Oceanic Bioregion: Provinces, Climate, Fauna And Flora

The oceanic bioregion is the name given to one of the world’s bioregions, which encompasses a series of islands located mainly in the Pacific Ocean. It is considered the smallest region on the planet and does not include large terrestrial bodies such as Australia or New Zealand (these belong to the Australian bioregion).

In the oceanic bioregion are the islands of Fiji, Hawaiian Islands, Micronesia and Polynesia. This region includes an area of ​​land of approximately one million square kilometers.

Not only is its size considered compared to other bioregions on the planet, but it is also classified as the youngest of all biodiverse systems. Its main attributes are high volcanic activity and extensive coral reefs.

Being made up of small terrestrial bodies in a vast oceanic extension, the study of this region has focused on the plant and animal qualities within each island, and on how human impact has been able to directly condition changes over time.

Among the Pacific Islands they share quite similar traits in terms of their biodiversity. It is a region with a low population density, calculating a population of five million inhabitants in a land area of ​​550,000 square kilometers, compared to 29 million square kilometers of aquatic bodies.

This has caused it to be a moderately conserved region compared to others, and whose preservation programs are still continuing. Nowadays, however, the conservation risks in these spaces have increased.

Provinces of the oceanic bioregion

The oceanic bioregion is divided into seven biogeographic provinces, based on their fauna and flora characteristics:

1- Province of Papua : includes the territories of Papua-New Guinea and the Bismarck and Solomon Islands. It is considered a distinctive entity due to its similarities with Australian lands in terms of climate, vegetation and fauna. The reason for this is the possibility that both territories were connected during the Pleistocene.

2- Province of Micronesia : includes the Bonin and Volcano islands; Looks, Sail, Wake and Marcus Islands Mariana, Caroline, Marshall Islands, and Palau Islands.

3- Hawaiian Province : includes all of the Hawaiian Islands, which are located at the northernmost point of the oceanic region. This province has a greater neotropical influence on its fauna than any other part of the region.

4- Province of South-Eastern Polynesia : it encompasses different groups of islands such as the Danger, Cook and Line and reaches far beyond Easter Island. Some studies include the Juan Fernández Islands, although these present qualities closer to the Neotropical region. This province is quite prolific in endemic species of flora and fauna.

5- Province of Central Polynesia : includes the islands of Phoenix, Ellis, Tokelau, Samoa and Tonga. The Karmadec group of islands is vying for its place between this province of the oceanic region or the Australian region (which includes New Zealand, close to this group).

6- Province of New Caledonia : it is considered unique in fauna and flora, although it is provisional. The islands included, Lord Howe and Norfolk, present vegetation and animal life very similar to that of the Antarctic regions. This is deduced from a late continental separation during the Cretaceous.

7- Eastern Melanesian Province : includes the groups known as the Fiji Islands and New Habrides.


The oceanic region is considered the youngest geologically due to the absence of large terrestrial bodies, and to the late separations that were forming the small groups of islands that remain until today.

The formation of natural bodies such as coral reefs is one of its oldest manifestations.

The distribution of the islands in the aquatic space is attributed to the volcanic activity of the region, which has allowed the formation of low-relief land portions up to mountainous islands such as Hawaii.

Climate and vegetation

The oceanic region has a generalized tropical or subtropical climate, where temperatures remain above 18 °, with high levels of humidity and specific stages of drought.

Despite the similarities, the most remote islands in the region may have temperate properties or even close to the Arctic.

The vegetation in this region then varies according to the geographical location of the land portion and the natural elements that characterize it.

Most of the islands have tropical or subtropical forests and savannas, while others, volcanic, may present a much rarer high altitude vegetation.

Fauna and Flora

Due to the position and geographical distance of the islands of the oceanic region, the animal and plant population has been, to a large extent, marked by the passage of man through these territories.

Although there are a good number of endemic species in several of the island groups, it has been the domestication of these territories and the importation of new species for a long time that has forged a stable population.

The flora of the oceanic islands is considered the result of years of sea and air currents that were moving particles and even seeds (algae, mosses, even coconut palm seeds), from Indonesia and the Philippines, towards the different terrestrial bodies.

From the side of America, the same could happen with certain plants found on Easter Island, for example.

However, the impact caused by the insertion and domestication of these species has been considered to guarantee the preservation of these territories.

The typical and most common animal species of these islands have been small and medium-sized reptiles, seabirds and bats. Any mammal that today inhabits these islands is considered as inserted by man.

The inserted animal and plant population that today inhabits the oceanic region has not been a destructive factor in the fragility of these ecosystems, but it is considered that they have unbalanced a certain natural order in a remote territorial group and whose own elements were the product of large bodies. terrestrial around him.


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  4. Schmidt, KP (1954). Faunal Realms, Regions, and Provinces. The Quarterly Review of Biology.
  5. Udvardy, MD (1975). A Classification of the Biogeographical Provinces of the World. Morges: International Union for Conservation of Nature and Natural Resources.

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