This paper characterizes historical (1981–2023) marine heatwaves in the tropical southwestern Pacific, where they pose a challenge for marine resource dependent Islands. Heatwaves are distinguished as a function of their spatial extent, signature at the coast, and seasonality, to allow a better understanding of their impacts on ecosystems. Marine heatwaves are getting longer and more frequent, with greater spatial extents. Our results aim to inform the Pacific Islands on their vulnerability.

Due to ocean warming, coral reef ecosystems are strongly impacted with dystrophic events and corals experiencing increasing frequencies of bleaching events. In-situ observation remains the best alternative for accurate characterization of trends and extremes in these shallow environments. This paper presents the coastal temperature dataset of the ReefTEMPS monitoring network which spreads over multiple Pacific Island Countries and Territories (PICTS) in the Western and Central South Pacific.

During 2018–2022, four pearl farming Tuamotu atolls (French Polynesia) were studied with oceanographic instruments to measure lagoon hydrodynamics and ocean-lagoon water exchanges. The goal was to gain knowledge on the processes influencing the spat collection of the pearl oyster Pinctada margaritifera, the species used to produce black pearls. A worldwide unique oceanographic atoll data set is provided to address local pearl farming questions and other fundamental and applied investigations.

From 2014 to 2021, extensive monitoring of hydrodynamics was deployed within five contrasted lagoons of New Caledonia during austral summers. These coastal physical observations encompassed unmonitored lagoons and captured eight major atmospheric events ranging from tropical depression to category 4 cyclone. The main objectives were to characterize the processes controlling hydrodynamics of these lagoons and record the signature of extreme events on land–lagoon–ocean continuum functioning.

Estuaries are key reactive ecosystems along the land–ocean aquatic continuum and are often strongly impacted by anthropogenic activities. We calculated nutrient in and out fluxes by using a 1-D transient model for seven estuaries along the French Atlantic coast. Among these, large estuaries with high residence times showed higher retention rates than medium and small ones. All reveal coastal eutrophication due to the excess of diffused nitrogen from intensive agricultural river basins.