scholarly journals Seasonal and interannual variability of the water exchange in the Turkish Straits System estimated by modelling

2015 ◽  
Vol 16 (2) ◽  
pp. 444 ◽  
Author(s):  
V. MADERICH ◽  
Y. ILYIN ◽  
E. LEMESHKO
Keyword(s):  
Interannual Variability ◽  
Black Sea ◽  
Lower Layer ◽  
Aegean Sea ◽  
The Black Sea ◽  
Freshwater Flux ◽  
Marmara Sea ◽  
Layered Model ◽  
Seasonal And Interannual Variability ◽  
Turkish Straits System

A chain of simple linked models is used to simulate the seasonal and interannual variability of the Turkish Straits System. This chain includes two-layer hydraulic models of the Bosphorus and Dardanelles straits simulating the exchange in terms of level and density difference along each strait, and a one-dimensional area averaged layered model of the Marmara Sea. The chain of models is complemented also by the similar layered model of the Black Sea proper and by a one-layer Azov Sea model with the Kerch Strait. This linked chain of models is used to study the seasonal and interannual variability of the system in the period 1970-2009. The salinity of the Black Sea water flowing into the Aegean Sea increases by approximately 1.7 times through entrainment from the lower layer. The flow entering into the lower layer of the Dardanelles Strait from the Aegean Sea is reduced by nearly 80% when it reaches the Black Sea. In the seasonal scale, a maximal transport in the upper layer and minimal transport in the bottom layer are during winter/spring for the Bosphorus and in spring for the Dardanelles Strait, whereas minimal transport in upper layer and maximal undercurrent are during the summer for the Bosphorus Strait and autumn for the Dardanelles Strait. The increase of freshwater flux into the Black Sea in interannual time scales (41 m3s-1 per year) is accompanied by a more than twofold growth of the Dardanelles outflow to the North Aegean (102 m3s-1 per year).

scholarly journals Nutrient exchange fluxes between the Aegean and Black Seas through the Marmara Sea

2002 ◽  
Vol 3 (1) ◽  
pp. 33 ◽  
Author(s):  
S. TUGRUL ◽  
T. BESIKTEPE ◽  
I. SALIHOGLU
Keyword(s):  
Black Sea ◽  
Lower Layer ◽  
Chemical Properties ◽  
Late Summer ◽  
Aegean Sea ◽  
The Black Sea ◽  
Marmara Sea ◽  
Nutrient Inputs ◽  
Deep Basin ◽  
Layer Flow

Long-term data obtained in the Turkish Strait System (TSS) including the Sea of Marmara, the Dardanelles and Bosphorus straits, during 1990-2000, have permitted us to calculate seasonal and annual fluxes of water and nutrients (nitrate, phosphate) exchanged between the Aegean and Black Seas through the TSS. Two-layer flow regimes in the TSS introduce the brackish waters of the Black Sea into the Aegean basin of the northeastern Mediterranean throughout the year. A counter flow in the TSS carries the salty Mediterranean water into the Black Sea via the Marmara deep basin. The annual volume influx from the Black Sea to the Marmara upper layer is nearly two-fold the salty water exported from the Marmara to the Black Sea via the Bosphorus underflow. The brackish Black Sea inflow is relatively rich in nitrate and phosphate in winter, decreasing to the lowest levels in late summer and autumn. Biologically labile nutrients of Black Sea origin are utilized in photosynthetic processes in the Marmara Sea and are partly exported to the Marmara lower layer. Eventually, the brackish Black Sea waters reach the Dardanelles Strait, with modified bio-chemical properties. On the other hand, the salty Mediterranean waters with low concentrations of nutrients enter the Marmara deep basin. During threir 6-7 year sojourn in the Marmara basin, the salty waters become enriched in nitrate (DIN) and phosphate (DIP), due to oxidation of planktonic particles sinking from the Marmara surface layer. The annual nutrient inputs from the Black Sea to the Marmara basin were estimated as 8.17x108 moles of DIN and 4.25x107 moles of DIP, which are much less than the importation from the Marmara lower layer via the Bosphorus undercurrent. The salty Aegean water introduces nearly 6.13x108 moles of DIN and 2.79x107 moles of DIP into the Marmara lower layer. The estimated DIP outflux from the Aegean Sea is nearly 2 times less than the importation from the Marmara Sea via the Dardanelles Strait.

scholarly journals Assessment of goatfish fisheries in Turkey based on the microdata set of official landing statistics

2021 ◽  
Vol 38 (3) ◽  
pp. 303-309
Author(s):  
Nuray Çelik Mavruk ◽  
Sinan Mavruk ◽  
Dursun Avşar
Keyword(s):  
Mediterranean Sea ◽  
Black Sea ◽  
Large Scale ◽  
Aegean Sea ◽  
Bottom Trawl ◽  
The Black Sea ◽  
Marmara Sea ◽  
Trawl Fishery ◽  
Red Mullet ◽  
The Mediterranean

Although goatfishes (Mullidae Rafinesque, 1815) are among the most important commercial fishes in Turkey, no research has been found investigating the characteristics and spatial patterns of goatfish fishery. Here, we assessed the goatfish fishery of Turkey based on the microdata set of Turkish National Fishery Statistics gathered by Turkish Statistical Institute (TÜİK) between 2014 and 2017. In this context, we investigated the variation of total goatfish catch by cities. In addition, we compared the contribution of small (boat <10m) and large scale (boat >10m) fishers as well as different fishing techniques to the total goatfish catch in Turkey. Finally, an evaluation was made on the discard rates recorded in the official landing statistics. The results showed that higher red mullet (Mullus barbatus Linnaeus, 1758) catch was reported in the eastern Mediterranean, whereas surmullet (Mullus surmuletus Linnaeus, 1758) catch was significantly higher in the western Black Sea. On the other hand, fishery-independent investigations revealed that the Turkish fishery fleet mostly catches red mullet throughout the coasts of Turkey. Therefore, the separate records of red mullet and surmullet in the landing statistics likely represent the local names of red mullet rather than two different species. Large scale fishers were the main source of fishery pressure in the Mediterranean Sea, the Aegean Sea and the Black Sea. However, the majority of the catch was landed by small scale fishers in the Marmara Sea. The bottom trawl fishery landed 88, 92 and 87% of total goatfish catch in the Black Sea, the Aegean Sea and the Mediterranean Sea, respectively. Purse seiners provided the largest part of total goatfish catch (40%) in the Marmara Sea, where the bottom trawl fishery is prohibited. The overall average for the discard rate was found to be 0.47%. There were no statistically significant differences among the discard rates of two species, marine regions or fishing methods.

scholarly journals Sea level changes along the Turkish coasts of the Black Sea, the Aegean Sea and the Eastern Mediterranean

2000 ◽  
Vol 1 (1) ◽  
pp. 141 ◽  
Author(s):  
B. ALPAR ◽  
E. DOGAN ◽  
H. YUCE ◽  
H. ALTIOK
Keyword(s):  
Sea Level ◽  
Black Sea ◽  
Eastern Mediterranean ◽  
The Black Sea ◽  
Marmara Sea ◽  
Sea Level Changes ◽  
Sea Levels ◽  
Sea Level Fluctuations ◽  
Short Period ◽  
Turkish Straits System

Short, tidal, subtidal, seasonal, secular sea-level variations, sea-level differences and interactions between the basins have been studied, based on the data collected at some permanent and temporary tide gauges located along the Turkish coasts, mostly along the Straits connecting the Marmara Sea to outer seas. Even though the deficiency of sufficient information prevented us to reach the desired results, many pre-existed studies have been improved. Short-period oscillations were clearly identified along the Turkish Strait System and related to their natu-ral periods. The tidal amplitudes are low along the Turkish coasts, except northern Aegean and eastern Mediterranean. The stability of harmonic constants of Samsun and Antalya were examined and most of the long period constituents were found to be unstable. Even the Marmara Sea is not affected from the tidal oscillations of Black and Aegean Seas, some interactions in low frequency band have been detected. Subtidal sea level fluctuations (3-14 day) have relations with the large-scale cyclic atmospheric patterns passing over the Turkish Straits System. Short-term effects of wind on sea level are evident.Seasonal sea-level fluctuations along the Turkish Straits System are in accord with Black Sea's hydrological cycle. The differential range of the monthly mean sea levels between the Black Sea and the Marmara Sea is highly variable; high during spring and early summer and low during fall and winter.On the average, there is a pronounced sea-level difference (55 cm) along the Turkish Straits System. However, the slope is nonlinear, being much steeper in the Strait of Istanbul. This barotrophic pressure difference is one of the most important factors causing the two-layer flow through the system. The topography and hydrodynamics of the straits, the dominant wind systems and their seasonal variations make this flow more complicated. For secular sea level changes, a rise of 3.2 mm/a was computed for Karsiyaka (1935-71) and a steady trend (-0.4 mm /a) has been observed for annual sea levels at Antalya (1935-77). The decreasing trend (-6.9 mm/a) at Samsun is contrary to the secular rising trend of the Black Sea probably because of its rather short monitoring period (1963-77).

Quantitative comparison of the influxes of nutrients and organic carbon into the Sea of Marmara both from anthropogenic sources and from the Black Sea

1995 ◽  
Vol 32 (2) ◽  
pp. 115-121 ◽  
Author(s):  
Suleyman Tugrul ◽  
Colpan Polat
Keyword(s):  
Organic Carbon ◽  
Black Sea ◽  
Lower Layer ◽  
Vertical Mixing ◽  
Anthropogenic Sources ◽  
Chemical Pollution ◽  
The Black Sea ◽  
Marmara Sea ◽  
Sea Of Marmara ◽  
Golden Horn

The Sea of Marmara, an intercontinental basin with two narrow and shallow straits permitting the exchange of the Mediterranean and Black Sea waters, receives 2.8×104 tons TP (total phosphorus), 2.7×105 tons TN (total nitrogen) and 1.9×106 tons TOC (total organic carbon) per year from the Black Sea inflow, from the lower layer by vertical mixing and from anthropogenic inputs of various origins including riverine discharges. The Black Sea input through the Bosphorus constitutes about 35, 64 and 77 %, respectively, of the total annual loads of TP, TN and TOC entering the Marmara surface waters. Pollution loadings from Istanbul make up a major fraction (40-65%) of the total anthropogenic discharges. The biochemical properties of the productive Marmara upper layer appear to be dominated by the inputs both from its lower layer by vertical mixing and from the Black Sea throughout the year. Pollution discharges from Istanbul have secondary importance for the nutrient and organic carbon pools of the Marmara Sea; however, the land-based chemical pollution has drastically modified the ecosystem of coastal margins and semi-enclosed bays (e.g. Golden Horn, Izmit and Gemlik) where water exchanges with the open sea are limited. Biologically labile nutrients increasingly exported from the Black Sea in the spring-early summer, are compensated by importation from the Marmara Sea through the Bosphorus underflow. The less labile dissolved organic nitrogen and carbon input from the Black Sea appears to reach as far as the Aegean basin of the Northeastern Mediterranean in 4-5 months without contributing to the net production in the Marmara Sea.

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