: An Updated List Using DNA Barcoding and Traditional Approaches.

Located in the heart of the South Pacific Ocean, the French Polynesian islands represent a remarkable setting for biological colonization and diversification, because of their isolation. Our knowledge of this region's biodiversity is nevertheless still incomplete for many groups of organisms. In the late 1990s and 2000s, a series of publications provided the first checklists of French Polynesian marine algae, including the Chlorophyta, Rhodophyta, Ochrophyta, and Cyanobacteria, established mostly on traditional morphology-based taxonomy. We initiated a project to systematically DNA barcode the marine flora of French Polynesia. Based on a large collection of ~2452 specimens, made between 2014 and 2023, across the five French Polynesian archipelagos, we re-assessed the marine floral species diversity (Alismatales, Cyanobacteria, Rhodophyta, Ochrophyta, Chlorophyta) using DNA barcoding in concert with morphology-based classification. We provide here a major revision of French Polynesian marine flora, with an updated listing of 702 species including 119 Chlorophyta, 169 Cyanobacteria, 92 Ochrophyta, 320 Rhodophyta, and 2 seagrass species-nearly a two-fold increase from previous estimates. This study significantly improves our knowledge of French Polynesian marine diversity and provides a valuable DNA barcode reference library for identification purposes and future taxonomic and conservation studies. A significant part of the diversity uncovered from French Polynesia corresponds to unidentified lineages, which will require careful future taxonomic investigation.

Seagrasses and seagrass habitats in Pacific small island developing states: Potential loss of benefits via human disturbance and climate change.

Seagrasses provide a wide range of services including food provision, water purification and coastal protection. Pacific small island developing states (PSIDS) have limited natural resources, challenging economies and a need for marine science research. Seagrasses occur in eleven PSIDS and nations are likely to benefit in different ways depending on habitat health, habitat cover and location, and species presence. Globally seagrass habitats are declining as a result of anthropogenic impacts including climate change and in PSIDS pressure on already stressed coastal ecosystems, will likely threaten seagrass survival particularly close to expanding urban settlements. Improved coastal and urban planning at local, national and regional scales is needed to reduce human impacts on vulnerable coastal areas. Research is required to generate knowledge-based solutions to support effective coastal management and protection of the existing seagrass habitats, including strenghened documentation the socio-economic and environmental services they provide. For PSIDS, protection of seagrass service benefits requires six priority actions: seagrass habitat mapping, regulation of coastal and upstream development, identification of specific threats at vulnerable locations, a critique of cost-effective restoration options, research devoted to seagrass studies and more explicit policy development.