oceansAugust 26, 2013, 11:51 am
47 Comments Papers Find Mixed Impacts on Ocean Species from Rising
CO2
By
ANDREW
C. REVKIN Royal Society
A detail from the cover of
a Royal Society journal issue focused on the
impacts of rising carbon dioxide levels on ocean ecosystems. The image is of CO2
bubbles rising from a volcanic vent near Naples.
Britain’s Royal Society has published a helpful new collection of papers in
Philosophical Transactions of the Royal Society B that provide fresh insights on
how the global buildup of carbon dioxide released by human activities could
affect ocean ecology.
The work adds to a growing body of science pointing to large changes, with
some types of marine organisms and ecosystems seemingly able to adjust and even
thrive, while others ail. And it’s quite clear that regions already heavily
affected by other human activities (coastal pollution, overfishing, etc.) are —
no surprise — likely to feel more stress from acidification.
The nine new studies in the Royal Society journal provide valuable detail and
find a mix of impacts. Experiments transplanting certain worms around a volcanic
carbon dioxide vent in the sea floor near Naples show remarkable adaptability in
these organisms, both through shifts in metabolism and genetics. A
poles-to-tropics assay of sea urchins shows significant impacts on larvae.
One study demonstrated that not all shifts in species’ prospects are the
result of changing pH. Competition matters. In this analysis, mat-forming algae
appeared to thrive in CO2-enriched marine conditions, to the detriment of corals
and kelp (an echo of how
some forests studies show vines thriving at the expense of
trees).
A year-long laboratory study of
coccolithophores — an
important type of phytoplankton — found they
remained capable of forming their calcium carbonate skeletons even in warmer,
more acidic water. The study, which propagated 700 generations of the
coccoliths*, pointed out the value of longer-duration experiments.
Most of the work is accessible only with a subscription but an excellent
summary is provided in an overview paper written by the two scientists, Jasmin
A. Godbold of University of Southampton and Piero Calosi of Plymouth University,
who assembled the package of studies. A link to their overview is below, along
with excerpts from university news releases on two of the papers.
As
Bryan Walsh summarized nicely in Time today, a
separate
review of existing research on marine animals in acidifying
conditions, published on Sunday in Nature Climate Change, found
uniformly negative impacts.
It’s great to see this emerging body of work given that the oceans, despite
occupying two thirds of Earth’s surface and showing signs of substantial change
driven by the buildup of carbon dioxide emitted by human activities, have
remained a secondary scientific focus.
The vast majority of research in recent decades on the carbon dioxide buildup
has been focused on the atmospheric impacts of the accumulating greenhouse-gas
blanket even though the vast majority of the heated trapped by these gases has
gone first into the seas — and the drop in seawater pH driven by CO2 has been a
clear signal of substantial environmental change.
In 2005, Britain’s Royal Society issued “
Ocean acidification due to increasing atmospheric carbon
dioxide,” a helpful report summarizing the state of knowledge at
the time.
Despite its climate-centric name and mission, the
Intergovernmental Panel on
Climate Change has been focusing
increasing attention on direct ocean impacts of carbon
dioxide, most notably in an excellent 2011 report, “
IPCC Workshop on Impacts of Ocean Acidification on Marine
Biology and Ecosystems.” The workshop summarized the state of
understanding, key uncertainties and next research steps on the shifting
chemistry of the oceans and the impacts on species and ecosystems, with a focus
on ecosystems of particular interest to humans.
You’ll see fresh detail, and fresh questions, in the panel’s fifth assessment
of climate science, which starts rolling out in late September.
Please click here to read the overview of the newly published studies by
Godbold and Calosi: “
Ocean acidification and climate change: advances in ecology and
evolution.”
Here’s an excerpt from the San Francisco State University news release on the
laboratory experiment with diatoms:
A year-long experiment on tiny ocean organisms called coccolithophores
suggests that the single-celled algae may still be able to grow their calcified
shells even as oceans grow warmer and more acidic in Earth’s near future.
The study stands in contrast to earlier studies suggesting that
coccolithophores would fail to build strong shells in acidic waters. The world’s
oceans are expected to become more acidic as human activities pump increasing
amounts of carbon dioxide into the Earth’s atmosphere.
But after the researchers raised one strain of the
Emiliania huxleyi coccolithophore for over 700 generations, which took about 12 months, under high
temperature and acidified conditions that are expected for the oceans 100 years
from now, the organisms had no trouble producing their plated shells. [
Read the rest.]
Here’s an excerpt from the news release on the fascinating work examining the
response of certain worm species when transplanted in and around the
1,850-year-old seabed CO2 vent off Naples:
Researchers have discovered that some species of polychaete worms are able to
modify their metabolic rates to better cope with and thrive in waters high in
carbon dioxide (CO2), which is otherwise poisonous to other, often
closely-related species.
The study sheds new light on the robustness of some marine species and the
relative resilience of marine biodiversity should atmospheric CO2 continue to
cause ocean acidification….
A team of scientists led by Plymouth University, and including colleagues
from the Naples Zoological Station in Ischia; the Marine Ecology Laboratory ENEA
in La Spezia, Italy; the University of Texas Galveston; and the University of
Hull, conducted a three-year research project into the potential mechanisms that
species of worm polychaetes use to live around the underwater CO2 vent of Ischia
in Southern Italy.
The researchers collected specimens found in waters characterised by either
elevated or low levels of CO2, and placed them in specially-constructed
‘transplantation chambers’, which were then lowered into areas both within and
away from the volcanic vent.
They monitored the responses of the worms and found that one of the species
that had been living inside the CO2 vent was physiologically and genetically
adapted to the acidic conditions, whilst another was able to survive inside the
vent by adjusting its metabolism.
Project leader Dr. Piero Calosi, of Plymouth University’s Marine Institute,
said: “Previous studies have shown that single-cell algae can genetically adapt
to elevated levels of carbon dioxide, but this research has demonstrated that a
marine animal can physiologically and genetically adapt to chronic and elevated
levels of carbon dioxide.
“Furthermore, we show that both plasticity and adaptation are key to
preventing some species’ from suffering extinction in the face of on-going ocean
acidification, and that these two strategies may be largely responsible to
defining the fate of marine biodiversity.”
The results revealed that species normally found inside the CO2 vent were
better able to regulate their metabolic rate when exposed to high CO2
conditions, whilst species only found outside the CO2 vent were clearly impaired
by acidic waters. In fact, their metabolism either greatly decreased, indicating
reduced energy production, or greatly increased, indicating a surge in the basic
cost of living, in both cases making life inside the vent unsustainable.
Dr. Maria-Cristina Gambi, of the Naples Zoological Station in Ischia,
explained: “Despite some species showing the ability to metabolically adapt and
adjust to the extreme conditions that are found inside the CO2 vents, others
appear unable to physiologically cope with such conditions.
”In this sense, our findings could help to explain mass extinctions of the
past, and potential extinctions in the future, as well as shed light on the
resilience of some species to on-going ocean acidification.”
The team also found that those species adapted to live inside the CO2 vent
showed slightly higher metabolic rates and were much smaller in size – up to 80%
smaller – indicating that adaptation came at a cost of energy for growth.
Dr. Calosi concluded that: ”Ultimately, species’ physiological responses to
high CO2, as those reported by our study, may have repercussions on their
abundance and distribution, and thus on the structure and dynamics of marine
communities. This in turn will impact those ecosystem functions that humans rely
upon to obtain goods and services from the ocean.” [
Read the rest.]
Here’s the full list of studies, with summaries:
Adaptation and acclimatization to ocean acidification in marine
ectotherms: an in situ transplant experiment with polychaetes at a shallow
CO2 vent system Calosi, Piero; Rastrick, Samuel; Lombardi, Chiara; de Guzman, Heidi;
Davidson, Laura; Jahncke, Marlene; Giangrande, Adriana; Hardege, Joerg;
Schultze, Anja; Spicer, John; Gambi, Maria Cristina To investigate the extent to which nature or nurture determines marine
animals’ responses to Ocean Acidification (OA) we carried out
in-situ transplants using tolerant and sensitive worms living around a natural
CO2 vent. Two tolerant species respond
differently. One shows adaptation, evolving higher metabolism and smaller size
(nature) but the other responds using acclimation, maintaining its size
(nurture). The metabolism of sensitive species altered greatly but
unpredictably. Marine animals can respond to OA by evolving or being plastic,
the response being species-specific. This work throws light on sensitivity of
species to past mass extinctions, and resilience to ongoing acidification.
Long-term effects of warming and ocean acidification are
modified by seasonal variation in species responses and environmental
conditions Godbold, Jasmin; Solan, Martin Over the last decade, the impacts of warming and ocean acidification have
received considerable attention, and there is clear consensus that these
stressors will have far-reaching consequences for species and ecosystems. Much
of the evidence, however, is based on short-term experiments that ignore
long-term variation in how species and ecosystems respond. Using the longest
study to date, we show that species can take much longer times to respond than
previously thought and that the impact of these responses on important ecosystem
properties varies with season. These findings suggest that the ecological
consequences of climate change may diverge from present expectations.
The other ocean acidification problem: CO2 as a resource among
competitors for ecosystem dominance Connell, Sean; Kroeker, Kristy; Fabricius, Katharina; Kline, David;
Russell, Bayden
We explore how ocean acidification combines with
complex environmental changes across a number of scales, highlight the
multiplicity of factors and complexities that cause variation, and raise
awareness of CO2 as a resource whose change in
availability could have wide ranging community consequences beyond its direct
effects. The positive effects of CO2 on
producers are likely to be highly variable among species. Accordingly, there is
an enormous potential for shifts in species dominance, as some species gain a
relative advantage in a high CO2 world.
Short- and long-term conditioning of a temperate marine diatom
community to acidification and warming Tatters, Avery; Roleda, Michael; Schnetzer, Astrid; Fu, Feixue; Hurd,
Catriona; Boyd, Phillip; Caron, David; Lie, Alle; Hoffmann, Linn; Hutchins,
David Ocean acidification and greenhouse warming will interactively influence
competitive success of key phytoplankton groups such as diatoms, but how
long-term responses to global change will affect community structure is unknown.
We incubated a natural diatom community from coastal New Zealand waters in a
short-term incubation experiment using a factorial matrix of temperature and
CO2, and measured effects on community
structure. Our results support the use of short-term manipulative experiments
spanning weeks as proxies to understand the potential effects of global change
forcing on diatom community structure over longer timescales such as years.
Ocean acidification and rising temperatures may increase biofilm
primary productivity but decrease grazer consumption
Russell, Bayden; Connell, Sean; Findlay, Helen; Tait, Karen; Widdicombe,
Stephen; Mieszkowska, Nova
Warming and acidifying oceans, a
consequence of carbon dioxide emissions, are changing coastal ecosystems; we
know this. Our experiment shows that these changes may be unpredictable because
the combination of temperature and acidification changes the amount and type of
biofilm, green rock slime at the base of the intertidal food web, while reducing
the ability of marine snails to eat it. This inability of snails to compensate
for higher maintenance costs, likely to be a stress response as they are pushed
beyond their normal functioning range, warns us that these ecosystems are likely
to change beyond what we currently know.
Bioturbation determines the response of benthic ammonia
oxidising microorganisms to ocean acidification
Laverock, Bonnie; Kitidis, Vassilis; Tait, Karen; Gilbert, Jack; Osborn,
A; Widdicombe, Stephen
Nitrification is a key process in coastal
sediments, contributing to the breakdown of organic matter and the recycling of
nutrients in both the sediments and the overlying water. However, microbial
nitrification rates in seawater are dramatically inhibited by ocean
acidification. We show that, in coastal sediments, the response may be dependent
upon animals living within the sediment. Under normal conditions, mud shrimps
enhance sediment nitrification rates, but at reduced seawater pH, this
functionality rapidly declines. Ocean acidification therefore has the potential
to significantly alter coastal nutrient cycling and productivity through
knock-on effects on animal-microbe interactions.
Effects of acidification on olfactory-mediated behaviour in
freshwater and marine ecosystems: a synthesis
Leduc, Antoine; Munday, Philip; Brown, Grant; Ferrari,
Maud
Aquatic ecosystem acidification has significant detrimental
consequences to olfaction and chemosensory abilities of aquatic organisms. This
loss of sensory function may lead to impaired behavioural responses of
potentially far-reaching consequences in population dynamics and community
structure. Whereas the ecological impacts of such impairments may be similar
between freshwater and marine ecosystems, the underlying mechanisms are quite
distinct. Molecular change to chemicals at low pH is the primary cause of
impaired olfactory-mediated behaviour of fishes in freshwater conditions. In
contrast, interference of high CO2 with brain
neurotransmitter functions is the primary cause of such impaired behaviour in
experiments simulating future ocean acidification.
The stunting effect of a high CO2 ocean on calcification and
development in sea urchin larvae, a synthesis from the tropics to the
poles
Byrne, Maria; Lamare, Miles; Uthicke, Sven; Dworjanyn, Symon; Winter,
David The ocean is warming, acidifying and decreasing in mineral saturation,
compromising the ability of larvae to make shells and skeletons. We analysed
responses of the calcifying larvae of sea urchins, an ecologically important
group, to ocean change stressors in a synthesis of data from species from
tropical to polar environments and from intertidal to subtidal habitats.
Acidification impairs calcification and growth while warming promotes growth. We
need to understand the effects of both stressors. Responses of larvae from
across world regions indicate overall trends despite disparate environments and
ecology as well as differences in the sensitivities of tropical and polar
species.
Emiliania huxleyi increases calcification but
not expression of calcification-related genes in long-term exposure to elevated
temperature and pCO2Benner, Ina; Diner, Rachel;
Lefebvre, Stephane; Li, Dian; Komada, Tomoko; Carpenter, Edward; Stillman,
Jonathon
We cultured a globally important calcifying phytoplankton, the
coccolithophore
Emiliania huxleyi, for >700 generations under present
and future ocean conditions of carbon dioxide and temperature, and analyzed
their physiological and genomic response. We found that cells produced more
calcium carbonate under future ocean conditions, but had the same amount of
organic carbon as in present conditions. Surprisingly, they did this without
altering the expression of genes thought to be involved with the calcification
process. Our findings have significance for global carbon cycling, oceanic
carbon sequestration, and the cellular biology of
coccolithophores.
Updated, 10:41 p.m. | At
the asterisk above, I originally used diatoms as a synonym for coccolithophores.
A reader pointed out the mistake.
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