Read what Canada has found to be true or at least, likely, of ocean acidification's effects on the Scotian Shelf ecosystem in the
State of the Scotian Shelf 2012, We observe that like theirs, our region's marine microbes that create tiny calcium based shells to live within are affected by reduced pH - as much as or more than we megafauna and macrophytes!
Here's the report's section on marine microbes
4.3 Calcifying Micro-
organism Productivity
Micro-organisms are small bacteria, phytoplankton,
zooplankton, and invertebrate species.
They are responsible for almost half of all
global primary productivity (Rost et al. 2008).
Primary productivity is the production of oxygen
and other organic compounds.
Micro-organisms
are also the basis of the marine food
web. Due to climate change, changes in dissolved
carbon dioxide concentrations, pH, dissolved
oxygen, temperature, and stratification
will all combine to influence the composition
and dominance of micro-organisms in the sea.
This will impact their role in respiration, nutrient
cycling, and many other important biological
processes (Rost et al. 2008) (see Climate
Change theme paper).
In some instances,
however, increased dissolved carbon dioxide in
ocean waters could exhibit beneficial impacts
on certain micro-organism species, due to
varying respiratory responses. For others, more
negative responses may be observed.
In short,
increased carbon dioxide dissolution in the sea
is expected to affect micro-organism species
differently, by impacting species-specific productivity,
composition, assemblage, and succession
(Orr et al. 2005; Rost et al. 2008).
Calcification is important to the prosperity of
many micro-organisms by way of body structure,
functioning, and protection (Pörtner 2008).
Calcification is often a function of complex physiological
processes in organisms that make use
of bicarbonate or trapped carbon dioxide rather
than carbonate, thus, although carbonate saturation
may be a good proxy for calcification it is
not necessarily a direct driver at the organism
level (Atkinson and Cuet 2008; Pörtner 2008).
Some calcareous-based micro-organisms can
survive extended periods of time in the absence
of their calcareous structures, while many oth
ers cannot (e.g., echinoderms such as starfish)
(Pörtner 2008). Typical calcareous marine
micro-organisms include foraminifera (calcite
shells), coccolithophores (calcite shells), and
euthecosomatous pteropods (aragonite shells).
They account for almost all of the flux of calcium
carbonate from the ocean’s surface waters to
the deep sea (Fabry et al. 2008). Foraminifera
and euthecosomatous pteropods are particularly
important inhabitants of sub-polar regions such
as the Scotian Shelf.
Micro-organisms vary in their response to
ocean acidification, even within like species,
and this has implications for the adaptation
of individual species (Fabry et al. 2008). For
lower trophic calcifying marine micro-organisms,
such as Emiliania huxleyi (Figure 7),
declines in their population may have significant
implications on the ecosystem as a whole,
by causing changes in food chain dynamics
(Riebesell et al. 2000; Fabry et al. 2008; Rost
et al. 2008). Emiliania huxleyi are commonly
found in the waters of Atlantic Canada, includi-
ng those on the eastern Scotian Shelf (Brown
and Yoder 1994). The species is particularly
vulnerable to changes in ocean pH. In general,
acute and long-term sensitivity to dissolved
carbon dioxide is likely to be highest in lower
trophic invertebrate species, which are poorlysuited
to tolerate changes that can influence
important life processes such as calcification
(Pörtner 2008). The result is a lower tolerance
of these species to changes in temperature
that will reduce their spatial distribution, associated
species interactions, and affect their role
in the ecosystem (Pörtner 2008). Pteropods
are particularly vulnerable to ocean acidification
due to their highly-soluble aragonite shells,
while very little is known about the impacts
of ocean acidification on cnidarians, sponges,
bryozoans, annelids, brachiopods, and tunicates
(Fabry et al. 2008). In contrast, increased
dissolved carbon dioxide appears to have
little impact on marine diatoms (Fabry et al.
2008). Some zooplankton species may exhibit
diminished respiration, with species reliant on
calcium carbonate showing signs of depressed
physiological function (Royal Society 2005;
Fabry et al. 2008; Rost et al. 2008)
FIGURE 7.
Evidence of reduced calcification in two calcareous
marine coccolithophore plankton species: Emiliania huxleyi
(see Panels a,b, d, and e) and Gephyrocapsa oceanica (see
Panels c and f) (Riebesell et al. 2000). The organisms were
exposed to simulated dissolved carbon dioxide concentrations
of approximately 300 ppm by volume (Panels a–c)
and 780-850 ppm by volume (Panels d–f), respectively.
The scale bar represents 1 micrometre (µm) in length
(one thousandth of a millimetre). At the higher simulated
dissolved carbon dioxide concentrations, organisms demonstrated
signs of malformation, as represented by abnormalities
in their shape and roughness of their edges (reprinted
with permission from the Nature Publishing Group, Macmillan
Publishers Ltd: Nature, Riebesell et al. 2000)..
Elevated dissolved carbon dioxide concentrations
favour plankton species with high
carbon demands and low surface area-tovolume
ratios, that is, larger micro-organism
species or species that lack carbon dependence.
As a result, increased dissolved
carbon dioxide may cause a shift in the
global ocean’s planktonic community structure
(Wolf-Gladrow et al. 1999). For instance,
non-photosynthetic micro-organisms
such as bacteria, fungi, and protists may
prosper under conditions of a lowered-pH
sea. Many of these organisms have greater
metabolic variability, which could give them
a competitive advantage (e.g., nitrogenfixing
cyanobacteria may benefit from ocean
acidification) (Royal Society 2005). This
could further contribute to an altered chem
stry of the sea (Orr et al. 2005). Last, increased
dissolved carbon dioxide in the sea
may increase the extra-cellular polysaccharides
found on surfaces of plankton organisms.
Extra-cellular polysaccharides behave
as a glue that binds multiple organisms into
large aggregates, subsequently altering the
residence time and flux of planktonic biomass
from surface waters into the deep sea
(Royal Society 2005). As a result, essential
minerals and energy found in the surface
ocean could also dramatically change
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