Biogeosciences, 6, 1747–1754, 2009
www.biogeosciences.net/6/1747/2009/
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.

Biogeosciences

Effect of CO2-related acidification on aspects of the larval
development of the European lobster, Homarus gammarus (L.)

K. E. Arnold1, H. S. Findlay2, J. I. Spicer3, C. L. Daniels1,3, and D. Boothroyd1

1National Lobster Hatchery, South Quay, Padstow, Cornwall, PL28 8BL, UK
2Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth, Devon, PL1 3DH, UK
3Marine Biology and Ecology Research Centre, School of Biological Sciences, University of Plymouth,
Plymouth, Devon, PL4 8AA, UK

Received: 20 February 2009 – Published in Biogeosciences Discuss.: 18 March 2009
Revised: 8 July 2009 – Accepted: 20 July 2009 – Published: 24 August 2009

Abstract. Oceanic uptake of anthropogenic CO2 results in
a reduction in pH termed “Ocean Acidification” (OA). Com-
paratively little attention has been given to the effect of OA
on the early life history stages of marine animals. Conse-
quently, we investigated the effect of culture in CO2-acidified
sea water (approx. 1200 ppm, i.e. average values predicted
using IPCC 2007 A1F1 emissions scenarios for year 2100)
on early larval stages of an economically important crus-
tacean, the European lobster Homarus gammarus. Culture in
CO2-acidified sea water did not significantly affect carapace
length of H. gammarus. However, there was a reduction in
carapace mass during the final stage of larval development in
CO2-acidified sea water. This co-occurred with a reduction
in exoskeletal mineral (calcium and magnesium) content of
the carapace. As the control and high CO2 treatments were
not undersaturated with respect to any of the calcium carbon-
ate polymorphs measured, the physiological alterations we
record are most likely the result of acidosis or hypercapnia
interfering with normal homeostatic function, and not a di-
rect impact on the carbonate supply-side of calcification per
se. Thus despite there being no observed effect on survival,
carapace length, or zoeal progression, OA related (indirect)
disruption of calcification and carapace mass might still ad-
versely affect the competitive fitness and recruitment success
of larval lobsters with serious consequences for population
dynamics and marine ecosystem function.

Correspondence to: K. E. Arnold
(katie.arnold@nationallobsterhatchery.co.uk)

1 Introduction

The ocean is a substantial reservoir of CO2 (Feely et al.,
2004; Sabine et al., 2004; Morse et al., 2006). Addition
of CO2 to sea water alters the carbonate chemistry and re-
duces pH, in an effect recently termed “Ocean Acidification”
(OA). Over the past 200 years increasing pCO2 has resulted
in a decrease in surface sea water pH of 0.1 units (Caldeira
and Wickett, 2003; Orr et al., 2005). It is predicted that at-
mospheric CO2 concentrations could reach 1200 ppm by the
year 2100 resulting in a decrease in average surface ocean
pH of 0.3 to 0.4 units (Caldeira and Wickett, 2003; Raven
et al., 2005). Our understanding of the biological and eco-
logical consequences of OA is, however, still in its infancy
(Raven et al., 2005). Reductions in seawater pH have been
demonstrated to affect the physiological and developmental
processes of a number of marine organisms (e.g. Pörtner et
al., 2004, 2005; Raven et al., 2005) through reduced internal
pH (acidosis) and increased CO2 (hypercapnia), raising the
possibility that not only species, but also ecosystems, will be
affected (Widdicombe and Spicer, 2008).

As CO2 increases and pH decreases there is a concomitant
reduction in carbonate ion (CO2−3 ) availability, which can
lead to increased dissolution of calcium carbonate (CaCO3)
structures. This may have a significant impact on species,
which have CaCO3 skeletons, such as reef building organ-
isms, some phytoplankton, molluscs, crustaceans and echin-
oderms. Research into the effects of OA has thus far pri-
marily investigated impacts on these calcareous marine or-
ganisms, particularly focusing on corals (e.g. Reynaud et al.,
2003; Langdon and Atkinson, 2005), molluscs (e.g. Michae-
lidis et al., 2005; Gazeau et al., 2007) and coccolithophores

Published by Copernicus Publications on behalf of the European Geosciences Union.

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1748 K. E. Arnold et al.: Ocean acidification and larval lobsters

(e.g. Riebesell, 2000; Zondervan et al., 2002; with reviews by
Paasche, 2001; Hinga, 2002; and Riebesell, 2004). Studies
to date have demonstrated a number of potentially important
effects including reduced growth rates (Gazeau et al., 2007),
decreased reproductive success (Kurihara et al., 2004b), shell
dissolution (Bamber, 1990) as well as acidification of internal
body fluids (Spicer et al., 2007), compromise of induced de-
fences (Bibby et al., 2007), increased susceptibility to infec-
tion (Holman et al., 2004) and impairment of immune func-
tion (Bibby et al., 2008). Unfortunately the majority of these
studies have investigated short-term responses with most at-
tention being paid to effects on adult organisms alone. Thus
there is an urgent need, both for more long-term data, es-
pecially for invertebrates (Langenbuch and Pörtner, 2002;
Pörtner et al., 2004; Michaelidis et al., 2005) and studies
of species at different stages of their larval development as
well as on adults (Widdicombe and Spicer, 2008). Research
into the effects during larval stages has mainly focused on
echinoderms (Kurihara and Shirayama, 2004; Havenhand et
al., 2008; Dupont et al., 2008), fish (Ishimatsu et al., 2004),
copepods (Kurihara et al., 2004b, 2007), amphipods (Egils-
dottir et al., 2009) and gastropods (Ellis et al., 2009) How-
ever, it is important to investigate potential effects of CO2-
induced acidification during early life stages, as they are
likely to be more sensitive to such environmental stressors
than adults (e.g. Kikkawa et al., 2003; Ishimatsu et al., 2004),
especially as many benthic species possess pelagic larval
stages which occur in the surface waters where increasing
pCO2 is occurring first (Calderia and Wickett, 2003). De-
termining how OA might affect larval development of ben-
thic organisms, particularly those that initiate calcification
processes while still in their planktonic phase, is critical to
predicting how these impacts might propagate through the
ecosystem. Early investigations suggest that early life stage
development may be slowed (Egilsdottir et al., 2009; Find-
lay et al., 2009) or even completely disrupted (Dupont et al.,
2008; Havenhand et al., 2008) at CO2 levels predicted for the
end of this century.

The European lobster Homarus gammarus is an economi-
cally important species contributing substantially to the con-
tinued survival of small coastal communities. Calcification
in the Norway lobster Nephrops norvegicus, closely related
to H. gammarus, occurs during very early development, with
a major change in the pattern of calcification observed as
the individual makes the transition from a planktonic zoea
to a benthic postlarva (Spicer and Eriksson, 2003). While
crustacean exoskeletons contain CaCO3, this most likely pre-
dominates in the more soluble polymorph, magnesium cal-
cite (Mg-CaCO3) (Boßelmann et al., 2007). It is believed
that crustaceans utilise either CO2 or bicarbonate (HCO

−

3 ),
not carbonate (CO2−3 ) as the primary source of carbon for
the formation of their CaCO3 structures (Cameron, 1989).
Therefore reduction in CO2−3 as a result of OA may not al-
ways be expected to directly impact their ability to produce
CaCO3. H. gammarus is cultured within hatcheries to aid

commercial catch and hence is an ideal model to use to un-
derstand the impacts that OA might have on the early devel-
opment stages of a commercially important crustacean. Con-
sequently, this study investigated the effect of CO2-induced
acidification on the early life stages of H. gammarus. The
patterns of growth and shell mineralogy of the carapace dur-
ing larval development were determined by measuring the
length, area, dry mass and Ca and Mg contents of the cara-
pace. As Mg-CaCO3 is more soluble than other polymorphs
of calcium carbonate, aragonite and calcite, (Feely et al.,
2004) it may be less advantageous to form Mg-CaCO3 un-
der decreasing pH as it will be the first to dissolve (Kley-
pas et al., 2006), hence these lobsters may be at greater risk
from dissolution. Exposure to long-term hypercapnia may be
energetically costly to marine organisms and therefore may
be detrimental to developmental processes, such as growth,
reproduction, natural recruitment and survival (Barry et al.,
2005; Wood et al., 2008).

2 Materials and methods

2.1 Animal material

Ovigerous females were supplied by local fishermen and held
in aquaria (160×100×35 cm) at the National Lobster Hatch-
ery (NLH) in Padstow, Cornwall, UK. Each aquarium was
constantly supplied with aerated, filtered re-circulating sea
water (T =17±1◦C, S=35) pumped directly from waters ad-
jacent to the NLH. Water was pre-treated in a pressurized
sand filter, passed through activated carbon, and finally UV-
irradiated. Adult lobsters were fed ad libitium with blue mus-
sels, Mytilus edulis. Experiments were carried out between
June and July 2007, to coincide with the natural hatching
season (between April and September).

Sea water was placed in ten open conical flasks (vol.=1 l)
and the CO2 concentration was modified by equilibrating the
water with air containing different CO2 concentrations ex-
actly as described by Findlay et al. (2008). Air/CO2 mixtures
were produced using a bulk flow technique where known
amounts of scrubbed air (CO2 removed using KOH) and CO2
gas were supplied, via flow meters (Jencons, UK, Roxspur,
France), and mixed before equilibrating with sea water. Con-
trol flasks were aspirated (10 l min−1) with an air mixture
containing 380 ppm of CO2, however the pressure was not
high enough to completely equilibrate these flasks, which
had high alkalinity, and hence the measured sea water CO2
value was slightly lower (mean 315 ppm). To produce the
reduced pH treatment, sea water was aspirated (1 ml min−1

CO2 mixed with 10 l min
−1 scrubbed air) with the high-CO2

air containing 1200 ppm of CO2. The pCO2 was monitored
regularly using a pCO2 micro-electrode (LazarLabs) and pH
using a pH probe (Denver). Any fluctuations in pH were
noted, and adjusted, via the flow meters, accordingly.

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K. E. Arnold et al.: Ocean acidification and larval lobsters 1749

Newly-hatched Zoea I larvae, from 3 different moth-
ers, were (carefully) distributed haphazardly between a
number of aquaria (flasks vol.=1 l; N =50 zoea per flask;
T =17±1◦C), with all flasks containing larvae from all fe-
males. Flasks contained one of the following aerated me-
dia: sea water (“untreated control”) or sea water with ele-
vated CO2 (1200 ppm) (N =5 for each treatment). Both treat-
ments commenced simultaneously and were incubated for
28 days. Media changes were performed every 24 h. The
elevated CO2 treatment flasks were left to equilibrate for 2 h
to the required CO2 levels before larvae were transferred to
them. Both moulted exoskeletons and mortalities were re-
moved before changing media. Larvae were fed (Artemia
nauplii, density=5 indiv ml−1 sea water) after media changes
(Carlberg and Van Olst, 1976).

2.2 Larval growth and development

Larvae were removed haphazardly from each flask (N =9),
at day 7, 14, 21 and 28. Larval development can vary de-
pending on temperature; therefore in order to ascertain larval
development times under the control conditions, preliminary
studies were first carried out. The sampling days represent
the mid-point of development through each of the four larval
stages (i.e. Zoea I, II, III, and IV). Individuals were washed
briefly in distilled water, carefully blotted dry with paper tis-
sue, and stored frozen (T =−20◦C). They were subsequently
freeze-dried (LYOVAC GT2, Leybold-Heraeus, Germany) to
a constant mass, before the carapace was carefully removed
and weighed using a microbalance (AT200, Mettler-Toledo,
Switzerland). Carapace length (CL) and carapace area (CA)
were measured using digital photographs under lower power
magnification (x 10) and ImageJ software. CL was calculated
as shown in Fig. 1, CA was calculated by taking measure-
ments of the removed and flattened carapace again using dig-
ital photography under lower power magnification (x 10) and
ImageJ software. Larval survival was observed daily, along
with moult stage, which was recorded as a measure of devel-
opment, and determined using the schemes of Aiken (1973)
and Chang et al. (2001); this involves detailed examination
of the exoskeleton and pleopods.

2.3 Carapace mineral content

Measurements of the calcium and magnesium content of the
carapace from the same individuals measured above, for each
of the four developmental stages (Zoea I, II, III, and IV),
were made using Inductively Coupled Plasma Spectrometry
(ICP). After the morphological measurements were made the
carapace was dissolved in concentrated nitric acid (75% pro
analysis) to extract the mineral portion. The resultant so-
lution was diluted with Milli-Q water before ICP analysis.
To compare between treatments and stages (these are rela-
tive measures and not absolute measures) the calcium and
magnesium concentrations are expressed both as a percent-

Fig. 1. Larval carapace length measured using digital photography
under lower power magnification (x 10) and image J software.

age of total mass of animal carapace and also per unit of to-
tal carapace area, exactly as presented by Spicer and Eriks-
son (2003). This gives an indication of the content of each
mineral as the animal grows relative to the previous devel-
opment stage and the percentage of total mass takes into ac-
count any differences in the thickness of the carapace.

2.4 Statistical analysis

Data are expressed as mean±1 S.E.; the data were tested
for normality using the Kolmogorov-Smirnov test and ho-
mogeneity of variances and applying Levene’s test prior to
analysis. Two-way repeated-measures ANOVA was used to
investigate significant differences in physiological parame-
ters as a result of CO2 and of exposure time, and least signif-
icant difference post hoc tests were carried out to assess the
significance of differences between treatment groups.

3 Results

3.1 Larval growth and development

There were no significant effects of hypercapnia on cara-
pace length in larval H. gammarus (p>0.05) when expressed
against time and developmental stage (Fig. 2a and b). There
was however, an observed effect of hypercapnia on carapace
mass throughout larval development, causing a significant re-
duction in mass at Zoea IV (p<0.05, Fig. 2c). As larvae
were removed for sampling throughout the experiment, sur-
vival could only be observed during experimental exposures.

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1750 K. E. Arnold et al.: Ocean acidification and larval lobsters

(a) (b)

(c)

Fig. 2. Relationships between growth and development for larval H. gammarus during exposure to CO2-acidification (1200 ppm). (a)
Carapace length (mm) and development time (days); (b) Carapace length (mm) and developmental stage; (c) Carapace mass (mg) and
developmental stage. Values represent mean±1 standard error; white, control; grey, 1200 ppm of CO2.

From these observations, incubation with CO2 did not appear
to have an affect on the survival of larval lobsters.

3.2 Carapace mineral content

Changes in calcium concentration of the carapace during lar-
val development are presented in Fig. 3. The calcium con-
tent in the carapace was significantly effected over time,
with respect to treatment, this was detectable both when ex-
pressed as concentration per surface area (p<0.05; Fig. 3a)
and when presented as a percentage of the total carapace con-
tent (p<0.05; Fig. 3b). In the high CO2 treatment, the cal-
cium concentration was almost half of the control at Zoea IV
(0.13 µg mm−2 S.E. 0.01 vs. 0.23 µg mm−2 S.E. 0.01). This
indicates that after metamorphosis into Zoea IV the increased
CO2 significantly impacted the carapace calcium content.

The effect of increased CO2 on magnesium in the cara-
pace, when expressed as a concentration per surface area
(Fig. 4a), produced a reduction in concentration over time
when compared to the control, with significant differences
occurring at Zoea IV (p<0.05). Reduction in magnesium
concentration, due to culture in CO2-acidified sea water,
were also apparent when expressed as a percentage of total
carapace content (p<0.05), with significant differences ev-
ident at Zoea III (Fig. 4b); 0.81% (S.E. 0.07) compared to
1.16% (S.E. 0.13) in the control larvae.

4 Discussion

4.1 Growth and carapace mineralogy

This is the first study, to the authors’ knowledge, to doc-
ument net changes in the calcium and magnesium content
of the carapace of any lobster species during larval devel-
opment. We found that larval length, area and mass of the
carapace are coupled with development stage of the zoea lar-
vae; and that there are progressive changes in the content
of calcium and magnesium. Calcium and magnesium form
the principal mineral portion of the crustacean exoskeleton
(Neufeld and Cameron, 1992); the concentrations of which
are most likely to be determined by environmental conditions
(Wickins, 1984). The pattern of calcification displayed by
H. gammarus generally follows a net increase in calcium as
the larvae moult through each progressive zoea, with meta-
morphosis into the Zoea IV containing the largest concen-
tration of calcium. However, when expressed as a percent-
age of mass, the proportion of calcium in relation to other
exoskeletal components stays fairly constant throughout lar-
val development. The only other study to investigate cal-
cification in larval lobsters was completed by Spicer and
Eriksson (2003), on the Norway lobster Nephrops norvegi-
cus. However, only Zoea III was examined and while N.
norvegicus Zoea III had 1.7 Ca µg mm2 (4.3% of mass), H.
gammarus had 0.2 Ca µg mm2 (9.7% of mass). H. gammarus
Zoea III values, in term of calcium concentration per surface
area, were much lower than those found in N. norvegicus.

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K. E. Arnold et al.: Ocean acidification and larval lobsters 1751

(a) (b)

Fig. 3. Changes in the calcium concentration of the carapace during development and exposure to CO2-acidification (1200 ppm), expressed
as (a) concentration per surface area and (b) % carapace dry mass. Values are means±1 standard error; white bar, control; grey bar, 1200 ppm
of CO2. Asterisk denotes significant differences from control (p<0.05).

(a) (b)

Fig. 4. Changes in the magnesium concentration of the carapace during development and exposure to CO2-acidification (1200 ppm), ex-
pressed as (a) concentration per surface area and (b) % carapace dry mass. Values are means±1 standard error; white bar, control; grey bar,
1200 ppm of CO2. Asterisk denotes significant differences from control (p<0.05).

However, the percentage of calcium in relation to mass was
double the value in H. gammarus compared to N. norvegicus,
indicating that the processes involved in calcification may be
reasonably different between the two species. Magnesium
concentrations were also measured and similarly displayed
an increase with development; although the ratios of cal-
cium to magnesium can be variable in many marine calcify-
ing species (Boßelmann et al., 2007). It is hypothesised that
in crustaceans, magnesium is often used as a substitute for
calcium in the mineral matrix of the exoskeleton (Richards,
1951). However, when the percentage of calcium increased
at Zoea IV the percentage of magnesium decreased, possibly
showing that calcium plays a more important role during the
final stages of development in H. gammarus.

4.2 Impacts of elevated CO2 on growth and carapace
mineralogy

This is also the first study to examine the effects of CO2-
induced acidification on growth and net carapace divalent
ion concentration (as a measure of calcification; Findlay et
al., 2009) of any lobster species. In the field increased moult
frequency and high rates of mortality are associated with lar-
val development; therefore these early stages may be partic-
ularly vulnerable to ocean acidification due to an increased
energy requirement for calcification of the exoskeleton (Hau-

gan et al., 2006). Carapace length in H. gammarus was
not significantly affected by culture in CO2-acidified sea wa-
ter (1200 ppm CO2), with all remaining coupled throughout.
However, both carapace mass and calcification were consid-
erably reduced during metamorphosis into Zoea IV due to in-
creased CO2. The fact that carapace length was not affected
by culture in CO2-acidified sea water even though both mass
and mineral content did appear to decrease, is feasible be-
cause Spicer and Eriksson (2003) indicates that the majority
of growth occurs through laying down organic material and
chitin and not CaCO3. The reduced carapace mass observed
was therefore most likely due to CO2-induced acidification
resulting in a decline in the net production of CaCO3, which
would potentially result in a lighter carapace.

It is thought that lobsters utilize HCO−3 or CO2 for the
precipitation of CaCO3 (Cameron, 1989) not CO

2−
3 there-

fore if the experimental conditions had resulted in under-
saturation with respect to carbonate minerals, we still might
not expect a direct impact on calcification in larval lobsters.
However, the sea water in both the control and the elevated
CO2 treatment had relatively high levels of CO

2−
3 , and nei-

ther became low enough to result in undersaturation with
respect to any of the calcium carbonate polymorphs rele-
vant here (�aragonite>2.5; Table 1). This seems to occur
as a result of naturally high alkalinity levels in the sea wa-
ter (>2450 µEq kg−1), and indicates that neither CO2−3 or

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1752 K. E. Arnold et al.: Ocean acidification and larval lobsters

Table 1. System data (mean±standard error) for the control
and the high CO2 treatment. Salinity, temperature, pH and
pCO2 were measured; all other data (DIC=dissolved inorganic
carbon, AT =total alkalinity; CO

2−
3 =carbonate ion concentration;

�calcite=calcite saturation state; �aragonite=aragonite saturation
state) were calculated from pH and pCO2 using CO2sys (Pier-
rot et al., 2006), with dissociation constants from Mehrbach et
al. (1973) refit by Dickson and Millero (1987) and KSO4 using
Dickson (1990).

Control High CO2 Treatment

CO2 (ppm) 315±18.83 1202±29.83
pH 8.39±0.006 8.10±0.009
Temp (◦C) 17.0±1.0 17.0±1.0
Sal (psu) 35.0±1.0 35.0±1.0
AT (µEq kg

−1) 2544±148.9 4290±145.9
DIC (µmol kg−1) 2152±131.1 3967±132.8
�calcite 6.71±0.43 6.79±0.32
�argonite 4.33±0.28 4.38±0.20
HCO−3 (µmol kg

−1) 1863±112.9 3651±119.5

CO2−3 (µmol kg
−1) 281±18.1 285±13.3

HCO−3 were limiting calcification, nor was there any indica-
tion of enhanced dissolution. One caution to these results is
that pH and pCO2 were measured during the experiment but
total alkalinity and DIC were calculated using CO2sys (Pier-
rot et al., 2006), with dissociation constants from Mehrbach
et al. (1973) refit by Dickson and Millero (1987) and KSO4
using Dickson (1990), and therefore these may not repre-
sent exact values, particularly as the sea water comes from a
coastal environment. The increased CO2, added through gas
bubbling, increased the total dissolved inorganic carbon, and
hence lowered the pH, although not below levels perceived
to be “normal”. Therefore the observed impacts on mass
and reduced calcium concentration in these larval H. gam-
marus may primarily be the result of hypercapnia interfering
with normal homeostatic function (perhaps via a trade-off),
and not a direct impact on calcification per se, e.g. general
physiological stress can result in a reduction in the energy
allocated to shell thickening (Henry et al., 1981). A sim-
ilar study by Gazeau et al. (2007), using comparable CO2
values, also displayed a net decline in the calcium carbon-
ate structure in the mussel, Mytilus edulis, and the Pacific
oyster, Crassostrea gigas. As in this study, they too found
that calcium carbonate polymorphs did not become under-
saturated, but did suggest that saturation states were corre-
lated with net calcification rates. Here we suggest that sat-
uration states may not always be the main limiting factor
for calcification under increasing CO2, as the processes and
mechanisms for calcification in multi-cellular organisms are
complex and are closely linked with many other physiolog-
ical processes (Pörtner, 2008). As the solubility of a calcite
structure increases with the incorporation of magnesium, un-

der increasing CO2 concentrations (Raven et al., 2005), sev-
eral species have the ability to secrete a lower concentration
of magnesium in response to environmental changes (Stan-
ley et al., 2002). However, as the decrease in magnesium
ions was fairly consistent with the decrease in calcium ions
it seems unlikely that this mechanism for dealing with an al-
tered environment was occurring in the present study.

CO2-induced acidification displayed a progressive long-
term CO2 effect on the calcified exoskeleton in Zoea IV,
which is arguably the most critical period for production of
viable post-larvae. There has been no examination of the ef-
fects of OA on post-larval lobsters completed to date. As
OA is predicted to occur over ocean surface waters, with a
great degree of certainty, and corrosive waters are already
seasonally observed in shelf sea upwelling areas (Feely et al.,
2008) and around major rivers (Salisbury et al., 2008), ma-
rine organisms inhabiting the pelagic zone will be unable to
avoid these unfavourable changes in ocean chemistry (Hau-
gan, 1997).

From most studies on marine organisms to date there ap-
pears to be a substantial cost involved with increased CO2 on
developmental processes, whether it be decreased calcifica-
tion or shell dissolution in order to maintain internal chem-
istry (Gazeau et al., 2007; Michaelidis et al., 2005), or in-
crease muscle wastage in order to maintain skeletal integrity
(Wood et al., 2008). A net decline in calcification, along with
a reduced shell mass of developing larval lobsters may affect
their competitive fitness and recruitment success; this could
trigger cascading trophic effects on population dynamics and
potentially on the functioning of marine ecosystems. It is
not certain whether the adverse effects associated with OA
may be counteracted by physiological acclimatization and/or
genetic adaptation of marine organisms (Riebesell, 2004).
However initial findings do not appear promising and assess-
ments of potential impacts are hampered by the scarcity of
relevant research (Orr et al., 2005).

Acknowledgements. We thank, R. Pryor, C. Ellis, and C. Wells
of the National Lobster Hatchery, Padstow, for their assistance
throughout these experiments. This research project was funded
by the National Lobster Hatchery and the European Social Fund
(ESF), as part of the Cornwall Research Fund managed by the
Combined Universities of Cornwall (CUC). H. S. Findlay is funded
from NERC Blue Skies PhD NER/S/A/2006/14324.

Edited by: H.-O. Pörtner

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