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Deformities in larvae and juvenile European lobster (Homarus gammarus) exposed to lower pH at different temperatures

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Trends of increasing temperatures and ocean acidification are expected to influence benthic marine resources, especially calcifying organisms. The European lobster (Homarus gammarus) is among those species at risk. A project was initiated in 2011 aiming to investigate long-term synergistic effects of temperature and projected increases in ocean acidification on the life cycle of lobster. Larvae were exposed to pCO2 levels of ambient water (water intake at 90 m depth, tentatively of 380 μatm pCO2), 727 and 1217 μatm pCO2, at temperatures 10 and 18 °C. Long-term exposure lasted until 5 months of age. Thereafter the surviving juveniles were transferred to ambient water at 14 °C. At 18 °C the development from Stage 1 to 4 lasted from 14 to 16 days, as predicted under normal pH values. Growth was very slow at 10 °C and resulted in only two larvae reaching Stage 4 in the ambient treatment. There were no significant differences in carapace length at the various larval stages between the different treatments, but there were differences in total length and dry weight at Stage 1 at 10 °C, Stage 2 at both temperatures, producing larvae slightly larger in size and lighter by dry weight in the exposed treatments. Stage 3 larvae raised in 18 °C and 1217 μatm pCO2 were also larger in size and heavier by dry weight compared with 727 μatm. Unfortunate circumstances precluded a full comparison across stages and treatment. Deformities were however observed in both larvae and juveniles. At 10 °C, about 20% of the larvae exposed to elevated pCO2were deformed, compared with 0% in larvae raised in pH above 8.0. At 18 °C and in high pCO2 treatment, 31.5% of the larvae were deformed. Occurrence of deformities after 5 months of exposure was 33 and 44% in juveniles raised in ambient and low pCO2, respectively, and 20% in juveniles exposed to high pCO2. Some of the deformities will possibly affect the ability to find food, sexual partner (walking legs, claw and antenna), respiration (carapace), and ability to swim (tail-fan damages).
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Biogeosciences, 10, 7883–7895, 2013
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Biogeosciences
Open Access
Deformities in larvae and juvenile European lobster (Homarus
gammarus) exposed to lower pH at two different temperatures
A.-L. Agnalt, E. S. Grefsrud, E. Farestveit, M. Larsen, and F. Keulder
Ann-Lisbeth Agnalt, Institute of Marine Research, P.O. Box 1870 Nordnes, 5817 Bergen, Norway
Correspondence to: A-L. Agnalt (ann-lisbeth.agnalt@imr.no)
Received: 31 March 2013 – Published in Biogeosciences Discuss.: 2 May 2013
Revised: 28 October 2013 – Accepted: 30 October 2013 – Published: 4 December 2013
Abstract. The ongoing warming and acidification of the
world’s oceans are expected to influence the marine ecosys-
tems, including benthic marine resources. Ocean acidifica-
tion may especially have an impact on calcifying organisms,
and the European lobster (Homarus gammarus) is among
those species at risk. A project was initiated in 2011 aim-
ing to investigate long-term effects of ocean acidification on
the early life-cycle of lobster under two temperatures. Larvae
were exposed to pCO2levels of ambient water (water intake
at 90 m depth), medium 750 (pH=7.79) and high 1200 µatm
pCO2(pH=7.62) at temperatures 10 and 18 C. The water
parameters in ambient water did not stay stable and were very
low towards the end of the experiment in the larval phase at
10C,with pH between 7.83 and 7.90. At 18, pH in am-
bient treatment was even lower, between 7.76 and 7.83, i.e.
close to medium pCO2treatment. Long-term exposure lasted
5 months. At 18C the development from stage 1 to 4 lasted
14 to 16 days, as predicted under optimal water conditions.
Growth was very slow at 10C and resulted in three larvae
reaching stage 4 in high pCO2treatment only.
There were no clear effects of pCO2treatment, on either
carapace length or dry weight. However, deformities were
observed in both larvae and juveniles. The proportion of lar-
vae with deformities increased with increasing pCO2expo-
sure, independent of temperature. In the medium treatment
about 23% were deformed, and in the high treatment about
43% were deformed. None of the larvae exposed to water
of pH>7.9 developed deformities. Curled carapace was the
most common deformity found in larvae raised in medium
pCO2treatment, irrespective of temperature, but damages in
the tail fan occurred in addition to a bent rostrum. Curled
carapace was the only deformity found in high pCO2treat-
ment at both temperatures. Occurrence of deformities after
five months of exposure was 33 and 44% in juveniles raised
in ambient and low pCO2levels, respectively, and 21% in
juveniles exposed to high pCO2. Deformed claws were most
often found in ambient and medium treatment (56%), fol-
lowed by stiff/twisted walking legs (39%) and puffy cara-
pace (39 %). In comparison, at high pCO2levels 71% of the
deformed juveniles had developed a puffy carapace. Overall,
about half of the deformed juveniles from the ambient and
medium pCO2treatment displayed two or three different ab-
normalities; 70 % had multiple deformities in the high pCO2
treatment. Some of the deformities in the juveniles may af-
fect respiration (carapace), the ability to find food, or sex-
ual partners (walking legs, claw and antenna), and ability to
swim (tail-fan damages).
1 Introduction
The world’s atmosphere is increasingly becoming more sat-
urated with the concentration of CO2as carbon emissions
from burning fossil fuels keep increasing (IPCC, 2007;
Caldeira et al., 2005). Atmospheric CO2is currently around
380ppmv, but is predicted to increase to 780ppmv and
1200 ppmv by 2100 and 2200, respectively (IPCC, 2007). In-
creased absorption of atmospheric CO2into the marine en-
vironment leads to an increase in total dissolved inorganic
carbon (DIC), which changes the chemistry and acid-base
balance and results in a decreased seawater pH (Dickson et
al. 2007). Currently the global average seawater pH is about
8.05 units, and is associated with a DIC of 2026 (Fabry et
al., 2008). It is predicted to drop by 0.3 to 0.4pH units by
2100 (Orr et al., 2005; Feely et al., 2009). At the same time,
depending on the emission scenarios, ocean temperature in
Published by Copernicus Publications on behalf of the European Geosciences Union.
7884 A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster
the upper 100m is predicted to increase by 0.6(RCP2.6) to
2C (RCP8.5) by 2100, (Blunden and Arndt, 2013). The ab-
sorption of CO2by the ocean and ocean acidification (OA)
occurs mostly in the upper 100m, and varies with latitude
and temperature (Orr et al., 2005; Fabry et al., 2008).
Regional monitoring of DIC at Station M in the eastern
Norwegian Sea shows a value of 2140 (Skjelvan et al., 2008),
which is above the global average of 2026. This agrees with
recent modeling that shows CO2uptake is higher and pH
lower in the eastern Norwegian Sea (Olsen et al., 2006). pH
levels will decrease with water depth at which aragonite be-
comes undersaturated, from 100 to 50m by 2100 at high
latitudes (Fabry et al., 2008). Marine organisms in colder re-
gions are therefore at a greater risk of being affected by the
effects of both warming and OA, especially calcifying ma-
rine organisms. One such species is an important predator,
the European lobster Homarus gammarus.
H. gammarus is found along the continental shelf in the
northeast Atlantic, which extends from the warm waters off
Morocco to the colder areas near the Arctic Circle, i.e. Tys-
fjord and Nordfolda (68N) (Agnalt et al., 2009). This distri-
bution covers a large latitudinal and temperature range. With
CO2absorption varying greatly with latitude and tempera-
ture, the effects of acidification may vary greatly for subpop-
ulations across the distribution range. The life cycle of H.
gammarus consists of four larval stages, a juvenile stage, a
sub-adult stage (50mm carapace length: CL) and adult of
>60mm CL (Factor, 1995); larvae are pelagic in the first
three stages (stage 1–3), after which they settle during larval
stage 4. Little is known about the benthic stages of H. gam-
marus juveniles less than 40mm CL in the wild (Linnane
et al., 2001). The European lobster is esteemed as a valu-
able marine resource and has supported the coastal fishery in
northern Europe for several centuries (Agnalt, 2008). In the
1960s, lobster populations in Norway were depleted below
sustainable levels and due to low recruitment, the recovery
has been slow. Any additional factors that reduce recruitment
and population size further may push this species to the brink
of extinction in these areas.
Only one study has investigated the effects of OA (pCO2)
in H. gammarus, focusing on larvae at the predicted future
scenario of pCO21200µatm (Arnold et al., 2009). Calcifi-
cation was significantly reduced in stages 3 and 4, with no
direct effect on growth observed. The decrease in calcifica-
tion observed in stage 4 at a pCO2of 1200µatm may have
been due to energy being channelled towards growth and
possibly acid-base regulation (Arnold et al., 2009). Growth
in crustaceans requires replacement of the old exoskeleton
by a new and larger exoskeleton, in a process called moult-
ing, occurring more frequently in juveniles compared with
adults. Moulting is highly temperature dependent, making
juveniles vulnerable to temperature changes (Waddy et al.,
1995). Moulting also involves depositing CaCO3to harden
the shell, which is energetically costly and therefore puts
great physiological stress on the animal. Low pH resulting
from OA increases physiological stress and may be devas-
tating to moulting juveniles already under metabolic stress.
Warmer temperatures, predicted to co-occur with increased
OA, may have its added metabolic stress on juvenile lobsters
(as seen in the crab Hyas araneus) if thermal tolerance lim-
its are exceeded (Walther et al., 2010). Ries et al. (2009) in-
vestigated the impact of OA on a range of benthic marine
calcifiers and found that Homarus americanus juveniles had
the highest net calcification at high pCO2levels (2856ppm).
The increase in calcification is thought to be initiated by ac-
tively increasing pH at the calcifying centres, therefore re-
ducing H+and converting bicarbonate (HCO
3)to carbon-
ate (CO2
3). CO2-induced acidosis in crustaceans is usually
compensated for by increasing bicarbonate production (Tru-
chot, 1978; Pörtner et al., 2004; Spicer et al., 2007). Bicar-
bonate production is energetically costly and may be reduced
over the long term if energy reserves are low.
The one study on OA in H. gammarus and studies con-
cerning other crustacean species suggest different impacts
occurring in different stages of the life cycle. The synergis-
tic effects of warming and OA on the life cycle of H. gam-
marus (and other lobster species) are unknown and urgently
need to be studied. A project was therefore initiated in 2011
aiming to investigate long-term synergistic effects of tem-
perature and projected increases in ocean acidification on the
early life cycle of lobster, i.e. the larval and juvenile phase
of H. gammarus. Here we use 18C, similar temperatures
to Arnold et al. (2009), which are optimal for hatching and
growth (Wickins and Lee, 2002; Kristiansen et al., 2004) and
10C which are less optimal conditions (Schmalenbach and
Buchholz, 2013). The temperatures chosen are not a likely
climate change scenario but a physiological test.
2 Material and methods
Experiments combining OA with temperature were con-
ducted at IMR-Matre (60520N, 05350E) over a pe-
riod of five months, lasting from 28 September 2011 to
22 March 2012. Raw water was pumped from 90m depth,
thus representing ambient water. Each experimental unit con-
sisted of a 400L tank of 0.87 ×0.87×0.53 m. Six of these
units were used for the ambient, medium (750µatm) and
high (1200µatm) pCO2treatment run at two temperatures
(10C and 18C). For the larval rearing, two 40L incuba-
tors (Hughes kreisel) were placed in each unit (12 in to-
tal, Fig. 1a). For on-growing, the juveniles were kept indi-
vidually in trays, placed in the experimental units (Fig. 1b).
From 5 months of age, the surviving juveniles were continu-
ously monitored but under ambient conditions at 14C, until
25 October 2012, by which time they were about 1 year old.
The larvae and juveniles were all kept in 8 to 10h light and
16 to 18h dark.
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A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster 7885
2.1 Water parameters
The salinity during the course of the experiment was on aver-
age 33.7±0.2 ppt. Temperature was run at 10 and 18 C, to
simulate a lower limit and an optimum threshold for homarid
lobsters, respectively (Wickins and Lee, 2002; Kristiansen et
al., 2004; Schmalenbach and Buchhoz, 2013). Initially a mid-
dle temperature of 14C was also included, but due to the
limited number of larvae available this had to be excluded.
The experiments were run in ambient water, believed to be at
a current pCO2of 380µatm occurring in the natural oceanic
environment; treatments with a medium pCO2of approxi-
mately 750 µatm and with a high pCO2aiming at 1200µatm,
to simulate low and medium OA scenarios predicted for 2100
and 2200, respectively. Multiple 2×2 AGA 25kg gas bot-
tles were used to induce CO2into two cones, creating seawa-
ter with pH=6. From each of these cones, CO2-rich water
was mixed with oxygen-rich seawater and the flow rates from
the cones were regulated by controllers to obtain the desired
seawater quality; pH=7.79 in medium pCO2treatment and
pH=7.62 in high pCO2treatment. Water from the enclo-
sures were supplied to and circulated through the experimen-
tal tanks. Temperature, pH and oxygen were monitored con-
tinuously in each experimental tank by probes connected to
a computer. The pH was measured several times daily using
Orbisint CPS11D from Endress+Hausser electrodes, using
the National Bureau of Standards (NBS) scale. pH was cali-
brated once a week with buffers of pH=4.0 and 7.0. In addi-
tion, calibration was also made by using a spectrophotometry
Hitachi U-2900 connected to a Refrigerated Heating Circula-
tor Julabo F12 combined with temperature sensors TD301A
from SAIV A/S. These measurements deviated from 0.001
to 0.053 from pHNBS and were considered acceptable for
this study. Samples for analysis of CO2content in seawa-
ter inµatm, total alkalinity (At)and total dissolved inorganic
carbon (Ct)were collected in 350 ml amber glass bottles with
minimal headspace. 300µL of saturated HgCl2solution was
added to preserve the sample. Aragonite and calcite satura-
tion state () and pH on the total hydrogen ion scale (pHt)
were then calculated.
In the medium pCO2treatment the content of pCO2was
727±12 µatm, and correspondingly 1198±157µatm in the
high pCO2treatment (Table 1), combined for both tempera-
tures. The water quality in ambient water, i.e. intake of raw
water at 90m depth, did not stay stable. At 10 C, pH in
the larval experiments was stable at an average 8.01 from
28 September until 11 November, then dropped to 7.92 and
even dropped further and was between 7.83 and 7.90 towards
the end of the experiment (Fig. 2). In ambient water at 18C
the pH was relatively stable but at 7.80±0.02 throughout the
larval phase. In other words, pH was above 7.9 only in two-
thirds of the larval phase at 10C. pH was relatively stable
in the experiments run at medium and high pCO2at both
temperatures, however with a few outliers (Fig. 2). In the ju-
venile experiments pCO2in ambient water was higher than
Table 1. Seawater parameters during the OA experiment. At: to-
tal alkalinity; Ct: total dissolved inorganic carbon. Analysis of
nutrition gave estimates of nitrate (12.3µmolkg1), phosphate
(1.3µmol kg1) and silicate (7.1µmolkg1) used in the calcula-
tions.
Ambient Medium pCO2High pCO2
treatment treatment
pCO2(µatm) 692±26 727 ±12 1198 ±157
Salinity (ppt) 33.37 ±0.12 33.37±0.12 33.34 ±0.09
At(µmolkg1) 2314.4 ±2.5 2310.3 ±1.1 2318±14.3
Ct(µmolkg1) 2168.3 ±6.6 2171.3 ±1.5 2266.4±31.8
HCO
32028.5±9.2 2034.6 ±2.6 2154.7 ±35.4
CO2
3116.2±3.7 112.0 ±1.5 66.1 ±11.0
pH 7.84±0.01 7.82 ±0.01 7.62 ±0.05
calcite 2.81±0.09 2.71 ±0.04 1.60 ±0.27
aragonite 1.81±0.06 1.75 ±0.02 1.02 ±0.18
expected (Fig. 3) and only slightly lower than the medium
pCO2treatment. In the experiments monitoring the surviv-
ing juveniles from the exposed treatments grown in ambient
water until 8 months of age, pH varied around 7.95 to 7.96
(data not shown).
2.2 Brood stock
Ovigerous females were collected from the H. gammarus
population in Øygarden (60350N; 4500E) during the com-
mercial fishing season October to November 2011, and trans-
ported to IMR-Matre. They were acclimatized at 6C in in-
dividual 75L tanks (52 ×52×28 cm) in a CT room with the
lighting set to a 12h dark:12 h light cycle. Lobsters were fed
frozen shrimps and fish twice a week. The CO2-control sys-
tem was operative in late Septmeber 2011, and the hatching
was postponed accordingly. In early September the temper-
ature was slowly increased to 18C, to induce hatching that
commenced 28 September 2011. Of a total of 14 females,
only four had eggs that hatched during the experimental pe-
riod. The sizes of the ovigerous females were 91, 110, 113
and 135mm carapace length (CL; measured as the distance
from the posterior rim of the eye socket to the posterior edge
of the carapace). The females hatched 15160 larvae in total.
2.3 Larval rearing and sampling
Each of the individual tanks with the ovigerous females had
an overflow through a 20mm water hose leading to separate
containers equipped with a filter to retain the hatched lar-
vae. Larvae normally hatch during late night/dawn and were
collected from the outflow containers each morning, counted
and transferred in equal numbers to the 40L upstream incu-
bators (plankton Kreisler; Hughes et al., 1974). However, all
females were not hatching at the same time, thus we chose to
run the experiments with pCO2treatments at 10C before
commencing at 18C. The incubators were supplied with
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7886 A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster
Tank 3
10 C -Medium pCO2
Incubator 3a
Incubator 3b
Tank 4
10 C -High pCO2
Incubator 4a
Incubator 4b
Incubator 13a
Incubator 13b
Tank 14
18 C -Medium pCO2
Incubator 14a
Incubator 14b
Tank 2
10 C - Ambient
Incubator 2a
Incubator 2b
Tank 15
18 C -Ambient
Incubator 15a
Incubator 15b
Tank 11
18°- Medium pCO2
Tank 12
18°C - Ambient
Tank 10
18°C - High pCO2
a) Larval phase b) Juvenile phase
Figure 1.
Fig. 1. Overview of the experimental setup during the (a) larval (two incubators as parallels in each tank unit) and in the (b) juvenile phase
with trays with individual compartments (several trays in each tank unit).
11L seawater per minute. The larvae were fed daily with
frozen Artemia sp. Larvae hatching over a period of 3 days
were mixed in the same incubator. Larvae with larger differ-
ence in age were not mixed due to increased risk of canni-
balism. Maximum density for each incubator was set to 1000
larvae, or 25 larvae per litre. Each treatment, i.e. temperature
and CO2had two replicates (as shown in Fig. 1). Every third
day the incubators were treated with Chloramid-T to con-
trol growth of the bacterium Leucothrix mucor, as previously
experienced in other lobster-rearing systems (A.-L. Agnalt,
personal communication, 2011.). The larvae were staged 1
to 4, according to Sars (1875) and Herrick (1909). Care was
taken to look for intermediate larval stages, as this has been
observed in American lobster (H. americanus), especially
between stage 2 and 3 and between stage 3 and 4 (Tem-
pleman, 1936; Wells and Spraque, 1976; Charmantier and
Aiken, 1987). Intermediate larval stages have also been ob-
served in hybrids, i.e. offspring from female American lob-
ster and male European lobster (Agnalt, unpublished data).
A total of 10 larvae at each development stage (1 to 4) from
each incubator were sampled for measurement of CL and dry
weight. At each stage, larvae had been exposed for a mini-
mum of three days before sampling. All measurements of CL
were recorded using a dissecting microscope. Dry weights
of individual larvae were recorded after 3 days of drying in
Termaks dry oven at 60C, and recorded to the closest mi-
crogram (mg) using a Mettler Toledo scale (AG204 Delta
Range). As many of the samples as possible were processed
while the larvae were still alive. When the time schedule was
too tight the larvae were frozen individually to be processed
at a later stage. To utilize the system fully, whenever an in-
cubator was terminated, and provided there were still newly
hatched larvae available, another production line was started.
Two batches of larvae production was made, with consec-
utive sampling, in incubator 2a, 2b, 3a, 14b, 15a and 15b
(Fig. 1). Unfortunately, during storage the freezer containing
many of the frozen samples of the larval stages broke. For
these samples, CL and dry weight were recorded for as many
larvae as possible. For the experiments run at 10C, 185 out
of 216 sampled larvae have size recordings, and correspond-
ingly at 18C, 224 out of 323 sampled larvae.
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A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster 7887
7,6
7,7
7,8
7,9
8,0
8,1
pH
.
.
.
.
.
.
7,6
7,7
7,8
7,9
8,0
8,1
Ambient
Medium
High
.
.
.
.
.
.
a) 10°C b) 18°C
Figure 2.
Fig. 2. Variation in pH in the larval phase run in ambient, medium
pCO2and high pCO2at (a) 10C and (b) 18 C in 2011. Ambi-
ent is raw water from 90m depth. Note that the 10 C experiment
started before 18 C.
2.4 Long-term exposure of juveniles at five months
While still pelagic, stage 4 larvae were collected one by one
and transferred to trays consisting of single-cell compart-
ments, made of black PVC plastic. Each tray consisted of
30 to 40 individual compartments with perforated bottoms
(1mm ×1mm holes) to ensure water flow. Three to four
trays were placed together in 400L units (87 ×87×53cm).
Each unit was given water quality according to ambient,
medium pCO2or high pCO2treatment. Water flow was set
to 18L per minute. The lobster juveniles were fed commer-
cially produced pellets (2mm), patented by Norwegian Lob-
ster Farm (http://www.norwegian-lobster-farm.com/no) and
produced by Nofima (http://www.nofima.no/). Whenever a
juvenile moulted, the old exoskeleton was not removed from
the compartment. On 22 March, CL were recorded for each
of the surviving juveniles.
2.5 Continued monitoring of surviving juveniles in am-
bient water until 1 year old
From five months the juveniles were all kept in ambient wa-
ter, i.e. the water quality in the raw water intake, at 14C
from 22 March to 25 October 2012. The purpose was to ver-
ify if the deformities observed were retained or lost through
moulting when kept in water of higher pH (between 7.95
and 7.96). The lobster juveniles were fed commercially pro-
duced pellets (5mm), patented by Norwegian Lobster Farm
(http://www.norwegian-lobster-farm.com/no) and produced
by Nofima (http://www.nofima.no/). At the end of the exper-
iment, CL was recorded for each surviving juvenile.
2.6 Statistics
To determine whether parallels could be pooled for each
pCO2treatment and each temperature we used Mann–
Whitney U test. A Kruskal–Wallis test was used to deter-
mine if there were significant differences between lobsters
undergoing the different pCO2and temperature treatments.
pH
7,6
7,7
7,8
7,9
8,0
8,1
Ambient
Medium
High
.
.
.
.
.
.
Figure 3.
Fig. 3. Variation in pH in the juvenile phase in ambient, medium
pCO2and high pCO2until 22 march 2012 in the experiments run
at 18C. Ambient is raw water from 90 m depth. Note that only
juveniles in 18C were monitored, as non larvae reached a viable
stage 4 in 10 C.
One-way ANOVA was used to analyse length frequency of
the juveniles raised in the different pCO2treatments.
3 Results
3.1 Growth
Growth was very slow at 10C, irrespective of pCO2level,
and after 5 weeks none of the larvae had moulted into stage
4. No larvae reached stage 3 in the medium pCO2treatment.
Eventually three larvae reached stage 4, in high pCO2treat-
ment only, but died within the following two days. At 18C,
development from stage 1 to 4 lasted from 14 to 16 days
independent of pCO2treatment as predicted under optimal
conditions. Of the 409 larvae investigated, none were found
in intermediate stages.
At 10 C, carapace length at stage 1 and stage 3 did not dif-
fer significantly between pCO2treatments (p > 0.5, Fig. 4.).
However, there were significant differences at stage 2 (p <
0.05), and the larvae produced in medium pCO2treatment
were slightly smaller in CL compared with ambient and high
pCO2treatment. At 18C, CL was significantly different at
stage 2 and stage 3 (p <0.05, Fig. 4.). At stage 2, larvae
reared in medium pCO2treatment were on average larger
than the larvae reared in the other treatments, but at stage 3
they were smaller. Dry weight differed significantly between
pCO2treatments at stage 1 and 2 at 10C, and stage 2 and 3
at 18 C (p < 0.05, Fig. 4). Larvae raised in ambient water at
10C were lighter in weight at stage 1 and heavier at stage 2
compared with the treated larvae. At 18 C, the stage 2 larvae
raised in ambient water were slightly heavier than the other
treatments but at stage 3 the high pCO2treatment larvae
were heavier. In other words, there was no consistence and
clear effect of pCO2treatment on either CL or dry weight.
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7888 A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster
18 C
10 C
39
40
20
10
10
9
20
16
1
17
27
0
4
8
12
16
1
2
3
4
40
49
10
25
33
19
21
20
0
4
8
12
16
1
2
3
4
Ambient
Medium
High
Larval stage
Larval stage
Mean dry weight (mg)
33
37
9
25
28
19
20
14
0
2
4
6
1
2
3
4
40
40
20
10
7
2
20
16
1
17
27
0
2
4
6
1
2
3
4
Mean carapace length (mm)
*
*
*
*
*
*
*
Figure 4.
Fig. 4. Mean carapace length (mm) and mean dry weight (mg) with
one standard deviation at each larval stage of Homarus gammarus
undergoing ambient, medium pCO2and high pCO2treatment run
at 10 and 18C. Number of observations in each stage is given
above the column. Note that at 10 C only three larvae reached stage
4 (high pCO2treatment), but they only survived for two days. Am-
bient is raw water from 90m depth. Star indicates significant dif-
ferences based on Kruskal–Wallis non-parametric test at p=0.05
level.
As only larvae raised at 18C successfully moulted into
stage 4, this was the only temperature for which long-term
exposure to pCO2could be monitored. Survival from stage
4 until 5 months age averaged 46% in ambient, 17 % in
medium and 61 % in high pCO2treatment. In total 148 juve-
niles survived. There were significant differences in CL as a
result of pCO2treatment (p<0.05, Fig. 5), but the sample size
was however low at the medium pCO2treatment (N=16),
accounting for the difference since there were no signifi-
cant differences between ambient and high pCO2treatment
(p > 0.1, Fig. 5).
3.2 Deformities
Deformities, i.e. a difference in the shape of a body part or
organ compared to the normal shape was found in the larvae
(Table 2) and the juveniles (Table 3). The morphological ab-
normalities in the larvae were classified as curled carapace
(Fig. 6), damages to the tail fan or that the rostrum was bent
(Table 2). No larvae suffered multiple deformities. The most
affected part was curled carapace, occurring in 59% of the
deformed larvae when combining all treatments. Bent ros-
trum was found in 27% and damages to the tail fan in 14 %
of all the deformed larvae. The deformities in the larvae were
Table 2. Classification of deformities found in larval stages 1 to 4 in
European lobster (Homarus gammarus) exposed to elevated pCO2
levels.
Category Organ affected Description
Curled
carapace Carapace The carapace was curled
at the edge, often forming
ridges penetrating the side
of the carapace.
Tail-fan
damages Uropod Damages to parts of the
tail fan, or even lacking
one or both of the tail
fans.
Bent
rostrum Rostrum The rostrum was bent, as
if not yet straighten out
after hatching.
observed and described in live samples only. It was difficult
to distinguish misshapes as described in Table 2 from arte-
facts due to the freezing process. Hence frozen samples were
not included in the calculations below.
The proportion of larvae with deformities increased with
increasing pCO2exposure, but was similar across the two
temperatures 10 and 18C. In the medium treatment, 22 and
24% were deformed at 10 and 18 C, respectively. At the
high treatment as much as 42 and 45% were deformed, re-
spectively. An overall 12% of the larvae in ambient water
raised in 18C developed deformities, though it is impor-
tant to note that pH in ambient treatment was only slightly
higher than in the medium pCO2treatment. At 10C, 5 %
of the larvae (N=2) were deformed, but these two speci-
mens were actually sampled after 11 November when pH
dropped to below 7.9. None of the larvae exposed to pH
above 7.9 developed deformities. Curled carapace was the
most common deformity (45%) found in larvae raised in
medium pCO2treatment at 10C, followed by damages in
the tail fan (33%) and bent rostrum (22 %). Concurrently, in
the high pCO2treatment curled carapace was the only defor-
mity. In the deformed larvae raised at 18C and in ambient
treatment, curled carapace (33.3%), damages to the tail fan
(33.3 %) and bent rostrum (33.3%) were equally distributed.
Concurrently, in the medium treatment half of the deformed
larvae had a bent rostrum, 38% a curled carapace and 12 %
were found with damages in the tail fan. Curled carapace
was the only deformity found in the larvae undergoing high
pCO2treatment.
Of the 148 juveniles that survived after five months, 41
were classified as morphologically deformed (see Table 2).
Overall, 33 and 44 % of the juveniles in ambient and medium
pCO2treatments, respectively, were deformed compared
with 21% in juveniles exposed to high pCO2(Fig. 8). In
ambient and medium pCO2treatment, deformed claws were
most often found (56%), followed by stiff/twisted walking
legs (39%) and puffy carapace (39 %). When the juveniles
Biogeosciences, 10, 7883–7895, 2013 www.biogeosciences.net/10/7883/2013/
A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster 7889
Table 3. Classification of deformities found in juvenile stages of European lobster (Homarus gammarus) exposed to elevated pCO2levels.
Category Organ affected Description
Puffy carapace Carapace Carapace puffy/swollen, or up-
folded on one side, often leav-
ing some parts of the gills ex-
posed.
Stiff/twisted
walking legs 2–5 pereopod The joints were fused together
as if the joints were over-
calcified. The entire pereopod
leg was like one stiff piece,
sometimes “frozen” in an
arbitrary/twisted position.
Misshaped
claw 1st pereopod/cheliped Various shapes of the cheliped,
but most often twisted,
deviating from normal.
Bent rostrum Rostrum The rostrum was bent, as if not
yet erected after hatching.
Tail-fan
damages Uropod Damages to parts of the tail fan,
or even lacking one or both of
the tail fans.
Twisted
abdomen Abdomen Abnormal shape of the
abdomen as if some of the
segments were once broken and
then grown back in the wrong
shape.
Stiff antenna 2 antenna Segments of the antenna were
fused, as if the joints were
over-calcified. Felt “stiff” when
touching. Difficult to observe
when animal was out of water.
from ambient and medium pCO2treatment had deformed
claw(s) about 54% had also developed stiff/twisted walking
legs. In comparison, at high pCO2, 71% of the deformed
juveniles had developed a puffy carapace. Of these, 24%
had also developed deformed claws. Overall, about half of
the deformed juveniles from the ambient and medium pCO2
treatment had developed two or three different abnormalities
(Fig. 10). In comparison, 70% of the deformed juveniles in
the high treatment had multiple deformities.
At one year of age, 76 of the 148 juveniles had survived.
Mortality was equally high for those juveniles that had 5
months’ exposure in ambient or in high pCO2. Overall, 28%
of the juveniles were deformed. The most common occurring
deformities (28%) were puffy carapace with stiff/twisted
walking leg, as illustrated in Fig. 10. Of the 40 deformed ju-
veniles found 22 March 2012, only 12 had survived another
seven months. Of these, six were still deformed (four of the
juveniles even developed at least one additional deformity).
In other words, 50% of the survivors had managed to recu-
perate, most likely through moulting. However, of the 108
juveniles classified as normal at five months of age, 15 had
developed deformities seven months later.
4 Discussion
Deformities were observed both in the larval and juvenile
phase in European lobster when exposed to higher pCO2
from hatching. The proportion of larvae with deformities
increased with increasing pCO2exposure and was similar
across the two temperatures 10 and 18C. In high exposure
as much as 45% of the larvae developed deformities. After
five months of exposure, 44 and 21% of the juveniles were
deformed in medium and high pCO2treatment, respectively.
Deformities in lobster larvae and juveniles have not previ-
ously been reported, either in European or American lob-
ster, although the scientific community have long-term ex-
perience in husbandry of these two species (Gruffydd et al.,
1975; Capuzzo and Lancaster, 1979; Latrouite and Lorec,
1991; Addison and Bannister, 1994; Uglem et al., 1995;
Agnalt et al., 1999, 2004; Nicosia and Lavalli, 1999; Lin-
nane et al., 2000; Jørstad et al., 2001; Wickins and Lee, 2002;
Kristiansen et al., 2004; Jørstad et al., 2005; Agnalt, 2008;
Arnold et al., 2009, Ries et al., 2009, Schmalenbach et al.,
2009, Keppel et al., 2012). Wickins et al. (1995) did report
moulting abnormalities in European lobster larvae in rela-
tion to testing different diets, but with no further description
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7890 A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster
0
5
10
15
20
25
30
4
5
6
7
8
9
10
11
12
13
14
0
5
10
15
20
25
30
4
5
6
7
8
9
10
11
12
13
14
0
5
10
15
20
25
30
4
5
6
7
8
9
10
11
12
13
14
Number of juveniles
Carapace length (mm)
Figure 5.
Fig. 5. Carapace length (mm) frequency of juvenile Homarus gam-
marus raised in 18 C, from newly hatched larvae until 5 months of
age in (a) ambient water, (b) medium pCO2treatment and (c) high
pCO2treatment. Size recordings were made 22 March 2012.
of what the abnormalities were. In aquaculture, hatchery-
induced changes due to feed, tank design and/or substrate
have been described for a number of fish and shellfish species
(Olla et al., 1998; Svåsand et al., 1998; Tsukamoto et al.,
1999; and references therein). In shellfish, most changes doc-
umented are morphological, e.g. lower shell strength in the
great scallop (Pecten maximus) (Grefsrud and Strand, 2006)
and queen conch (Strombus gigas) (Stoner and Davis, 1994),
lack of spines in top shell (Trochus niloticus) (Purcell 2002)
or lack of differentiation in the claws in lobster Homarus
spp. (Govind and Pearce, 1986). Deformities of 40 to 58%
have also been found in wild populations of shrimps of the
genus Palaemon in the Gironde estuary in France (Béguer
et al., 2008, 2010). The deformities (wrinkled or bent cara-
pace, bent rostrum and damages in the tail fan) were reported
to affect adult individual mortality and egg production. The
cause of these deformities was not identified, although stress,
pollution or even elevated pCO2levels may be explanatory
factors. In future studies it will be vital to differentiate de-
Figure 6.
Fig. 6. A stage 3 Homarus gammarus larvae raised in an environ-
ment with pH lower than 7.9. The carapace is curled, leaving “curls”
on the side (indicated with the arrow). This is classified as a defor-
mity.
formities caused by ocean acidification from effects due to
hatchery production or other environmental factors.
Why are we so sure that the deformities observed in this
study were due to high exposure pCO2? The Institute of Ma-
rine Research has since the early 1990s hatched and pro-
duced larvae and juvenile European lobster for various stud-
ies such as, e.g. stock enhancement (Agnalt et al., 1999,
2004; Agnalt 2008), fitness and genetic studies (Jørstad et
al., 2001; Jørstad et al., 2005), carrying capacity (Agnalt, un-
published data) and conditioning juveniles for release pur-
poses (Agnalt, 2013; Aspaas, 2012; Trengereid, 2012). We
have only in a few occasions found that the first pair of peri-
opods (claws) was misshaped but this trait was lost after one
or two moults. None of these misshapes looked like the claw
deformities found in the present study. Assessing deformities
demands experience with observing larvae and juveniles, as
subtle trait changes might be missed. In the present study,
deformities in the larval phase were found in the carapace
(termed “curled” in larvae and “puffy” in juveniles), tail fan
or in the rostrum (termed “bent rostrum”) (Tables 2 and 3).
Inexperienced personnel might miss these traits. In this study,
measurements were made by one person to ensure consis-
tency and the individuals were classified blindly. Experience
should be accounted for also in future studies, whenever pos-
sible.
Our study shows that deformities occur in lobster larvae
raised in pCO2levels higher than 727µatm, independently
of temperatures being 10 or 18C. Deformities due to OA
has been documented on the embryonic in some marine in-
vertebrate species, often resulting in low or even no hatching
success (Parker et al., 2009; Kawaguchi et al., 2010; Byrne,
2011), but also in the larval stages in a few species (Kurihara,
2008; Byrne et al., 2011, and references therein). White-
ley (2011) stated that the exoskeleton of planktonic decapod
larvae is unmineralised and elevated pCO2should therefore
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A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster 7891
0
10
20
30
40
50
% deformed
Figure 7.
Fig. 7. Percentage of Homarus gammarus with deformities in the
larval phase in the different temperature, 10 and 18C, and pCO2
treatments (ambient, medium and high).
not affect larval conditions. However, Arnold et al. (2009)
analysed the calcium and magnesium concentrations per sur-
face area of the carapace of H. gammarus larvae. They found
significant reductions at elevated pCO2of 1200µatm in stage
4 larvae; calcium decreased from 0.24 to 0.13µg mm2and
magnesium decreased from 0.019 to 0.012µg mm2. Cal-
cium and magnesium seem to be important mineral compo-
nents in the exoskeleton of the lobster larvae. However, Mg-
CaCO3is more soluble than pure calcite or aragonite (An-
dersson et al., 2008) and since Aragonite was at the lowest
1.02 in this study, elevated pCO2could definitely have an
effect on e.g. formation of the new exoskeleton. A thinning
of the shell has been reported in blue mussels Mytilus edulis
and Pacific Oyster Crassostrea gigas (Gazeau et al., 2007;
Melzner et al.; 2011). A thinner shell in lobster larvae may
not be strong enough to keep its shape, especially when cov-
ering organs like the gills where water flow continuously and
applies pressure on the shell. This may explain the “puffy”
carapace observed in the present study.
In the high pCO2treatment carapace was the most af-
fected organ, both in larvae and in the juveniles. In the ju-
veniles, the deformities generally affected carapace (puffy or
swollen, thus often leaving part of the gills exposed), walk-
ing legs (stiff), claws (twisted), abdomen (stiff joints), tail fan
and even antenna (stiff). The latter is of vital importance for
lobster communication, including finding a partner (Johnson
and Atema, 2005). Fewer deformities were found in juve-
niles exposed to high pCO2compared with medium expo-
sure. However, those affected had also developed multiple
deformities, i.e. more severe damages. We found that dam-
ages to the tail fan could not be repaired through moulting,
while walking legs and “puffy” carapace would become nor-
mal after several moultings. The exoskeleton in sub-adult and
adult lobster can be divided into three layers: epi-, exo- and
endocuticle (e.g. Sachs et al., 2006; Bosselmann et al., 2007;
Romano et al., 2007; Al-Sawalmih et al., 2008; Sachs et al.,
2008; Fabritius et al., 2009). The exoskeleton of Homarus
sp. consists of chitin, protein, calcium, magnesium, phos-
45
18
85
148
25
4
47
76
0
10
20
30
40
50
60
70
80
22 March 2012
25 October 2012
% deformed
Figure 8.
Fig. 8. The percentage of juveniles with deformities. Light grey bar
represents juveniles surviving five months of pCO2exposure (am-
bient, medium and high) and darker grey bar the juveniles after an-
other seven months in ambient water only. Total number of juveniles
in each category is given above each column.
phate and a few other compounds (Ba, Mn, Sr), although
variable in composition in the different layers (Al-Sawalmih
et al., 2008; Kunkel et al., 2012). The epicuticle is partic-
ularly rich in calcium, magnesium and phosphate. The out-
ermost exocuticle consists of a thin calcite-containing layer
while the rest is fully mineralized, mostly with amorphous
calcium carbonate that is highly soluble and acts as a tran-
sient source of calcium. The endocuticle consists of crys-
talline calcite. Moulting is a complex process (Greenaway,
1985; Dillaman et al., 2005; Politi et al., 2010), and for
instance, reabsorption of calcium occurs from the old ex-
oskeleton before it is shed. The new exoskeleton is uncal-
cified and rapidly needs to harden by deposition of calcium
carbonate. In other words, elevated pCO2can affect vari-
ous cuticle layers and various stages of the moulting cycle.
Thus, the deformities may have been caused by irregulari-
ties in the depositing of Mg-CaCO3in the shell. Too high
deposits, a possible compensation for low hemolymph pH
(acidosis), may have resulted in the stiff walking legs ob-
served in our study. Whereas too little depositing of CaCO3
in the shell may result in the incomplete formation of certain
structures in the exoskeleton. This could be related to de-
pleted energy resources (to maintain homeostasis) required
for converting HCO
3to CO2+
3and therefore the depositing
of enough CaCO3.
No consistent and clear effect of pCO2treatment was
found in this study on neither carapace length, or on dry
weight. This is coherent with observations with the same
species by Arnold et al. (2009). Neither was moulting fre-
quency affected by increased acidification in this study. How-
ever, Keppel et al. (2012) found decreased carapace length
with increased pCO2in the closely related H. americanus,
and the moulting cycle was prolonged with about 2 days in
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7892 A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster
CE2:
Page 10 in proof, Fig. 9, caption: Please delete “occurrence of” and replace the caption with
the following text: “The percentage of lobster juveniles with single or multiple deformities
when exposed to elevated levels of pCO2 (ambient, medium and high) for five months.”
Figure 9. The word deformities in 3 deformities” is now correct.
0
10
20
30
40
50
60
70
1 deformity
2 deformities
3 deformities
4 deformities
% Occurence
18°C/Ambient
18°C/Medium pCO2
18°C/High pCO2
TS2:
The correct reference for Byrne et al. 2011 is as follows:
Byrne, M., Ho, M.A., Wong, E., Soars, N., Selvakumaraswamy, P., Sheppard Brennand, H.,
Dworjanyn, S.A., and Davis, A.R.: Unshelled abalone and corrupted urchins, development of
marine calcifiers in a changing ocean, Proc. Rol. Soc. Ser. B, 278, 2376-2383,
doi:10.1098/rspb.2010.2404, 2011.
The reference Agnalt et al. 2001 should be corrected to Agnalt et al. 2004:
Agnalt, A.-L., Jørstad, K.E., Kristiansen, T.S., Nøstvold, E., Farestveit, E., Næss, H., Paulsen,
O.I., and Svåsand, T.: Enhancing the European lobster (Homarus gammarus) stock at Kvitsøy
Islands; Perspectives of rebuilding Norwegian stocks, pp. 415-426, In: Leber, K.M., Kitada,
S., Blankenship, H.L., and Svåsand, T. (eds): Stock enhancement and sea ranching
developments, pitfalls and opportunities, Blackwell Publishing Ltd, Oxford, 562 p., 2004.
Fig. 9. The percentage of lobster juveniles with single or multi-
ple deformities when exposed to elevated levels of pCO2(ambient,
medium and high) for five months.
larvae raised at pH=7.7 compared with pH =8.1. It seems
that the growth and moulting cycle is affected in H. ameri-
canus (Keppel et al., 2012), while larvae and juveniles of H.
gammarus maintain growth rates at the cost of mineralization
of the exoskeleton.
A major concern with the present study was the very low
pH with corresponding high pCO2(average 692±26 µatm)
found in ambient water taken from a locality in Masfjorden
at 90m depth. Compared to pH in ambient water at IMR’s
research stations Austevoll (pH 7.98, Andersen et al., 2013)
and Parisvatn (pH 8.11; Agnalt, personal communication) lo-
cated in outer coastal areas in the same region, the water
in Masfjorden seems to have quite a large natural variation
and may drop to levels well below global average pH of 8.05
(Fabry et al., 2008). European lobster is not normally found
at the depths of 90m at this locality in Masfjorden, but is
found in the fjord system at shallower depths. Knowledge
about the pH in the Norwegian fjord systems and how it fluc-
tuates between seasons and years is scarce. However, mea-
surements from other locations in the Northern Hemisphere
shows that pH in coastal areas can be highly variable and as
low as 7.7–7.6. Barton et al. (2012) showed that pH in Ore-
gon coastal water varied from 7.6 to 8.2 in the early summer
of 2009. Newton et al. (2012) reported a pH of 7.72 at 100m
depth in Puget Sound and the Strait of Juan de Fuca, on the
East Coast of the USA during February 2008. Even in the
“closer to home” North Sea, there are already indications that
the level of pH is variable and decreasing (Olsen et al., 2006;
Blackford and Gilbert, 2007; Bellerby et al., 2005). Based on
these studies, we assume that fjord systems also are affected
by the ongoing ocean acidification and may explain the low
ambient conditions in Masfjorden. However, more effort is
needed to verify this hypothesis.
Figure 10.
Fig. 10. Homarus gammarus juvenile, one year of age, exposed
to pH<8.1 since hatch displaying deformities as puffy carapace
(circle), stiff/twisted walking legs (arrow) and lacking antennas
(square).
5 Conclusions and future work
There were no clear effects of pCO2treatment, on either
carapace length or dry weight in H. gammarus larvae. How-
ever, the high ratio of larvae and juveniles with deformed
exoskeletons strongly indicates a negative effect of elevated
pCO2on European lobster from hatching to one year of
age. Some of the deformities may affect the ability to find
food and partners (walking legs, claw and antenna), respi-
ration (carapace), and the ability to swim (tail-fan damages).
Thus further studies on behaviour and respiration are needed.
Studies have already commenced to elucidate mineralization
of the exoskeleton in lobster juveniles exposed to various lev-
els of pCO2and elevated temperature.
Acknowledgements. We thank the staff at the Institute of Marine
Research, Matre Research Station, for helpful assistance during
the project period. We also thank the two anonymous referees
and Daniela Schmidt for their valuable comments. This study was
supported by the Institute of Marine Research through the project
13193-01, Ocean Acidification-Lobster.
Edited by: D. Schmidt
Biogeosciences, 10, 7883–7895, 2013 www.biogeosciences.net/10/7883/2013/
A-L. Agnalt et al.: Deformities in larvae and juvenile European lobster 7893
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... Homarus congeners suggest a range of responses to end-century acidification and warming as joint stressors (Agnalt et al., 2013;Keppel et al., 2012;Menu-Courey et al., 2019;Rato et al., 2017;Ries et al., 2009;Small et al., 2015;Waller et al., 2017). Elevated temperature and pCO 2 can interact to cause changes in behavior, carapace length, carbon content, and development time; however, reports are conflicting in some cases (Small et al., 2015;Waller et al., 2017). ...
... Elevated temperature and pCO 2 can interact to cause changes in behavior, carapace length, carbon content, and development time; however, reports are conflicting in some cases (Small et al., 2015;Waller et al., 2017). The few studies to date that have tested thermal and pCO 2 effects together under similar experimental designs suggest that larval or postlarval physiological and behavioral response to predicted end-century warming may be greater than that of pCO 2 alone (Agnalt et al., 2013;Small et al., 2015;Waller et al., 2017). ...
... our knowledge, this is the first study to examine how the joint stressors of these SST warming and acidification conditions may affect gene expression of American lobster postlarvae. DESeq2 analysis indicates that postlarval response to elevated pCO 2 is more pronounced relative to warming than indicated in physiological and morphometric studies reported to date(Agnalt et al., 2013;Keppel et al., 2012;Menu-Courey et al., 2019;Rato et al., 2017;Ries et al., 2009;Small et al., 2015;Waller et al., 2017). In addition, analysis of gene regulatory responses revealed an even greater response to joint effects of elevated pCO 2 and temperature on transcripts involved in developmental processes and immune function of lobster postlarvae.Contrary to the DESeq2 results, the analysis using EdgeR did not detect any statistically significant differential expression under the pCO 2 treatment and detected fewer differentially expressed(DE) genes within other treatments. ...
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... Furthermore, other physicochemical factors such as dissolved oxygen, pH, light, and pollutants can also exert major effects. As these environmental factors are often covarying, their combined effects have received increasing attention more recently, specifically in relation to research on climate change (e.g., Walther et al. 2010, Whiteley 2011, Agnalt et al. 2013, Gonzalez-Ortegón et al. 2013, Wood et al. 2015. One section of this chapter is hence devoted to discuss this important new trend. ...
... For example, elevated pCO 2 (pH 7.18) led to a narrowing window of thermal tolerance by H. araneus zoeae when compared to the control (pH 8.04) (Walther et al. 2010). The combined effects of predicted OA and global warming on crustacean larval growth, however, do not present a clear pattern, and appear to be both species and stage specific (Walther et al. 2010, Agnalt et al. 2013, Schiffer et al. 2013, 2014a also see examples in the "Increased Carbon Dioxide Levels" section in this chapter). For instance, elevated pCO 2 and temperature was found to extend the duration of larval development and reduced larval weight in H. araneus (Agnalt et al. 2013), but not in H. gammarus (Schiffer et al. 2014b). ...
... The combined effects of predicted OA and global warming on crustacean larval growth, however, do not present a clear pattern, and appear to be both species and stage specific (Walther et al. 2010, Agnalt et al. 2013, Schiffer et al. 2013, 2014a also see examples in the "Increased Carbon Dioxide Levels" section in this chapter). For instance, elevated pCO 2 and temperature was found to extend the duration of larval development and reduced larval weight in H. araneus (Agnalt et al. 2013), but not in H. gammarus (Schiffer et al. 2014b). Finally, it is worth noting that an interesting comprehensive study at different levels-from the molecular to the whole animal-on underlying mechanisms of tolerance to combined hypercapnia and warming changes during ontogeny of H. araneus has led to a conceptual model being developed (Fig. 7.6) (Schiffer et al. 2014a). ...
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The vast majority of crustaceans are aquatic, living in either marine or freshwater environments. Marine crustaceans, such as copepods in particular, are ubiquitous in the oceans and perhaps the most numerous metazoans on Earth. Because crustaceans occur in all marine habitats, their larvae are exposed to highly diverse and sometimes variable environmental conditions, including extreme situations in which various environmental factors exert significant effects on larval growth and development. This chapter first describes the effects of food availability on crustacean larvae. Food paucity is a commonly occurring scenario in the wild, which can directly affect larval growth and development and, in severe cases, results in mortality. In the subsequent sections, we cover the effects of temperature and salinity—the two most prominent physical parameters in the aquatic environments on growth and development of crustacean larvae. We then discuss the influence of other important physicochemical factors in aquatic environments on larval growth and development, including dissolved oxygen, light, ocean acidification, and pollutants. Finally, the last two sections of this chapter discuss synergistic effects of different environmental factors and suggest future research directions in this field.
... 42,43 Commercial holding systems (containing high densities of wild caught lobsters) have also suffered rapid transmission of disease vectors. 44 Further studies on the impact of ocean acidification have also detailed changes in H. gammarus moulting during pH or alkalinity extremes 45,46 suggesting that the available high standards of water quality monitoring, feedback and corrective systems are required to safeguard stock production and successive moulting for H. gammarus. ...
... In larval rearing tanks, high bacterial loading is most obvious following blooms of filamentous bacteria (e.g. Leucothrix mucor 45 ), which can rapidly proliferate in rearing tanks and foul larval appendages, restricting movement and feeding. In addition to larval mortality, sub-lethal effects can impact on larval performance, for example microbial infection of gill surfaces, potentially impairing gas transfer. ...
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... Since lobsters were rearing in a recirculation system in which its nitrification process needed bicarbonate ions (HCO3 -), hence control treatment (without CaCO3 addition) must have lower alkalinity than other treatments. According to Agnalt et al. (2013), low pH values will interfere calcification process during molting and disturb the swimming ability of Homarus gammarus lobster juveniles. Meanwhile, L. vannamei shrimp will have the best survival rate (92.12 ± 5.30%) when reared in 225 mg L -1 CaCO3 of water alkalinity level (Furtado et al. 2014). ...
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Spiny lobsters (Panulirus sp.) were valuable and one of the most popular Indonesian export commodities. Some approaches were made to increase the quantity and quality of cultivated spiny lobsters. Land-based mariculture with Recirculating Aquaculture System (RAS) was applied to increase lobster harvesting and optimize environmental quality by adjusting water alkalinity. This study aimed to determine the optimum level of alkalinity for spiny lobsters Panulirus homarus rearing in RAS. This study investigated the effects of applying four water alkalinity levels (Control, 125, 200, and 275 mg L-1 CaCO3) on the biochemical responses of P. homarus observed in the hemolymph in terms of Total Hemocyte Count (THC), glucose, total protein, calcium, and pH levels. Furthermore, we also studied the alkalinity effects on lobster production performance parameters in terms of body weight gain, body length, Survival Rate (SR), Specific Growth Rate (SGR), and Feed Conversion Ratio (FCR). Lobsters with an initial weight rate of 58.05±1.69 g and an initial total length rate of 115.33±1.52 mm were reared for 60 days in a recirculation system. Results of water quality parameters such as ammonia, nitrite, nitrate, dissolved oxygen, temperature, and salinity during the study were available for lobster rearing. Different alkalinity levels affected the biochemical responses and production performance of lobsters. The best alkalinity level to reared Panulirus sp. in the recirculation system during this study was 200 mg L-1 CaCO3 so that it could achieve the highest survival rate of 86.67% with SGR 0.60±0.01 % day-1.
... In the present study, a diet of enriched Artemia naupli proved successful for the growth of lobster larvae until stage IV. The growth of larvae during the pelagic stages was similar to those reported in other studies (Agnalt et al., 2013;Middlemiss et al., 2015;Powell et al., 2017). In this study, feeding time was limited to 10 hours (09:30 -19:30) and no feed was given after lights were turned off. ...
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... The larvae were maintained at optimal temperature (24 ° C ) and salinity (35 PSU) corresponding to field conditions (range: 23--24.5 ° C and 34.5--35.3 PSU salinity) where phyllosomas survive and grow (Agnalt et al., 2013;Smith et al., 2017) and consistent with conditions in the hatchery. The phyllosomas were exposed to the treatments for 11 days. ...
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... Most of these studies have focused on the earliest life stages of lobsters, including embryos (N. norvegicus: Styf et al. 2013); larvae (H. gammarus: Arnold et al. 2009, Agnalt et al. 2013, Small et al. 2015H. americanus: Keppel et al. 2012, Waller et al. 2016; and early benthic juveniles (H. ...
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