Sea of Marmara

Sea of Marmara

The location of the Sea of Marmara, circled by red; from www.consumereurope.dk

The Sea of Marmara is located at the south-eastern corner of EU Member States’ boundaries and it is a basin connecting the Black Sea and Aegean Sea through Turkish Straits System, i.e., Straits of Dardanelles and Bosphorus.

Sea of Marmara

GFCM’s statistical grid system for the Sea of Marmara

General Fisheries Council of Mediterranean (GFCM) has amended its resolution GFCM/31/2007/2 by resolution of GFCM/33/2009/2 and established 31 Geographical Sub-Areas (GSAs) for statistical purpose. The Sea of Marmara is defined as a Geographical Sub-Area 28.FAO has also defined the Sea of Marmara as Division 4.1 of Black Sea Subarea 37.4 in Area 37 (www.fao.org/fishery/area/Area37/en)which refers the Mediterranean and Black as one of the worlds Major Fishing Areas.

 
The human activities in the catchment basin surrounding the Sea of Marmara generates over %40 of Turkey’s gross domestic products (GDP) as the most developed and populated socio-economic region comprising all types of activities ranging from agriculture to heavy industry. Among them, maritime transportation, fisheries and recreational activities have some outstanding site-specific properties since the Turkish Strait System (TSS: Dardanelles-The Sea of Marmara-Bosphorus) is one of the busiest maritime passages, i.e., 50-55.000 vessels per year; of which %20 is oil tankers; 18% of Turkish fishing fleet which is composed of 14300 vessels, is registered in the ports in the Sea of Marmara, and over 20.000.000 inhabitant (~30% of Turkey’s population) exploits its resources in their recreational activities, particularly for yachting, surfing, SCUBA diving, etc.
The Sea of Marmara has an unique ecosystem as transitional medium between Mediterranean sea and Black Sea. With its 11,500 km² surface area and over 1000 m depth, it is a quite small but deep basin in which waters from Black Sea and Mediterranean Sea creates oppositely flowing two layers with different densities by forming an additional permanent interstitial layer in between. The dynamic character of this interaction greatly reduces the inertness in the basin which increases ecosystem sensitivity to the climatic alterations occurred in those major basins that feed the system.

Consequently, the biodiversity in the Sea of Marmara has a site-specific variability depending on the ecological conditions dictated by the water influxes of the two neighboring basins in terms of volume physical, chemical and biological properties. Despite the deterioration in environmental conditions due mainly to the anthropogenic impacts northern coasts, The Sea of Marmara has still remarkably high biodiversity, since 507 species out of 795 species consisting Turkey’s marine flora are distributed mostly in the southern coasts. The number of fish species has reportedly been declining form 200 species which was reported by Slastenenko due to the overfishing, pollution and habitat destruction. A very recent review, Yuksek (in printing) reveals that the diversity of fish species (Shannon-Veawer index), based mostly on the occurrence and abundance of demersal species, varies sharply between 0-3.8. The marginal low values represent the inner most zones of some embayment which are under intensive anthropogenic pressures. Nevertheless, the changes in migratory behavior of some major fishes species, between Mediterranean and Black Sea, mainly those belongs Scombridae, Carangidae, Clupeidea and Pomatomidae, have also direct influences on the fish species diversity. Regarding pelagic system, the dynamic physical conditions have precipitated high variability in plankton communities which are under influences of the inflows from the neighbouring basins. Deniz and Tas reported 115 phytoplankton species for the epipelagic zone in the north-eastern section of the Sea of Marmara while this number might decrease down to 44 species in eutrophicated coastal zones. For the structure of zooplankton community, Unal et al. provides data on 111 copepod species, while Svetlichny et al. reported 58 zooplankton species of which 23 have Black Sea and 35 have Mediterranean. Moreover, a most recent study, Isinibilir reveals that only 43 zooplankton species could have been sampled in two bays at the southern section of the Sea of Marmara.
Acting as a barrier or a corridor between Black Sea and Mediterranean, the Sea of Marmara has a prominent role for the biodiversity of both major basins. Together with its ecosystem sensitivity to the climatic alterations occurred in those major basins that feed the system , it is a perfect experimental site for investigations on the impacts of climate changes, in terms of biodiversity.