Mediterranean algae lost their tropical element between 5 and 7 mln yrs ago

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Washington, July 8 (ANI): A new research has suggested that Coralline algae in the Mediterranean Sea lost their tropical element between 5 and 7 million years ago.

The international team of researchers studied the coralline algae fossils that lived on the last coral reefs of the Mediterranean Sea between 7.24 and 5.3 million years ago.

The research team from the University of Granada (UGR) and the University of Modena and Reggio Emilia (Italia) show coralline algae distribution patterns in the west and centre of the Mediterranean Sea (in Salento, Italy and Almería, Spain) by way of a fossil register of 21 species collected in the two areas.

The study describes and interprets the disappearance of the last Messinian coral reefs (between 7.24 and 5.3 million years ago) in the Mediterranean Sea.

"In subsequent, more recent eras, this sea has not had the right oceanographic conditions (above all a high enough temperature) to house coral reefs," said Juan C. Braga, the chief author and a researcher at the Stratigraphy and Paleontology Department of the UGR.

During the period studied by the scientists through the coralline algae fossils found in the Mediterranean, the last few reefs boasted very little coralline diversity.

"This is the result of the long history of global cooling over the last 20 million years and the isolation (separation) of the Mediterranean from the Indian Ocean, some 15 million years ago," according to the research.

According to the results of the research, the relative abundance of coralline algae in reefs and slope deposits is 1-5 percent and 18 percent lower respectively in the Sorbas basin (Almería) than in Salento (Italy).

Furthermore, the main components of the coralline algae assemblages found in shallow water are extant species that are very common in the Mediterranean.

"Just like reef corallines, algae flora reflects the cooling of the Mediterranean and its isolation from the Indian Ocean, and only a few tropical biotas existed in the Messinian era. Moreover, most of them already had Atlantic affinities and resembled the algae that still inhabits our coasts today," said Braga.

The Mediterranean-Atlantic characteristics of Messinian reef corallines therefore reflect the decrease in tropical biotas that occurred during the Miocene (around 20 million years ago).

According to the research team, the widespread decline of this type of algae was due to global cooling and the isolation of the Mediterranean during the middle Miocene. (ANI)

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