Alboran Sea

The Alboran Sea is the westernmost part of the Mediterranean Sea.

It occupies a unique space between the Iberian Peninsula and North Africa. To the north, the sea is bordered by Spain. To the south, it sits near Morocco and Algeria. At its westernmost edge, the Strait of Gibraltar connects the Mediterranean to the Atlantic Ocean.

This connection makes the Alboran Sea a vital gateway for water moving between two massive bodies of water.

The oceanography of this region is defined by a complex movement of water. Surface currents are driven by prevailing winds to flow toward the east. These currents carry Atlantic Ocean water into the Mediterranean Sea. However, deeper subsurface currents move in the opposite direction. They flow westward, carrying saltier Mediterranean water through the Gibraltar sill and into the Atlantic. This constant exchange creates a vertical rotary circulation known as a gyre. This gyre is a fundamental part of how the region manages its salt and temperature levels.

Geologically, the seafloor is highly complex and varied. The area contains several sub-basins, which are deep depressions in the ocean floor. These include the West, East, and South Alboran Basins. The seabed also features various ridges and seamounts. The most prominent feature is the Alboran Ridge. This structure stretches southwest from the volcanic Alborán Island. The seafloor is made mostly of continental crust. This crust was formed by the subduction of terranes between the African and Eurasian Plates. Subduction occurs when one tectonic plate moves under another. This process happened as the Tethys Ocean closed.

This geological activity is still happening today. Earthquakes occur frequently at a depth of about 30 kilometers. These tremors indicate ongoing interactions between the lithosphere and the mantle. The lithosphere is the rigid outer layer of the Earth. The mantle is the layer beneath it. The internal zones of the Alboran domain consist of rocks from the Late Paleozoic to the Triassic periods. These rocks were piled up during the Tertiary period. Since the Early Miocene, this area has undergone extension. The region is also surrounded by the Gibraltar Arc. This arc includes the Baetic Cordillera in Spain and the Rif Mountains in Morocco.

Ecologically, the Alboran Sea serves as a critical transition zone. It sits between the Atlantic and Mediterranean ecological zones. Because of this, it contains a mix of species from both environments. The sea provides habitat for the largest population of bottlenose dolphins in the area. It is also the last home for harbour porpoises in the western Mediterranean. For loggerhead sea turtles, this sea is the most important feeding ground in Europe. The surrounding Baetic-Rifan complex is a biodiversity hotspot. The Atlantic Ocean provides a moderating influence on the climate here. This has allowed relict species to survive for millions of years. A relict species is one that survives from an earlier time.

Human activity and conservation efforts are also significant in this sea. The Alboran Sea supports important commercial fisheries. People catch species such as sardines and swordfish. However, certain fishing methods have caused environmental concerns. In 2003, the World Wildlife Fund noted that drift net fishing could endanger dolphins and turtles. To address these issues, international cooperation has increased. In 2023, the European Union, Morocco, and Algeria reached an agreement. They banned bottom fishing practices around the Cabliers Bank. This specific action protects the only known cold-water coral reef in the Mediterranean.

Finally, several small islands are scattered throughout the Alboran Sea. These include the Isla de Alborán, which gives the sea its name. Other islands include the Islas Chafarinas, Peñón de Alhucemas, and Peñón de Vélez de la Gomera. Most of these islands, even those near the African coast, belong to Spain. These islands and the surrounding waters remain a vital part of the Mediterranean's natural and political landscape.