View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Electronic Publication Information Center Polar Biol (2004) 27: 195–201 DOI 10.1007/s00300-003-0583-z REVIEW Sven Thatje Æ Wolf E. Arntz Antarctic reptant decapods: more than a myth? Received: 21 August 2003 / Accepted: 28 November 2003 / Published online: 10 February 2004 Ó Springer-Verlag 2004 Abstract The impoverished Antarctic decapod fauna is dition of the German Polar Commission to South one of the most conspicuous biodiversity phenomena in Georgia in 1882–1883 (Pfeffer 1887). polar science. Although physiological and ecological Since then, a few new species and records of decapods approaches have tried to explain the reason for the low have been reported from the Southern Ocean (Yaldwyn decapod biodiversity pattern in the Southern Ocean, the 1965; Kirkwood 1984; Tiefenbacher 1990; Thatje 2003). complexity of this problem is still not completely However, known Antarctic decapod diversity remains understood. The scant records of crabs south of poor, represented by approximately only a dozen ben- the Polar Front were always considered as exceptional, thic natant (caridean shrimp) species. Some of those and have mostly been ignored by marine biologists species are known to occur in high abundances on the world-wide, creating one of the most dogmatic para- high-Antarctic Weddell Sea shelf (Arntz and Gorny digms in polar science. We herein review the record of 1991; Arntz et al. 1992; Gorny 1999). both adults and larvae of reptants from the Southern Low temperature is the main physiological impact Ocean. At present, several species of only lithodid crabs on life in polar areas, and results in low metabolic rates maintain considerable adult populations in circum- in polar ectotherms (Clarke 1983; Peck 2001). Low Antarctic waters, although they remain absent from the temperatures in general have been hypothesised to re- high-Antarctic shelves. duce decapod activity, especially in combination with high [Mg2+] levels in the haemolymph, as [Mg2+] has a relaxant effect (Frederich 1999; Frederich et al. 2001). 2+ Since Reptantia regulate [Mg ]HL only slightly below Introduction the [Mg2+] of seawater, their activity should be ham- pered. In contrast, Natantia are known to regulate 2+ ‘‘Everybody who has worked in Antarctic waters has [Mg ]HL to very low levels (Tentori and Lockwood been struck by the peculiar absence of crabs, lobsters, 1990; Frederich et al. 2001). The combined effect of low 2+ shrimps.....in shallow waters’’ (H. Broch 1961). temperatures and high [Mg ]HL might explain the The impoverished Antarctic decapod fauna, com- limits of cold tolerance in decapods and might be the pared with the high diversity of decapod crustaceans principal reason for the absence of reptant decapods recorded in the Subantarctic (Gorny 1999), constitutes from the high polar regions (Frederich et al. 2001). one of the most enigmatic phenomena in present-day At present only lithodids may tolerate environmental marine biodiversity research. Although Broch (1961) and physiological constraints imposed by the low tem- described the decapod diversity pattern in the Southern peratures and short periods of food availability at high- Ocean particularly in shallow waters, his statement was Antarctic latitudes (Clarke 1983), a pattern that appears not strictly correct, since the first Antarctic caridean to be very similar in the Arctic (>70°N, Woll and shrimp species (Chorismus antarcticus, Notocrangon Burmeister 2002; Zaklan 2002). This may be due to their antarcticus) had already been discovered by the Expe- prolonged brooding, as well as food independent and completely endotrophic and abbreviated larval devel- opment. These life-history features, among others, may allow lithodids to sustain the mismatch of prolonged developmental times at low temperatures and in short S. Thatje (&) Æ W. E. Arntz Alfred Wegener Institute for Polar and Marine Research, periods of food availability (see Clarke 1983; for review, P.O. Box 120 161, 27515 Bremerhaven, Germany see Anger et al. 2003, 2004; Kattner et al. 2003; Thatje E-mail: [email protected] et al. 2003a; Thatje 2004). 196 Fig. 1 Lithodid records from the Southern Ocean (southernmost America and Antarctic Peninsula; Antarctic without indication of ice shelves; 500-m isobath has been marked). Information obtained from the literature: Arana and Retamal (1999); Ba´ez et al. (1986); Birstein and Vinogradov (1972); Boschi et al. (1992); Collins et al. (1992); Garcı´a- Raso et al. (2004); Gorny (1999); Klages et al. (1995); Lo´pez and Balguerı´as (1994); Macpherson (1988a); Retamal (1981, 1992); Takeda and Hatanaka (1984); Zaklan (2002) Systematics to the division into Reptantia and Natantia (Boas 1880; Borradaile 1907) to facilitate discussion of low reptant Boas (1880) and Borradaile (1907) introduced a sys- decapod diversity in high-Antarctic latitudes. tematic division of the Decapoda into the suborders This review includes Antarctic (south of the Antarctic Reptantia and Natantia. Recently, Ka¨stner (1993) di- Convergence) and southernmost South American re- vided the taxon into the suborders Dendrobranchiata cords of larval and adult reptant crabs (Fig. 1, Table 1), (infraorder Penaeidae) and Pleocyemata (infraorders including also the local South American literature. It Stenopodidea, Caridea, Astacidea, Thalassinidea, Pal- also includes a brief outline of the relevant fossil record inura, Anomura and Brachyura), thus dissolving the of those regions. suborders Reptantia and Natantia. Ka¨stner’s classifica- tion (1993) considers the Natantia to be paraphyletic (Abele 1991; Scholtz and Richter 1995), but does not The fossil record in an Antarctic context consider the Reptantia as a true monophyletic group (Scholtz and Richter 1995). As the systematics of the Antarctic marine biodiversity is strongly influenced by Decapoda are still unresolved (Abele 1991; Ka¨stner the geological and glaciological history of the Antarctic 1993; Scholtz and Richter 1995), the present work refers continent. The origin of distinct benthic marine inver- Table 1 Records of reptant crabs (adults and larvae) from Antarctic waters Suborder Family Species Antarctic record Bathymetric Life-history Remarks Reference distribution stage Brachyura Pinnotheridae Pinnotheres sp. King George Island Larvae (early and Superficial plankton Thatje and (62°14.33S, 58°43.81W) advanced zoeae) samples (10–0 m) Fuentes (2003) Palinura Polychelidae Stereomastis suhmi Drake Passage Larvae Plankton samples Tiefenbacher (1994) (57°08.5¢S, 55°06.0¢W) (Eryoneicus stage) from 400 to 800 m Anomura Hippidae Emerita sp. King George Island Larvae (early zoeae) Superficial plankton Thatje and Fuentes (62°14.33¢S, 58°43.81¢W) samples (10–0 m) (2003) Anomura Lithodidae Lithodes murrayi Peter I Island, Bellingshausen 183–257 m Adult specimens, 4 males trawled, Klages et al. (1995) Sea (68°52.0¢S, 90°51.2¢W; carapace length 5 specimens 68°51.4¢S, 90°52.6¢W) from 36 to 100 mm video observed; water temperature +1.8°C salinity 34.7 Anomura Lithodidae Lithodes turkayi Apparently at Peter I Island 622–1,696 m Adult specimens Associated with capture Arana and Retamal (compare Arana and Retamal of Paralomis birsteini (1999) 1999 with Klages et al. 1995) Anomura Lithodidae Neolithodes Peter I Island, Bellingshausen 1,129 m 1 adult specimen Associated with capture Arana and Retamal diomedeae Sea (68°42.1¢S, 90°54.9¢W) of Paralomis birsteini (1999) Anomura Lithodidae Paralomis birsteini Peter I Island, Bellingshausen Sea 660–1,876 m A total of 88 adult For further station data Arana and Retamal (68°42.1¢S, 90°54.9¢W), specimens (77 males in the vicinity of (1999) Gerlache sea mount and 11 females indicated stations (65°25.6¢S, 90°38.96¢W), of which 10 see Arana and Scotia Sea (59°24.39¢S, 44°24.02¢W) were ovigerous) Retamal (1999) Anomura Lithodidae Paralomis birsteini Antarctic Ocean off Ross Sea, 500–1,080 m Adult specimens, Macpherson (1988b) Scott Island (67°29¢S, 179°55¢W) 1 female, 4 males, carapace length from 55 to 68 mm Anomura Lithodidae Paralomis spectabilis Antarctic Ocean off Ross Sea, 1,470–2,075 m Adult specimens Macpherson (1988a); Scott Island (67°23¢S, 179°53¢W) Zaklan (2002) Anomura Lithodidae Paralomis spectabilis Scotia Sea (59°58.6¢S, 32°24.6¢W) 563–605 m 1 adult male Birstein and Vinogradov (1972) Anomura Lithodidae Paralomis formosa Scotia Sea (59°53.1¢S, 32°19.5¢W; 523–671 m, 1 male, 2 males Macpherson (1988a) 59°58.6¢S, 32°24.6¢W) 536–605, respectively Anomura Lithodidae Lithodes sp. Peter I Island, (68°83.5¢S, 90°82.2¢W; 218 m, 375 m 2 specimens, 1 female From trap Garcı´a-Raso et al. 68°70.2¢S, 90°68.9¢W) and Agassiz trawl (2004) Anomura Lithodidae Paralomis sp. Bellingshausen Sea, 68°95.2¢S, 1,408–1,947 m 1 male, 1 female From Agassiz trawl Garcı´a-Raso et al. 78°23.3¢W (2004) 197 198 tebrate faunas in both Antarctic and Subantarctic wa- Bay, South Orkney Islands (Fig. 1). This material was ters can be traced back as far as the Early Cretaceous, probably collected during the Scottish National Ant- about 130 million years ago when the break-up of the arctic Expedition in 1903, and Stebbing’s record was Gondwana continent first became evident, and eastern based on museum material only. Yaldwyn (1965) was Gondwana became isolated in the high southern lati- the first to doubt that the occurrence of H. planatus at tudes (Lawver et al. 1992; Crame 1999). At the Late the South Orkney Islands was possible. Although this Cretaceous-Early Cenozoic boundary, the Austral species is very common in intertidal to shallow subtidal Province showed temperate aspects in its marine inver- waters in the Magellan region, including the Falkland tebrate fauna, as evidenced by the rich decapod fossil Islands, and the genus has a circum-polar Subantarctic record (Feldmann et al.