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Vulnerability and adaptation of US shellfisheries to ocean acidification



Ocean acidification is a global, long-term problem whose ultimate solution requires carbon dioxide reduction at a scope and scale that will take decades to accomplish successfully. Until that is achieved, feasible and locally relevant adaptation and mitigation measures are needed. To help to prioritize societal responses to ocean acidification, we present a spatially explicit, multi-disciplinary vulnerability analysis of coastal human communities in the United States. We focus our analysis on shelled mollusc harvests, which are likely to be harmed by ocean acidification. Our results highlight US regions most vulnerable to ocean acidification (and why), important knowledge and information gaps, and opportunities to adapt through local actions. The research illustrates the benefits of integrating natural and social sciences to identify actions and other opportunities while policy, stakeholders and scientists are still in relatively early stages of developing research plans and responses to ocean acidification.
The ocean has absorbed about 25% of anthropogenic
atmospheric CO2 emissions, progressively increasing dis-
solved CO2, and lowering seawater pH and carbonate ion
levels1. On top of this progressive global change in oceanic car-
bon conditions, local factors such as eutrophication2,3, upwelling
of CO2-enriched waters4 and river discharge5 temporarily increase
anthropogenic ocean acidication (OA)6 in coastal waters7–9. Ocean
acidication could primarily aect human communities by chang-
ing marine resource availability1. Studies have shown that, in gen-
eral, shelled molluscs are particularly sensitive to these changes in
marine chemistry10–12. Shelled molluscs comprise some of the most
lucrative and sustainable sheries in the United States13. Ocean
acidication has already cost the oyster industry in the US Pacic
Northwest nearly $110 million, and directly or indirectly jeopard-
ized about 3,200 jobs13. e emergence of real, economically meas-
urable human impacts from OA has sparked a search for regional
responses that can be implemented immediately, while we work
towards the ultimate global solution: a reduction of atmospheric
CO2 emissions. Yet there is little understanding about which loca-
tions and people will be impacted by OA, to what degree, and why,
and what can be done to reduce the risks.
Here, we present the rst local-level vulnerability assessment
for ocean acidication for an entire nation, adapting a well-estab-
lished framework and focusing on shelled mollusc harvests in the
United States; for other evaluations of OA social vulnerability, see
Vulnerability and adaptation of US shellfisheries
to ocean acidification
Julia A. Ekstrom*†1, Lisa Suatoni2, Sarah R. Cooley3, Linwood H. Pendleton4,5, George G. Waldbusser6,
Josh E. Cinner7, Jessica Ritter8, Chris Langdon9, Ruben van Hooidonk10, Dwight Gledhill11,
Katharine Wellman12, Michael W. Beck13, Luke M. Brander14, Dan Rittschof15, Carolyn Doherty†15,
Peter Edwards16 and Rosimeiry Portela17
Ocean acidification is a global, long-term problem whose ultimate solution requires carbon dioxide reduction at a scope and
scale that will take decades to accomplish successfully. Until that is achieved, feasible and locally relevant adaptation and
mitigation measures are needed.To help to prioritize societal responses to ocean acidification, we present a spatially explicit,
multi disciplinary vulnerability analysis of coastal human communities in the United States.We focus our analysis on shelled
mollusc harvests, which are likely to be harmed by ocean acidification.Our results highlight US regions most vulnerable to
ocean acidification (and why), important knowledge and information gaps, and opportunities to adapt through local actions. The
research illustrates the benefits of integrating natural and social sciences to identify actions and other opportunities while policy,
stakeholders and scientists are still in relatively early stages of developing research plans and responses to ocean acidification.
refs14–16. We explored three key dimensions—exposure, sensitivity
and adaptive capacity (Fig.1, Supplementary Fig. S1)—to assess
the spatial distribution of vulnerable people and places to OA. e
underlying assumption guiding this assessment is that addressing
existing vulnerability can reduce future vulnerability to OA, some-
times called ‘human-security vulnerability’15.
Exposure of marine ecosystems addresses acidication driven
by global atmospheric CO2 and amplied by local factors in coastal
waters. We divided the coastal waters around the United States into
existing National Estuary Research Reserve System bioregions17
(Supplementary Fig.S7), and for each bioregion, examined: (1) pro-
jected changes to ocean chemistry based on a reduction in aragonite
saturation state (ΩAr) (Supplementary Fig.S2), and (2) the preva-
lence of key local ampliers of OA, including upwelling, eutrophi-
cation and input of river water with low-aragonite saturation
state [AU: OK?], for each bioregion (Supplementary Figs S4–S6).
Aragonite saturation state (ΩAr) is a measure of the thermodynamic
stability of this mineral form of calcium carbonate that is used by
bivalve larvae and other molluscs, which is also commonly used to
track OA1. Declining ΩAr makes it more dicult and energetically
costly for larval bivalves to build shells even before ΩAr becomes
corrosive [AU: is it ΩAr that becomes corrosive, or should this
be OA?], and ΩAr seems to be the important variable for the most
sensitive early stage of bivalve larvae18. We evaluated relative expo-
sure to anthropogenic OA as the time [AU: i.e. ‘time until’, or ‘the
1Natural Resources Defense Council, 111Sutter Street, SanFrancisco,California 94104, USA; 2Natural Resources Defense Council, 40West 20th Street,
New York, New York10011,USA; 3Ocean Conservancy, 1300 19th Street NW, Washington DC20036,USA; 4Nicholas Institute, Duke University, Durham,
North Carolina27708,USA; 5University of Western Brittany Brest, 29238 Brest, France; 6College of Earth, Ocean, and Atmospheric Sciences, Oregon
State University, Burt 200, Corvallis, Oregon 97331USA; 7ARC Centre of Excellence Coral Reef Studies, James Cook University, Townsville, Queensland,
Australia; 8US Senate Commerce Committee, WashingtonDC, USA; 9Department of Marine Biology and Ecology, Rosenstiel School of Marine &
Atmospheric Science, University of Miami, Florida 33149,USA; 10NOAA Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida33149,
USA; 11NOAA Ocean Acidification Program, Silver Spring, Maryland 20910,USA; 12Northern Economics, Seattle, Washington98107,USA; 13The Nature
Conservancy, Santa Cruz, California 95060, USA; 14Independent Consultant, Hong Kong [AUTHOR: full street address including zip/postcode?] 15Duke
Marine Lab, Duke University, Beaufort, North Carolina 28516,USA; 16NOAA Habitat Conservation Restoration Center, Silver Spring, Maryland20910,USA;
17Conservation International, Arlington Virginia 22202,USA. †Present address: Policy Institute for Energy, Environment, and the Economy, University of
California at Davis, 1605 Tilia Street 100, Davis 95616, California, USA (J.A.E.); Oce of Marine Conservation, US State Department, Washington DC,
USA (C.D.). *e-mail:
extent of time for which’?] mean annual surface seawater exceeds
an empirically informed absolute ΩAr threshold for several spe-
cies of bivalve larvae. is indicator for disruption to the biologi-
cal processes of calcication and development in larval molluscs
was favoured over alternatives (for example time until the historic
range of ΩAr is exceeded) because the biological mechanism was
clear19 and empirical evidence exists20. For comparison purposes,
the Supplementary Information includes the time until the historic
range of ΩAr is exceeded (Supplementary Fig. S3), but below we
document the outcomes based on the ΩAr threshold projections and
local ampliers of OA.
Sensitivity of social systems was evaluated at the scale of ‘clus-
ters of coastal counties’ around the United States, using three indi-
cators of community dependence on shellsh, adapted from the
National Marine Fisheries Service’s shing community vulnerabil-
ity and resilience index21: (1)the 10-year median landed value of
shellsh (including both wild and aquaculture harvests); (2) the
10-year median proportional contribution of shellsh to total
value of commercial landings; and (3)the 5-year median number
of licences (representing jobs) supported by shelled mollusc shing
(Supplementary Information). Sensitivity indicators were re-scaled
and combined into a single index (Supplementary Information and
Supplementary Fig.S8).
Adaptive capacity of social systems to cope with and adapt to
OA is represented by three classes of indicators: status of state gov-
ernment climate and OA policies, local employment alternatives
and availability of science. We examined a total of six indicators
representing adaptive capacity that are derived largely from the
broader economic and policy landscape, yet are directly relevant
for dealing with the threat of OA (Supplementary Fig. S9). is
is a deliberate departure from studies conducted at broader and
ner geographic scales that use general demographic indicators
(see Supplementary Information). We assessed ‘potential govern-
ment support for adaptation’ through measures of: (1) the status
of state legislative action on OA and (2)the status of state climate
adaptation planning. ese indicators reect social organization
and assets at the state jurisdictional level that could be used by
communities to adapt to, cope with, or avoid the impacts of lost
shellsh harvests. We examined aspects of employment alterna-
tives through: (3) the diversity of shelled mollusc harvests, sug-
gesting potential alternative shellsh that could be harvested and
(4) the diversity of non-shellsh-related employment industries.
ese reect the likelihood of job alternatives for shellsh har-
vesters and those in the aquaculture industry. Finally, we captured
‘access to and availability of science’ through (5) a score for marine
laboratoriesdeveloped totake into account the high local inuence
that such laboratories can have as well as the potential contribution
beyond their immediate vicinity. For each county cluster, a metric
based on the number ofuniversity marine laboratories(on-campus
and satellite laboratories) in that county cluster was averaged with
a metric based on the total number of university marine laborato-
ries in that state (see Supplementary Information for more infor-
mation) and (6)Sea Grant state budgets normalized by shoreline
length. ese indicators represent the availability of local scientic
capacity, the potential for troubleshooting assistance, and the pos-
sibility of access to a range of tools and data products, such as avail-
able early warning information. We attributed each county cluster
(as used in Sensitivity) to each variable score of the six indicators.
We then combined into a single index by averaging re-scaled (0–1)
overall component scores for sensitivity and adaptive capacity
(Supplementary Information Fig.S9). Coincidence of high marine
ecosystem exposure to OA with high sensitivity and low adaptive
capacity of social systems reveals the areas at highest overall vul-
nerability to OA.
Places vulnerable to ocean acidification
Our results show that 16out of 23 bioregions around the United
States are exposed to rapid OA (reaching Ar 1.5by 2050) or at
least one amplier (Fig.2; Supplementary TableS1); 10 regions are
exposed to two or more threats of acidication (note that Alaska
and Hawaii are missing local amplier data; Fig. 2). e marine
ecosystems and shelled molluscs around the Pacic Northwest
and Southern Alaska are expected to be exposed soonest to ris-
ing global OA, followed by the north-central West Coast and the
Gulf of Maine in the northeast United States. Communities highly
reliant on shelled molluscs in these bioregions are at risk from
OA either now or in the coming decades. In addition, pockets of
marine ecosystems along the East and Gulf Coasts will experi-
ence acidication earlier than global projections indicate, owing
to the presence of local ampliers such as coastal eutrophication,
upwelling and discharge of low-Ar river water (see Supplementary
FigsS4–S6, Supplementary TableS1).e inclusion of local ampli-
ers reveals more coastline segments around the United States that
are exposed to acidication risk than when basing exposure solely
on global models.
Combining sensitivity and adaptive capacity reveals that the
most socially vulnerable communities are spread along the US East
Coast and Gulf of Mexico (Fig.2), yet the sources of high social
vulnerability are very dierent between these two regions (see
Supplementary Information for breakdown separated by sensitivity
and adaptive capacity, FigsS8 and S9). Specically, the East Coast
is dominated by high levels of sensitivity, or economic depend-
ence, from strong use of shellsh resources. For example, south-
ern Massachusetts measures as having the highest sensitivity. is
county cluster ranks in the top four for all three sensitivity indica-
tors (Supplementary Fig.S8), meaning that this area has the highest
mollusc harvest revenues of any coastal area in the United States,
second highest number of licences and fourth highest proportion
of seafood revenues coming from molluscs. In contrast, the Gulf
of Mexico region is socially vulnerable from low adaptive capacity,
owing to social factors such as low political engagement in OA and
climate change, low diversity of shellsh shery harvest and rela-
tively low science accessibility (Supplementary Fig.S9).
Importantly, our visually combined overall vulnerability analy-
sis reveals that a number of socially vulnerable communities lie
adjacent to water bodies that are exposed to a high rate of OA
or at least one local amplier, indicating that these places could
be at high overall vulnerability to OA (Fig. 2). e areas that are
exposed to OA (including local ampliers) and high and medium–
high social vulnerability coincide include southern Massachusetts,
Rhode Island, Connecticut, New Jersey and portions around the
Overall vulnerability
Marine ecosystem exposure
Marine ecosystems exposed to
ocean acidification (OA)
Social vulnerability
Local societal
of shellfish
Assets available
to help prepare
for or avoid
impacts of OA
Figure 1 | Conceptual framework structuring the analysis of vulnerability
to ocean acidification. Vulnerability analyses can focus on three key
dimensions (exposure, sensitivity and adaptive capacity): (1) the extent
and degree to which assets are exposed to the hazard of concern; (2)the
sensitivity of people to the exposure; and (3) the adaptive capacity
of people to prepare for and mitigate the exposure’s impacts. These
three dimensions together provide a relative view of a place’s overall
vulnerability. Adapted conceptual model components from refs 16,52–55.
Chesapeake Bay, the Carolinas, and areas across the Gulf of Mexico
(Fig. 2b–d). Interestingly, global ocean models that project the
advance of OA, primarily as a result of atmospheric CO2, do not
reveal these areas as exposed to global OA until aer 2099, based on
our study’s Ar threshold (Table1). e marine ecosystem exposure
in the areas located along the Atlantic coast and the Gulf of Mexico
is from low-Ar conditions caused primarily by the addition of river
water and eutrophication, local factors that have only more recently
been considered major ampliers of nearshore acidication6,7. ese
coastal processes are likely to tip coastal oceans past organism
thresholds as atmospheric CO2 uptake continues in the future (see
ref. 22). Although the Pacic Northwest, northern California and
Maine exhibit only medium and medium–low social vulnerability
(Fig.2a,b), these areas are particularly economically sensitive and
lie adjacent to marine ecosystems highly exposed to global OA23,24
(sensitivity, Supplementary Fig.S8). is prole of relatively high
dependency and high exposure in these three regions has already
activated signicant research and local action/engagement among
local scientists, government and shellsh growers (see for example
refs 25,26). is engagement has driven up adaptive capacity (based
on our study’s indicators) in these areas, which reduces their social
vulnerability relative to other regions across the United States. In
comparison, the lower level of OA-related action in other regions
such as the Gulf of Mexico (Fig.2d), Massachusetts (Fig.2b) and
Mid-Atlantic (Figs 2c,d) with high overall vulnerability proles
might be partly because their marine ecosystem exposure is domi-
nated by the presence of local OA ampliers rather than global OA
(Supplementary Fig.S2, Supplementary TableS1). At the same time,
some of these areas (for example Maryland) do have strong advo-
cates for addressing water quality which could provide an oppor-
tunity to address locally driven acidication as awareness of the
issue grows.
Hawaiian Islands
Gulf of
Gulf of Mexico
Pacific Ocean
Pacific Ocean
Pacific Ocean
Pacific Ocean
Alabama Georgia
North Carolina
Puget Sound
E(5/8) E(3/6)
R(7/9) R(2/12)
Social vulnerability (land)
Highest SV (top 20%)
Medium high
Medium SV (middle 20%)
Medium low
Lowest SV (bottom 20%)
Marine ecosystem exposure (water)
Year hits threshold
After 2099
U: Upwelling is strong
River drainage low saturation state
and high annual discharge volume
nd: No data available for E or R
Highly eutrophic estuaries presentE:
Local amplifiers
Figure2 | Overall vulnerability of places to ocean acidification. Scores of relative social vulnerability are shown on land (by coastal county cluster) and
the type and degree of severity of OA and local amplifiers to which coastal marine bioregions are exposed, mapped by ocean bioregion: (a) contiguous US
West Coast; (b) Northeast; (c) Chesapeake Bay; (d) Gulf of Mexico, and Florida and Georgia’s coast; (e) Hawaii Islands; and (f) Alaska. Social vulnerability
(red tones) is represented with darker colours where it is relatively high. Exposure (purple tones) is indicated by the year at which sublethal thresholds
for bivalve larvae are predicted to be reached, based on climate model projections using the RCP8.5 CO2 emission scenario27. Exposure to this global OA
pressure is higher in regions reaching this threshold sooner. Additionally, the presence and degree of exposure to local amplifiers of OA are indicated for
each bioregion: E(x/y)marks bioregions [AU: OK?] in which highly eutrophic estuaries are documented, x is the number of estuaries scored as high, and y
is the total number evaluated in each bioregion (source: ref. 56), locations of highly eutrophic estuaries are marked with a star; R(x/y) marks bioregions in
which sampled river water draining into bioregion scored [AU: this description is not clear grammatically: should it be ‘bioregions in which... water was
scored’, or is something missing here? Also, does ‘scoring in the top quintile’ here mean top quintile of discharge volume only? Please clarify phrasing]
based on very low saturation state and high annual discharge volume (top quintile, calculated by authors from US Geological Survey57), x is the number
of rivers scoring in the top quintile of those evaluated, and y is the total number evaluated in this study. Approximate locations of river outflows of those
rivers scoring in the top quintile are marked with a delta [AU: a yellow triangle?]; and U marks bioregions where upwelling is very strong in at least part of
the bioregion (source: ref. 58).
Robustness of analysis
To examine the robustness of these spatial patterns of vulnerability,
we varied the index aggregation methodology and the selection of
indicators. To test the dierence in index aggregation methods for
social vulnerability, we compared the output of adding and multi-
plying sensitivity and adaptive capacity indices and found little dif-
ference; the same set of county clusters made up the top 10 most
socially vulnerable places using either aggregation method.
To explore the eect of indicator selection on adaptive capac-
ity (and thus social vulnerability), we compared a set of commonly
used generic indicators for adaptive capacity relating to income,
poverty, education and age with the set of threat-specic indi-
cators developed for this study (see Table 3 and Supplementary
FigsS10and S11). Using the generic capacity measures to calculate
social vulnerability, we found that six of the same county clusters
measured within the top 10 highest socially vulnerability places in
the United States as those found using the threat-specic indicators
(see Supplementary Information for analysis and maps). is is con-
siderable overlap given that the two sets of variables indicate entirely
dierent notions of adaptive capacity. Because the sensitivity indica-
tors were developed and vetted by sheries social science research-
ers21 and alternative potentially appropriate data were not available
nationwide, we did not have a useful comparison for this element
from which to draw.
To explore the criterion for Ar, we examined one alternative
for disruption of biological processes with respect to rising atmos-
pheric CO2: the time until average surface waters move outside
the present range of Ar (that is, exceeding a historic envelope)27.
e map generated by this ‘historic envelope’ approach shows that
southern areas experience potential OA exposure earlier, which
is nearly an inverse pattern to our chosen criterion of a chemical
threshold when calcication and development of larval molluscs
may decrease (Supplementary Fig. S3). is dierence in pat-
terns is because natural variability is much smaller in southern
regions, although evidence of greater sensitivity in populations
of bivalves that live in tropical and subtropical waters is lacking.
is discrepancy underscores the need for targeted research inte-
grating a physiological, ecological and evolutionary perspective on
the potential and limitations of strong local biological adaptation
to dierent carbonate regimes for commercially valuable shelled
mollusc populations.
Overall, we found that variable selection has stronger eects
than aggregation methods, which provides high condence in our
aggregation methods for social vulnerability. e dierences found
in variable selection identify research needs relating to what factors
underlie vulnerability on the ground that are relevant to OA; this
conversation has only just begun.
Opportunities to reduce vulnerability to ocean acidification
Social–environmental syntheses, including vulnerability analyses,
can help to identify opportunities for actionable solutions to address
the potential impacts of ocean acidication. Our analysis reveals
where and why the overall vulnerability from OA varies among
the many coastal areas of the United States, and thus identies
opportunities to reduce harm.
One way to tackle OA is by reducing marine ecosystem exposure
to it. Several portions of the east coast are highly exposed to OA
from high levels of eutrophication (Fig.2b–d). In addition to releas-
ing extra dissolved CO2 and enhancing acidication, eutrophication
can also decrease seawater’s ability to buer further acidication3.
People in these regions are uniquely positioned to reduce expo-
sure to OA through regional actions by curtailing eutrophication
(as compared, for example, with regions exposed to upwelling).
Although a signicant challenge, reducing nutrient loading to the
coastal zone in these areas could provide multiple benets, mak-
ing it a no-regrets option. Reducing eutrophication can decrease
hypoxia and harmful algal blooms, in addition to reducing risk
from fossil-fuel-derived OA at the local and regional level. Policy
Table 1 | Indicators of drivers and amplifiers of ocean acidification, and the criterion for each used in this study.
Factors causing and amplifying OA
(reducing ΩAr)
Indicator Scoring scale Criterion for ranking the risk factor
as ‘high’
Rising atmospheric CO2 reduces ΩAr
causing chronic stress to shelled
mollusc larvae
Projected year that surface water will
reach 1.5ΩAr (ref. 27)
Continuous scale from current year
to 2099
1.5ΩAr threshold reached by 2050
Eutrophication increases pCO2 locally
via respiration, leading to reduced ΩAr
Degree of eutrophication56 Eutrophication scored on a five-point
scale: low to high
Presence of a high-scoring eutrophic
estuary in bioregion
River water can reduce ΩAr locally in
coastal waters
Combined metric of river’s aragonite
saturation state and annual
discharge volume
Rivers scored on a five-point scale:
low to high
Presence of high scoring river (for
low aragonite saturation and high
discharge volume) in bioregion
Significant seasonal upwelling
delivers water rich in CO2 to shallow
waters, leading to reduced ΩAr
Degree of upwelling58 Coastal zones scored on a five-point
scale: low to high
Presence of high upwelling zone
in bioregion
Table 2 | Indicators representing ‘sensitivity’ (people’s dependency) on organisms expected to be aected by ocean acidification
(in this study, shelled molluscs).
Indicator or measure Source Raw format Processing for subindex
Landed value
(median of 10 years)
Regional fisheries databases (ACCSP,
GulfBase, PacFIN), and States of
Alaska and Hawaii
US dollars, annual Calculated median for years
Winsorized the top 10%
Percentage of shellfish by value [AU:
i.e. as percentage of all fish caught?]
(median of 10 years)
For each year: shelled molluscs
value/total commercial landed value
Divided landed value of shellfish by
landed value of all fish
Winsorized the top 10%
Number of licences as proxy for jobs
(median over 5 years)
Number of commercial
licences, annual
Winsorized the top 10%
All indicators are in units of county clusters.
[AU: Please indicate where Table 2 should be cited in the text.]
instruments to reduce eutrophication exist in the United States28
and can be leveraged to facilitate eorts to reduce OA8.
Another important way to combat the eects of OA will be
by reducing social vulnerability. In regions where high sensitiv-
ity (one component of social vulnerability) arises from the struc-
ture of the shing industry, an entirely dierent approach to
adaptation may be more appropriate than those geared to reduce
marine ecosystem exposure. For example, where shery harvest
portfolios are dominated by a single species, such as in the Gulf
of Mexico where mollusc production is limited to the eastern oys-
ter (Crassostrea virginica), diversication of the species harvested
might be a benecial strategy.
A further way to reduce social vulnerability may be by increas-
ing adaptive capacity of people and regions. Access and availability
to science already has helped shellsh aquaculturists in the Pacic
Northwest to identify and avoid some of the consequences of OA20.
Working with local scientists, hatcheries have implemented several
strategies to adapt and mitigate OA eects on bivalve seed produc-
tion. rough local industry–research partnerships in the Pacic
Northwest, implementation of real-time monitoring of saturation
state, chemical buering of water, changes in timing of seasonal seed
production and use of selectively bred lines of oyster broodstock, this
collaboration has prevented collapse of the regional oyster industry.
In every case, when developing a broader array of adaptation
strategies, it is critical to work directly with the coastal communities
in each region so they can develop context-appropriate and feasi-
ble adaptation options. Targeted projects to develop local adapta-
tion plans may even require developing further regionally relevant
indicators of adaptive capacity and community resilience that this
nationwide study does not capture. In fact, zooming in to assess par-
ticular regions at a higher resolution would enable regional stake-
holders to provide input into a possible dierent set of variables that
denes vulnerability in their particular region based on values and
social or economic context.
Barriers to and path forward for addressing OA
is study oers the rst nationwide vulnerability assessment of
the spatial distribution of local vulnerability from OA focusing on a
valuable marine resource. But it is just a rst step to understanding
where and how humans and marine resources are at highest risk to
OA and its local ampliers. Another key nding of this assessment is
that signicant gaps in the scientic understanding of coastal ocean
carbonate dynamics, organismal response and people’s depend-
ence on impacted organisms limit our ability to develop a full suite
of options to prepare for, mitigate and adapt to the threats posed
by OA, and these can be considered in a structured way using the
framework (Fig.3). e types of gaps identied—as commonly clas-
sied in information science and other disciplines29,30—range from
data inaccessibility to knowledge deciencies.
Marine ecosystem exposure. Key gaps remain in understanding
how global and local processes interact to drive nearshore OA,
and how this will aect marine organisms and ecological systems.
Recent studies suggest that the biogeochemical interaction between
global OA and local ampliers is additive3,22,31; however, most ocean
models used to project future OA cannot adequately resolve these
processes, which are also increasingly aected by human activity7,32.
Even though direct measurements incorporate an ever-growing
global network of monitoring instruments, they are oen located
oshore and remain too sparse in space and time to resolve the
dynamics of seawater chemistry near shore, where most shellsh
live. Historically, OA monitoring has focused on oshore regions,
where long-term, high-accuracy and precise measurements enabled
detection and attribution of the rising atmospheric CO2 acidica-
tion signal. But many commercially and nutritionally important
organisms live in the coastal zone where they experience the com-
bined eects of multiple processes that alter the carbonate chemis-
try7. is results in greatly variable ‘carbonate weather’ for a given
location33. Characterizing this variation, including modelling how
rising atmospheric CO2 will increase the frequency, duration and
severity of extreme events [AU:OK?], would provide a fuller picture
of how OA is unfolding within the dynamic coastal waters.
To improve our understanding of which marine ecosystems
and organisms are most susceptible to ocean acidication, addi-
tional information on the ΩAr thresholds below which reproduc-
tion and survival are disrupted is needed. In the US context, the
Table 3 | Threat-specific indicators used to assess capacity of fishing communities to deal with impacts of ocean acidification.
Group Indicator Source Raw format Processing for subindex
Access to scientific
Budget of Sea Grant
National Sea Grant State-level total funds of
budget (state and federal
contributions combined, 2013)
Re-scaled (0–1)
Attributed normalized
scores to each
county cluster
Number of university marine
Direct count from registries
and Internet
Latitude/longitude location
of laboratories
Combined score of
laboratories per state/
shoreline length and labs
per county cluster
Employment alternatives Shelled mollusc diversity Regional fisheries databases
(ACCSP, GulfBase, PacFIN),
and States of Alaska
and Hawaii
Ratio of landing revenues for
each taxon by county cluster
Calculated Shannon
Weiner Diversity Index
Economic diversity ACS Census Proportion of county
population employed in
each industry
Calculated Shannon
Weiner Diversity Index
for county clusters
Political action Legislative action for OA Keyword searches on
legislature websites and
follow-up calls
Established five-point scale
for state’s legislative progress
on OA
Re-scaled 0–1
Attributed score to
county clusters
Climate adaptation planning Georgetown Law School
Climate programme website
Status of climate adaptation
plan for state
Re-scaled 0–1
Attributed score to
country clusters
See Supplementary Information for discussion and presentation of alternative indicators and measures.
concentration of value in a limited number of shellsh species
means that the identication of biologically susceptible and resist-
ant species and populations is both prudent and feasible. Based
on total landed value from 2003to 2012, approximately 95% of
shelled-mollusc revenues in the United States come from only
10 species (and 80% from ve).ese species include sea scallop
(52.9%), eastern oyster (11.3%), Pacic geoduck (5.8%), Pacic
oyster (5.2%) and six species of clam (that range from 5% to
2.6% of total value)34. ere is some evidence of local biological
adaptation of other marine taxa to varying carbonate chemistry
regimes35–37. is potential genetic variation, if present, could be
documented to aid in the development of resistant strains of cul-
tured or other organisms.
Social vulnerability. Our study also revealed large gaps in infor-
mation about mollusc-dependent communities to inform measures
of social vulnerability. We do not have high-resolution nationwide
data on the full cultural and societal signicance of shelled mol-
luscs. Even data on the contributions of shellsh to human nutri-
tion, shoreline protection, and water ltration were inadequate
nationwide. Incorporation of these other ecosystem services pro-
vided by molluscs could alter the social vulnerability landscape. For
the commercial sheries data that we did obtain, condentiality
constraints forced us to aggregate our analysis into county clusters,
preventing county-specic or port-level analyses of social vulner-
ability that might have revealed more spatial heterogeneity. We also
lack social science data that describe use at species-, human com-
munity-, port- or household levels. We lack data on the value chain
that links threatened organisms to harvesters, processors and end-
users. Finally, empirically tested adaptive capacity measures could
contribute to a more rigorous evaluation of social vulnerability.
is includes data on scientic spending and infrastructure directly
relevant to end-users, as well as social and demographic data that
are reective of end-users (for this study, shing and aquaculture
communities) and not the general population (for example generic
indicators quantifying education and income).
Beyond helping in prioritizing and developing adaptation strate-
gies, social science is also useful to inform and guide planning for
social adaptation and mitigation. As with climate change adapta-
tion, preparing for and adapting to the impacts of OA is a social
process1,38,39. Implementation does not occur automatically once
strategies are developed, but instead must oen overcome a suite
of institutional (including legal), political, psychological and other
types of barriers40. As learned from climate change initiatives, the
‘soer side’ of adaptation (such as coordination among stakehold-
ers, industry and scientists) is the rst step towards preparing for
a threat like OA41. Despite its fundamental importance, this type of
eort is oen overlooked and remains underfunded. Social science
can also help practitioners even in early stages of adaptation g-
ure out how to engage public and policy-makers eectively in OA
issues42–44. Farther along in adaptation processes, social science can
inform the development of strategies by accounting for social val-
ues45,46 and existing property rights in use and norms47,48 and even
helping to work out what type of information is salient for and
trusted by decision-makers49,50. Although important for reducing its
risks, social science relevant for understanding OA has been mini-
mal thus far. A budget assessment conducted by the Interagency
Working Group on Ocean Acidication reported that federal
research in scal year 2011 allocated $270,000of Federal funds for
social science research related to OA, which represents 0.9% of the
entire OA spending for that year’s budget51.
As with other global environmental changes, acidication of the
oceans is a complex and seemingly overwhelming problem. Here we
have focused only on OA (and nearshore ampliers) as the threat to
coastal species. Although other stressors also threaten coastal eco-
systems, our single-threat assessment allows us to tease out where
OA in isolation could hit people and organisms the hardest, which
can inform research agendas and decision-making geared speci-
cally to address OA. A vulnerability framework helps to structure
our thinking about the ways in which ocean acidication will aect
What is the Ar
threshold for
each species?
Where are the
shellfish beds?
What is the ecological and
economic productivity
of beds?
How does atmospheric
CO2-driven OA cumulate
with local drivers?
Community and
household reliance
on shellfish
What is ‘successful’
adaptation for
Community- and
attributes that improve
capacity deal with OA
Importance of shellfish
to community
Types of gap
Data access
Relative eort
needed to fill
Overall vulnerability
Marine ecosystem exposure
Marine ecosystems exposed to
ocean acidification (OA)
Social vulnerability
Local societal
of shellfish
Assets available
to help prepare
for or avoid
impacts of OA
Figure 3 | Sample of gaps in knowledge related to OA vulnerability, information and data organized around components of the framework. Dierent
types of gaps are classified by the level of eort that is required to fill them (gaining knowledge is the most challenging, whereas data access tends to be
the most straightforward).
ecosystems and people. e framework also helps to identify and
organize the opportunities and challenges in dealing with these
problems. But this study is the beginning; adaptation to OA and
other global environmental change is an iterative process that
requires both top-down and bottom-up processes. Our analysis of
OA as it relates to [AU: OK?] US shelled mollusc sheries makes
clear just how much the pieces of the OA puzzle vary around the
country. Marine ecosystem exposure, economic dependence and
social capacity to adapt create a mosaic of vulnerability nation-
wide. An even more diverse set of strategies may be needed to help
shellsh-dependent coastal communities adapt to OA. Rather than
create and apply a nationwide solution, decision-makers and other
stakeholders will have to work with shing and aquaculture com-
munities to develop tailored locally and socially relevant strategies.
Meaningful adaptation to OA will require planning and action at all
levels, including regional and local levels, which can be supported
with resources, monitoring, coordination and guidance at the
national level.
Over the past decade, scientists’ understanding of ocean
acidication has matured, awareness has risen and political action
has grown. e next step is to develop targeted eorts tailored to
reducing social and ecological vulnerabilities and addressing local
needs. Tools like this framework can oer a holistic view of the
problem and shed light on where in the social–ecological system to
begin searching for locally appropriate solutions.
Received 22 August 2014; accepted 19 December 2014; published
online xx February 2015.
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is work was supported by the National Socio-Environmental Synthesis Center
(SESYNC) under funding received from the National Science Foundation DBI-1052875.
Support for R.v.H. to generate model projections was provided by NOAA’s Coral Reef
Conservation Program. We thank the institutions and individuals that provided data (see
Supplementary Information for full details), and W. McClintock and his laboratory for
use of to enable collaborative discussions of spatial data and analysis. We
are grateful for the contributions and advice provided by E. Jewett throughout the project.
Author contributions
All authors provided input into data analysis and research design, and participated in at
least one SESYNC workshop; J.A.E. led the draing of the text with main contributions
from L.S., S.R.C., L.H.P., G.G.W. and J.E.C.; R.v.H. contributed projections of ocean
acidication; J.A.E., L.S., S.R.C., J.R. and C.D. collected the data; J.A.E. carried out data
analysis and mapping.
Additional information
Supplementary information is available in the online version of the paper. Reprints
and permissions information is available online at
Correspondence should be addressed to J.A.E.
Competing financial interests
e authors declare no competing nancial interests. [AUTHORS: OK?]
... The large differences between the nearshore and the open waters of the SOG implies that ship-based data collection in open waters is not adequate for characterising and capturing the variability of carbonate chemistry and the extremes that vulnerable organisms experience at the nearshore. In addition, although numerical biogeochemical models are able to capture variability on a finer temporal scale than our observational data, even high-resolution models average spatially (e.g., Jarníková, et al., 2022) or are built on open ocean data (e.g., Ekstrom et al., 2015) and are not likely to fully capture the high diel and seasonal 840 variability observed in the nearshore. High resolution models which are built upon locally collected nearshore data could provide a more accurate representation of the variability and conditions at locations where OA sensitive organisms are present; ...
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Ocean acidification reduces seawater pH and calcium carbonate saturation states (Ω), which can have detrimental effects on calcifying organisms such as shellfish. Nearshore areas, where shellfish aquaculture typically operates, have limited data available to characterize variability in key ocean acidification parameters pH and Ω, as samples are costly to analyse and difficult to collect. This study collected samples from four nearshore locations at shellfish aquaculture sites on the Canadian Pacific coast from 2015–2018 and analysed them for dissolved inorganic carbon (DIC) and total alkalinity (TA), enabling the calculation of pH and Ω for all seasons. The study evaluated the diel and seasonal variability in carbonate chemistry conditions at each location and estimated the contribution of drivers to seasonal and diel changes in pH and Ω. Nearshore locations experience a greater range of variability and seasonal and daily changes in pH and Ω than open waters. Biological uptake of DIC by phytoplankton is the major driver of seasonal and diel changes in pH and Ω at our nearshore sites. The study found that freshwater is not a key driver of diel variability, despite large changes over the day in some locations. Shellfish mortality events coincide with highly favourable pH and Ω conditions during summer and are most likely linked to high surface temperatures and disease rather than ocean acidification. To reduce shellfish mortality, shellfish could be hung lower in the water column (5–20 m) to avoid high temperatures and disease, while still experiencing favourable pH and Ω conditions for shellfish.
... Organisms such as phytoplankton, zooplankton and invertebrates (e.g., clams, oysters and corals) that form shells and skeletons of calcium carbonate (CaCO 3 ) may have difficulty maintaining or forming hard structures in undersaturated waters. It should be noted, however, that several studies have identified higher critical thresholds ( ∼ 1.3-2) for marine organisms (e.g., Ekstrom et al., 2015;Waldbusser et al., 2015;Siedlecki et al., 2021). The two most common forms of CaCO 3 are calcite and aragonite. ...
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The Atlantic Zone Monitoring Program (AZMP) was established by Fisheries and Oceans Canada (DFO) in 1998 with the aim of monitoring physical and biological ocean conditions in Atlantic Canada in support of fisheries management. Since 2014, at least two of the carbonate parameters (pH; total alkalinity, TA; and dissolved inorganic carbon, DIC) have also been systematically measured as part of the AZMP, enabling the calculation of derived parameters (e.g., carbonate saturation states, Ω, and partial pressure of CO2, pCO2). The present study gives an overview of the spatiotemporal variability in these parameters between 2014 and 2022. Results show that the variability in the carbonate system reflects changes in both physical (e.g., temperature and salinity) and biological (e.g., plankton photosynthesis and respiration) parameters. For example, most of the region undergoes a seasonal warming and freshening. While the former will tend to increase Ω, the latter will decrease both TA and Ω. Spring and summer plankton blooms decrease DIC near the surface and then remineralize and increase DIC at depth in the fall. The lowest pCO2 values (down to ∼ 200 µatm) are located in the cold coastal Labrador Current, whereas the highest values (>1500 µatm) are found in the fresh waters of the Gulf of St. Lawrence and the St. Lawrence Estuary. The latter is also host to the lowest pH values of the zone (7.48 in the fall of 2022). Finally, most of the bottom waters of the Gulf of St. Lawrence (>90 %) are undersaturated with respect to aragonite (Ωarg<1). In addition to providing a baseline of carbonate parameters for the Atlantic Zone as a whole, this comprehensive overview is a necessary and useful contribution for the modelling community and for more in-depth studies. The full dataset of measured and derived parameters is available from the Federated Research Data Repository: (Cyr et al., 2022a).
... OA can both directly impact local marine creature population and indirectly impact the marine food web and ecosystem, especially for shelly invertebrates (Fay et al. 2017;Ekstrom et al. 2015). Furthermore, some shellfish like Placopecten magellanicus are the ideal species which is an applied comprehensive assessment model to evaluate the influence of global climatic change towards wild capture fisheries (Rheuban et al. 2018), and this may be part of the reasons why America has wide-related research towards OA (Fig. 1) as its aquaculture has grown substantially (Coleman et al. 2023). ...
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... Coastal communities and countries around the world have a history of benefitting economically from shellfisheries along with having an integrated maritime culture based on harvesting and growing shellfish leading to millions of dollars in landings (Lellis-Dibble et al., 2008). Bivalve shellfish represent a $2B USD industry in the US (Ekstrom et al., 2015), a multi-million dollar industry on Long Island alone and are known to provide natural filtration for shallow embayed areas (Cerrato et al., 2004;Lellis-Dibble et al., 2008). Restoration efforts have been implemented to promote shellfish population recovery from anthropogenically-caused population declines, such as hard clam spawning sanctuaries in Great South Bay and Shinnecock Bay, NY (Doall et al., 2008;. ...
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Harmful algal blooms (HABs) such as those formed by the ichthyotoxic dinoflagellate , Margalefidinium (aka Cochlodinium ) polykrikoides can have adverse effects on bivalves. While M. polykrikoides has caused significant die offs of bivalves and other marine organisms, the Northern quahog or hard clam, Mercenaria mercenaria , is comparatively more resistant to this HAB. This study quantified clearance rates of juvenile hard clams (10-20 mm) exposed to three different North American populations of M. polykrikoides (bloom, strain CP1, strain CPSB-1G) as well as the nonharmful cryptophyte, Rhodomonas salina and the nonharmful dinoflagellate, Gymnodinium aureolum , in single and mixed algal exposures. Multiple biovolume exposures with M. polykrikoides bloom water and R. salina (1,000, 1,500, 3,000 cells mL ⁻¹ M. polykrikoides biovolume equivalent) were completed to assess the effects of increasing biomass on hard clam clearance rates and selection. Hard clams opened and actively cleared algal mixtures at and below 1,000 M. polykrikoides cells mL ⁻¹ . During single species exposures, strain CPSB-1G and R. salina were cleared significantly faster than wild M. polykrikoides populations and strain CP1. During mixed exposures, R. salina was cleared significantly faster than CPSB-1G but not other M. polykrikoides populations and there was no difference between hard clam clearance rates of G. aureolum and R. salina . Clearance rates of M. polykrikoides at ≥1,500 cells mL ⁻¹ M. polykrikoides/R. salina mixtures were not significantly different than zero unlike clearance of those at <1,000 cells mL ⁻¹ indicating a density dependent effect of blooms. Collectively, the results demonstrate that hard clams can actively clear M. polykrikoides cells at moderate (≤1,000 cells mL ⁻¹ ) but not elevated (> 1,000 cells mL ⁻¹ ) bloom densities. Given this, and the documented survival of hard clams during blooms, M. mercenaria may be candidate for aquaculture and restoration in regions prone to HABs caused by M. polykrikoides .
... For example, increased acidity negatively impacts marine organisms that build calcium carbonate shells or skeletons (Azetsu-Scott et al. 2010) (e.g., corals, bivalves, coccolithophores, and pteropods), which may have consequences for marine food webs (Fabry et al. 2008;Haigh et al. 2015), including the culturally and economically relevant species that rely on them. Key commercial species such as oysters, mussels, and lobsters are particularly vulnerable to ocean acidification effects (Barton et al. 2012;Ekstrom et al. 2015;McLean et al. 2018), jeopardizing Canadian aquaculture revenues of approximately $115 million per year (Fisheries and Oceans Canada 2019a) and fisheries revenues of $3.6 billion per year (Fisheries and Oceans Canada 2019b). Coastal communities, especially First Nations that have constitutionally protected rights to traditional harvests, will likely incur unquantifiable social, cultural, and economic losses through the consequences of ocean acidification. ...
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Improving our understanding of how the ocean absorbs carbon dioxide is critical to climate change mitigation efforts. We, a group of early career ocean professionals working in Canada, summarize current research and identify steps forward to improve our understanding of the marine carbon sink in Canadian national and offshore waters. We have compiled an extensive collection of reported surface ocean air-sea carbon dioxide exchange values within each of Canada's three adjacent ocean basins. We review the current understanding of air-sea carbon fluxes and identify major challenges limiting our understanding in the Pacific, the Arctic, and the Atlantic Ocean. We focus on ways of reducing uncertainty to inform Canada's carbon stocktake, establish baselines for marine carbon dioxide removal projects, and support efforts to mitigate and adapt to ocean acidification. Future directions recommended by this group include investing in maturing and building capacity in the use of marine carbon sensors, improving ocean biogeochemical models fit-for-purpose in regional and ocean carbon dioxide removal applications, creating transparent and robust monitoring, verification, and reporting protocols for marine carbon dioxide removal, tailoring community-specific approaches to co-generate knowledge with First Nations, and advancing training opportunities for early career ocean professionals in marine carbon science and technology.
... Okyanus-Deniz asitlenmesine bağlı olarak balıkçılık sektörünün kırılgan hale gelmesi istihdam alanlarının kaybıyla sonuçlanacağı barizdir. Örneğin yapılan hesaplamalara göre asitlenmenin Amerika'nın istiridye ve midye endüstrisine olan zararının 110 milyon dolar olduğu ve bu sektörde bulunan 3200 kişinin istihdamını olumsuz etkilediği belirtilmektedir (Ekstrom et al. 2015). Ayrıca asitlenmeyle birlikte sektörde adaptasyon maliyetlerinin yükselmesi sonucunda ülkelerin mavi ekonomiler açısından karşılaştırmalı üstünlüklerini kaybetmesi muhtemeldir. ...
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Okyanus-deniz asitlenmesi, ülkelere ait mavi ekonomileri tehdit eden önemli bir konudur. Karbondioksit yoğunluğundaki artışlar denizleri giderek asitli hale getirmektedir. Asitlenmedeki artış karbonat doygunluğunun azalmasına ve deniz canlılarının biyolojik açıdan olumsuz etkilenmelerine neden olmaktadır. Asitlenmeye bağlı olarak tüm ekosistemin etkilenmesinin hem toplumsal hem de ekonomik sonuçları bulunmaktadır. Çalışmanın temel amacı Türkiye’nin mavi ekonomi (balıkçılık sektörü için) endüstri-içi ticaret yapısının asitlenmeden etkilenip etkilenmediğini incelemektir. Bu nedenle çalışmada 1990-2019 dönemine ilişkin karbondioksit eşdeğerli toplam sera gazı, reel gayrisafi yurtiçi hâsıla ve Grubel-Lloyd endeks değerleri değişken olarak kullanılmıştır. Değişkenler arası eş bütünleşme ilişkisinin belirlenimi ile kısa-uzun dönemli katsayıların elde edilmesinde ARDL-ECM yönteminden yararlanılmıştır. Yapılan analizlerin sonuçlarına göre; i) Değişkenler arasında eş bütünleşme ilişkisi bulunmaktadır. ii) Uzun dönemde karbondioksit eşdeğerli toplam sera gazındaki artışlar endüstri-içi ticareti arttırmaktadır. iii) Kısa ve uzun dönemde reel gayrisafi yurtiçi hasıladaki artışlar endüstri-içi ticareti arttırmaktadır. Sonuç olarak okyanus-deniz asitlenmesi mavi ekonomilere ait olan endüstri-içi ticareti değiştirebilme gücüne sahiptir.
Puget Sound (Washington, USA) is a large estuary, known for its profitable shellfish aquaculture industry. However, in the past decade, scientists have observed strong acidification, hypoxia, and temperature anomalies in Puget Sound. These co-occurring environmental stressors are a threat to marine ecosystems and shellfish aquaculture. Our research assesses how environmental variability in Puget Sound impacts two ecologically and economically important bivalves, the purple-hinge rock scallop (Crassodoma gigantea) and Mediterranean mussel (Mytilus galloprovincialis). Our study examines the effect of depth and seasonality on the physiology of these two important bivalves to gain insight into ideal grow-out conditions in an aquaculture setting, improving the yield and quality of this sustainable protein source. To do this, we used Hood Canal (located in Puget Sound) as a natural multiple-stressor laboratory, which allowed us to study acclimatization capacity of shellfish in their natural habitat and provide the aquaculture industry information about differences in growth rate, shell strength, and nutritional sources across depths and seasons. Bivalves were outplanted at two depths (5 and 30 m) and collected after 3.5 and 7.5 months. To maximize mussel and scallop growth potential in an aquaculture setting, our results suggest outplanting at 5 m depth, with more favorable oxygen and pH levels. Mussel shell integrity can be improved by placing out at 5 m, regardless of season, however, there were no notable differences in shell strength between depths in scallops. For both species, δ13C values were lowest at 5 m in the winter and δ15N was highest at 30 m regardless of season. Puget Sound's combination of naturally and anthropogenically acidified conditions is already proving to be a challenge for shellfish farmers. Our study provides crucial information to farmers to optimize aquaculture grow-out as we begin to navigate the impacts of climate change.
Ocean acidification is a major threat to marine ecosystems. It is caused by increasing carbon dioxide concentrations in the atmosphere due to anthropogenic emissions and has socio-ecological and socio-economic ramifications for many countries. However, in some critical areas like the Philippines, a known center of marine biodiversity, no legislation currently exists to manage it. This could be due to lack of understanding of the problem, conflicting priorities, or difficulties in implementation common to many developing countries. We consider a possible incremental pathway for the mitigation of ocean acidification impacts on Philippine marine ecosystems using existing laws on marine pollution. This could complement longer term efforts to formalize legislation and institutionalize efforts to address its effects in the country. The approach may possibly be applied in other areas where no specific legislation exists to address crucial environmental problems.
Ocean acidification (OA) has considerably changed the metabolism and structure of plankton communities in the ocean. Evaluation of the response of the marine bacterioplankton community to OA is critical for understanding the future direction of bacterioplankton‐mediated biogeochemical processes in the ocean. Understanding the diversity of functional genes is important for linking the microbial community to ecological and biogeochemical processes. However, the influence of OA on the functional diversity of bacterioplankton remains unclear. Using high‐throughput functional gene microarray technology (GeoChip 4), we investigated the functional gene structure and diversity of bacterioplankton under three different p CO 2 levels (control: 175 μ atm, medium: 675 μ atm, and high: 1085 μ atm) in a large Arctic Ocean mesocosm experiment. We observed a higher evenness of microbial functional genes under elevated p CO 2 compared with under low p CO 2 . OA induced a more stable community as evaluated by decreased dissimilarity of functional gene structure with increased p CO 2 . Molecular ecological networks under elevated p CO 2 became more complex and stable, supporting the central ecological tenet that complexity begets stability. In particular, increased average abundances were found under elevated p CO 2 for many genes involved in key metabolic processes, including carbon degradation, methane oxidization, nitrogen fixation, dissimilatory nitrite/nitrate reduction, and sulfide reduction processes. Altogether, these results indicate a significant influence of OA on the metabolism potential of bacterioplankton in the Arctic Ocean. Consequently, our study suggests that biogeochemical cycling mediated by these microbes may be altered by the OA in the future.
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Due to seasonal upwelling, the upper ocean waters of the California Current System (CCS) have a naturally low pH and aragonite saturation state (Ω<sub>arag</sub>), making this region particularly prone to the effects of ocean acidification. Here, we use the Regional Oceanic Modeling System (ROMS) to conduct preindustrial and transient (1995–2050) simulations of ocean biogeochemistry in the CCS. The transient simulations were forced with increasing atmospheric p CO<sub>2</sub> as projected by the NCAR CSM 1.4 model run under either the IPCC SRES A2 or B1 scenarios. Using ROMS, we investigate the timing of transition decades during which pH and Ω<sub>arag</sub> depart from their modeled preindustrial (1750) and present-day (2011) variability envelopes. We report these transition decades by noting the midpoint of the ten-year transition periods. In addition, we also analyze the timing of near permanent aragonite undersaturation in the upper 100 m of the water column. Our results show that an interplay of physical and biogeochemical processes create large seasonal variability in pH (∼ 0.14) and Ω<sub>arag</sub> (∼ 0.2). Despite this large variability, we find that present-day pH and Ω<sub>arag</sub> have already moved out of their preindustrial variability envelopes due to the rapidly increasing concentrations of atmospheric CO<sub>2</sub>. The simulations following the A2 emissions scenario suggest that nearshore surface pH of the northern and central CCS will move out of their present-day variability envelopes by 2045 and 2037, respectively. However, surface Ω<sub>arag</sub> of the northern and central CCS subregions are projected to depart from their present-day variability envelopes sooner, by 2030 and 2035, respectively. By 2025, the aragonite saturation horizon of the central CCS is projected to shoal into the upper 75 m for the duration of the annual cycle, causing near permanent undersaturation in subsurface waters. Overall, our study shows that the CCS joins the Arctic and Southern Oceans as one of only a few known ocean regions presently approaching this dual threshold of undersaturation with respect to aragonite and a departure from its variability envelope. In these regions, organisms may be forced to rapidly adjust to conditions that are both inherently chemically challenging and also substantially different from prior conditions.
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Ocean acidification results in co-varying inorganic carbon system variables. Of these, an explicit focus on pH and organismal acid–base regulation has failed to distinguish the mechanism of failure in highly sensitive bivalve larvae. With unique chemical manipulations of seawater we show definitively that larval shell development and growth are dependent on seawater saturation state, and not on carbon dioxide partial pressure or pH. Although other physiological processes are affected by pH, mineral saturation state thresholds will be crossed decades to centuries ahead of pH thresholds owing to nonlinear changes in the carbonate system variables as carbon dioxide is added. Our findings were repeatable for two species of bivalve larvae could resolve discrepancies in experimental results, are consistent with a previous model of ocean acidification impacts due to rapid calcification in bivalve larvae, and suggest a fundamental ocean acidification bottleneck at early life-history for some marine keystone species.
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This study examines the potential effects of ocean acidification on countries and fisheries of the Mediterranean Sea. The implications for seafood security and supply are evaluated by examining the sensitivity of the Mediterranean to ocean acidification at chemical, biological, and macro-economic levels. The limited information available on impacts of ocean acidification on harvested (industrial, recreational, and artisanal fishing) and cultured species (aquaculture) prevents any biological impact assessment. However, it appears that non-developed nations around the Mediterranean, particularly those for which fisheries are increasing, yet rely heavily on artisanal fleets, are most greatly exposed to socioeconomic consequences from ocean acidification.
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The highly productive fisheries of Alaska are located in seas projected to experience strong global change, including rapid transitions in temperature and ocean acidification-driven changes in pH and other chemical parameters. Many of the marine organisms that are most intensely affected by ocean acidification (OA) contribute substantially to the state’s commercial fisheries and traditional subsistence way of life. Prior studies of OA’s potential impacts on human communities have focused only on possible direct economic losses from specific scenarios of human dependence on commercial harvests and damages to marine species. However, other economic and social impacts, such as changes in food security or livelihoods, are also likely to result from climate change. This study evaluates patterns of dependence on marine resources within Alaska that could be negatively impacted by OA and current community characteristics to assess the potential risk to the fishery sector from OA. Here, we used a risk assessment framework based on one developed by the Intergovernmental Panel on Climate Change to analyze earth-system global ocean model hindcasts and projections of ocean chemistry, fisheries harvest data, and demographic information. The fisheries examined were: shellfish, salmon and other finfish. The final index incorporates all of these data to compare overall risk among Alaska’s federally designated census areas. The analysis showed that regions in southeast and southwest Alaska that are highly reliant on fishery harvests and have relatively lower incomes and employment alternatives likely face the highest risk from OA. Although this study is an intermediate step toward our full understanding, the results presented here show that OA merits consideration in policy planning, as it may represent another challenge to Alaskan communities, some of which are already under acute socio-economic strains.
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We discuss approaches to the assessment of vulnerability to climate variability and change and attempt to clarify the relationship between the concepts of vulnerability and adaptation. In search of a robust, policy-relevant framework, we define vulnerability in terms of the capacity of individuals and social groups to respond to, that is, to cope with, recover from or adapt to, any external stress placed on their livelihoods and well-being. The approach that we develop places the social and economic well-being of society at the centre of the analysis, focussing on the socio-economic and institutional constraints that limit the capacity to respond. From this perspective, the vulnerability or security of any group is determined by resource availability and by the entitlement of individuals and groups to call on these resources. We illustrate the application of this approach through the results of field research in coastal Vietnam, highlighting shifting patterns of vulnerability to tropical storm impacts at the household- and community-level in response to the current process of economic renovation and drawing conclusions concerning means of supporting the adaptive response to climate stress. Four priorities for action are identified that would improve the situation of the most exposed members of many communities: poverty reduction; risk-spreading through income diversification; respecting common property management rights; and promoting collective security. A sustainable response, we argue, must also address the underlying causes of social vulnerability, including the inequitable distribution of resources.
Future changes in climate pose significant challenges for society, not the least of which is how best to adapt to observed and potential future impacts of these changes to which the world is already committed. Adaptation is a dynamic social process: the ability of societies to adapt is determined, in part, by the ability to act collectively. This article reviews emerging perspectives on collective action and social capital and argues that insights from these areas inform the nature of adaptive capacity and normative prescriptions of policies of adaptation. Specifically, social capital is increasingly understood within economics to have public and private elements, both of which are based on trust, reputation, and reciprocal action. The public-good aspects of particular forms of social capital are pertinent elements of adaptive capacity in interacting with natural capital and in relation to the performance of institutions that cope with the risks of changes in climate. Case studies are presented of present-day collective action for coping with extremes in weather in coastal areas in Southeast Asia and of community-based coastal management in the Caribbean. These cases demonstrate the importance of social capital framing both the public and private institutions of resource management that build resilience in the face of the risks of changes in climate. These cases illustrate, by analogy, the nature of adaptation processes and collective action in adapting to future changes in climate.
We report results from an oyster hatchery on the Oregon coast, where intake waters experienced variable carbonate chemistry (aragonite saturation state , 0.8 to . 3.2; pH , 7.6 to . 8.2) in the early summer of 2009. Both larval production and midstage growth (, 120 to , 150 mm) of the oyster Crassostrea gigas were significantly negatively correlated with the aragonite saturation state of waters in which larval oysters were spawned and reared for the first 48 h of life. The effects of the initial spawning conditions did not have a significant effect on early-stage growth (growth from D-hinge stage to , 120 mm), suggesting a delayed effect of water chemistry on larval development.