424
H. Giiner and V. Aysel
distribution limits of oxygen and hydrogen sulphide, which dominates
the deeper waters, vary between years and seasons.
Another feature of the Black Sea is the nutrient concentration. Phosphate predominates over nitrate which is virtually absent in the waters
between 200 and 300 m depth. In periods of intensive production of
phytoplankton, especially in summer, nitrate may completely disappear,
whereas phosphate remains available in sufficient quantities.
18.2.2 The Sea of Marmara
The Bosphorus (Istanbul Strait), the Sea of Marmara and Dardanelles
(Canakkale Strait) together constitute the system of Turkey Straits. These
systems share unique topographical and hydrographical attributes that
determine their biological and ecological characteristics. Hydrographical
studies on the Marmara Sea and Straits date back to the seventeenth
century, but biological research, in particular phycological studies started
at the end of the last century. Since the 1970s, studies with the pollution of
the Marmara Sea and Straits have gained prominence. The Marmara Sea,
which constitutes the centre of the system of Turkish Straits, has the
characteristics of an inland sea. It is connected to the Black Sea via the
Bosphorus and to the Mediterranean through the Dardanelles. While the
surface waters of the Marmara Sea are effected by the Black Sea, its deeper
waters remain under Mediterranean influence. Therefore, the Marmara Sea
has the typical attributes of an estuary. The two water layers do not mix
and a stable density gradient is established. Numerous locations suitable
for marine aquaculture exist around the Marmara Sea which, however, is
confronted by a constantly growing threat of pollution.
The Marmara Sea is the smallest of the Turkish Seas with respect
to both its surface area and volume (total surface 11 500 km 2 , volume
3378 km 3 , depths average 35 m, maximal 110 m) with a coastline length
of 927 km.
The drainage area of the Marmara Sea makes up 3.1% of Turkey's
land area (24 100 km 2 ). The annual discharge of the rivers in the drainage area is about 6.6 x 10 9 m 3 •
Tides are barely noticeable in the Marmara Sea. The hydrologial properties are influenced by both the neighbouring Black Sea and
Mediterranean, and by wind. Sometimes under the effect of very strong
winds water levels may fluctuate 1 m along the northern and southern
shores.
The temperatures of the surface waters of the Bosphorus are under the
influence of the Black Sea and range between 4 and 24°C. The salinity
H. Giiner and V. Aysel
distribution limits of oxygen and hydrogen sulphide, which dominates
the deeper waters, vary between years and seasons.
Another feature of the Black Sea is the nutrient concentration. Phosphate predominates over nitrate which is virtually absent in the waters
between 200 and 300 m depth. In periods of intensive production of
phytoplankton, especially in summer, nitrate may completely disappear,
whereas phosphate remains available in sufficient quantities.
18.2.2 The Sea of Marmara
The Bosphorus (Istanbul Strait), the Sea of Marmara and Dardanelles
(Canakkale Strait) together constitute the system of Turkey Straits. These
systems share unique topographical and hydrographical attributes that
determine their biological and ecological characteristics. Hydrographical
studies on the Marmara Sea and Straits date back to the seventeenth
century, but biological research, in particular phycological studies started
at the end of the last century. Since the 1970s, studies with the pollution of
the Marmara Sea and Straits have gained prominence. The Marmara Sea,
which constitutes the centre of the system of Turkish Straits, has the
characteristics of an inland sea. It is connected to the Black Sea via the
Bosphorus and to the Mediterranean through the Dardanelles. While the
surface waters of the Marmara Sea are effected by the Black Sea, its deeper
waters remain under Mediterranean influence. Therefore, the Marmara Sea
has the typical attributes of an estuary. The two water layers do not mix
and a stable density gradient is established. Numerous locations suitable
for marine aquaculture exist around the Marmara Sea which, however, is
confronted by a constantly growing threat of pollution.
The Marmara Sea is the smallest of the Turkish Seas with respect
to both its surface area and volume (total surface 11 500 km 2 , volume
3378 km 3 , depths average 35 m, maximal 110 m) with a coastline length
of 927 km.
The drainage area of the Marmara Sea makes up 3.1% of Turkey's
land area (24 100 km 2 ). The annual discharge of the rivers in the drainage area is about 6.6 x 10 9 m 3 •
Tides are barely noticeable in the Marmara Sea. The hydrologial properties are influenced by both the neighbouring Black Sea and
Mediterranean, and by wind. Sometimes under the effect of very strong
winds water levels may fluctuate 1 m along the northern and southern
shores.
The temperatures of the surface waters of the Bosphorus are under the
influence of the Black Sea and range between 4 and 24°C. The salinity