206
The aim of this study is to characterize optical properties of
Chromophoric Dissolved Organic Matter (CDOM) and
Fluorescent Dissolved Organic Matter (FDOM) in Nordic
Seas. The experimental material has been collected during
three summer seasons (2013–2015) onboard Polish r/v Oceania
and Norwegian r/v Lance in the western and northern
Spitsbergen Shelf, Norwegian Sea, Barents Sea and in the
Fram Strait. Spatial distribution of DOM absorption and fluorescence from water samples is presented. A three channel
WET Labs WET Star fluorometer was deployed, with channels
for humic- and protein-like DOM and used to assess distribution of different FDOM fractions. A relationship between fluorescence intensity of the protein-like fraction of FDOM and
chlorophyll a fluorescence was found and indicated the importance of phytoplankton biomass in West Spitsbergen Current
waters as a significant source of protein- like FDOM. East
Greenland Current waters has low concentration of chlorophyll
a, and were characterized by high humic-like FDOM fluorescence. An empirical relationship between humic-like FDOM
fluorescence intensity and CDOM absorption was derived and
confirms the dominance of terrigenous like CDOM on the
composition of DOM in the East Greenland Current. These
high resolution profile data offer a simple approach to fractionate the contribution of these two DOM source to DOM across
the Fram Strait and may help refine estimates of DOC fluxes in
and out of the Arctic through this region.
3.3 Abstracts of Poster Presentations
3.3.1 100 Years of North Sea Clarity and Color
Changes
J. Schmitz
1*
, M. Wernand
2
, J. Wollschläger
1
, O. Zielinski
1
1
University of Oldenburg, Institute for Chemistry and
Biology of the Marine Environment, Schleusenstraße 1,
26382 Wilhelmshaven, Germany
2
NIOZ Royal Netherlands Institute for Sea Research, PO
Box 59, 1790 AB Den Burg (Texel), The Netherlands
*corresponding author: jana.schmitz@uni-oldenburg.de
Keywords: Light, Water clarity, Water color, North Sea,
Time series analysis
Thermal stratification and generation of currents, degradation of dissolved organic material and production of biomass by photosynthesis – all those processes are driven by
light energy introduced into the seas and oceans. For visual
predators and organisms depending on a circadian rhythm,
light is furthermore essential for survival. Underwater light
quality and penetration depth are largely determined by
water constituents present (phytoplankton, colored dissolved
organic matter and suspended sediments) and can be inferred
from observations of water clarity and water color. Simple
instruments that provide information about these parameters,
the Secchi disc and the Forel-Ule scale, have been introduced
more than 100 years ago. Originally, they were used by sailors for navigation purposes. Nowadays, in combination with
modern instruments like submersible and above-water radiometers, their application provides a link between historical
observations and modern light field measurements. The project Coastal Ocean Darkening aims to examine the changes of
the light climate in coastal seas to get a better understanding
of this highly sensitive and utilized ecosystem supporting its
protection and sustainable use. The analysis of a large historic dataset of Secchi disc and Forel-Ule scale measurements of the past century is one core topic. Trends of
darkening coastal seas are examined in detail with a focus on
the North Sea. By making use of hydrographic parameters
like temperature, salinity, and depth, a natural classification
of the North Sea area into regions will be established. Clarity
and color changes are analyzed with respect to these regions
in order to investigate spatial variability in the large-scale
trend of decreasing light availability. The results of this analysis will be used together with data of current measurements
and lab experiments for modeling future scenarios within the
Coastal Ocean Darkening project.
3.3.2 Land-Ocean Interactions in Arctic Coastal
Waters – Ocean Color Remote Sensing in Optical
Complex Waters
Bennet Juhls
1*
, Birgit Heim
2
, P. Paul Overduin
2
, Jürgen
Fischer
1
1
Institute of Space Sciences, Freie Universität Berlin,
Carl-Heinrich-Becker-Weg 6-10, D-12165 Berlin, Germany
2
Alfred Wegener Institute, Telegrafenberg A43, D-14473
Potsdam, Germany
*corresponding author: bjuhls@wew.fu-berlin.de
Keywords: Arctic, Ocean Color, Laptev Sea,
Biogeochemical, OLCI
Arctic coastal waters and shelf regions such as the Laptev
Sea are rapidly changing environments influenced by climate
warming and consequent permafrost thaw and sea ice reduction, causing a longer open-water period. Biogeochemical
interactions between land and ocean, e.g., river discharge
and coastal erosion, control the ecosystem of these regions.
During the short ice-free season, extremely dynamic and
chaotic processes such as river and sea-ice break-up strongly
influence the aquatic ecosystem for the rest of the year. In
this season, large amounts of suspended sediments and dissolved organic matter discharged into the Arctic Ocean by
the Lena River and along the coast control the transparency
of the water. Therefore, it is highly important to obtain a synoptic view to complement spatially or temporally limited in
situ data. Ocean Color Remote Sensing (OCRS) is a tool
which provides high temporal resolution and synoptic information for biogeochemical water constituents in surface
waters. Times series for up to 17 years can be used to detect
interannual and long-term trends. The use of several satellites is increasing temporal data coverage. Besides the OLCI
(Ocean and Land Colour Instrument) sensor on-board the
Appendices
The aim of this study is to characterize optical properties of
Chromophoric Dissolved Organic Matter (CDOM) and
Fluorescent Dissolved Organic Matter (FDOM) in Nordic
Seas. The experimental material has been collected during
three summer seasons (2013–2015) onboard Polish r/v Oceania
and Norwegian r/v Lance in the western and northern
Spitsbergen Shelf, Norwegian Sea, Barents Sea and in the
Fram Strait. Spatial distribution of DOM absorption and fluorescence from water samples is presented. A three channel
WET Labs WET Star fluorometer was deployed, with channels
for humic- and protein-like DOM and used to assess distribution of different FDOM fractions. A relationship between fluorescence intensity of the protein-like fraction of FDOM and
chlorophyll a fluorescence was found and indicated the importance of phytoplankton biomass in West Spitsbergen Current
waters as a significant source of protein- like FDOM. East
Greenland Current waters has low concentration of chlorophyll
a, and were characterized by high humic-like FDOM fluorescence. An empirical relationship between humic-like FDOM
fluorescence intensity and CDOM absorption was derived and
confirms the dominance of terrigenous like CDOM on the
composition of DOM in the East Greenland Current. These
high resolution profile data offer a simple approach to fractionate the contribution of these two DOM source to DOM across
the Fram Strait and may help refine estimates of DOC fluxes in
and out of the Arctic through this region.
3.3 Abstracts of Poster Presentations
3.3.1 100 Years of North Sea Clarity and Color
Changes
J. Schmitz
1*
, M. Wernand
2
, J. Wollschläger
1
, O. Zielinski
1
1
University of Oldenburg, Institute for Chemistry and
Biology of the Marine Environment, Schleusenstraße 1,
26382 Wilhelmshaven, Germany
2
NIOZ Royal Netherlands Institute for Sea Research, PO
Box 59, 1790 AB Den Burg (Texel), The Netherlands
*corresponding author: jana.schmitz@uni-oldenburg.de
Keywords: Light, Water clarity, Water color, North Sea,
Time series analysis
Thermal stratification and generation of currents, degradation of dissolved organic material and production of biomass by photosynthesis – all those processes are driven by
light energy introduced into the seas and oceans. For visual
predators and organisms depending on a circadian rhythm,
light is furthermore essential for survival. Underwater light
quality and penetration depth are largely determined by
water constituents present (phytoplankton, colored dissolved
organic matter and suspended sediments) and can be inferred
from observations of water clarity and water color. Simple
instruments that provide information about these parameters,
the Secchi disc and the Forel-Ule scale, have been introduced
more than 100 years ago. Originally, they were used by sailors for navigation purposes. Nowadays, in combination with
modern instruments like submersible and above-water radiometers, their application provides a link between historical
observations and modern light field measurements. The project Coastal Ocean Darkening aims to examine the changes of
the light climate in coastal seas to get a better understanding
of this highly sensitive and utilized ecosystem supporting its
protection and sustainable use. The analysis of a large historic dataset of Secchi disc and Forel-Ule scale measurements of the past century is one core topic. Trends of
darkening coastal seas are examined in detail with a focus on
the North Sea. By making use of hydrographic parameters
like temperature, salinity, and depth, a natural classification
of the North Sea area into regions will be established. Clarity
and color changes are analyzed with respect to these regions
in order to investigate spatial variability in the large-scale
trend of decreasing light availability. The results of this analysis will be used together with data of current measurements
and lab experiments for modeling future scenarios within the
Coastal Ocean Darkening project.
3.3.2 Land-Ocean Interactions in Arctic Coastal
Waters – Ocean Color Remote Sensing in Optical
Complex Waters
Bennet Juhls
1*
, Birgit Heim
2
, P. Paul Overduin
2
, Jürgen
Fischer
1
1
Institute of Space Sciences, Freie Universität Berlin,
Carl-Heinrich-Becker-Weg 6-10, D-12165 Berlin, Germany
2
Alfred Wegener Institute, Telegrafenberg A43, D-14473
Potsdam, Germany
*corresponding author: bjuhls@wew.fu-berlin.de
Keywords: Arctic, Ocean Color, Laptev Sea,
Biogeochemical, OLCI
Arctic coastal waters and shelf regions such as the Laptev
Sea are rapidly changing environments influenced by climate
warming and consequent permafrost thaw and sea ice reduction, causing a longer open-water period. Biogeochemical
interactions between land and ocean, e.g., river discharge
and coastal erosion, control the ecosystem of these regions.
During the short ice-free season, extremely dynamic and
chaotic processes such as river and sea-ice break-up strongly
influence the aquatic ecosystem for the rest of the year. In
this season, large amounts of suspended sediments and dissolved organic matter discharged into the Arctic Ocean by
the Lena River and along the coast control the transparency
of the water. Therefore, it is highly important to obtain a synoptic view to complement spatially or temporally limited in
situ data. Ocean Color Remote Sensing (OCRS) is a tool
which provides high temporal resolution and synoptic information for biogeochemical water constituents in surface
waters. Times series for up to 17 years can be used to detect
interannual and long-term trends. The use of several satellites is increasing temporal data coverage. Besides the OLCI
(Ocean and Land Colour Instrument) sensor on-board the
Appendices