PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON l09(2):286-298. 19% Occurrence of anomuran crabs (Crustacea: Decapoda) in hydro thermal vent and cold-seep communities: a review Pierre Chevaldonne and Karine Olu (PC & KO) Laboratoire d'Ecologie Abyssale, IFREMER, B.P. 70, 29280 Plouzane, France; (PC) Present address: Institute of Marine and Coastal Sciences. Rutgers University, Dudley Road, Cook College. New Brunswick, New Jersey 08903, U.S.A. Abstract.—Crabs of the family Lithodidae are frequently encountered in the vicinity of deep-sea hydrothermal vents and cold-seeps. Together with crabs of the families Galatheidae and Chirostylidae, they are the main contributors to the scavenging/predatory fauna of these highly productive areas, and a potential vector for the export of organic carbon to the surrounding deep-sea commu­ nities. A review of the literature indicates that anomuran crabs have been re­ ported from such environments since their discovery, and occur virtually any­ where a reducing habitat is found. These three families are represented by at least eight genera, with at least 14 species occurring in hot vent areas, and eight in cold-seep associated communities. Two species of lithodid crabs have re­ Vents and seeps are environments where cently been reported from the south Bar­ biomass and biological production are high bados accretionary prism cold-seeps at compared to that of the surrounding abyssal depths of 1200-1700 m (Macpherson plains, due to utilization of the expelled re­ 1994). In addition to the description of a duced compounds by chemoautotrophic mi­ new species, Paralomis arethusa, Macpher­ croorganisms that constitute the first step of son mentioned that his new species and Li- a trophic web independent from sea-surface thodes manningi Macpherson, 1988, were production. Although organisms exclusive­ the first records of the family Lithodidae to ly dependent on fluid emissions usually be found in hydrothermal vent and cold- dominate these communities and live close seep areas. However, a review of the liter­ to the expelled fluids, other inhabitants of ature showed that occurrence of lithodid the neighboring deep-sea environment are crabs in such environments has been known attracted by the high food supply and enter at least since 1985 (Suess et al. 1985). The these environments. Like anomurans, most taxonomic literature on deep-sea hydrother­ of these organisms are filter-feeders, scav­ mal vent and cold-seep organisms often engers, or predators. As top predators/scav­ lacks ecological data, and ecological sur­ engers, anomurans are rivalled only in some veys frequently present vague taxonomic cases, in particular by the hydrothermal-en- information. This review is intended to demic brachyuran crab family Bythograei- dae. demonstrate that the Anomura are a partic­ ularly well represented group in deep-sea Infraorder Anomura chemosynthetically-based ecosystems, and Superfamily Paguroidea (sensu Forest to present a literature survey of the species 1987) and accompanying information relevant to biogeographic studies. This superfamily comprises the Lithodi­ dae and two families of hermit crabs. Pa- TfWPPr ^ •<jt iiHMHaaiiiHi VOLUME 109. NUMBER 2 287 guridae and Parapaguridae. Only one her­ tionary prism, and was identified by Mac­ mit crab has been reported to date from pherson (1994). The species is known from cold seeps of the Barbados accretionary depths of 640-777 m in the Caribbean prism, at depths of 1000-2000 m (K. Olu, (Macpherson 1988). pers. obs.), and another one from Monterey Two species of lithodid crabs found at Bay seeps at 600-1000 m (J. P. Barry, pers. seeps of the Monterey Bay, at 600-1000 m, comm.). The Barbados specimen seems to have been assigned tentatively to the genus belong to the genus Parapagurus (M. de Lithodes (J. P. Barry, pers. comm.). These Saint Laurent, pers. comm.). Although the crabs are not considered as seep-endemics. Monterey Bay hermit crab has not been identified, it is possible that it is also a par- Genus Lopholithodes Brandt, 1848 apagurid, which are common at these Lopholithodes foraminatus (Stimpson, depths. 1859) As previously mentioned, Carey et al. Family Lithodidae (1988) observed dense aggregations of Lo­ The first report of the occurrence of Lith­ pholithodes foraminatus while exploring odidae in hydrothermal vent or cold-seep apparently extinct seepage areas of the up­ habitats, is a "large crab," clearly a lith­ per Oregon subduction zone, at a depth of odid, illustrated in a sketch of the benthic ca. 250 m. There is no mention of this spe­ community associated with cold-seeps cies at active seeps, but it could be the same along the lower Oregon subduction zone at species as the "large crab" observed at 2037 m depth (Suess et al. 1985, Kulm et 2037 m by Suess et al. (1985). However, al. 1986). Subsequently, Carey etal. (1988) this occurrence would be much deeper than observed Lopholithodes foraminatus from a the known depth range of L. foraminatus, shallower part of this subduction zone. which is known from British Columbia to Whether the "large crab*' and L. forami­ southern California, at 0-547 m (Hart natus are the same species is not stated. 1982). Tunnicliffe & Jensen (1987) proposed that the deeper water species from the lower Genus Neolithodes Milne Edwards & zone could be the same Paralomis sp. they Bouvier, 1894 found at hydrothermal vents in the Juan de Neolithodes diomedeae (Benedict, 1894) Fuca Ridge. This species represents the first reported In total, four lithodid crabs have been occurrence of Lithodidae in hydrothermal identified to the species level from cold- vents. Grassle (1986) described it as the seep areas, and the status of four others re­ most common crab found at the active hy­ mains uncertain. The Lithodidae are repre­ drothermal vents, at 2000 m, in the Guay- sented at hydrothermal vents by two species mas Basin, Gulf of California. It is known and six occurrences not yet clearly assigned from southern California to South Georgia, to species. Two of the described species at depths of 640-2450 m (Macpherson {Paralomis arethusa and P. jamsteci) are 1988). until now known only from reducing envi­ ronments. No lithodid species is definitely Genus Paralithodes Brandt, 1848 known from both vents and seeps. Based on submersible observations, Sa- galevich et al. (1992) reported Paralithodes Genus Lithodes Latreille, 1806 sp., at 350-400 m, on the periphery of ac­ Lithodes manningi Macpherson, 1988 tive hydrothermal vents on the summit of One specimen was collected at 1236 m Piyp Volcano, in the Bering Sea, on dense depth in cold seeps of the Barbados accre­ populations of actinians. 288 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Genus Paralomis White, 1856 Paralomis multispina (Benedict, 1894) This is the best represented of the lith- Horikoshi & Ishii (1985), Hashimoto et odid genera in chemosynthetically-based al. (1987, 1989), and Ohta (1990b) have de­ communities. At least four species have scribed cold-seep communities of Sagami been reported, including two exclusively Bay in Japan, at depths of 900-1200 m, from reducing habitats. Considering the nu­ where large Paralomis multispina and the merous reports of "Paralomis sp." found clams Calyptogena soyoae are the dominant in the literature, more species are likely to species. P. multispina is known from Japan be discovered in the future. to California, at 500-1665 m (Hart 1982). Paralomis verrilli (Benedict, 1894) Paralomis arethusa Macpherson, 1994 Paralomis verrilli is believed to be the Paralomis arethusa is one of two lith- species found at hydrothermal vents of the odid crabs known from cold-seep commu­ Iheya Ridge, at 1400 m, in the Mid-Oki­ nities of the Barbados accretionary prism at nawa Trough (S. Ohta, pers. comm.; Ohta 1691 m depth. This species is known only 1990a; Kim & Ohta 1991; Hashimoto et al. from this location (Macpherson 1994). 1995). Although still to be confirmed, this occurrence would not be surprising as P. verrilli is usually found at depths of ca. Paralomis cubensis Chace, 1939 1500-3500 m around Japan and from the Bering Sea to California (S. Ohta, pers. Sassen et al. (1993) produced a photo­ comm.). Crabs tentatively assigned to this graph of a "crab" (clearly a lithodid) crawl­ species were also reported from the Sagami ing on tubeworms and mussels at the Green Bay cold-seeps, but in much lower numbers Canyon methane seep, on the upper conti­ than the dominant P. multispina (J. Hashi­ nental slope of the Gulf of Mexico, at 620 moto, pers. comm.). m. It was subsequently identified as Para­ lomis cubensis. It is considered as a "va­ Additional occurrences of Paralomis spe­ grant" species of the Gulf of Mexico seeps cies.—Several authors have reported the by Carney (1994), and is not commonly in occurrence of lithodid crabs as belonging to direct contact with the seep community. P. the genus Paralomis. Most reports have cubensis is known from east Florida to Bra­ been based on collected specimens. Two yet zil, at 329-730 m (Macpherson 1988). unidentified species of Paralomis occur at the Minami-Ensei vents (Mid-Okinawa Trough), living on mytilids or around bac­ Paralomis jamsteci Takeda & Hashimoto, terial mats, together with the vent endemic 1990 P. jamsteci (Hashimoto et al. 1995). In the hydrothermal areas of the North-Fiji back- In hydrothermal areas of the Okinawa arc basin (2000 m) the "white-coloured Trough, lithodid crabs have been observed lithodid crabs" observed by Jollivet et al. on the Minami-Ensei Knoll, at 700 m, (1989), were later identified as belonging to where a new species was described as Par­ the genus Paralomis, and have also been alomis jamsteci (Hashimoto et al. 1990, sampled at 1800 m in venting areas of the Takeda & Hashimoto 1990). This species is Lau back-arc basin (Desbruyeres et al. living among mytilid beds, near vent open­ 1994).