INSTITUT FÜR OSTSEEFORSCHUNG WARNEMÜNDE an der Universität Rostock BALTIC SEA RESEARCH INSTITUTE Leibniz Institute for Baltic Sea Research Warnemünde C r u i s e R e p o r t r/v "Elisabeth Mann Borgese" Cruise-No. 06EZ/12/13 Monitoring Cruise 25 July 4 August 2012 Kiel Bight to Northern Baltic Proper This report is based on preliminary data Leibniz-Institut für Ostseeforschung Warnemünde an der Universität Rostock Seestraße 15 D-18119 Rostock- Warnemünde GERMANY +49-381-5197-0 +49-381-5197 440
1. Cruise No.: 06EZ/12/13 2. Dates of the cruise: from 25 July to 4 August 2012 3. Name: Elisabeth Mann Borgese Nationality: Germany Operating Authority: Leibniz Institute of Baltic Sea Research (IOW) 4. Geographical area in which ship has operated: Kiel Bight to Northern Baltic Proper 5. Dates and names of ports of call 28.07.2012: Saßnitz 6. Purpose of the cruise Baltic monitoring in the frame of the COMBINE Programme of HELCOM 7. Crew: Name of master: Uwe Scholz Number of crew: 10 8. Research staff: Chief scientist: Dr. N. Wasmund Participants: Donath, Jan Schuffenhauer, Ingo Jakobs, Gunnar Sadkowiak, Birgit Lerz, Astrid Tschakste, Andrea Pötzsch, Michael Kießlich, Katrin Oestmann, Jan Puk, Laura 9. Co-operating institutions: All institutions dealing with HELCOM monitoring programmes. 10. Scientific equipment CTDO bathysonde, water samplers, plankton nets, in-situ-pump 11. General remarks and preliminary results The area under investigation extended from Kiel Bight to the Northern Gotland Sea (station map see Figs. 1 and 2). On the way back, selected HELCOM stations in the Bornholm Sea, Arkona Sea and Mecklenburg Bight were sampled a second time for nutrient, phytoplankton and zooplankton data. The hydrographical, chemical and biological investigations were performed according to the Manual of the COMBINE Programme of HELCOM. Concerning the conditions, the cruise can roughly be divided into 4 periods: 1.) The first part of the cruise covered the western Baltic and the Arkona Sea; it ended on the evening of 27 July in the port of Saßnitz, where one participant left the ship after her task was fulfilled. The first part of the cruise was characterized by high air pressure (1014-1016 hpa), low wind (<5 m/s, air temperature during the day > 18 C
and blue sky. Due to the calm conditions, the water column was strongly stratified. In Mecklenburg Bight and Kiel Bight, a lot of jellyfish (Aurelia aurita) drifted in the water with maximum occurrence in the Fehmarn Belt. The halocline started at a depth of 17 m in Kiel Bight, but in the deeper areas of Mecklenburg Bight (Stat. TF0012), salinity increased continuously with depth from 12 g/kg at the surface to 24 g/kg near the bottom. In the Arkona Sea, an intrusion of higher temperature (15 C) and slightly higher salinity (9.5 g/kg) was found at stations TF0115 and TF0114 at a depth of 18-22 m and 24-29 m, respectively, and even at stat. TF0111 (19-24 m), but it dissipated at stations TF0069 and FT0113, forming some deeper temperature peaks. This roughness in the vertical T and O2 profiles indicated quite recent water substitution processes. In the strong salinity gradient near the bottom, the oxygen concentration decreased to <2 ml/l in some deeper areas (> 43 m). Jellyfish was rare in the Arkona Sea and Pomeranian Bight, but cyanobacteria aggregates appeared, which enriched to surface blooms in some areas: east of station TF0115, at stations TF0069 and TF0152 and in the central Pomeranian Bight. The cruise was continued in the morning of the 28 July 2012, simultaneously with a change of weather conditions. 2.) The main part of the cruise extended from Saßnitz (28.7.2012) via Bornholm Sea, Eastern Gotland Basin (station 271), Landsort Deep (station 284) and western Gotland Sea back to the Bornholm Sea (3.8.2012). In this period, two deep-pressure fronts (1004 hpa) crossed the area while cruising in the Bornholmgat (on 28.7.2012) and in the southern Gotland region (on 29.7.2012; this time with thunderstorm and wind up to 14 m/s), From 30 July to the morning of 2 August, i.e. during the track from the Eastern Gotland Sea (Stat. 271) to the Landsort Deep (Stat. 284), air pressure increased from 1011 to 1018 hpa and it became partly sunny with wind speed from 5 to 12 m/s. The 3.8.2012 was cloudy (1012-1015 hpa). Due to wind and waves the surface water was mixed what inhibits the development of cyanobacteria blooms. During an earlier cruise with R/V Meteor during the first three weeks of July 2012, the expected cyanobacteria bloom development in the Eastern Gotland Sea and the northern Baltic Proper was not detected. Also during the present cruise, only few cyanobacteria aggregates were visible in the water and no bloom appeared in the investigated areas of the Baltic Proper (except for Arkona Sea). The halocline started at about 50-53 m in the Bornholm Basin and at about 60-65 m in the Eastern Gotland Basin. In contrast to the summer cruise from 2011, when oxygen concentrations became zero below approximately 80 m depth in the Bornholm Basin, no oxygen depletion was found in that area in July 2012. In the Gotland Deep (stat. TF0271), oxygen was depleted below a depth of 89 m and in the Farö Deep (stat. TF0286), Landsort Deep (stat. TF0284) and Karlsö Deep (stat. 245) at about 90 m. The inflow event from December 2011 was obviously too small to reach the Gotland Basin. 3.) When the Arkona Sea was reached on 3 August 2012, it became sunny and the wind decreased. Correspondingly, cyanobacteria enriched at the surface in smaller areas, e.g. 3 nm east of station TF0113. At that station, a layer of slightly increased salinity and temperature was still found at 15-19m depth. In Mecklenburg Bight (on 4.8.2012, stat. TF0046), the wind calmed down to about 1 m/s and cyanobacteria appeared at the surface in larger areas. Nevertheless, Secchi depth was 7.5 m. Also Aurelia aurita appeared again. The surface water temperatures (0-10 m; C) of selected stations of this cruise are compared with early long-term mean values (1971-1990, numbers in brackets) collected during our summer cruises (end of July-beginning of August) in the 1970s and 1980s in the table below. They reflect that the summer 2012 was nearly as cold (cloudy and windy) as that of 2011, which becomes obvious in comparison with surface water temperatures of a warm summer (2010):
Area: 2012 2011: 2010: 1971-1990: Mecklenburg Bight (stat. TF0012) 17.3 17.2 19.0 17.7 Arkona Sea (stat. TF0113) 19.1 17.3 22.6 17.0 Bornholm Sea (stat. TF0213) 18,4 18.5 18.4 17.6 Eastern Gotland Sea (stat. TF0271) 16.9 19.1 22.0 17.3 Farö Deep (stat. TF0286) 17.1 19.4 20.9 17.7 Landsort Deep (stat. TF0284) 15.9 17.9 19.4 18.2 Karlsö Deep (stat. TF0245) 17.7 17.3 20.9 16.9 The long-term trend of increasing water temperature [ C] in the deep water layers in the western and northern deeps was not continuing but nevertheless recent deep-water temperatures are still higher than the mean values of the 1970s and 1980s: July Aug. July July July July Mean 2012 2011 2010 2007 2005 2003 1971-1990 Bornholm Deep 6.6 6.1 7.5 8.8 7.0 3.7 6.1 Gotland Deep 6.4 6.4 6.4 6.8 6.0 4.6 5.6 Farö Deep 6.2 6.4 6.8 6.1 6.0 6.0 5.2 Landsort Deep 5.4 5.9 6.1 5.7 5.8 5.9 4.8 Karlsö Deep 5.3 5.4 5.5 5.1 5.3 4.9 4.2 Attachments Tables 1& 2: Preliminary results for selected parameters in the surface layer and the nearbottom layer (unvalidated results) Figs. 1-3: Fig. 4: Fig. 5: Station grid (total grid and two sub-maps) Transsect from the Kiel Bight to the Farö Deep for temperature, salinity and oxygen (unvalidated data) Oxygen /hydrogen sulphide concentrations in the near-bottom layer for selected stations Dr. Norbert Wasmund Scientist in charge
Table 1: Surface layer (0-10m) Area Station Temperature Salinity PO 4 3- NO 23 - * Date Name/ No. ** C PSU mol/dm 3 mol/dm 3 Kiel Bight 25.07.2012 Meckl. Bight Lübeck Bight Arkona Basin Bornholm Deep Stolpe Channel SE Gotland Basin Gotland Deep 30.07.2012 Fårö Deep 31.07.2012 Landsort Deep 02.08.2012 Karlsö Deep 02.08.2012 TF0360/ 005 TF0012/ 007 TF0022/ 006 TF0113/ 017 TF0213/ 040 TF0222/ 042 TF0259/ 044 TF0271/ 051 TF0286/ 053 TF0284/ 056 TF0245/ 058 18.5 14.90 0.01 0.26 17.3 12.02 0.07 0.18 17.5 12.03 0.04 0.21 19.1 7.87 0.07 0.19 18.4 7.55 0.21 0.14 18.3 7.37 0.16 0.12 18.4 7.30 0.07 0.30 16.9 7.02 0.08 0.23 17.1 6.94 0.06 0.28 15.9 5.81 0.12 0.16 17.7 6.70 0.09 0.21 * NO 2 - + NO 3 ; NO 2 was present only in traces in most areas under investigation ** Station name see maps (Fig. 1-3)
Table 2: Bottom-near water layer Area Station Sampl. Depth Temp. Salinity O 2 PO 4 3- NO 23 - * Date Name/ No. ** m C PSU cm³/dm³ mol/dm 3 mol/dm 3 Kiel Bight 25.07.2012 Meckl. Bight Lübeck Bight Arkona Basin Bornholm Deep Stolpe Channel SE Gotland Basin Gotland Deep 30.07.2012 Fårö Deep 31.07.2012 Landsort Deep 02.08.2012 Karlsö Deep 02.08.2012 TF0360/ 005 TF0012/ 007 TF0022/ 006 TF0113/ 017 TF0213/ 040 TF0222/ 042 TF0259/ 044 TF0271/ 051 TF0286/ 053 TF0284/ 056 TF0245/ 058 17 12.7 22.59 4.10 0.07 0.31 23 10.4 24.18 3.71 0.87 2.12 20 10.5 19.12 2.24 0.84 4.48 45 14.4 16.65 4.93 0.46 1.25 86 6.6 15.66 0.64 1.33 11.41 88 4.7 12.30 2.70 1.62 6.44 86 5.0 10.22 0.29 2.69 4.09 231 6.4 12.19-7.60 5.45 0.00 186 6.2 11.64-4.09 4.67 0.00 423 5.4 10.51-0.60 3.80 0.00 106 5.3 9.80-0.92 3.65 0.00 * NO 2 - + NO 3 ; NO 2 was present only in traces in most areas under investigation ** Station name see maps (Fig. 1-3)
54 55 56 57 58 59 06EZ1213 / map all monitoring 25.07.2012-04.08.2012 58 stations / 05 repeated stations Odense Lübeck DENMARK TF0361 TF0360 TF0010 Gedser Fehmarn TF0011 TF0041 Kiel TF0012 TF0022 TF0040 TF0046 TFO5 Rostock GERMANY Kopenhagen TF0002 TF0001 TF0030 Trelleborg Ystad SWEDEN TF0144 TF0102 TF0145 BORNHOLM Ronne TF0069 TF0105 TF0104 TF0103 TF0109 TF0113 TF0114 TF0115 ABBoje TF0111 TF0112 TF0121 TF0150 TF0152 Sassnitz TF0160 OBBoje map 1 TF0140 TF0142 map 2 Karlskrona TF0210 TF0200 TF0211 Longitude [ ] TF0212 TF0213 TF0221 TF0214 Koszalin 10 11 12 13 14 15 16 17 18 19 20 21 22 Kalmar Västervik ÖLAND TF0222 POLAND TF0245 TF0240 TF0284 Visby GOTLAND TF0256 TF0259 TF0255 Gdynia Slite Gdansk TF0253 TF0283 TF0250 TF0263 TF0260 limit 10-22 / 53.5-59 // scale 26-18 TF0286 TF0272 TF0270 TF0271 TF0285 Kalingrad Liepaja LATVIA Klaipeda Ventspils 0-30 -60-90 -120-150 -180-210 -240-270 -300-330 -360-390 -420-450 -480-510 -540 2012 Department Physical Oceanography Jan Donath Leibniz Institute for Baltic Sea Research Warnemünde Latitude [ ] Fig. 1: Total map of the stations of the cruise 06EZ1213. 53.5 54.0 54.5 55.0 55.5 56.0 06EZ1213 / map 1 monitoring 25.07.2012-04.08.2012 58 stations / 05 repeated stations Kiel 0-5 -10-15 -20-25 -30-35 -40-45 -50-55 -60-65 -70-75 -80 Odense TF0360 TF0361 Lübeck Fehmarn TF0022 TF0010 TF0011 TF0012 DENMARK Gedser TF0040 TF0046 TF0041 TFO5 GERMANY Rostock Longitude [ ] Kopenhagen TF0030 TF0001 TF0002 Trelleborg TF0113 TF0114 TF0115 Fig. 2: Detailed map of the western Baltic Sea with sampling stations of cruise 06EZ1213. Sassnitz Ystad Ronne BORNHOLM 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.0 TF0069 TF0102 TF0105 TF0104 TF0103 TF0109 limit 10-15 / 53.5-56 // scale 24-18 TF0111 ABBoje TF0112 TF0121 TF0150 TF0152 TF0160 TF0145 OBBoje TF0140 TF0142 TF0144 2012 Department Physical Oceanography Jan Donath Leibniz Institute for Baltic Sea Research Warnemünde Latitude [ ]
55.0 55.5 56.0 56.5 57.0 57.5 58.0 58.5 59.0 06EZ1213 / map 2 monitoring 25.07.2012-04.08.2012 58 stations / 05 repeated stations Karlskrona Kalmar TF0210 TF0200 TF0211 TF0212 TF0213 TF0221 TF0214 Västervik ÖLAND TF0222 TF0245 TF0240 TF0284 Longitude [ ] GOTLAND Fig. 3: Detailed map of the Baltic Proper with sampling stations of cruise 06EZ1213. Visby TF0256 TF0255 TF0259 15.0 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5 22.0 Slite TF0253 TF0283 TF0250 TF0263 TF0260 TF0286 TF0272 TF0270 TF0271 TF0285 limit 15-22 / 55-59 // scale 23-18 Liepaja Klaipeda Ventspils LATVIA 0-25 -50-75 -100-125 -150-175 -200-225 -250-275 -300-325 -350-375 -400-425 -450 2012 Department Physical Oceanography Jan Donath Leibniz Institute for Baltic Sea Research Warnemünde Latitude [ ]
Fig. 4: Transsect from the Kiel Bight to the Farö Deep for temperature, salinity and oxygen (unvalidated data)
06EZ1213 / map O2 monitoring 25.07.2012-04.08.2012 oxygen bottom - concentration [ml/l] Longitude [ ] 54 55 56 57 58 59 Latitude [ ] Kiel Odense 4.10 Lübeck Fehmarn 2.77 DENMARK 3.71 Gedser Rostock GERMANY Kopenhagen 4.78 Trelleborg 4.93 Ystad Sassnitz 5.80 SWEDEN BORNHOLM Ronne Karlskrona 0.10 Kalmar 0.64 2.70 Koszalin Västervik ÖLAND POLAND -0.6(H2S) -0.87(H2S) -0.92(H2s) Visby GOTLAND 0.29 Gdynia Slite Gdansk limit 10-22 / 53.5-59 // scale 26-18 -4.09(H2S) -2.76(H2S) -7.6(H2S) Kalingrad Liepaja Klaipeda Ventspils LATVIA 2012 Department Physical Oceanography Jan Donath Leibniz Institute for Baltic Sea Research Warnemünde 0-30 -60-90 -120-150 -180-210 -240-270 -300-330 -360-390 -420-450 -480-510 -540 10 11 12 13 14 15 16 17 18 19 20 21 22 Fig. 5: Oxygen /hydrogen sulphide concentrations in the near-bottom layer for selected stations