DISEASES AQUATIC ORGANISMS Vol. 1: 141-146. 1986 OF Published July 15 Dis. aquat. Org. I

Discovery of an apostome ciliate (Collinia beringensis n. sp.) endoparasitic in the Bering Sea euphausiid inermis

Gerard M. capriulol & Eugene B. small2

' Division of Natural Sciences, State University of New York at Purchase, New York 10577, USA ' Department of Zoology, University of Maryland at College Park, Maryland 20742, USA

ABSTRACT: The discovery is reported of a of apostome cihate, CoLluua beringensis, n. sp., Living endoparasitically in the haemocoel cavity of the Bering Sea euphausiid Thysanoessa inermis. This ciliate bears a falciform field and rosette structure in the protomite 2 stage and has a y (but not the full X, y, z) kinetid arrangement. Trophont, tomont, protomite 1 and tomitogenesis stages were also observed. The tomont, trophont and protomite 1 stages are characterized by an astomatous condition, and a denuded field was observed in the tomont and protomite 1 stages.

INTRODUCTION phenomena which might affect the growth, reproduc- tion and general well-being of euphausiid popula- Euphausiids occur in vast numbers, represent a sig- tions. nificant proportion of the biomass of the oceans of the world and are an important and often major food Euphausiid parasites source for many marine including whales, fish, seals, and birds (Mauchline & Fisher 1969). Sev- A review of the parasites of euphausiids can be era1 species of euphausiids including Meganyctiph- found in Mauchline (1980). Three types of ectopara- anes norvegica (Sars), Thysanoessa inermis (Kroyer) sites are found and include: ellobiopsids, dajid isopods and, at times, T. raschii (Sars), occur in extremely high and apostome ciliates (Table 24 of Mauchline 1980). densities in northern seas, as do related species in The ellobiopsids have been classed as fungi, dino- Antarctic waters. flagellates or rhizopod Protozoa (Mauchline & Fisher The importance of Euphausia superba Dana to 1969). Certain of these parasites affect host develop- baleen whales has been demonstrated (Marr 1962). ment, for example Notophryxus lateralis (which para- The significance of several euphausiid species as food sitizes Nematoscelis difficilis in the Santa Barbara for a variety of fish including hake (Hickling 1927), Channel, California) and Thalassornyces fagei may hening and mackerel (Mauchline & Fisher 1969) and inhibit moulting in their host euphausiids (Field 1969). fish of the Skagerrak, has also been pointed out. The Apostome clliate resting cysts have been reported euphausiids Meganyctiphanes norvegica and Thy- attached to various species such as Meganyc- sanoessa inermis have been shown to be main food tiphanes norvegica, Nyctiphanes couchi, Euphausia items for whales of the northern seas (Hjort & Ruud hemigibba, E. krohni, Thysanoessa gregaria, T. iner- 1929). The significance of krill as food for whales arises mis, T. longicaudata, T. raschi and Nematoscelis not from high numbers alone, but also from their megalops in the North Atlantic (Lindley 1978). Infecv. swarming behavior, which results in patches of high tion ranges from 3 to 16 % of the population. Lindley concentration which can be detected by their pre- described the geographical distribution of infected dators. euphausiids and concluded that neritic species and In view of the importance of euphausiids to pelagic populations are more Liable to infection than offshore food webs, it is of obvious value to understand various oceanic species and populations.

O Inter-Research/Printed in F. R. Germany 142 Dis. aquat. Org. 1:141-146, 1986

The known endoparasites of euphausiids have also (Smith 1971, Lindley 1977) as well as in other been described by Mauchline (1980). Euphausiids are euphausiid species (Shimazu & Oshima 1972). Parasi- the intermediate host of certain nematodes (species of tic trernatodes (Sars 1885, Kornaki 1970., Shimazu & Anisakis; Komaki 1970). Oshima (1969) experimen- Kagei 1978), cestodes (Shimazu 1975) and acatho- tally infected Euphausia pacifica and E. similis with cephalan larvae (Sars 1885, Shimazu 1975, Lindley Anisakis larvae, and also Shirnazu & Oshlma (1972) 1977) have also been reported for euphausiids. demonstrated natural infection of North Pacific None of the above works note the occurrence of an euphausiids by Anisakis larvae. Parasites have also endoparasitic ciliate in any species of euphausiid. We been found in Barents Sea here describe a prevously unknown apostome ciliate (Uspenskaya 1963), North Sea Thysanoessa species endoparasite of the euphausiid Thysanoessa inermis.

Fig. 1. ColLinea beringensis. Light micrographs including (A) the protomite 2 stage with rosette structure (arrow), (B) the tomont stage and (C) tomitogenesis (cell division) Capriulo & Small: Discovery of an endoparasit~cciliate in a euphausiid 143

Apostomatid ciliates succession of distinguished stages (phoront, trophont, protomont, tomont, protomite, tomite) some of which This group of parasites is characterized in Corliss are depicted in Fig. 1 & 2. The structure of the cytos- (1979) and Small & Lynn (1985). The apostomes are tome-cytopharyngeal rosette has not been completely associated with marine and fresh water , resolved, although Bradbury (1966a, b, 1973) has done cephalopods, ophiurans, coelenterates, ctenophores, much to describe the structure. Apostome life cycles polychaete annelids and possibly edaphic (terrestrial) have been described by Chatton & Lwoff (1935), Kirby acari. The best known species are commonly found in (1941), Lwoff (1950) and Bradbury (1966a) and certain marine hosts such as hermit crabs and kinetal segments or fields have been found to be copepods. Those with 2 known hosts have sea strongly thigmotactic. Collin (1909) described conju- anemones as the second. Those forms found on fresh gation in the apostome Collinia branchiarum (Stein). and salt water invertebrates, such as the crustaceans Chatton & Lwoff (1930) wrote an extensive monograph including krill, are ectoparasitic forms (as are most on the systematics of the apostomes as known to that apostomes) which excyst at the time when their host date. ecdyses, whereupon the excysted ciliate goes through In addition to the references cited above, several a polymorphic life history in which nourishment is other works by Bradbury and her associates have done derived from the exuvial fluid of the ecdysed exoskele- much to enhance our understanding of this group of ton (Corliss 1979). Freshwater hosts include shrimp ciliates (Bradbury & Pitelka 1965, Bradbury & Trager (Miyashta 1933) and gammarids (Penard 1922). Faure- 1967a, b, Bradbury & Clamp 1973, Bradbury 1974, Fremiet & Mugard (1949) described as an apostome 1975, Bradbury et al. 1974, Bradbury & Goyal 1976, Cyrtocaryum sp., occurring in annelids, but according Johnson & Bradbury 1976). to Corliss (1979) this genus is not representative of the Endoparasitic apostomes have been noted in crusta- group. Several papers on host-parasite relations con- ceans such as Orchestia garnrnarella (Puytorac & Grain cerning the apostomes can be found (Puytorac 1953, 1975); Gammarus pulex (Puytorac 1953) freshwater Debaisieux 1957, 1969, Trager 1957, Puytorac & Lom isopods of the genus Asellus (Balbiani 1885), as well as 1962, Fenchel 1965, Jakschnik 1967, Jankowski 1967, in other crustaceans (Puytorac & Lom 1962). CoUin Grimes 1976, Lindley 1978), none of which described (1909) found endoparasitic apostomes in amphipods apostomes endoparasitic in krill. and speculated that transfer occurred when the Apostome are characterized as possessing an incon- amphipods were injured by attacks from other spicuous cytostome or no cytostome, an organelle amphipods. In general apostomes belonging to the which when present is often accompanied by a unique family Colhniidae are usually found as parasites in the rosette structure (Corliss 1979), and as exhibiting a body cavity fluids of fresh-water crustaceans (i. e. complex polymorphic life cycle involving an orderly Gammarus, Asellus and ~e6ni~har~u.s).The new

Fig. 2. Cohea beringensis. hne drawings of the 5 observed stages of development with the rosette structure (R), flaciform field (F) and y kinetid arrangement (Y) seen in the protomite 2 stage; and the denuded somatic region seen in the tomont and protomite 1 stages. 'Ratio' = length to width ratio of the particular stage. The overtly large macronucleus pre- BODY sent in all observed stages is MACRONUCLEUS 75pm X 25pm 42pm X 2 1pm shown with the noted nucleoli in the trophont and tomitogenesis RATIO 2.3:l (cell division) stages. As depicted KlNETlES 3 4 3 0 in the division stage, elongate TOMONT OBSERVED nucleoli were observed TROPHONT DIVISION 144 Dis. aquat. Org. 1: 141-146, 1986

species herein described in our view belongs to the served either in formalin or Bouin's fixative, revealed 5 family Colliniidae and extends the host list to include individuals with a haemocoel cavity that appeared to the marine krill species Thysanoessa inermis. be 'cloudy' or opaque white. These individuals were carefully opened and found to be densely packed with clliates. The ciliates were removed and stained with MATERIALS AND METHODS protargol (Fig. 1). It can be noted that T. inermis with opaque white haemocoels may be filled with ciliates, The euphausiids examined in this study were col- although larger sample sizes are still needed to fully lected both by means of multiple opening closing net confirm this correlation. The ciliates were found to (MOCNES) tows and oblique, l mm mesh, plankton completely fill the haemocoel cavity of the infected net tows. Samples were collected by Dr. Sharon Smith individuals examined. and Mr Dominick Ninivaggi as part of the Brookhaven This endoparasitic clliate is an apostome which National Laboratories' involvement in the National bears a falciform field and rosette structure in the Science Foundation funded PROBES project. Samples protomite 2 stage as well as a y (but not the full X, y, z) were taken from the entire water column at several kinetid arrangement (Fig. 1A & 2).Trophont, tomont stations in the Bering Sea, and were fixed in 10 5% and protomite 1 stages were also observed (Fig. 2) as buffered formalin. was tomitogenesis (Fig. 2, observed division; Fig. 1C). Some of the above samples were transferred to The observed number of kineties varies from 24 to 80 Bouin's fixative (see Small's procedure in Lee et al. (Fig. 2, Table 1)and the tomont, trophont and proto- 1985) which is a saturated solution of picric acid in mite 1 stages are characterized by an astomatous (no CaCo3 buffered formaldehyde plus 1 % v/v glacial mouth) condition with the tomont and protomite 1 acetic acid added at the time of dilution in a 20:l stages additiondy characterized by a denuded soma- seawater to fixative ratio. Stomach and intestinal sec- tic region. tions of some of the Thysanoessa inermis individuals were dissected out and prepared, along with entire DISCUSSION organisms, for protargol silver staining following the procedure of Small as presented in Lee et al. (1985). This parasitic apostome, in our opinion, most closely The purpose of the stain was to facilitate examination resembles other known species in the genus Collinia for the potential presence of ciliate food items. in the family Colliniidae (Tables 1 & 2). The following similarities exist between the knll apostome and other described CoIlimNaspp.: (1) pre- RESULTS sence of rosette structure and special kinetal y seg- ment; (2)haemocoel dwelling forms in crustaceans; (3) Examination of the stained intestines of Thysanoessa all are forms whose complete life history is unknown; inermis revealed cysts possibly belonging to a ciliate. (4) major stages in which the mechanism of food inges- Follow-up examination of 50 other euphausiids, pre- tion is pinocytosis rather than phagocytosis; (5) are

Table 1. Collinia spp. Life history stage comparisons

Cell cycle stage with respective length/width measurements and number of kineties Species and host Trophont Tomont Protomite 1 Protomite 2 Tomite 1 Tomite 2

C. branchiarum (Stein) 100 X 80 pm Host: Gammarus pdex 60 34-37 34 9 ? ? Rosette + X, y, z Astomatou- Apostomatous Colliru'a sp.; n. sp. 9Ox80pm 65x25~ 35X25pm 20x15~ 18x10~ lOx6pm Host: Bactrurus mucronatus 40 16 14 12 11 10 Astomatou- Apostomatou- Astomatous Division and Division and conjugation conjugation noted noted C. beringensis n,sp. 90x30~ 58x25~ 47x26~ 45x28~ Not observed- Host: Thysanoessa inermis 80 34 28 24 - ? ? Rosette + y (no X, z) Astomatou- Apostomatous

Small, unpubl. data Capriulo & Small: Discovery of an endoparasitic clliate in a euphausi~d 145

Table 2. Known species of the genus Collinia with respective hosts, host distnbution and geographic localities

Species Host Geographic localities

1. C. branctuarum (Stein 1852) Garnmarus pulex: Germany, freshwater synonyms: OpaLma branchiarum (Stein 1852) freshwater amphlpod, England, freshwater Anaplophrya branctuarum epigean France, freshwater (Stein 1852) Czechoslovalua, freshwater 2. C. circdans (Balbiani 1885) Asellus aquatiaus: France, freshwater syn. A. circulans (Balbiani) Schneider 1885 freshwater isopod, Germany, freshwater epigean 3. C. neopharq~(Cepede 1910) Neoniphargus rnoniezi: France, freshwater freshwater, subterranean 4. C. orchestiae (Summers & hdder) Orchestia agAs: USA, Woods Hole marine beach Puytorac & Lom marine sandy beaches 5. C. garnrnan (Cheissin 1930) PaUasea cancelloides USSR, Lake Baikal Echmogamrnarus Maah 6. C. sp. (an unpublished species, Small) Bactrurus rnucronatus: USA, Ilhnois drainage hles freshwater, subterranean

forms which appear to be functional astomes with samples. This research was made possible in part by a grant minimal apostome traits for the life history stages from the Hudson River Foundation for Science and Environ- known at this time. mental Research (to GMC) and NSF Grant DPP-7623340 (to SS). Since trophic forms of this krill apostome are astomatous and haemocoel dwelling, and because they LITERATURE CITED so resemble Anoplophrya, a true astome, perhaps the other haemocoel-dwelling Anoplophrya-Like astomes Balbiani, E. G. (1885). Sur un infusoire cihe parasite du sang de l'aselle aquatique (Anoplophrya circulans). 2001. are also apostomes with arrested polymorphic life hs- Suisse 2: 277-305 tories. Bradbury, P. C. (1966a). The life cycle and morphology of the Each knll host examined contained thousands of apostomatous ciliate, Hyalophysa chattom. ng, ns. J. Pro- apostome cihates. The paclung of these ciliates was so tozool. 13: 209-225 tight that each cell had an irregular shape apparently Bradbury, P. C. (1966b). The fine structure of the mature tomite of Hyalophysa chattoni. J. Protozool. 13: 591-607 determined by the degree of packing in the host at its Bradbury, P. C. (1973). The fine structure of the cytostome of respective location. Such parasite densities as obser- the apostomatous ciliate Hyalophysa chattoni. J. Pro- ved here suggest that impairment of normal physi- tozool. 20: 405414 ological functioning (as well as possible death) of the Bradbury, P. C. (1974). The fine structure of the phoront of the apostomatous date Hyalophysa chattoni. J. Protozool. host may be occurring. 21: 112-120 The mechanism by which this cihate endoparasite Bradbury, P. C. (1975). Stored membranes associated with infects its host is puzzling since the euphausiid feeding in apostome trophonts with different diets. Protis- haemocoel cavity is enclosed at all times during its tologica 10: 533-542 development. Possibly, transfer of the parasite into the Bradbury, P. C., Clamp, J. C. (1973).Hyalophysa lwoffi sp. n. from the fresh water shrimp Palaemonetes paludosus and euphausiid occurs at predator-inficted injury sites as revision of the genus Hyalophysa. J. Protozool. 20: was suggested by Colhn (1909) with regard to a cihate 21C-213 endoparasite found in an amphipod. Bradbury, P. C., Goyal, V. (1976). The flne structure of a At the present time we do not have informaton on the parasitic date Terebrospva during ingestion of the exo- extent of parasitism of the Bering Sea euphausiid Thy- skeleton of a shrimp Palaernonetes. Tissue Cell 8: 573-582 Bradbury, P. C., Pitelka, D. R. (1965). Observations on kineto- sanoessa inermis, how infestation varies temporally or some formation in an apostome ciliate. J. Mcros. (Paris) 4: spatially, nor what the likelihood is that other 805810 euphausiids of the region, and perhaps even other Bradbury, P. C., Trager, W. (1967a). Excystation of apostome crustaceans such as copepods, are also parasitized by of Hyalophysa chattonj. J. Protozool. 13: 591-607 Bradbury, P. C., Trager, W. (1967b). Excystation of apostome this ciliate. Also, we have not as yet determined which ciliates in relation to molting of their crustacean hosts. 11. organs might be affected. Such information is obvi- Effect of glycogen. Biol. Bull. mar, biol. Lab., Woods Hole ously essential to an understanding of the ciliate's 133: 31C316 ecology and what affect the chates might have on the Bradbury, P. C., Clamp, J. C., Lyon, J. (1974). Terebrospira host's physiology. chattoni sp. n. a parasite of the endocuticle of the shrimp Palaemonetes pugio Holthius. J. Protozool. 21: 678:686 Acknowledgements: We thank Dr. Sharon Smith and Chatton, E., Lwoff, A. (1930). Impregnation par diffusion Dominlck Ninivaggi for providing us with the euphausiid argentique de I'infraciliature des ches marin et d'eau 146 Dis. aquat. Org. 1: 141-146, 1986

douce, apres fixation cytologique et sans dessication. C. r. Lwoff, A. (1950). Problems of morphogenesis in ciliates. Wiley Seanc. Soc. Biol. 104: 834-836 & Sons, New York Chatton, E., Lwoff, A. (1935). Les des apostomes. Mor- Marr, J. W. S. (1962). The natural history and geography of the phologie, cytologie, ethologie, evolution, systematique. antarctic knll (Euphausia superba Dana). 'Discovery' Rep. Premi6re partie. Aper~u historique et general. Etude 32: 33-464 monographique des genres et des especes. Archs Zool. Mauchhne, J., Fisher, L. R. (1969). The biology of exp. gen. 77: 1453 euphausiids. In:Russell, F. S., Yonge, M. (ed.) Advances Coh, B. (1909). La conjugaison d'Anoplophrya bran- in marine biology Vol. 7. Academic Press, London, p. chiarium. Archs Zool. Paris (ser. 5) 1: 325-388 1454 Corliss, J. 0. (1979). The ciliated Prototoa: characteristics, Mauchline, J. (1980). The biology of mysids and euphausiids. classification and guide to the Literature. 2nd edn. Perga- In: Blaxter. J. H. S., Russell, F. S., Yonge, M. (ed.) Ad- mon Press, Oxford vances in marine biology Vol. 18. Academic Press, London Debaisieux, P. (1957). Foettingeride a migration trans- p. 1-681 cuticulaire. Bull. Acad. r. Belg. Cl. Sa. (ser. 5) 43: 98-105 Miyashita, Y. (1933). Studies on a freshwater foettingeriid Debaisieux, P. (1960). Cihate apostomes parasites de date, Hyalospira can'dinae n. g. n. sp. Jap. J. 2001. 4: 439 palaemon. Cellule 60: 331-352 Oshima, T. (1969). A study of the first host of Anisalas. Fawe-Fremiet, E., Mugard, H. (1949). Un infusoire apostome Saishin-Igaku 24: 401404. Fish. Res. Bd Can. Trans. No. parasite d'un polychete: Cyrtocaryum halosydnae, n. g. n. 1325, 1-12 sp. C. r. hebd. Seanc. Acad. Sa., Paris 228: 1753-1755 Penard. E. (1922). Etudes sw les lnfusoires d'eau douce. Fenchel, T. (1965). On the ciliate fauna associated with the Georg. and Cie, Geneve marine species of the amphlpod genus Gammarus. Puytorac, P. de. (1953). Anoplophrya branchiarum (Stein), Ophelia 2: 251-303 die sancyico!e de Gammams p~dex,n'est pas LT astorce, Field, L. H. (1969). The biology of Notophryxus laterds mais un apostome. C. r. hebd. Seance. Acad Sa.. Paris (Isopoda: Epicandea), parasite on the euphausiid 237: 1787-1789 Nernatoscelis difficilis. J. Parasit. 55: 127 1-1277 Puytorac, P. de, Lom, J. (1962). La tomitogenesis des Cohnia Grirnes, B. H. (1976). Notes on the distribution of Hyalophysa dies apostomes sanguicoles endoparasites des crustaces. and Gymnodinioides on crustacean hosts in coastal Ann. Parasit. Hum. et Comp. 37 (3): 195209 N. Carolina and a description of Hyalophysa tragen sp. n. Puytorac, P. de, Grain, J. (1975). Etude de la tomitogenese et J. Protozool. 23: 246-251 des le ultrastructure des Corn-a orchestiae diae apos- Hickling, C. F. (1927). The natural history of the hake. Fishery tome sanguicoloe endoparasite du crustace Orchestiae Invest.. Lond. Ser. 11, 10: 1-100 gammarella Pallas. Protistologica 8: 61-64 Hjort, J., Ruud, J. T. (1929). Whaling and fishing in the North Sars, G. 0. (1885). Report on the Schizopoda collected by Atlantic. Rapp. P.-v. RBun. Cons. perm. int. Explor. Mer. H. M. S. Challenger during the years 1873-1876. The 56: 5-123 Voyage of H. M. S. Challenger 13 (37): 158-161 Jakschnik, H. D. (1967). Distribution of the date fauna Schauer, R. V. (1972). Excystation of the apostomatous ciliate associated with the subterranean fresh-water amphipod, Halophysa chattoni, without metamorphosis. Biol. Bull. Bactnuus mucronatus (Forbes) Hay. M. S. thesis. Univ. of mar. biol. Lab., Woods Hole 143: 215-221 Illinois Shimazu, T., Oshima, T. (1972). Some larval nematodes from Jankowslu, A. W. (1967). Ciliates from the mantle cavity of euphausid crustaceans. In: Takenouti, A. Y. et al. (ed.) Balanus in Barents Sea. Parazitologia 1: 82-93 Bioloycal oceanography of the northern North Pacific Johnson, C. A. 111, Bradbury, P. C. (1976). Observations on the Ocean. Idernitsui Shoten, Tokyo, p. 403-409 ocuurrence of the parasitic date Synophrya in decapods Shimazu, T. (1975). Some cestode and acanthocephalan lar- in coastal waters off the southeastern United States. vae from euphausiid crustaceans collected in the northern J. Protozool. 23: 252-256 North Pacific Ocena. Bull. Jap. Soc. scient. Fish. 41: Kirby, H. (1941). Relationships between certain Protozoa and 813-821 other animals. h: Calluns, G. N., Summers, F. M. (ed.) Shimazu, T., Kagei, N. (1978). A metacercaria of the genus Protozoa in biological research. Columbia Univ. Press, Paronatrema (Trematoda: Syncoelliidae) parasitic in New York, p. 899-1008 Euphausia pacifjca (Crustacea: Euphausiidae) from the Komah, Y. (1970). On the parasitic organisms in a knll, East Chma Sea. Zool. Mag., Tokyo 87: 158-161 Euphausia similis, from Suruga Bay. J. oceanogr. Soc. Small, E. B., Lynn, D. (1985). The phylum Ciliophora Doflein. Japan 26: 283-295 In: Lee, J. J., Hutner, S. H., Bovee, E. C. (ed.)An illustrated Lee, J. J., Small, E. B., Lynn, D. H., Bovee, E. C. (1985). Some guide to the Protozoa. Allen Press and Soc. of Protozoolog- techniques for collecting, cultivating and observing Pro- ists, Kansas tozoa. In: Lee, J. J., Hutner, S. H., Bovee, E. C. (ed.) An Smith, J. W. (1971). Thysanoessa inermis and. T. longicaudata illustrated guide to the Protozoa. Men Press and Soc. of (Euphausiidae) as first intermediate hosts of Anisakis sp. Protozoologists, Kansas, p. 4-5 (Nematoda: Ascaridata) in the northern North Sea, to the hdley, J. A. (1977). Continuous plankton records: the &S- North of Scotland and Farore. Nature, Lond. 234: 478 tribution of the Euphausiacea (Crustacea: ) Trager, W. (1957). Excystation of apostome dates in relation in the north Atlantic and the North Sea 19661967. J. to molting of their crustacean hosts. Biol. Bull. mar. biol. Biogeograph. 4: 121-133 Lab., Woods Hole 112: 132-136 bdley, J. A. (1978). Continuous plankton records: the Uspenskaya, A. V. (1963). Parasite-Fauna of benthic crusta- occurrence of apostome ciliates (Protozoa) on ceans in the Barents Sea. Murmanskii Morskoii Biologis- Euphausiacea in the North Atlantic Ocean and North Sea. cheskii Institut. Akademia Nauk, SSSR, Moscow Mar. Biol. 46: 131-136 Responsible Subject Editor: Dr. K. Rohde; accepted for printing on March 11, 1986