The State of the Mediterranean Marine and Coastal Environment

Seabed habitats inWestern Mediterranean

Shallow

Shelf

Photic rock or biogenic reef Aphotic rock or biogenic reef Sands Muds Coarse or mixed sediments

Rock or biogenic reef Sands Muds Coarse or mixed sediments Sands Muds Coarse or mixed sediments

Bathyal

Abyssal

Sands Muds

Source: adapted from the European Marine Observation and Data Network, EUSeaMap web-GIS, accessed on December 2011.

cial catches) and other demersal species are of special concern (Tudela 2004). Fisheries impacts extend beyond elasmobranchs, finfish, or other target species. Longline fishing is a main cause of seabird mortality in the Mediterranean, while longline and other fisheries kill sea turtles incidentally (Tudela 2004). Longline fleets are a particular threat to the loggerhead turtle population, as are trawlers and small-scale gears in some areas, such as in the Gulf of Gabès. Driftnet fisheries and, to a much lesser extent, small- scale fisheries using fixed nets and purse seines, appear to ac- count for the highest impact on the region’s cetaceans. They are also responsible for the highest rates of direct human-induced mortality. The population of monk seals in the Mediterranean continues to be at risk from direct mortality by artisanal fishing crews and, to a lesser extent, by their gear. The Mediterranean Basin has a wide array of habitats that in- clude sea grass beds, intact rocky shorelines, persistent frontal systems, estuaries, underwater canyons, deepwater coral assem- blages and sea mounts (UNEP/MAP 2012). Sea grass meadows are among the most important and pro- ductive habitats in the Mediterranean, providing spawning and nursery grounds for many commercial species. Five species of sea grasses are found in the Mediterranean: Cymodocea nodosa , Habitat biodiversity

individuals. Their greatest concentration occurs along the Turk- ish and Greek coasts. Very small populations remain in Cyprus, Croatia and maybe Libya, with vagrants occurring in Syria, Alge- ria and Tunisia. About twenty cetacean species have been reported in the Medi- terranean Sea, about half of which come from Atlantic popula- tions entering the sea only sporadically. Only nine small cetacean species and three large whale species are sighted frequently in the Mediterranean Sea. They are the minke whale ( Balaenoptera acutorostrata ), fin whale ( Balaenoptera physalus ), short-beaked common dolphin ( Delphinus delphis ), long-finned pilot whale ( Globicephala melas ), Risso’s dolphin ( Grampus griseus ), killer whale ( Orcinus orca ), sperm whale ( Physeter macrocephalus ), false killer whale ( Pseudorca crassidens ), striped dolphin ( Stenella coeruleoalba ), rough-toothed dolphin ( Steno bredanensis ), bot- tlenose dolphin ( Tursiops truncatus ) and Cuvier’s beaked whale ( Ziphius cavirostris ). The Aegean Sea is of particular importance to the harbour porpoise ( Phocoena phocoena ), a rare species not found elsewhere in the Mediterranean region except in the Black Sea (UNEP/MAP 2012). The Mediterranean fish fauna is diverse, but fisheries are gener- ally declining. Of the 900 or so known fish species, approximately 100 are commercially exploited. Unsustainable catch rates of rays (including the disappearance of certain taxa from commer-

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HUMAN PRESSURE, STATE AND IMPACTS ON MEDITERRANEAN ECOSYSTEMS