Black Sea Water Environment Along the Bulgarian Coast

Bulgarian Journal of Agricultural Science, 19 (Supplement 1) 2013, 6–11 Agricultural Academy

BLACK SEA WATER ENVIRONMENT ALONG THE BULGARIAN COAST

S. DINEVA Institute of Fish Resources, BG – 9000 Varna, Bulgaria

Abstract

DINEVA, S., 2013. Black Sea water environment along the Bulgarian coast. Bulg. J. Agric. Sci., Supplement 1: 6–11

Recent performed hydrological and hydrochemical survey along the Bulgarian Black Sea coast has aimed to update the knowledge for principal characteristics of the water environment under climate change impact. Study of the waters along the Bul- garian Black Sea coast at 1 mile in front of Cape Kaliakra, Balchik, Albena, Cape Galata, Cape Ilandzik, Kamchia River outfall, Dvoinitsa River outfall, Cape Emine, and Nesebar was carried out in 2011. Research of Varna Bay at net of stations and of Burgas Bay at Koketrice Bank was performed. In order to investigate the inﬂ uence of Beloslav Lake and Varna Lake on the Varna Bay, the Lake system was studied, as well. In-situ measurements of temperature, salinity, dissolved oxygen, and oxygen saturation were done. Some of the expected main climate change outcomes for the Mediterranean, including the Black Sea region, during the 21st century were ascertained along the Bulgarian Black Sea coast. Climate change impact on the thermo-haline structure of the Bulgarian Black Sea was found. The year’s maximum sea temperature both of surface and bottom coastal waters in August 2011 was above the long-term mean, and sea temperature was with anomaly in excess of 0.87°C in the surface waters and 2.97°C in the bottom waters. Increase in salinity with 0.96 psu in the coastal waters over 2011 in comparison with 1990s was found. Salinity was above the long-term average with 2.22 psu in June. Varna Bay’s salinity during 2011 was above the long-term average with 0.46 psu in the surface waters and 0.80 psu in the bottom waters. Considerable deviations of the ecosystems from the equilibrium state in both the Varna Bay and Beloslav–Varna Lake system were established. The obtained results throughout the performed survey are of key importance as to the Black Sea ecosystem function assessment along the Bulgarian coast. This research is essential for safeguarding the future security, health, well-being of human societies, marine and ﬁ sh industry development, and installation of the necessary infrastructure related to appropriate facilities, as well. Key words: Bulgarian Black Sea; Varna Bay; Beloslav–Varna Lake system; Koketrice Bank (Burgas Bay); hydrological and hydrochemical research; climate change impact Abbreviations: Sea surface salinity (SSS); Sea surface temperature (SST); Station (St.)

Introduction The main climate change outcomes for the Mediter- The climate of the Earth is changing and the changes ranean, including the Black Sea region (Alcamo et al., will have enormous inﬂ uence on the water resources, 2007; Dineva, 2010), during the 21st century comprise ecosystems, people, urban areas, and using of the energy. increased drought, rise in sea temperature affecting During the remainder of this century, different loca- ecosystems, increased salinity of coastal waters, sea tions will experience greater or lesser increases in tem- level rise- and surge- driven ﬂ ooding, increased land perature, with the greatest impact toward the North Pole loss in estuaries and deltas, severe biodiversity losses, and the least increase toward the South Pole and in the increased health effects of heat waves, reduced summer tropics (IPCC, 2007; Dineva, McKay, 2012, pp. 33–36). tourism.

E-mail: [email protected] Black Sea Water Environment along the Bulgarian Coast 7

Common amount of precipitation and river discharges is decreasing, especially in the Black Sea region. Effects of global climate change were observed in Bulgaria. The country is in the zone of drying. According to Fourth National Communication on Climate Change by Republic of Bulgaria (2006), Cli- mate Change Scenarios are developed for 2015, for the 2020s, 2050s, 2080s, and for the end of the 21st century. Some of the climate models simulate an increase of the air temperature in Bulgaria from 2 to 5 ºC, with a two- fold increase of the carbon dioxide concentration in the atmosphere. Climate change impact was established in the Bay, coastal and open Black Sea waters in front of the Bul- garian coast (Dineva, 2006; Dineva, 2008; Dineva, 2009; Dineva, 2010a; Dineva, 2010b). With aim to update and expand the knowledge for principal characteristics of the water environment along the Bulgarian Black Sea coast under climate change impact, hydrological and hydrochemical research was carried out in 2011. The obtained results throughout the study are of key importance for Black Fig. 1. Map of the Bulgarian Black Sea coast Sea ecosystem function assessment along the Bulgar- ian coast. The performed investigations are essential as to safeguarding the future security, health, well-being of human societies, marine and ﬁ sh industry development, and installation of the necessary infrastructure related to appropriate facilities, as well.

Material and Methods A

Hydrological and hydrochemical study of the waters along the Bulgarian Black Sea coast (Figure 1; Figure 2B), at 1 mile in front of Cape Kaliakra, Bal- chik, Albena, Cape Galata, Cape Ilandzik, Kamchia River outfall, Dvoinitsa River outfall, Cape Emine, and Nesebar was carried out in 2011. In long-term aspect, the Control Station for the coastal waters was at 3 miles in front of Cape Galata, therefore this Station was surveyed, as well. Study of Varna Bay was performed at a net of Stations B (Figure 2 A). In long-term aspect, the Control Station is St. B5. Burgas Bay was surveyed at Koketrice Bank. Fig. 2. Maps of the sampling stations: (A.) in the Varna Bay; In order to investigate the inﬂ uence of Beloslav (B.) in front of Cape Kaliakra (St. K1), Cape Galata (St. G1, Lake and Varna Lake on the Varna Bay, the Lake sys- St. G3), and Cape Emine (St. E1) 8 S. Dineva tem (Figure 3) was studied, as well. St. A22 is assumed 0.46 psu in the surface waters and 0.80 psu in the bottom for Control Station. waters. Measurements of temperature, salinity, dissolved Over April small drop in temperature – from 7.27˚С to oxygen, and oxygen saturation were done by CTD 60 6.18 ˚С down the vertical was ascertained in the coastal (Sea & Sun Technology GmbH, 2001). In-situ observa- waters in front of Cape Galata. Sea surface salinity was tions were carried out. 16.22 psu and the increase into the bottom was approxi-

Results and Discussion

Black Sea has specifi c thermo-haline structure and water exchange (Sorokin, 1982). Black Sea waters are mainly formed as result by mixing of fresh waters and waters coming from the Sea of Marmora through the Bosphorus (Rjabinin et al., 1991). Danube River greatly infl uences the Bulgarian Black Sea waters. The Bulgar- ian Rivers discharge into the Black Sea is comparatively small. Kamchia River has local coastal infl uence. Danube River current is essential for Black Sea salinity forming in Fig. 4. Sea surface salinity at 3 miles in front of Cape front of the Bulgarian coast. Galata in 2011 in comparison with 1995–2000 mean Salinity of the Bulgarian Black Sea coastal zone during 2011 was above the long-term (1995–2000) average (Dineva, 2005; Dineva, 2007; Dineva, 2011) throughout the surface – bottom layer (Figures 4 and 5). Increase in salinity was 0.96 psu. Salinity was above the long-term average with 2.22 psu in June. The year’s maximum sea temperature both of the surface and bottom coastal waters in August 2011 was above the 1995-2000 mean (Dineva, 2007; Dineva, 2011), and sea temperature was with anomaly in excess of 0.87°C in the surface waters and 2.97°C in the bottom waters. Salinity of the Varna Bay during 2011 was above the long-term (1995–2000) average (Dineva, 2007; Dineva, Fig. 5. Sea bottom salinity at 3 miles in front of Cape 2011) throughout the whole layer. Increase in salinity was Galata in 2011 in comparison with 1995–2000 mean

Fig. 3. Map of the sampling stations in the Beloslav Lake and Varna Lake (A10, A14, A16, A18, A22) Black Sea Water Environment along the Bulgarian Coast 9 mately 1 psu. Considerable oxygen defi cit in the 3-mile Table 1 zone was established. Temperature, salinity, dissolved oxygen, and oxygen Sea surface temperature has ranged from 7.58˚С to saturation in the Beloslav Lake and Varna Lake in 8.54˚С in the Varna Bay. Coolest were the bottom waters May 2011 of St. B5 – 6.39˚С. Drop in salinity reached 15.76 psu Station Depth T S O2 O2 in the surface waters of St. B3 under infl uence of Varna m ˚С psu μM % Lake waters. Oxygen defi cit was ascertained throughout A10 0 m 17.25 13.28 896.43 162.01 the Varna Bay. bottom 13.01 14.92 1102.68 184.22 In May, surface water warming has reached 16.88 ˚С A14 0 m 17.98 14.66 625.89 115.70 – 17.99˚С in the Beloslav and Varna Lakes. Drop in salin- bottom 13.00 14.96 1070.54 178.88 ity approached 13.28 psu in the Beloslav Lake. Consider- A16 0 m 17.99 14.75 900.00 166.54 able oxygen super-saturation throughout the Beloslav and bottom 11.54 15.57 1204.47 195.66 Varna Lakes was found (Table 1). A18 0 m 17.29 14.85 958.93 175.09 Oxygen super-saturation, increasing toward the bot- bottom 11.94 15.66 1093.75 179.30 tom was ascertained in the Varna Bay, as well. Oxygen A22 0 m 16.88 14.96 997.32 180.76 bottom 12.58 15.57 1212.5 201.52 super-saturation peaks were in the Varna Lake stream waters in the southern Varna Bay area. Oxygen super-sat- Table 2 uration was ranging from 231.28% to 290.68% through Temperature and salinity in the Varna Bay, Burgas the surface – bottom layer of St. B3 and from 233.20% Bay, and coastal (1 mile offshore) waters of the Bul- to 247.63% at St. B6. The dissolved oxygen is an indica- garian Black Sea in June 2011 tor of the balance of the marine ecosystem (Bogdanova, Station Depth T S 1959; Bordovsky, Ivanenkov, 1979 pp. 133–164; Sapozh- m ˚С psu nikov, 1992) and the established super-saturation has indi- Cape Kaliakra 0 m 22.27 16.58 cated prevailing production processes. bottom 11.44 18.04 In the east direction – from 1 mile offshore toward 3 Balchik 0 m 21.01 16.72 miles offshore, drop in sea surface temperature was from bottom 14.52 17.45 15.98˚С to 14.99˚С, i.e. 1˚С. Bottom coastal waters were Albena 0 m 21.61 16.89 cool – 9.23–10.10˚С. The 3-mile zone in front of Cape bottom 13.58 17.67 Galata was under strong Danube transformed waters in- Barna Bay 0 m 20.64 15.36 fl uence. (St. B5) bottom 13.18 17.72 SST has ranged from 20.64˚С to 24.28˚С in the wa- Cape Galata 0 m 21.35 16.67 ters along the Bulgarian Black Sea coast in June (Table bottom 11.27 17.84 2). The cool bottom water was with temperature range Cape Ilandzik 0 m 22.64 16.58 bottom 10.38 18.07 9.34 ˚С (in front of Cape Emine) – 14.52˚С (in front of Kamchia River Balchik). SSS was ranging from 15.36 psu (St. В5) to outfall 0 m 22.82 16.52 16.89 psu (in front of Albena). Sea bottom salinity was bottom 11.98 18.02 17.45 psu (in front of Balchik) – 18.26 psu (in front of Dvoinitsa River Cape Emine). outfall 0 m 24.04 16.69 The coastal, Bay and Lake waters (Table 3) were bottom 10.16 18.09 warmed throughout the surface–bottom layer in August. Cape Emine 0 m 24.28 16.77 Surface temperature range was 23.64˚С – 25.23˚С. Bot- bottom 9.34 18.26 tom temperature was ranging from 20.26˚С (in front of Nesebar 0 m 23.62 16.49 Cape Galata) to 24.61˚С (St. A22). Salinity was lowest bottom 10.41 18.14 at St. A22 – 16.28 psu in the layer, and has reached 17.81 Koketrice Bank 0 m 23.62 16.49 psu in the bottom waters in front of Kamchia River out- (Burgas Bay) bottom 10.41 18.14 10 S. Dineva

Table 3 Table 4 Temperature, salinity, dissolved oxygen, and oxygen Temperature, salinity, dissolved oxygen, and oxygen saturation in the Varna Lake (St. A22), Varna Bay saturation in the Varna Bay and in coastal waters of (St. B5), and in coastal waters of the Black Sea (1 the Black Sea (1 mile offshore and 3 miles offshore) mile offshore) in August 2011 in October 2011

Station Depth T S O2 O2 Station Depth T S O2 O2 m ˚С psu μM % m ˚С psu μM % Cape Ka- 0 m B3 0 m 15.55 16.93 558.04 99.60 liakra 24.00 17.24 508.04 106.93 bottom 15.80 17.52 551.79 99.34 bottom 21.52 17.48 548.22 110.42 B4 0 m 16.65 17.38 533.04 97.53 Balchik 0 m 23.64 17.33 457.14 95.65 bottom 16.13 17.52 516.97 93.65 bottom 22.64 17.45 475.00 97.63 B5 0 m 16.84 17.43 537.50 98.88 Albena 0 m 24.29 17.16 491.97 104.06 bottom 16.03 17.52 534.82 96.83 bottom 21.69 17.53 535.72 108.23 G1 0 m 16.57 17.50 514.29 93.98 Varna Bay 0 m 24.64 17.04 646.43 137.54 bottom 15.28 17.66 496.43 88.52 (St.B5) bottom 21.75 17.69 604.47 122.51 G3 0 m 16.81 17.36 528.57 97.08 Varna Lake 0 m 24.71 16.25 464.29 98.39 bottom 15.25 17.67 521.43 92.99 (St. A22) bottom 24.61 16.31 683.93 144.82 Cape Galata 0 m 24.99 17.26 469.64 100.70 Conclusions bottom 20.26 17.75 516.07 101.64 Cape Ilandzik 0 m 24.18 17.36 487.50 103.02 The recent performed hydrological and hydrochemi- bottom 20.68 17.74 497.32 98.68 cal research updated and expanded the knowledge for Kamchia 0 m River outfall 24.11 17.37 469.64 99.08 principal characteristics of the Black Sea water environ- bottom 22.15 17.81 470.54 96.13 ment along the Bulgarian coast under climate change Dvoinitsa 0 m impact. The obtained results are of key importance for River outfall 24.90 17.40 484.82 103.87 the Black Sea ecosystem function assessment. The per- bottom 22.83 17.62 512.50 105.78 formed investigations are essential as to safeguarding Cape Emine 0 m 25.09 17.24 474.11 101.70 the future security, health, well-being of human societ- bottom 22.84 17.67 494.64 102.15 ies, marine and fi sh industry development, and installa- Nesebar 0 m 24.92 17.25 536.61 114.95 tion of the necessary infrastructure related to appropriate bottom 22.67 17.53 563.39 115.95 facilities, as well. Some of the expected main climate Koketrice 0 m change outcomes for the Mediterranean, including the Bank 25.23 17.22 459.82 98.92 Black Sea region, during the 21st century as increased (Burgas Bay) bottom 22.94 17.60 504.47 104.41 drought, rise in sea temperature affecting ecosystems, fall. Signifi cant oxygen super-saturation of water was and increased sea salinity of coastal waters were ascer- ascertained in Varna Bay – 130.03% (St.B5) in the sur- tained. The Black Sea in front of the Bulgarian coast be- face – bottom layer and 144.82% in the bottom waters comes high sensitive to climate change. Climate change of St. A22. impact on the thermo-haline structure of the Bulgarian The drop in SST (Table 4) in the Varna Bay and in Black Sea was found. The year’s maximum sea tem- the coastal water in front of Cape Galata has approached perature both of surface and bottom coastal waters in 15.55˚С – 16.84˚С in October. The drop in the sea bot- August 2011 was above the 1995-2000 mean, and sea tom temperature has reached 15.25˚С – 16.13˚С. Salin- temperature was with anomaly in excess of 0.87°C in ity was varied from 16.93 psu (St. B3, 0 m) to 17.67 the surface waters and 2.97°C in the bottom waters. In- psu (St. G3, bottom). 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