Leibniz Institute for
Baltic Sea Research
Warnemünde
Cruise Report
r/v "Elisabeth Mann Borgese "
Cruise- No. EMB 055
This report is based on preliminary data
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.:
EMB 055
2. Dates of the cruise:
from 20.08.2013
to 31.8.2013
3. Particulars of the research vessel:
Name:
Elisabeth Mann Borgese
Nationality:
Germany
Operating Authority:
Leibniz Institute for Baltic Sea Research Warnemünde
4. Geographical area in which ship has operated:
Baltic Proper, Himmerfjärden
5. Dates and names of ports of call
none
6. Purpose of the cruise
education of students master Marine Biology
7. Crew:
Name of master:
Number of crew:
Scholz
10
8. Research staff:
Chief scientist:
Dr. Maren Voss
Scientists:
13
Engineers:
0
Technicians:
4
9. Co-operating institutions:
Stockholm University, Baltic Sea Center
10. Scientific equipment
CTD system with water bottles, nets, multicorer, VanVeen grab
11. General remarks and preliminary result (ca. 2 pages)
Cruise report
The purpose of the cruise was the education of Swedish and German students in the field of biological
oceanography. They were supposed to learn all basic sampling methods and gain hands-on training for
most commonly used gears like CTD with rosette of water bottles, multicorer, plankton net, and grab
sampler. Moreover a typical coastal eutrophication situation should be studied by means of sampling
along the Himmerfjärden area which is an intensively monitored region in the Swedish coastal waters.
On our way to Sweden we collected samples already in the Arkona basin (AB, figure 1), the Bornholm
basin (BD2, figure 2) and the Landort Deep (LD284, no figure). Profiles were generally typical for the
late summer situation. In the Arkona Basin we found a warm surface layer extending down to 22m
depth and a 10m thick thermocline (Fig. 1). The salinity increase was quite pronounced from the base
of the thermocline towards the sea bottom where values of almost 20 were reached.
Fig 1. Seabird profiles of the sensor readings from the Arkona Basin (red: temperature, blue: salinity, green: oxygen, brown:
turbidity, light blue: chlorophyll fluorescence)
The Bornholm situation was quite similar with a 20m mixed layer on top of a thermocline which
reached down to app. 35m depth (Fig. 2). Below a strong salinity increase concomitant with an oxygen
decrease was found.
Fig 2. Seabird profiles of the sensor readings from the Bornholm Basin (red: temperature, blue: salinity, green: oxygen,
brown: turbidity, light blue: chlorophyll fluorescence)
Along the Himmerjärden five stations were visited twice and water and sediment samples collected to
understand how eutrophication impacts the nutrient cycle. We found a strong thermocline (Fig.3) along
the Fjärd and reduced oxygen concentrations (Fig. 4) at the station H5 which is closely situated to the
STP outlet.
Fig. 3 Temperature along the Himmerfjärden area.
Fig. 4 Oxygen concentrations along the Himmerfjärden
Although late summer is a season where nutrients are usually at detection limit and a late bloom of
nitrogen fixing cyanobacteria may still be present, we found nitrate and ammonium (Fig. 5) still at the
northernmost station.
Fig. 5 Ammonium concentrations (µmol l-1) along the Himmerfjärden
The presence of high concentrations of ammonium is a sign of significant eutrophication and taken as
indication of high organic matter loading and recycling of nutrients. The oxidation of the nutrients to
nitrate seems not take place may be due to a lack in oxygen.
Moreover, experiments were set up which studied nutrient limitation and organic matter recycling.
Nutrient limitation was tested in bottle experiments where bottles were enriched with phytoplankton
and amended with either nitrate or phosphate or both. A control with no additions was incubated in
parallel. This experiment was carried out twice and gave ambitious results. It seemed, however, that
cyanobacteria – mostly Aphanizomenon - could still profit by the phosphate addition and start biomass
buildup within hours after the nutrient was added.
Sediment cores were incubated in the lab and oxygen consumption followed over up to 48 hours.
Organic matter and/or benthic animals were added to the cores. The effect was a very rapid oxygen
consumption with animals and with the organic material.
The cruise took place under perfectly calm weather conditions which facilitated the sampling and the
numerous analysis an board. We left Askö already in the night of the 29th after a crayfish- farewell
party and sailed home under very calm conditions. Therefore we already arrived Rostock in the
morning of August 31st.
The feedback of the students was entirely positive and the learning effect with hand-on training will
remain the best way to introduce students to marine sciences.
Appendix: map and list of stations
Upper figure shows all stations where samplese were collected.
Lower figure shows the Himmerfjärden in detail, where all stations were visited twice.
Please note: The resolution is not good enough to correctly show the land water distribution.
60
western Baltic and Baltic Proper
59
Latitude
58
H5
H4
H3
18
H2
Trans_A
LD
0
-50
-100
-150
57
-200
56
-250
BD2
55
-300
AB
-350
Test
54
10
-400
11
12
13
14
15
16
17
18
19
Longitude
59.3
Himmerfjärden Area
0
-50
59.1
-100
H5
-150
Latitude
H4
-200
H3
18
58.9
-250
As
H2
kö
-300
Trans_A
-350
58.7
-400
LD
58.5
-450
-500
17.6 17.8 18.0 18.2 18.4
Longitude
Stations list:
H5
H4
H3
18
H2
TRANS_A
N
59 02,190
58 59,014
58 56,140
58 53,692
58 50,550
58 43,800
E
17 43,400
17 43,971
17 43,713
17 42,540
17 47,420
18 02,000
Test_Darss
TF113
BD2
TF 284
54 23,600
54 55,485
55 28,000
58 35,900
12 18,720
13 29,950
16 07,950
18 14,500