La macroflore marine de l'archipel des Marquises

Until the Pakaihi i te Moana 2011 expedition, there were only ten known species of marine plants from the Marquesas Islands. Following this survey, 144 additional records (excluding Corallinales and Peyssonnelia spp.) were identified from the nine islands studied. These include 94 Rhodophyta (red algae), 38 Chlorophyta (green algae) and 12 Phaeophyceae (brown algae), with several undescribed species. Due to the dynamic water motion around these wave-swept islands, the dominant flora, from the surface until about 40 meters depth, consists of red encrusting coralline algae. The broad types of habitats seen include sedimentary plains, rubble, coralline habitats dominated by the genera Porites and Millepora, bare vertical drop-offs and escarpments, and algal beds. The latter consist mainly of several species of Halimeda, notably H. distorta, H. melanesica, H. heteromorpha and H. discoidea. Species richness varies within the archipelago and from one island to the other, with a higher number of species in the central and southern islands. Half of the species were recorded only from a single island, and only 16% of the species were recorded from four or more of the nine surveyed islands. The islands of Ua Huka and Nuku Hiva show the highest diversity, notably because of a greater number of habitats, including rock pools and crevices of the basalt ledges. It is in these habitats, that are particularly rich in algal diversity, that the inhabitants of the Marquesas still collect today various edible species for use as food. The Marquesas Islands stand out from the rest of Polynesia by quite a number of aspects, and show biogeographical affinities with the Hawaiian Islands, as well as the Eastern Pacific (Guadelupe, Revillagigedo and Galápagos islands). The natural and ecological characteristics of the marine flora, together with traditional cultural practices still very much alive today, impart a special place to this archipelago within Polynesian society. These unique characteristics contribute towards supporting a regional conservation program