THE PELAGIAN ISLANDS
The Pelagian Islands (from Ancient Greek πέλαγος Pèlagos, i.e. "open sea") is a southern Italian archipelago located in the Sicilian Chanel.
This group of islands forms the southernmost Italian archipelago and it is made up of Lampedusa (the main island, calcareous), Linosa (second by in size, of volcanic origin) and Lampione (a small and uninhabited calcareous islet).
At present, the archipelago forms part of the Pelagian Islands Marine Protected Area, which was established by decree of the Ministry of Environment on 21st October 2001.
EXPLORATION oF tHE PELAGIAN nATURAL hISTORY
In 1828, between the 2nd and 31st August, Gussone explored the island of Lampedusa (visiting also Lampione on the 15th and Linosa on 30th August), he then published in 1839 an account of the 274 species of plants he found.
Eighteen years after Gussone`s visit, in 1846 Pietro Calcara published his "Report on the scientific journey performed in the islands of Lampedusa, Linosa and Pantelleria, and elsewhere in Sicily", presenting the first serious contribution to the description of these islands. Appointed by the King to carry out "study of the natural sciences" of the island of Lampedusa, the following year he published his "Description of the island of Lampedusa", which we can consider the first accurate compilation of its characteristics, taken from the visit that he took place between 18th May and 15th June 1846, and also provided the first list of invertebrates of the island, listing 16 species of insects, which were added to the three previously found in Linosa between the 8th and 10th June 1846. With regards to the islet of Lampione this author has limited himself to reporting the notes of the botanist Giovanni Gussone, who had described it as a calcareous slab corroded by the impetus of the sea, yet once inhabited and cultivated by man, as evidenced by the mosaic floor formed by irregular cubes of raw marble embedded in the cement, as well as the roof of another building supported by an arch, already described by Captain Smyth in 1824. With regards to the plants, Calcara reports a total of 114 species, 23 of which were not previously reported by Gussone. He also created a geological map of Lampedusa and Linosa and carried out the description of the latter.
BIOGEOGRAPHY OF THE PELAGIAN ISLANDS
Lampedusa and Linosa are very different islands, one is calcareous, the other volcanic; therefore it is understandable that the fauna is also different. However, most of the species present on these two islands have either migrated to them or, in the case of Lampedusa, they represent a proof of an ancient connection with Tunisia.
One point on which each and everyone agree upon is the fact that the Pelagian islands, compared to other Mediterranean islands, hosts the least number of species. This owes its main explanation to their distance from the mainland. Linosa, located 163 km from the nearest coast, is certainly the most isolated of the two; its small size, combined with this remarkable isolation, although dampened by the presence of other islands (the Maltese archipelago to the East, Lampedusa to the South-West and Pantelleria to the North-West) with the possibility of stepping stones (lands of gradual colonization), as well to the poor environmental heterogeneity, justify its faunal poverty. Lampedusa, in comparison with Linosa, although having a modest surface and altitude, is proportionally richer in species; this can be mainly explained by its calcareous nature, which seems to offer more opportunities for settlement to many species of Arthropods.