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Article Index
Geography and Geology
Terrestrial Biodiversity
Marine Biodiversity
Biodiversity Research
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Marine Biodiversity

The most outstanding detail of the global picture of the marine fauna and flora is the low number of endemic species. In fact, evidence of endemism among the Azorean marine and maritime biota is sparse and clearly apparent only with regard to the supralittoral, maritime vegetation. Most of the organisms now present probably reached the Azores in the last 17 thousand years - a too short period of time for species differentiation. This “late arrival” provides an explanation for the existence of fewer species - 2100 fauna species and over 300 species of algae - and the low amount of endemisms in the Azores. The lack of extensive margins of shallow water also obstructs colonization of the islands by littoral organisms and the uniformity of shore types limits recruitment, even of successful immigrants, and coastal diversity and sources of primary productivity are only enriched in a few significant wetlands. The greater distance from continental coasts is another important factor contributing to the low number of shore fishes in the Azores.

The majority of the Azorean coastal and marine biota is very modem and comprises species that have arrived predominantly from the eastern Atlantic, especially the area between southern Europe (Lusitanian Region) and northwest Africa (Mauretanian Region), including the Mediterranean, but also contains species from other Atlantic sources. The picture that emerges is that the Azores is at a ‘cross-roads’ where shallow marine fauna and flora of different origins meet. Regardless of their geographic origin, most representatives of the coastal Azorean marine biota are chance survivors of recent chance immigrants probably delivered to these shores in a variety of ways, but predominantly through currents. Some marine colonisers have received human assistance, particularly the maritime vegetation and other well known exotics.

In 1994, Neto reported the existence of 256 species of algae for the archipelago but on-going work with this group of flora led to the current number of approximately 400 species identified (Tittley et al., 2009). Schmidt (1931 in Neto, 1994) listed 8 species as endemic, but most of these were never confirmed in posterior work. The only exception is the green algae Codium elisabethae, which lost the status of Azorean endemism when it was reported for Madeira (Neto et al., 2001).
In terms of marine invertebrates, the shallow subtidal fauna is diverse and abundant, but taxonomic knowledge of this group is only relatively adequate for the larger-size species. Possibly more than 1000 species are reported, but inventories are incomplete and scattered (Cardoso et al., 2008). Endemisms are lacking in demosponges and hydroids (Santos et al., 1995), but there are clear signs of endemism in molluscs and amphipods. This lack of endemism (or of confirmation) is probably a result of the reduced knowledge of the greater part of the taxa (e.g. Lopes et al., 1993; Ávila, 2005 in Cardoso et al., 2008), as marine invertebrate taxonomy has not been a priority research area in the Region. This should be cause of major concern as these species are threatened by over-exploitation and some even of local extinction, which allied to ignorance, can result in species depletion (Cardoso et al., 2008).   
Fig 10_Endemic marine fishes are almost absent in the Azores. Scorpaena azorica described by Eschmeyer in 1969 (Santos et al., 1995) and Centrolabrus caeruleus described in Azevedo, 1999 - and more recently considered as to belonging to the genus Symphodus (Symphodus caeruleus) by Almada et al. (2002) – are the only two species of marine littoral fish confirmed to date. However, it is thought that an important component (possibly circa 15%) of the coastal fish species of the Azores is endemic of Macaronesia.

Fig 11
Sites of the Azores archipelago are considered as important areas for several species of marine birds (at least 10), some of which are included in Annex I of the EU Birds Directive and Annex 2 of Bern Convention and considered as Species of Conservation Concern in Europe. However, many populations are now confined to the steep cliffs or small islets due to, among other factors, the introduction of rats. The archipelago concentrates around 70% of the world population of the Cory’s shearwater Calonectris diomedea borealis during the species’ breeding season and for this reason, since 1995 the Region promotes a campaign for the protection of juveniles that abandon their nests for their first trans-oceanic flight. The Azores counts with one endemic marine bird species only recently described: Monteiro’s Storm-petrel (Oceanodroma monteiroi).

As for reptiles, there are 5 known species of marine turtles to occur in the Azores. In terms of marine mammals, the region is a privileged location for sighting whales and dolphins, with over 20 species commonly observed in the Azorean waters near the coasts of most islands.