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Polar Biol (2010) 33:919–928
DOI 10.1007/s00300-010-0768-1
123
ORIGINAL PAPER
Ion regulatory capacity and the biogeography of Crustacea
at high southern latitudes
Astrid C. Wittmann · Christoph Held ·
Hans O. Pörtner · Franz J. Sartoris
Received: 7 September 2009 / Revised: 4 January 2010 / Accepted: 17 January 2010 / Published online: 6 February 2010
© Springer-Verlag 2010
Abstract Brachyuran and anomuran decapod crabs do
not occur in the extremely cold waters of the Antarctic con-
tinental shelf whereas caridean and other shrimp-like deca-
pods, amphipods and isopods are highly abundant.
DiVering capacities for extracellular ion regulation, espe-
cially concerning magnesium, have been hypothesised to
determine cold tolerance and by that the biogeography of
Antarctic crustaceans. Magnesium is known to have a
paralysing eVect, which is even more distinct in the cold.
As only few or no data exist on haemolymph ionic compo-
sition of Sub-Antarctic and Antarctic crustaceans, haemo-
lymph samples of 12 species from these regions were
analysed for the concentrations of major inorganic ions
(Na+, K+, Ca2+, Mg2+, Cl¡, SO42¡) by ion chromatography.
Cation relationships guaranteed neuromuscular excitability
in all species. Sulphate and potassium correlated positively
with magnesium concentration. The Antarctic caridean
decapod as well as the amphipods maintained low (6–20%
of ambient sea water magnesium concentration), Sub-
Antarctic brachyuran and anomuran crabs as well as the
Antarctic isopods high (54–96% of ambient sea water mag-
nesium concentration) haemolymph magnesium levels. In
conclusion, magnesium regulation may explain the bioge-
ography of decapods, but not that of the peracarids.
Keywords Antarctic · Haemolymph ion composition ·
Decapoda · Isopoda · Amphipoda · Magnesium
Introduction
Decapod crustacean diversity is low in Antarctic compared
to Sub-Antarctic regions (Gorny 1999). Over 130 benthic
and pelagic decapod species occur in the Southern Ocean,
but only 27 species are present south of the Polar Frontal
Zone (PFZ). Brachyuran crabs are completely absent,
whereas at least nine species of the anomuran family
Lithodidae have been found south of the PFZ (Gorny 1999;
García Raso et al. 2005; Thatje et al. 2005). Anomuran and
brachyuran crabs still inhabited nearshore habitats of Ant-
arctica in the late Eocene (Feldmann and Zinsmeister
1984a, b). The extinction or migration of brachyuran crabs,
which today are restricted to warmer shallow waters of the
Sub-Antarctic (Gorny 1999), likely happened during cool-
ing trends in the Miocene, when isopods radiated in the
Antarctic and occupied ecological niches vacated by the
decapods (Aronson et al. 2007 and references therein;
Brandt 1999; Held 2000). Accordingly, amongst the Crus-
tacea the taxon Peracarida is the most abundant and speci-
ose in the Antarctic today, with over 400 isopod and over
500 amphipod species (Brandt 1999; Gutt et al. 2004).
Antarctica is encircled by a strong water current (Antarc-
tic Circumpolar Current or ACC), which developed during
the Oligocene and led to climatic cooling of the Southern
Ocean (Lawver and Gahagan 2003). At about 50°S cold
water masses coming from the South (surface temperature
ca. 2°C) meet warmer waters from the North (surface tem-
perature ca. 8°C; Orsi et al. 1995). The sharp change in
water temperature is detectable to signiWcant depth and
may pose an oceanographic barrier, called the Polar Front.
However, near the bottom this diVerence will be less dis-
tinct, depending on the depth of the seabed (Orsi et al.
1995). Potential seabed temperatures at 50°S are ca. 2°C on
continental shelf (0–1,000 m), 0–2°C on continental slope
A. C. Wittmann (&) · C. Held · H. O. Pörtner · F. J. Sartoris
Alfred Wegener Institute for Polar and Marine Research,
Am Handelshafen 12, 27570 Bremerhaven, Germany
e-mail: Astrid.Wittmann@awi.de
920 Polar Biol (2010) 33:919–928
123
(1,000–3,000 m) and ¡1–0°C in deep-sea areas (>3,000 m;
Clarke et al. 2009). At high southern latitudes, seabed
potential temperature is highest on the shelf of the western
Antarctic Peninsula (ca. 1°C), whereas it is lowest on the
shelves of the Weddell and Ross Seas (ca. ¡1.5°C; Clarke
et al. 2009).
The repeated extension and retreat of the Antarctic shelf
ice and formation and melting of a multiyear sea-ice layer
during earth history might have contributed to the current
distribution pattern of Antarctic crustaceans. Expansion
periodically reduced the space of the shelf habitat and due
to a decline of light penetration decreased primary produc-
tivity. This may have selected for species, which were able
to adapt to or were already adapted to continental slope or
deep-sea environments. This may explain why the recent
invertebrate shelf fauna is characterised by a large number
of eurybathic species (Brey et al. 1996) and of groups,
which are important components of the deep-sea fauna, like
echinoderms and isopods (Aronson et al. 2007). Further-
more, skeleton-crushing predators amongst crabs and Wsh
are missing. These predators disappeared at about the same
time when climatic cooling occurred. Declining predation
pressure caused a fundamental shift in the structure of the
Antarctic benthic community and a reestablishment of its
archaic character that we observe today (Aronson et al.
2007).
South of the PFZ, species-level endemism is high in the
ocean (Arntz et al. 1997). However, endemism may have
been overestimated and there are species, which occur both
north and south of the PFZ (Barnes and Peck 2008; Thatje
et al. 2005). Furthermore, larvae of South American decapod
species have been found in Antarctic water masses (Thatje
and Fuentes 2003). This indicates that isolation of the Ant-
arctic continent may not be as pronounced as formerly
thought and that reinvasion is possible (Clarke et al. 2005).
However, the establishment of a species on the Antarctic
shelf requires adaptations to constantly low temperature, high
pressure and pronounced seasonality of available resources
(Aronson et al. 2007; Clarke 1988; Clarke et al. 2009).
Reproductive and developmental adaptations have been
discussed to determine decapod distribution patterns
(Thatje et al. 2003). Many subpolar and polar marine inver-
tebrate groups have evolved a high degree of endotrophy
and an abbreviation of larval development to compensate
for scarcity and pronounced seasonality of food supply
(Thorson’s rule, Mileikovsky 1971; Clarke 1988). Whereas
lithodid crab species as well as caridean shrimp species
have adopted these characteristics to various degrees, there
are only few subpolar brachyuran species, which have
developed these traits (Thatje et al. 2003). By contrast,
peracarids keep their young in a brood pouch until they
have completed direct development to juveniles (Luxmoore
1982; Ruppert and Barnes 1994). The female will protect
their young from predators and might even provide nutri-
tion to the more advanced oVspring (Heilmayer et al. 2008;
Janssen and Hoese 1993). It is interesting to note in this
context, that similar to the echinoderms of the Antarctic
shelf (Poulin et al. 2002), the number of crustacean species
with planktonic larvae (decapods) has declined during earth
history, whereas brooding crustaceans (peracarids) have
radiated.
The biogeography of lithodid crabs is probably con-
strained by temperature, as this group has only been found
in waters warmer than 0°C (Hall and Thatje 2009) with
their southernmost habitat being the continental slope of the
western Antarctic Peninsula in the Bellingshausen Sea
(García Raso et al. 2005; Thatje et al. 2008). In contrast,
caridean decapods as well as amphipods and isopods toler-
ate temperatures as low as ¡1.8°C, and are frequently
observed in shallower waters of the continental shelf of
Antarctica (Brandt 1999; Gutt et al. 1991). Most rates of
locomotory activity as well as metabolic and developmen-
tal rates are slower in polar than in temperate species with
similar ecological function. This indicates that these pro-
cesses are not or only poorly temperature-compensated
(Barnes and Peck 2008; Young et al. 2006).
Furthermore, the activity level (quantiWed as righting or
walking speed, relative heart rate and oxygen consumption)
is negatively correlated with haemolymph magnesium con-
centration in decapods (Sartoris et al. 1997; Walters and
Uglow 1981; Watt et al. 1999) and amphipods (Spicer et al.
1994), as reviewed by Morritt and Spicer (1993). This
might be based on the fact that magnesium slows down
neuromuscular transmission by blocking calcium channels,
which makes it useful as anaesthetic (Iseri and French
1984; Katz 1936; Lee et al. 1996; Pantin 1948; Waterman
1941). Quantal content of crayWsh axons, a direct measure
of transmitter release, is reduced at high extracellular mag-
nesium concentration (Parnas et al. 1994). Magnesium
inhibits the secretion of neurohormones from the X-organ-
sinus gland of the land crab Cardisoma carnifex at physio-
logical extracellular levels of 10–15 mmol L¡1 by blocking
calcium currents (Richmond et al. 1995). Similarly, low
temperature reduces the amount of transmitter release in
crayWsh axons, which is thought to be the result of reduced
calcium inXux through calcium channels (Dunn and Mer-
cier 2003). High haemolymph magnesium concentration
and low temperature may therefore work in concert to
decline neuromuscular transmission and rates of activity.
For example Frederich et al. (2000b) observed that the spi-
der crab Hyas araneus was threefold slower at righting
itself at ¡2°C (18.5 s) than at temperatures above 0°C
(6.5 s). When magnesium concentration was experimen-
tally reduced from the natural level of 50 to 6 mmol L¡1,
the mean time-to-right remained at 6.5 s over the entire
investigated thermal range (¡2–6.5°C).
Polar Biol (2010) 33:919–928 921
123
Moreover, all muscular systems, including those of ven-
tilation and circulation may be aVected (Frederich 1999;
Frederich et al. 2000a, b). Low temperature may constrain
physiological functions and this may inXuence the distribu-
tion pattern of crustaceans, following the rationale of the
concept of oxygen limited thermal tolerance (Pörtner
2002). In the temperate spider crab Maja squinado, toler-
ance to cold was constrained by ineYcient ventilation of
the gills and reduced circulation of the haemolymph, which
led to a decline of haemolymph oxygenation and Wnally to
the onset of anaerobic metabolism during progressive cool-
ing (Bock et al. 2001; Frederich and Pörtner 2000). Judged
from a threefold increase in mean cardiac output, the low
threshold for optimal performance (pejus temperature) of
Maja squinado was shifted from 8 to 6°C in an incubation
of low magnesium concentration (6 mmol L¡1) compared
to natural conditions (50 mmol L¡1, Frederich et al. 2000a).
Based on these and further results, the hypothesis was
brought forward that crustaceans which are thought to have
a high capacity for haemolymph magnesium extrusion (car-
idean shrimps, amphipods and isopods) would be more
cold tolerant than those crustaceans which are thought to be
poor magnesium regulators (brachyuran and anomuran
crabs, Sartoris et al. 1997; Frederich et al. 2000b). Today,
this seems to be accepted as the primary explanation for the
biogeography of crustaceans in Antarctica (Aronson et al.
2007; Thatje et al. 2005). Whereas there is experimental
evidence for the relationships between temperature, magne-
sium and physiological functions in temperate and subpolar
brachyuran crabs (Frederich et al. 2000a, b), temperate and
polar caridean shrimps (Sartoris and Pörtner 1997a, b) and
temperate amphipods (Spicer et al. 1994), we do not know
whether there is a relation between temperature, the capac-
ity for magnesium extrusion and other physiological func-
tions in anomuran crabs, amphipods, isopods and other
crustacean groups from the Southern Ocean.
Primary sites for extracellular ion regulation are the gills
and the antennal (decapods, amphipods) or maxillary (iso-
pods) glands (Ruppert and Barnes 1994). These tissues pos-
sess high concentrations of the enzyme Na+/K+-ATPase,
which provides at least part of the driving force for trans-
epithelial ion transport (Khodabandeh et al. 2005; Lucu and
Towle 2003). Sodium, chloride and calcium ion uptake and
secretion may take place across the gill epithelium. In
osmoregulating brachyuran crabs, ionocytes are especially
abundant in the posterior gills. These exhibit a higher Na+/
K+-ATPase activity than the anterior portion of the gills,
which are characterised by a thin epithelium facilitating gas
exchange (Copeland and Fitzjarrell 1968; Neufeld et al.
1980). Urine formation together with magnesium and sul-
phate excretion occurs in the antennal glands. Furthermore,
calcium and potassium ions may be reabsorbed in exchange
for sodium at this site (reviewed by Freire et al. 2008).
In those crustaceans, which have been investigated so
far, haemolymph sodium, chloride and potassium concen-
trations are usually kept at levels similar to those in sea
water (Mantel and Farmer 1983). Extracellular calcium
concentration varies during the molt cycle (Robertson
1960). Magnesium concentration is strongly hyporegulated
in caridean shrimp, amphipod and most isopod species
([Mg2+]HL < 20 mmol L¡1) and to a much lesser extent in
anomuran and brachyuran crab species ([Mg2+]HL = 20–
50 mmol L¡1, Burton 1995 and references therein; Frede-
rich 1999; Robertson 1953). Sulphate seems to show the
same pattern, but only few measurements have been under-
taken, particularly few in amphipods and isopods (Mantel
and Farmer 1983).
In this study, we present the Wrst analyses of ionic com-
position of the haemolymph of Antarctic amphipods and
isopods and of lithodid crab species occurring near Sub-
Antarctic islands. Altogether, we provide information on 12
species of decapods, isopods and amphipods and discuss
the results with a focus on the hypothesis that extracellular
magnesium regulation shapes the biogeography of crusta-
ceans in the Southern Ocean.
Materials and methods
Sample collection
Haemolymph samples of Lithodes confundens, Paralomis
formosa, Paralomis spinosissima and Peltarion spinosulum
were collected during the ICEFISH Cruise in June 2004
(http://www.icefish.neu.edu/). Specimens of Notocrangon
antarcticus, Eurythenes gryllus, Abyssorchomene plebs,
Eusirus propeperdentatus, Glyptonotus antarcticus, Nata-
tolana sp. and Ceratoserolis trilobitoides were obtained
during Polarstern expedition ANT XXIII/8 in the Antarctic
summer 2007. Haemolymph samples were collected either
on board directly (RV Nathaniel B. Palmer or RV Polar-
stern) or from live animals transported back to the Alfred
Wegener Institute for Polar and Marine Research in Brem-
erhaven, Germany (AWI) after an acclimation period of
1 week at 0°C and 32.5 ppt. Male specimens of Paralomis
granulosa were obtained from local Wshermen in Punta
Arenas, Chile in April 2008, the collection site is therefore
not known precisely (Table 1). These animals were trans-
ported to the AWI on board RV Polarstern and kept in a
recirculating aquarium system at 4°C and 32.5 ppt for
1 year until haemolymph samples were taken. Laboratory-
kept animals were fed ad libitum with pieces of Mytilus
edulis, Cerastoderma edule or Crangon crangon.
Animals were blotted dry before haemolymph was with-
drawn either with a syringe and hypodermic needle, which
was inserted through an arthrodial membrane at the coxa of
922 Polar Biol (2010) 33:919–928
123
a walking leg (crabs), in the heart region (N. antarcticus,
E. gryllus, E. propeperdentatus) or by inserting a pointed
glass capillary dorsally into the heart region of the animals
(remaining species). Samples were stored at ¡20°C or
¡80°C until being analysed.
Sea water ion composition at 35 ppt salinity was taken
from Atkinson and Bingman (1997) for comparison with
Weld-sampled individuals and calculated for 32.5 ppt for
comparison with laboratory-kept animals (Table 2).
Ion chromatography
Ion composition of haemolymph was determined by ion
chromatography (ICS-2000, Dionex®, Idstein, Germany)
after dilution of the samples with deionised water. A con-
ductivity cell and a self-regenerating suppressor were
used to reduce background conductivity. Cations (Na+,
K+, Mg2+, Ca2+) were separated on an IonPac® CS16 col-
umn with methane sulfonic acid (30 mmol L¡1) as eluent
at a Xow rate of 0.36 mL min¡1 at 40°C. Anions (Cl¡,
SO42¡) were separated on an IonPac® AS11-HC column
with potassium hydroxide (30 mmol L¡1) as eluent at a
Xow rate of 0.30 mL min¡1 at 30°C. Ion concentrations
were calculated in mmol L¡1 relative to the Dionex® Six
Cation-II or Five Anion Standards and are also given in
percent of the ambient sea water ion concentrations to
make data of Weld-sampled and laboratory-kept animals
comparable.
Statistical analyses
Before calculating means §standard deviation (SD), outli-
ers were identiWed by use of the Nalimov test on the sum of
all ions of each individual. One-way ANOVA and post hoc
Dunett’s multiple comparison tests were run to compare
means of percentages of ions in haemolymph with those of
sea water (always 100%). DiVerences were termed “signiW-
cant” if p values were below 0.05. ANOVA as well as lin-
ear regression and Pearson correlation analyses were
performed by use of Prism 4.0a.
Results
For each collection site monthly means of water tempera-
tures at the respective depth were taken from Locarnini
et al. (2006, Table 1). Anomuran and brachyuran decapods
were found in waters with temperatures above 0°C while
the caridean decapod Notocrangon antarcticus as well as
most of the peracarids were collected in waters of or below
0°C.
All species except Peltarion spinosulum displayed sig-
niWcantly lower haemolymph magnesium levels compared
to sea water (Fig. 1, Table 2). Despite of this, there are
diVerences in the extent of downregulation of magnesium
between groups. Whereas brachyuran and anomuran deca-
pods as well as isopods maintained rather high haemo-
lymph magnesium levels between 54 §2% and 82 §6%
of sea water, those of the caridean decapod Notocrangon
antarcticus and the amphipods were well below half of the
value of sea water, between 6% (E. propeperdentatus) and
20 §2% (E. gryllus).
Likewise, the haemolymph sulphate content of all spe-
cies except that of Peltarion spinosulum was signiWcantly
lower than that in sea water (Table 2). The amphipod E.
gryllus exhibited the lowest value of 7 §2%.
Table 1 Collection sites, mean Wshing depth (m) of the sampled crustaceans and approximate ambient water temperature (°C) at the time of
collection (Locarnini et al. 2006)
Taxon Species Collection sites Depth (m) Temperature (°C)
Decapoda, Brachyura Peltarion spinosulum 51°41⬘ S, 57°27⬘ W 130 6.0
Decapoda, Anomura Lithodes confundens 53°39⬘ S, 40°44⬘ W 410 2.0
Paralomis formosa 56°19⬘ S, 27°27⬘ W 340 1.0
Paralomis granulosa Magellan region Unknown 5.0–8.0?
Paralomis spinosissima 53°39⬘ S, 40°44⬘ W 410 2.0
Decapoda, Caridea Notocrangon antarcticus 65° 32⬘ S, 61° 30⬘ W 490 ¡1.0 to ¡0.5
Peracarida, Amphipoda Abyssorchomene plebs 60° 57⬘ S, 55° 55⬘ W 231 0.0
Eurythenes gryllus 62° 58⬘ S, 57° 58⬘ W 839 1.5
Eusirus propeperdentatus 62° 58⬘ S, 57° 58⬘ W 839 1.5
Peracarida, Isopoda Glyptonotus antarcticus 61° 20⬘ S, 55° 32⬘ W 137 ¡1.0
62° 19⬘ S, 60° 27⬘ W 109 ¡1.0
Natatolana sp. 60° 57⬘ S, 55° 55⬘ W 231 0.0
Ceratoserolis trilobitoides 70° 31⬘ S, 8° 48⬘ W 297 0.0
61° 22⬘ S, 56° 1⬘ W 353 ¡0.5
Polar Biol (2010) 33:919–928 923
123
Species which maintained low haemolymph magnesium
concentrations usually maintained low sulphate levels as
well (Fig. 2). This resulted in a signiWcantly (p= 0.0023)
positive, linear correlation between magnesium and sul-
phate percentages with Pearson r= 0.8147 and r2= 0.6638
where all investigated species were considered, except E.
propeperdentatus, which was excluded because of the
small sample size. Only the isopod Natatolana sp., which
showed a signiWcantly reduced sulphate percentage in spite
of a high magnesium percentage deviated from this rela-
tionship.
Haemolymph sodium content was equal to or slightly
lower than in sea water in most species and only signiW-
cantly reduced in Natatolana sp. and C. trilobitoides with
values of 87 §10% and 87 §6% (Table 2).
In most investigated species haemolymph calcium was
not signiWcantly diVerent from the sea water level. Only
Peltarion spinosulum exhibited a remarkably low value of
54 §34% of sea water calcium concentration (Table 2).
Haemolymph potassium concentrations were close to
sea water level in the majority of species. However, E.
propeperdentatus displayed an extremely low value of
59%, N. antarcticus, A. plebs and E. gryllus had signiW-
cantly decreased potassium values and L. confundens had a
signiWcantly increased level compared to sea water
(Table 2). Furthermore, there was a signiWcantly
(p= 0.0044) positive correlation between magnesium and
potassium percentages amongst all species in this study (E.
propeperdentatus was excluded) with Pearson r= 0.7824
(Fig. 3).
Table 2 Haemolymph inorganic ion composition of Sub-Antarctic and Antarctic crustaceans determined by ion chromatography (mmol L¡1) and
expressed as percent of ambient sea water ion concentrations given as means §SD, n number of individuals sampled
aField sampling, % values calculated in relation to ambient sea water with salinity 35 ppt
bAnimals kept in the laboratory prior to sampling, fed ad libitum, % values calculated in relation to ambient sea water with salinity 32.5 ppt
*SigniWcantly diVerent from ambient sea water (100%)
nUnit Na+Cl¡K+Ca2+ Mg2+ SO42¡
Sea water % 100 100 100 100 100 100
32.5 ppt mmol L¡1446 522 9.7 9.8 50.3 26.6
35 ppt mmol L¡1481 563 10.4 10.5 54.2 28.6
Peltarion spinosuluma4% 99§485§7 112 §12 51 §34* 96 §4 104 §12
mmol L¡1477 §19 479 §39 11.6 §1.2 5.4 §3.5 51.7 §1.9 30.3 §3.4
Lithodes confundensa9% 100§688§7 133 §20* 119 §14 68 §15* 77 §12*
mmol L¡1478 §28 505 §43 13.9 §2.0 12.5 §1.4 37.0 §7.6 22.4 §3.4
Paralomis formosaa7% 106§5100§3 101 §10 104 §17 73 §7* 79 §14*
mmol L¡1508 §24 563 §17 10.6 §1.0 10.9 §1.8 39.5 §3.8 22.8 §4.1
Paralomis granulosab8% 97§294§3 118 §13 110 §580§4* 63 §8*
mmol L¡1431 §11 491 §15 11.4 §1.3 10.8 §0.5 40.0 §1.9 16.9 §2.2
Paralomis spinosissimaa10 % 99 §395§5 105 §10 106 §16 75 §5* 71 §8*
mmol L¡1475 §15 533 §29 10.9 §1.0 11.2 §1.7 40.7 §2.6 20.5 §2.4
Notocrangon antarcticusa6% 98§782§9* 72 §16* 140 §20 16 §11* 33 §10*
mmol L¡1476 §34 477 §60 7.7 §1.7 14.5 §2.0 11.0 §8.5 10.6 §4.0
Abyssorchomene plebsb5% 89§577§4* 60 §6* 112 §16 20 §2* 33 §9*
mmol L¡1397 §22 404 §21 5.9 §0.6 11.0 §1.6 10.0 §0.8 8.9 §2.3
Eurythenes gryllusa10 % 101 §595§568§4* 95 §40 20 §2* 7 §2*
mmol L¡1479 §29 530 §36 7.1 §0.4 9.9 §4.0 11.1 §0.9 2.0 §0.6
Eusirus propeperdentatusa2 % 119 112 59 99 6 33
mmol L¡1574 629 6.2 10.4 3.5 9.7
Glyptonotus antarcticusb5% 93§493§4 126 §12 101 §654§2* 31 §2*
mmol L¡1415 §15 509 §53 12.2 §1.2 9.8 §0.6 30.4 §8.5 12.4 §9.6
Natatolana sp.b6% 87§10* 83 §10* 106 §19 111 §782§6* 46 §10*
mmol L¡1390 §47 437 §52 10.3 §1.8 10.9 §0.7 41.0 §3.0 12.5 §2.6
Ceratoserolis trilobitoidesb6% 87§6* 83 §8* 99 §10 97 §11 60 §12* 69 §10*
mmol L¡1388 §25 435 §41 9.6 §0.92 9.5 §1.0 29.8 §5.8 18.7 §2.7
924 Polar Biol (2010) 33:919–928
123
Haemolymph chloride levels of most investigated ani-
mals were equal to or lower than that in sea water. In N.
antarcticus, A. plebs, Natatolana sp. and C. trilobitoides
haemolymph chloride content even was signiWcantly below
that of sea water and comprised only 82 §9% of the sea
water concentration in N. antarcticus (Table 2).
Discussion
Sub-Antarctic lithodid crab species exhibited a relatively
low but signiWcant capability for magnesium extrusion
from the haemolymph. Our data compare well to those
obtained in previous studies on the northern species Lith-
odes maja (where [Mg2+]HL =50mmolL
¡1, which corre-
sponds to about 92% of sea water concentration, Robertson
1953), Paralithodes camtschatica ([Mg2+]HL = 37 mmol L¡1,
t69%, Mackay and Prosser 1970) and Neolithodes grimal-
dii collected during summer ([Mg2+]HL =33mmolL
¡1,
t61%, McAllen et al. 2005). However, our value for
P. granulosa is twice as high as that recorded by Frederich
(1999) for this species (17–24 mmol L¡1, t31–44%). This
diVerence might be attributable to a diVerent nutritional
state of the animals because McAllen et al. (2005) found
signiWcantly lower haemolymph magnesium levels
Fig. 2 Relationship between magnesium and sulphate in the haemo-
lymph (% of ambient sea water ion concentrations) of all species inves-
tigated except Eusirus propeperdentatus, which was excluded because
of the low sample size. SigniWcant positive correlation with Pearson
r= 0.8147, p= 0.0023, and linear regression of r2= 0.6638 with 95%
conWdence bands. Values are means §SD
Fig. 1 Magnesium concentra-
tion in the haemolymph of
Sub-Antarctic and Antarctic
crustaceans (% of ambient sea
water magnesium concentra-
tion). Values are means §SD.
All values except that of Peltari-
on spinosulum are signiWcantly
diVerent from ambient sea water
(100%)
Fig. 3 Relationship between magnesium and potassium in the haemo-
lymph (% of ambient sea water ion concentrations) of all species inves-
tigated except Eusirus propeperdentatus, which was excluded because
of the low sample size. SigniWcant positive correlation (Pearson
r= 0.7824, p= 0.0044) and linear regression of r2= 0.6122 with 95%
conWdence bands. Values are means §SD
Polar Biol (2010) 33:919–928 925
123
([Mg2+]HL = 20 mmol L¡1, t37%) in N. grimaldii along
with signiWcantly lower haemolymph protein levels during
spring when food was presumably scarce. Extracellular
protein concentration decreases during starvation (Dall
1974). Whereas the activation of energy demanding magne-
sium excretion appears paradoxical during food depriva-
tion, its physiological role could be an activation of the
organism to trigger foraging activity (McAllen et al. 2005).
An increase in walking activity was observed when
brachyuran crabs were experimentally exposed to artiWcial
sea water with reduced magnesium concentration (Frede-
rich et al. 2000b).
The haemolymph magnesium concentration of the
brachyuran Peltarion spinosulum from the Falkland Islands
did not diVer signiWcantly from that of sea water. Our data
were similar to those previously recorded for P. spinosulum
and for other subtidal brachyuran species from the Sub-
Antarctic (e.g. Eurypodius latreillei; Frederich 1999) and
from temperate northern latitudes (e.g. Dromia vulgaris,
Hyas araneus; Robertson 1953; Frederich 1999).
Previous analyses of haemolymph ion composition in
isopods were focused on species from intertidal, estuarine
or semiterrestrial habitats. These species regulate magne-
sium down to below 20 mmol L¡1 (Burton 1995 and refer-
ences therein; Parry 1953; Ziegler et al. 2000). In contrast,
the extracellular magnesium concentration of the deep-sea
isopod Bathynomus doderleini does not diVer from that of
sea water (F.-Tsukamoto et al. 2000). Despite this, the rela-
tively well-developed ability to downregulate magnesium
in temperate intertidal isopods has been extrapolated to be
valid for polar species and has served as a possible explana-
tion for their advantage over decapod crabs to colonise high
Antarctic waters (Frederich et al. 2000b; Thatje et al.
2005). Here, we showed that the capacity for magnesium
regulation of the polar isopods was in the same range as
that of the lithodid crabs. A high level of magnesium in the
haemolymph therefore does not constrain the isopods to
warmer waters. However, a correlation between the general
life style/activity and haemolymph magnesium concentra-
tion may be postulated. Glyptonotus antarcticus exhibited a
relatively low magnesium fraction and is described as a
“rude carnivorous benthic scavenger and predator” (Jans-
sen and Hoese 1993) and actively forages for food (C.
Held, personal observation). Natatolana sp. possessed a
high haemolymph magnesium fraction and are burrow
dwellers similar to Natatolana borealis from Scottish
waters (Taylor and Moore 1995). These animals adopt a sit-
and-wait strategy (C. Held, personal observation): when
dwelling in the burrow, the animals remain inactive except
for ventilatory burrow irrigation. However, they exhibit
excellent swimming behaviour once carrion or prey is
detected by them. After feeding, they return to an inactive
mode and digest while staying in their burrows. High extra-
cellular magnesium concentration and reduced activity lev-
els may increase tolerance to hypoxia (Sartoris and Pörtner
1997a), which is frequently encountered by infaunal spe-
cies. Whereas investigations on the relationships between
nutritional state, activity, cold tolerance and haemolymph
magnesium levels in isopods are still missing, we may
hypothesise that neuromuscular transmission of isopods is
less sensitive to magnesium than that of decapods. Further-
more, it is possible that haemolymph magnesium concen-
tration varies according to the nutritional condition of the
animals and that this inXuences their activity level. These
adaptations may allow them to thrive in the extremely cold
waters of the Antarctic shelf despite relatively high haemo-
lymph magnesium concentration as observed in our well-
fed laboratory animals.
The Antarctic amphipods as well as the caridean shrimp
were found to be excellent magnesium regulators similar
to their temperate counterparts (Mantel and Farmer 1983;
Normant et al. 2005) or tropical oceanic relatives (Tentori
and Lockwood 1990). Therefore, ion regulation is not con-
strained by low temperature but is compensated by these
cold adapted species. This was also found in the Arctic
amphipod Apherusa glacialis (Kiko et al. 2009), the north-
ern caridean prawn Pandalus borealis (Sartoris and Pört-
ner 1997b) and the Antarctic caridean shrimp Chorismus
antarcticus (Frederich 1999). In contrast, when the tem-
perate amphipod sandhopper Talitrus saltator was
exposed to winter cold, it ceased to extrude magnesium
from the haemolymph and fell into a torpor state (Spicer
et al. 1994). Similarly, the capacity for magnesium regula-
tion was hampered in tropical pelagic amphipods, when
experimentally exposed to temperatures far below their
natural temperature range (Tentori and Lockwood 1990).
Amongst the caridean shrimps, the temperate Crangon
crangon exhibited increased haemolymph magnesium
concentrations during short-term exposure to cold (Sarto-
ris and Pörtner 1997a).
The strong positive correlation between haemolymph
magnesium and sulphate levels indicates that sulphate is
regulated in parallel to magnesium for compensation of
osmotic equilibrium (Robertson 1953). The mechanisms
for magnesium and sulphate excretion in the antennal gland
are not known in detail, but there is evidence that they func-
tion independently of each other. When exposed to salinity
variations, sulphate extrusion ceased earlier than magne-
sium extrusion in e.g., an amphipod (Kiko et al. 2009) and
a brachyuran decapod (Zanders 1980). Furthermore, it is
known from both lobster hepatopancreas and Xounder kid-
ney, that sulphate is exported by use of sulphate-anion
exchangers (Gerencser et al. 2001). Sulphate excretion in
the antennal gland may be based on a similar mechanism
and therefore may work independently of magnesium trans-
port.
926 Polar Biol (2010) 33:919–928
123
Extracellular sodium, chloride and potassium were kept
close to equilibrium with sea water in most species. This is
a general pattern found in marine crustaceans (Mantel and
Farmer 1983). Calcium is the major component of the cara-
pace, therefore extracellular concentrations vary during the
molt cycle (Mantel and Farmer 1983; Robertson 1960).
Cation relationships were similar to those collected by Bur-
ton (1995) in over 70 sea water and freshwater crustacean
species. He concluded that “haemolymph composition has
evolved in such a way as to preserve the transmembrane
potential” across the cell membrane. Maintenance of the
transmembrane potential is crucial for animals, because it
guarantees the excitability of nerve and muscle and drives
ion transport processes (Eckert et al. 2000). If so, we can
conclude from this, that our sampled individuals were in
good health.
In summary, our results comply with previous assump-
tions and Wndings (Frederich et al. 2000b; Thatje et al.
2005), that lithodid crabs from the Southern Ocean are
rather poor haemolymph magnesium regulators and do
not thrive in waters colder than 0°C and that caridean
shrimps which exhibit a high capacity for magnesium reg-
ulation can be found in high Antarctic waters of tempera-
tures below 0°C. Amongst the peracarids, the Antarctic
amphipod species displayed a magnesium regulatory
capacity similar to species examined in previous studies
from tropic, temperate and polar latitudes (Kiko et al.
2009; Mantel and Farmer 1983; Spicer et al. 1994; Ten-
tori and Lockwood 1990). In contrast, the Antarctic iso-
pods only regulated extracellular magnesium to the same
extent as the lithodids. The isopods must therefore pos-
sess diVerent physiological and ecological adaptations,
which give them an advantage over the decapod crabs and
which enable them to thrive in high Antarctic waters.
Concerning the physiology, this could be a reduced sensi-
tivity of neuromuscular systems to magnesium compared
to the lithodid crabs. Apart from this, diVerent reproduc-
tive traits, like a direct development of the young, which
may remain rather inactive as they are carried in a brood
pouch or diVerent food preferences could have contrib-
uted to the success of the peracarids in the Antarctic
(Janssen and Hoese 1993; Brandt 1999).
Acknowledgments We would like to thank Timo Hirse and Florian
Leese for sample collection. We greatly appreciate the help of the crew
of RV Polarstern during the transport of live animals. The experiments
comply with the current laws of the country in which they were per-
formed. This study was supported by Deutsche Forschungsgemeins-
chaft grants no. SA 1713 and He 3391/3 and by National Science
Foundation grant no. OPP V01-32032. This is publication 25 of the
ICEFISH cruise 2004.
ConXict of interest statement The authors declare that they have no
conXict of interest
References
Arntz WE, Gutt J, Klages M (1997) Antarctic marine biodiversity: an
overview. In: Battaglia B, Valencia J, Walton DWH (eds) Antarc-
tic communities: species, structure and survival. Cambridge Uni-
versity Press, Cambridge, pp 3–14
Aronson RB, Thatje S, Clarke A, Peck LS, Blake DB, Wilga CD, Sei-
bel BA (2007) Climate change and invasibility of the Antarctic
benthos. Annu Rev Ecol Syst 38:129–154
Atkinson MJ, Bingman C (1997) Elemental composition of commer-
cial seasalts. J Aquacult Aquat Sci 8:39–43
Barnes D, Peck LS (2008) Vulnerability of Antarctic shelf biodiversity
to predicted regional warming. Clim Res 37:149–163
Bock C, Frederich M, Wittig R-M, Pörtner HO (2001) Simultaneous
observations of haemolymph Xow and ventilation in marine spi-
der crabs at diVerent temperatures: a Xow weighted MRI study.
Magn Reson Imaging 19:1113–1124
Brandt A (1999) On the origin and evolution of Antarctic Peracarida.
Sci Mar 63:261–274
Brey T, Dahm C, Gorny M, Klages M, Stiller M, Arntz WE (1996) Do
Antarctic benthic invertebrates show an extended level of eury-
bathy? Antarct Sci 8:3–6
Burton RF (1995) Cation balance in crustacean haemolymph: relation-
ship to cell membrane potentials and membrane surface charge.
Comp Biochem Physiol A 111:125–131
Clarke A (1988) Seasonality in the Antarctic marine environment.
Comp Biochem Physiol B 90:461–473
Clarke A, Barnes DKA, Hodgson DA (2005) How isolated is Antarc-
tica? Trends Ecol Evol 20:1–3
Clarke A, GriYths HJ, Barnes DKA, Meredith MP, Grant SM (2009)
Spatial variation in seabed temperatures in the Southern Ocean:
implications for benthic ecology and biogeography. J Geophys
Res 114:G03003. doi:10.1029/2008JG000886
Copeland DE, Fitzjarrell AT (1968) The salt absorbing cells in the gills
of the blue crab (Callinectes sapidus Rathbun) with notes on mod-
iWed mitochondria. Z Zellforsch 92:1–22
Dall W (1974) Indices of nutritional state in the western rock lobster,
Panulirus longipes (Milne Edwards). I. Blood and tissue constit-
uents and water content. J Exp Mar Biol Ecol 16:167–180
Dunn TW, Mercier AJ (2003) Synaptic modulation by a neuropeptide
depends on temperature and extracellular calcium. J Neurophysi-
ol 89:1807–1814
Eckert R, Randall D, Burggren WW, French K (2000) Tierphysiologie.
Thieme, Stuttgart
Feldmann RM, Zinsmeister WJ (1984a) First occurrence of fossil
decapod crustaceans (Callianassidae) from the McMurdo Sound
region, Antarctica. J Paleontol 58:1041–1045
Feldmann RM, Zinsmeister WJ (1984b) New fossil crabs (Decapoda:
Brachyura) from the La Meseta Formation (Eocene) of Antarc-
tica: paleogeographic and biogeographic implications. J Paleontol
58:1046–1061
Frederich M (1999) Ecophysiological limits to the geographical distri-
bution of reptant decapod crustaceans in the Antarctic. Rep Polar
Res 335
Frederich M, Pörtner HO (2000) Oxygen limitation of thermal toler-
ance deWned by cardiac and ventilatory performance in the spider
crab, Maja squinado. Am J Physiol Regul Integr Comp Physiol R
279:1531–1538
Frederich M, DeWachter B, Sartoris FJ, Pörtner HO (2000a) Cold tol-
erance and the regulation of cardiac performance and hemolymph
distribution in Maja squinado (Crustacea: Decapoda). Physiol
Biochem Zool 73:406–415
Frederich M, Sartoris FJ, Arntz WE, Pörtner HO (2000b) Haemo-
lymph Mg2+ regulation in decapod crustaceans: physiological
Polar Biol (2010) 33:919–928 927
123
correlates and ecological consequences in polar areas. J Exp Biol
203:1383–1393
Freire CA, Onken H, McNamara JC (2008) A structure-function anal-
ysis of ion transport in crustacean gills and excretory organs.
Comp Biochem Physiol A 151:272–304
F.-Tsukamoto Y, Kuwasawa K, Takeuchi S, Mano M (2000) Physio-
logical saline suitable for the marine isopod crustacean Bathyno-
mus doederleini. Zool Sci 17:425–430
García Raso JE, Manjón-Cabeza ME, Ramos A, Olaso I (2005) New
record of Lithodidae (Crustacea, Decapoda, Anomura) from the
Antarctic (Bellingshausen Sea). Polar Biol 28:642–646
Gerencser GA, Ahearn GA, Zhang J, Cattey MA (2001) Sulfate trans-
port mechanisms in epithelial systems. J Exp Zool 289:245–253
Gorny M (1999) On the biogeography and ecology of the Southern
Ocean decapod fauna. Sci Mar 63:367–382
Gutt J, Gorny M, Arntz WE (1991) Spatial distribution of Antarctic
shrimps (Crustacea: Decapoda) by underwater photography. Ant-
arct Sci 3:363–369
Gutt J, Sirenko BI, Smirnov IS, Arntz WE (2004) How many macro-
zoobenthic species might inhabit the Antarctic shelf? Antarct Sci
16:11–16
Hall S, Thatje S (2009) Global bottlenecks in the distribution of marine
Crustacea: temperature constraints in the family Lithodidae. J
Biogeogr. doi:10.1111/j.1365-2699.2009.02153.x
Heilmayer O, Thatje S, McClelland C, Conlan K, Brey T (2008)
Changes in biomass and elemental composition during early
ontogeny of the Antarctic isopod crustacean Ceratoserolis trilob-
itoides. Polar Biol 31:1325–1331
Held C (2000) Phylogeny and biogeography of serolid isopods (Crusta-
cea, Isopoda, Serolidae) and the use of ribosomal expansion seg-
ments in molecular systematics. Mol Phylogen Evol 15:165–178
Iseri LT, French JH (1984) Magnesium: nature’s physiologic calcium
blocker. Am Heart J 108:188–193
Janssen HH, Hoese B (1993) Marsupium morphology and brooding
biology of the Antarctic giant isopod Glyptonotus antarcticus
Eights 1853 (Crustacea, Isopoda, Chaetiliidae). Polar Biol
13:145–149
Katz B (1936) Neuro-muscular transmission in crabs. J Physiol
87:199–221
Khodabandeh S, Charmantier G, Charmantier-Daures M (2005) Ultra-
structural Studies and Na+, K+-ATPase immunolocalization in
the antennal urinary glands of the lobster Homarus gammarus
(Crustacea, Decapoda). J Histochem Cytochem 53:1203–1214
Kiko R, Werner I, Wittmann A (2009) Osmotic and ionic regulation in
response to salinity variations and cold resistance in the Arctic un-
der-ice amphipod Apherusa glacialis. Polar Biol 32:393–398
Lawver LA, Gahagan LM (2003) Evolution of Cenozoic seaways in
the circum-Antarctic region. Palaeogeogr Palaeoclimatol Palaeo-
ecol 198:11–38
Lee C, Zhang X, Kwan WF (1996) Electromyographic and mechano-
myographic characteristics of neuromuscular block by magne-
sium sulphate in the pig. Br J Anaesth 76:278–283
Locarnini RA, Mishonov AV, Antonov JI, Boyer TP, Garcia HE
(2006) Temperature. In: Levitus S (ed) World Ocean Atlas 2005,
vol 1. U.S. Government Printing OYce, Washington D.C.
Lucu C, Towle DW (2003) Na++K+-ATPase in gills of aquatic crusta-
cea. Comp Biochem Physiol A 135:195–214
Luxmoore RA (1982) The reproductive biology of some serolid iso-
pods from the Antarctic. Polar Biol 1:3–11
Mackay WC, Prosser CL (1970) Ionic and osmotic regulation in the
king crab and two other North PaciWc crustaceans. Comp Bio-
chem Physiol 34:273–280
Mantel LH, Farmer LL (1983) Osmotic and ionic regulation. In: Bliss
DE (ed) The biology of Crustacea, vol 5. Academic Press, New
York, pp 53–161
McAllen R, Taylor A, Freel J (2005) Seasonal variation in the ionic
and protein content of haemolymph from seven deep-sea decapod
genera from the Northeast Atlantic Ocean. Deep Sea Res (1 Oce-
anogr Res Pap) 52:2017–2028
Mileikovsky SA (1971) Types of larval development in marine bottom
invertebrates, their distribution and ecological signiWcance: a
re-evaluation. Mar Biol 10:193–213
Morritt D, Spicer JI (1993) A brief re-examination of the function and
regulation of extracellular magnesium and its relationship to
activity in crustacean arthropods. Comp Biochem Physiol A
106:19–23
Neufeld GJ, Holliday CW, Pritchard JB (1980) Salinity adaptation of
gill Na, K-ATPase in the blue crab, Callinectes sapidus. J Exp
Zool 211:215–224
Normant M, Kubicka M, Lapucki T, Czarnowski W, Michalowska M
(2005) Osmotic and ionic haemolymph concentrations in the
Baltic Sea amphipod Gammarus oceanicus in relation to water
salinity. Comp Biochem Physiol A 141:94–99
Orsi AH, Whitworth T, Nowlin WD (1995) On the meridional extent
and fronts of the Antarctic Circumpolar Current. Deep-Sea Res (1
Oceanogr Res Pap) 42:641–673
Pantin CFA (1948) Notes on microscopocal techniques for zoologists.
Cambridge University Press, Cambridge
Parnas H, Parnas I, Ravin R, Yudelevitch B (1994) Glutamate and N-
methyl-D-aspartate aVect release from crayWsh axon terminals in
a voltage-dependent manner. Proc Natl Acad Sci USA 91:11586–
11590
Parry G (1953) Osmotic and ionic regulation in the isopod crustacean
Ligia oceanica. J Exp Biol 30:567–574
Pörtner HO (2002) Climate variations and the physiological basis of
temperature dependent biogeography: systemic to molecular hier-
archy of thermal tolerance in animals. Comp Biochem Physiol A
132:739–761
Poulin E, Palma AT, Feral JP (2002) Evolutionary versus ecological
success in Antarctic benthic invertebrates. Trends Ecol Evol
17:218–222
Richmond J, Sher E, Keller R, Haylett B, Reichwein B, Cooke I (1995)
Regulation of calcium currents and secretion by magnesium in
crustacean peptidergic neurons. Invertebr Neurosci 1:215–221
Robertson JD (1953) Further studies on ionic regulation in marine
invertebrates. J Exp Biol 30:277–296
Robertson JD (1960) Ionic regulation in the crab Carcinus maenas (L.)
in relation to the moulting cycle. Comp Biochem Physiol 1:183–
212
Ruppert EE, Barnes RD (1994) Invertebrate zoology, 6th edn. Saun-
ders College Publishing, Orlando
Sartoris FJ, Pörtner HO (1997a) Increased concentrations of haemo-
lymph Mg2+ protect intracellular pH and ATP levels during tem-
perature stress and anoxia in the common shrimp Crangon
crangon. J Exp Biol 200:785–792
Sartoris FJ, Pörtner HO (1997b) Temperature dependence of ionic and
acid-base regulation in boreal and arctic Crangon crangon and
Pandalus borealis. J Exp Mar Biol Ecol 211:69–83
Sartoris FJ, Frederich M, Pörtner HO (1997) Does the capability to
regulate magnesium determine the composition of the Antarctic
crustacean fauna? Verh Dtsch Zool Ges 90:144
Spicer JI, Morritt D, Taylor AC (1994) EVect of low temperature on
oxygen uptake and haemolymph ions in the sandhopper Talitrus
saltator (Crustacea: Amphipoda). J Mar Biol Assoc UK 74:313–
321
Taylor AC, Moore PG (1995) The burrows and physiological adapta-
tions to a burrowing lifestyle of Natatolana borealis (Isopoda:
Cirolanidae). Mar Biol 123:805
Tentori E, Lockwood APM (1990) Haemolymph magnesium levels in
some oceanic Crustacea. Comp Biochem Physiol A 95:545–548
928 Polar Biol (2010) 33:919–928
123
Thatje S, Fuentes V (2003) First record of anomuran and brachyuran
larvae (Crustacea: Decapoda) from Antarctic waters. Polar Biol
26:279–282
Thatje S, Schnack-Schiel S, Arntz WE (2003) Developmental trade-
oVs in Subantarctic meroplankton communities and the enigma of
low decapod diversity in high southern latitudes. Mar Ecol Prog
Ser 260:195–207
Thatje S, Anger K, Calcagno GA, Lovrich GA, Pörtner HO, Arntz WE
(2005) Challenging the cold: crabs reconquer the Antarctic. Ecol-
ogy 86:619–625
Thatje S, Hall S, Hauton C, Held C, Tyler P (2008) Encounter of litho-
did crab Paralomis birsteini on the continental slope oV Antarc-
tica, sampled by ROV. Polar Biol 31:1143–1148
Walters NJ, Uglow RF (1981) Haemolymph magnesium and relative
heart activity of some species of marine decapod crustaceans.
J Exp Mar Biol Ecol 55:255–265
Waterman TH (1941) A comparative study of the eVects of ions on
whole nerve and isolated single nerve Wber preparations of crus-
tacean neuromuscular systems. J Cell Comp Physiol 18:109–126
Watt AJS, Whiteley NM, Taylor EW (1999) An in situ study of respi-
ratory variables in three British sublittoral crabs with diVerent
routine rates of activity. J Exp Mar Biol Ecol 239:1–21
Young JS, Peck LS, Matheson T (2006) The eVects of temperature on
walking and righting in temperate and Antarctic crustaceans. Po-
lar Biol 29:978–987
Zanders IP (1980) The control of magnesium and sulphate excretion in
Carcinus maenas (L.). Comp Biochem Physiol A 66:69–76
Ziegler A, Grospietsch T, Carefoot TH, Danko JP, Zimmer M, Zerbst-
BoroVka I, Pennings SC (2000) Hemolymph ion composition and
volume changes in the supralittoral isopod Ligia pallasii Brandt,
during molt. J Comp Physiol B 170:329–336
