59
DOC than DON is produced, presumably by phytoplankton
(Kirchman et al. 1991). The amount of DOC bacteria can
assimilate depends on the phytoplankton species releasing it
(Malinsky-Rushansky and Legrand 1996). Phytoplankton
release of DOC alone cannot meet bacterial needs and thus
allochthonous DOC sources as well as sloppy feeding, viral
lysis, hydrolysis by exoenzymes, and zooplankton excretion
play a role in releasing additional DOC into the ocean
(Fig. 2) (Mopper and Lindroth 1982; Baines and Pace 1991;
Jiao and Azam 2011). DOC produced by phytoplankton contains both high and low molecular weight substances.
Bacteria assimilate these low molecular weight substances,
such as amino acids, peptides, and carbohydrates rather
quickly. High molecular weight substances are only slowly
or not at all assimilated and can contribute to refractory DOC
(Sundh 1992). During phytoplankton blooms, polysaccharide particle formation can transform DOC to particulate
organic matter. Such polysaccharides can provide binding
sites for trace metals and could participate in controlling
their residence time in the ocean (Engel et al. 2004).
Therefore, a variety of potentially relevant bioactive molecules exists within the complex DOC pool produced by phytoplankton that influences the ecological interplay of
phytoplankton with its environment.
Methods for Studying Phytoplankton Species
Composition
Several comprehensive reviews providing good overviews
over a variety of methods are available for plankton research.
Techniques to assess phytoplankton diversity were collected
by Johnson and Martiny (2015). Applications of flow cytometry have been reviewed by Dubelaar and Jonker (2000). A
revision of case studies for molecular methods to estimate
diversity is available from Medlin and Kooistra (2010).
Reviews for nutrient quantification, pigment analysis and
remote sensing are also available (Cloern 1996; Jeffrey et al.
1999; Roy et al. 2011; Blondeau-Patissier et al. 2014).
Methods that yield useful approaches to help understanding phytoplankton species composition and its interconnection to environmental conditions are summarized in Fig. 3.
Climate Influences on Phytoplankton
Since the beginning of the industrial era, anthropogenic
influences on the climate have steadily increased. Covering
more than two thirds of the Earth’s surface, the area for
exchange between the atmosphere and sea surface is large.
Apart from that, the ocean is subject to several effects triggered by climate change.
Climate Change in the Ocean
The two most prominent changes to the ocean triggered by
climate change are ocean warming and acidification. Both
aspects affect the ocean globally. Increasing anthropogenic
carbon dioxide emissions have increased partial pressure of
carbon dioxide, both, in the atmosphere and the ocean. The
ocean acts as sink for anthropogenic carbon dioxide and is,
by increasingly taking up carbon dioxide, gradually acidified. It is estimated that surface water pH decreased by 0.1
since the beginning of the industrial era. With increasing
acidification, ocean surface water becomes gradually corrosive to calcium carbonate minerals, of which many seashells
are composed (Fig. 4) (Ciais et al. 2013; Rhein et al. 2013).
The ocean has a high heat capacity and absorbs solar radiation more readily than ice. It is virtually certain that the
upper ocean has warmed. This warming dominates the global
energy change inventory and accounts for more than 90% of
the total energy change inventory, while melting ice, warming of continents, and the warming of the atmosphere play
only a minor role. Warming of the upper ocean is an important factor that has led to an average sea level rise of 0.19 m
between 1901 and 2010 and it is likely that the sea level rise
will accelerate (Fig. 4) (Rhein et al. 2013).
Furthermore, there are plenty of regional changes connected to climate change such as patterns of salinity trends.
The IPCC report defines a region as a territory characterized
by specific geographical and climatological features, whose
climate is affected by scale features (e.g., topography, land
use characteristics, and lakes) and remote influences from
other regions (IPCC 2013). Local changes in salinity are
expected (Fig. 4). In general, a higher contrast between fresh
and salty regions is expected with salty regions becoming
saltier and vice versa. Sea level rise in combination with
wind stress is expected to result in high waves in some
regions. Intermediate and deep water changes are yet difficult to assess, since long-term data are lacking. Generally,
changes in salinity, density, and temperature appear to occur
regionally. Anthropogenic influences on coastal runoff and
atmospheric deposition of nutrients are another important
regional factor. Changing nutrients, such as the input of
nitrogen fertilizers, can influence the biological carbon pump
and ultimately lead to an increasing eutrophication of waters
(Fig. 4) (Ciais et al. 2013; Rhein et al. 2013).
Seasonality and Future Changes
in Phytoplankton Communities
Phytoplankton communities undergo seasonal changes.
Depending on regional properties like climatic or biogeographic conditions, the changes can differ greatly. While
Phytoplankton Responses to Marine Climate Change – An Introduction
DOC than DON is produced, presumably by phytoplankton
(Kirchman et al. 1991). The amount of DOC bacteria can
assimilate depends on the phytoplankton species releasing it
(Malinsky-Rushansky and Legrand 1996). Phytoplankton
release of DOC alone cannot meet bacterial needs and thus
allochthonous DOC sources as well as sloppy feeding, viral
lysis, hydrolysis by exoenzymes, and zooplankton excretion
play a role in releasing additional DOC into the ocean
(Fig. 2) (Mopper and Lindroth 1982; Baines and Pace 1991;
Jiao and Azam 2011). DOC produced by phytoplankton contains both high and low molecular weight substances.
Bacteria assimilate these low molecular weight substances,
such as amino acids, peptides, and carbohydrates rather
quickly. High molecular weight substances are only slowly
or not at all assimilated and can contribute to refractory DOC
(Sundh 1992). During phytoplankton blooms, polysaccharide particle formation can transform DOC to particulate
organic matter. Such polysaccharides can provide binding
sites for trace metals and could participate in controlling
their residence time in the ocean (Engel et al. 2004).
Therefore, a variety of potentially relevant bioactive molecules exists within the complex DOC pool produced by phytoplankton that influences the ecological interplay of
phytoplankton with its environment.
Methods for Studying Phytoplankton Species
Composition
Several comprehensive reviews providing good overviews
over a variety of methods are available for plankton research.
Techniques to assess phytoplankton diversity were collected
by Johnson and Martiny (2015). Applications of flow cytometry have been reviewed by Dubelaar and Jonker (2000). A
revision of case studies for molecular methods to estimate
diversity is available from Medlin and Kooistra (2010).
Reviews for nutrient quantification, pigment analysis and
remote sensing are also available (Cloern 1996; Jeffrey et al.
1999; Roy et al. 2011; Blondeau-Patissier et al. 2014).
Methods that yield useful approaches to help understanding phytoplankton species composition and its interconnection to environmental conditions are summarized in Fig. 3.
Climate Influences on Phytoplankton
Since the beginning of the industrial era, anthropogenic
influences on the climate have steadily increased. Covering
more than two thirds of the Earth’s surface, the area for
exchange between the atmosphere and sea surface is large.
Apart from that, the ocean is subject to several effects triggered by climate change.
Climate Change in the Ocean
The two most prominent changes to the ocean triggered by
climate change are ocean warming and acidification. Both
aspects affect the ocean globally. Increasing anthropogenic
carbon dioxide emissions have increased partial pressure of
carbon dioxide, both, in the atmosphere and the ocean. The
ocean acts as sink for anthropogenic carbon dioxide and is,
by increasingly taking up carbon dioxide, gradually acidified. It is estimated that surface water pH decreased by 0.1
since the beginning of the industrial era. With increasing
acidification, ocean surface water becomes gradually corrosive to calcium carbonate minerals, of which many seashells
are composed (Fig. 4) (Ciais et al. 2013; Rhein et al. 2013).
The ocean has a high heat capacity and absorbs solar radiation more readily than ice. It is virtually certain that the
upper ocean has warmed. This warming dominates the global
energy change inventory and accounts for more than 90% of
the total energy change inventory, while melting ice, warming of continents, and the warming of the atmosphere play
only a minor role. Warming of the upper ocean is an important factor that has led to an average sea level rise of 0.19 m
between 1901 and 2010 and it is likely that the sea level rise
will accelerate (Fig. 4) (Rhein et al. 2013).
Furthermore, there are plenty of regional changes connected to climate change such as patterns of salinity trends.
The IPCC report defines a region as a territory characterized
by specific geographical and climatological features, whose
climate is affected by scale features (e.g., topography, land
use characteristics, and lakes) and remote influences from
other regions (IPCC 2013). Local changes in salinity are
expected (Fig. 4). In general, a higher contrast between fresh
and salty regions is expected with salty regions becoming
saltier and vice versa. Sea level rise in combination with
wind stress is expected to result in high waves in some
regions. Intermediate and deep water changes are yet difficult to assess, since long-term data are lacking. Generally,
changes in salinity, density, and temperature appear to occur
regionally. Anthropogenic influences on coastal runoff and
atmospheric deposition of nutrients are another important
regional factor. Changing nutrients, such as the input of
nitrogen fertilizers, can influence the biological carbon pump
and ultimately lead to an increasing eutrophication of waters
(Fig. 4) (Ciais et al. 2013; Rhein et al. 2013).
Seasonality and Future Changes
in Phytoplankton Communities
Phytoplankton communities undergo seasonal changes.
Depending on regional properties like climatic or biogeographic conditions, the changes can differ greatly. While
Phytoplankton Responses to Marine Climate Change – An Introduction