International Council for CM 2001 / K:21 The exploration of the Sea Response of Cephalopod Populations and Fisheries to Changing of Environment and Ecosystems

THE MACRO-ECOSYSTEM VARIATIONS OF HELMINTH FAUNA IN OMMASTREPHID SQUID STHENOTEUTHIS OUALANIENSIS FROM INDIAN OCEAN AND EAST TROPICAL PACIFIC

by

Nigmatullin Ch.M., Shukhalter O.A.

Atlantic Research Institute of Fisheries and Oceanography (AtlantNIRO), Donskoj st. 5, Kaliningrad 236000 Russi [Tel: (0112) 225885; Fax: (0112) 219997; E-mail: [email protected]]

ABSTRACT

During 1978-1986 oceanic squid Sthenoteuthis oualaniensis ) have been studied for parasitic helminths: 303 squid from open waters of the Indian Ocean and 146 squid from nerito-oceanic part of the East Pacific (2°N-12°S. Eleven species of parasitic helminths were recorded: 2 Trematoda species, 5 – Cestoda, 3 – Nematoda and 1 – Acantocephala. All these helminths occurred as larval stages. In each region nine species were found, seven of them being common. The total prevalence of infection was 98.4% in the Indian squids and 71.3% in the Pacific ones. But main helminths of the Indian Ocean had significantly higher infestation parameters (the prevalence 50-95%, the intensity tens and hundreds specimens) while in the Pacific Ocean these values were 20-32% and up to several dozen specimens. There were revealed geographic patterns of helminth fauna changes too. This squid is a member of the complicated and diverse tropho-parasite system that includes the most of ecosystem web at the consumer level. Thus, the revealed differences in parasite fauna and its infestation rates are a sensible indicator of the differences in both trophic and parasite structures in these two ecosystems.

Key words: purpleback squid, Sthenoteuthis oualaniensis, parasites as ecosystem indicator

INTRODUCTION

The animal parasites may be used as sensible indicators (= tags) for study the different hierarchic levels of the ecological processes – from cohort and population analyses of hosts till their role in the local ecosystems and macro-biocoenoses (Dogel, 1962; Rohde, 1987; Moser, 1991: Williams et al., 1992). The helminths of cephalopod hosts are a suitable for this aim also. There are many publications on using the parasites for different aspects of cephalopod biology studies (reviews: Hochberg, 1990; Pascual and Hochberg, 1996). However, there are only two papers on the

2 study of cephalopod parasites as tags of their biocoenotic relationships in different macro- ecosystems for oceanic ommastrephid squids Ommastrephes bartrami in North and South Atlantic (Gaevskaya and Nigmatullin, 1976) and Dosidicus gigas in Nicaraguan, Equatorial and Peruvian areas in the East Pacific (Shukhalter and Nigmatullin, 2001). The latitude aspect of the squid ecosystem relations variability was analyzed in both these investigations. Sthenoteuthis oualaniensis is an abundant tropical Indo-Pacific oceanic nektonic squid. There are five intraspecific forms that are distinguished by size of adult animals, some morphological and ecological traits, and geographical distribution. The most numerous and widely distributed is the middle-sized late-maturing form with one year life cycle. Its range coincides with the species range. Mantle length (ML) of mature males of this form ranges 11-25 cm and mature females 15-34 cm (Zuev et al., 1985, 2001; Nigmatullin et al., 1991). Squids of this form play the key-role in pelagic oceanic and nerito-oceanic ecosystems as consumers of II-IV orders, and they are the important transport hosts for some helminths between invertebrates, small teleosts and sharks, large fishes and mammals (Zuev et al., 2001). The composition of the helminth fauna of Sthenoteuthis oualaniensis and the helminths location in squid body are relatively well studied (reviews: Gaevskaya et al., 1983; Nigmatullin et al., 1985; Naidenova et al., 1985; Hochberg, 1990; Zuev et al., 1985, 2001; Shukhgalter, 1988, 1992). But the ecological aspects of its parasite-host relations are not investigated in deep. The aim of the present paper is to provide the comparative study of helminth fauna and the values of its infection rates in the middle-sized late-maturing form of the ommastrephid squid Sthenoteuthis oualaniensis in the tropical zone of the Indian Ocean and East Pacific. The final aim of this study is to elaborate the parasite indication of the squid ecosystem relation peculiarities in these two tropical macro-ecosystems.

MATERIALS AND METHODS

The samples of squids were collected during 1978-1986. In the oceanic part of the Indian Ocean (8-15° S – 55-90° E) squid were caught in the cruise R/V “Professor Vodjanitsky” (Institute of Biology of the Southern Sea, Sevastopol) from May to August 1978 (Fig. 1). From the Indian Ocean 303 squid of ML 2-26 cm were studied. In the nerito-oceanic part of the East Pacific (2° N-12° S – 82-100° W) 146 squids of ML 7- 32 cm were collected during 1981-1986 in the cruises of AtlantNIRO research vessels (Fig. 1). Both Indian and Pacific investigated squids include males and females in different stages of maturation, from juveniles and immature to mature. All squids were caught at the light drift stations

3 by handle net and mainly by jigs. For each studied squid mantle length (ML), sex and stage of maturity were recorded by Zuev et al. (1985). Method of helminthological investigation of squids was a standard one (Zuev et al, 1985). All worms were collected from fresh or frozen squids. As plerocercoids of Pelichnibothrium speciosum were very numerous, intensity of plerocercoids encysted in the rectum wall was taken by multiplication of the mean number of cysts in 1mm² of rectum wall surface. These plerocercoids very similar to P.speciosum were not assessed quantitatively in the Indian Ocean squids, but some of investigated squids were infested by them. The rates of infection for main and secondary helminths in the equal-sized males and females were quasi-similar. Therefore for the comparative analysis data on helminth fauna of equal sized specimens of different sex are combined. The following ecological terms – prevalence, intensity and mean dintensity were used in accordance with the recommendations by Margolis et al. (1982). The definitions of these terms are followings. Prevalence is the number of individuals of a host species infected with a particular or all parasite species and it is expressed as a percentage of number of infected hosts to number of all hosts examined in the sample. Intensity is the number of individuals of a particular parasite species in each infected host in the sample. Mean intensity (= density) is the mean number of individuals of a particular parasite species per infected host in the sample.

RESULTS AND DISCUSSION

In total, twelve species of the parasitic helminths were revealed: Trematoda (2 species), Cestoda (5), Nematoda (3) and Acanthocephala (2) (Table 1). But it’s necessary to say that in the stomachs of two adult squids from the Indian Ocean were found 12-18 specimens of not unidentified Acanthocephala in bad digested condition. Therefore this helminth must not be considered as the true parasite of these squids, and there are eleven species of true parasitic helminths. All these helminths occurred as larval stages. In each region nine species were found, seven of them being common (Table 1). The differences of the helminth species composition are mainly due to rare species. It is characteristic especially for Pacific squid fauna. The species that absent in Indian squid fauna are represented here another species of given genus Nybelinia and Anisakis. Long worms with length 10-20 cm (probably primitive Acanthocephala) from pericardial coelomic cavity were discovered in both Sthenoteuthis species in Tropical Atlantic and Indian Ocean only (Naidenova, Zuev, 1978; Naidonova et al., 1995). During intensive study on the parasitic helminths of Dosidicus gigas and another species of ommastrephid squids in same area of the East Pacific there were not found these worms (Gaevskaya

4 et al., 1983; Schukhalter, 1988; Shukhalter and Nigmatullin, 2001). Thus, in general the helminth faunas compositions of Sthenoteuthis oualaniensis in these two regions are similar. The most common and wide distributed representatives of the fauna are metacercaria of didymozoids, the larvae of nematode Anisakis sp., Porrocaecum sp., and the cestodes Nybelinia sp., Phyllobotrium sp. and Pelichnibotrium-like plerocercoids. These helminths are typical for all oceanic nektonic ommastrephid squids of the World Ocean (Gaevskaya and Nigmatullin, 1976, 1981; Naidenova and Zuev, 1978; Gaevskaya et al., 1983; Hochberg, 1990; Shukhgalter and Nigmatullin, 2001). The total prevalence of infection is 98.4% in the Indian squids and 74.0% in the Pacific ones. The more low level of infection in the East Pacific is due to the differences in the prevalence values in small squids of ML 7-16 cm (0-68%) from Pacific and of ML 2-16 cm (80-100%) in Indian ones. In general samples main helminths of the Indian Ocean had significantly higher infestation parameters (the prevalence 46-95%, the intensity tens and hundreds specimens) while in the Pacific Ocean these values were 20-38.4% and from few specimens up to several dozen (Table 1). The same situation was observed in the equal-sized adult squid (Table 1). The total prevalence of infection of Indian squid was 1.3 times more than in Pacific ones. Most of helminth species in Indian squid has both the prevalence and density values 3-10 times more than Pacific ones. But there was the solely exception of Anisakis sp.: its prevalence value was higher at 4.5 time for Pacific squid. The ontogenetic variations in the helminths infestation data on five squids’ size groups in these two regions were compared (Fig. 2, 3). Bearing in mind monocyclia and one year life of the middle-sized late-maturing form of Sthenoteuthis oualaniensis in both areas (Nigmatullin et al., 1991; Zuev et al., 2001) these series nearly completely (with exception of larvae and frys) cover their life cycle. In both areas parameters of infection rates by all helminths are more or less increasing during ontogenesis of squid. There is the except for metacercaria of didymozoids in Pacific squid. Their prevalence value has tendency to decrease, and intensity value is quasi-stable. There were found significant differences in ontogenetic infection dynamic of squids from Indian and East Pacific regions (Fig. 2, 3). Some helminths begin infect squids of the different sizes (3 species). Curves describing infection dynamics are different for 5 species. In 5 species these curves move on the different levels and have differences in prevalence of 30-50% and up to 70-80%.

CONCLUSION

All revealed helminths (except for long acantocephala-like worms) have very broad

5 specificity. They use various planktonic invertebrates, small fishes and squids at same stages of their life cycles. Infection of Sthenoteuthis oualaniensis occurs when they eat infected preys, which are the second or paratenic intermediate hosts for these helminths. This squid is the transport (paratenic) host. Transfer of these helminths to definitive hosts (sharks, tunas, xiphoid fishes and mammals) occurs when they consume infected squids. The life cycles of these helminths are realized by trophic chains of the pelagic communities (Nigmatullin, 1987; Hochberg, 1990). Thus, Sthenoteuthis oualaniensis and its helminths are members of the complicated, diverse and synchronized tropho- parasite system that includes the most part of epi- mesopelagic oceanic ecosystem members at the consumer level till top-predators. This is why the helminth data of this squid may be the important ecosystem-condition indicator. In general for both western and eastern borders of species range, the similarity of the helminth fauna composition is characteristic. This similarity testifies the proximity of the main traits of the ecological niches of these two geographical squid populations, and spatial stability of middle- sized form Sthenoteuthis oualaniensis’ position in trophic-parasite web of pelagic ecosystems in range limits. But there were revealed the significant differences in the infestation levels, and geographical patterns of helminth fauna ontogenetic changes. These data suggest earlier and more mass infestation of squids and accordingly squid participation in helminths life cycles in the Indian Ocean than in East Pacific. In general in the life cycle of Indian squid population the prevalence and intensity parameters of parasitic helminths were increased synchronously, and as the result of that the adult part of squid population had maximal values of infested squids and maximal numbers of helminth larvae in hosts. In East Pacific squid population this tendency is less expressed, and the significant accumulation of helminth specimens in hosts does not occur. These two types ontogenetic infestation exist due to the differences in the infestation rates of squid preys in these areas. But ultimately this is due to the differences in the infestation rates of final hosts of these helminths (high in Indian Ocean and low in East Pacific). Another version is following: probably this is due to the features of quantitative distribution in these areas of the final hosts. But in both cases this leads to differences of infection of planktonic crustacea and small fish that are preys of the squid, and accordingly to differences in infection of Sthenoteuthis oualaniensis. These revealed differences suggested that the parasite-host systems, population parameters of helminths and probably the quantitative aspects of the trophic relations in the Indian Ocean and East Pacific are not similar. The real bases of this are the different types of oceanographic conditions and communities. In Indian Ocean the studied squid inhabits the typical oceanic ecosystems, and in East Pacific – typical nerito-oceanic (intermediate between neritic and oceanic) ecosystem. They have very significant differences in water masses circulation, predictability of the environmental traits,

6 level of productivity, complexity of trophic structure and so on (Beklemishev, 1969; Vinogradov and Sushkina, 1987). Thus, the revealed differences in helminth fauna and its infestation rates are the sensible indicator of the similarity and differences in both trophic and parasite structures in these two macro- ecosystems.

ACKNOWLEDGEMENTS

We would like to express our cordial thanks to N.N. Naidenova and A.V. Gaevskaya for help with the helminths identifications; A.A. Kovaleva, S.S. Shulman, F.G. Hochberg and K.N. Nesis for useful discussion of results; Bazanov S.I., Tjupa V.N., Schetinnikov A.S., Parfenjuk A.N., Sabirov R.M. and Gordeev V.A. for the samples collection in research cruise; Bazanov S.I. and Schetinnikov A.S. for collection of the helminths from squids’ stomachs and caecums.

REFERENCES

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Dogiel, V.A. 1962. General parasitology. Leningrad University Press, Leningrad, 464 pp. (In Russian).

Gaevskaya, A.V. and Nigmatullin, Ch.M. 1976. Biotic relationships of Ommastrephes bartrami (Cephalopoda: Ommastrephidae) in the northern and southern parts of the Atlantic Ocean. Zoologicheskij Zhurnal, 55: 1800-1810 (In Russian, English abstract)

Gaevskaya, A.V., Nigmatullin, Ch.M., 1981. Several ecological aspects of the parasitic relationships of the flying squid Sthenoteuthis pteropus (Steenstrup, 1855). Biologicheskie Nauki, Ser. Biol. (Moscow), 1: 52-57 (In Russian, English abstract).

Gaevskaya, A.V., Nigmatullin, Ch.M. and Shukhgalter, O.A. 1983. Helminth fauna of three dominant species of squids of the family Ommastrephidae from Southeastern Pacific and general remarks about its formation in this family. In: Taxonomy and Ecology of Cephalopods (Starobogatov, Ya.I. and Nesis, K.N., eds.). Zoological Institute of the USSR Academy of Sciences, Leningrad: 132-134 (In Russian).

Hochberg, F.G. 1990. Diseases of Mollusca: Cephalopoda. In: Diseases of marine animals, vol. III. Cephalopoda to Urochordata (Kinne, O., ed.), Biologisches Anstalt Helgoland, Hamburg: 47-227.

Margolis, L., Esch, G.W., Holmes, J.M., Kuris, A.M. and Shad, G.A. 1982. The use of ecological terms. J. Parasitol., 68: 131-133.

Moser, M. 1991. Parasites as biological tags. Parasitology Today, 7: 182-185.

Naidenova, N.N., Nigmatullin, Ch.M. and Gaevskaya, A.V. 1985. The helminth fauna and host- parasite relations of squids Sthenoteuthis oualaniensis (Lesson) (Cephalopoda, Ommastrephidae) in the Indian Ocean and the Red Sea. In: Hargris, W.J.Jr., (ed.). Parasitology and pathology of marine organisms of the World Ocean. NOAA Technical Reports, NMFS 25: 113-116.

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Naidenova N.N. and Zuev G.V. 1978. To helminths fauna of the orangeback squid Sthenoteuthis pteropus (St., 1855) in the eastern central Atlantic. Biol. Morya (Kiev), 45: 55-65 (In Russian, English summary).

Nigmatullin, Ch.M. 1987. The rules in ecological parasitology in application to nektonic squids. In: Parasitology and pathology of marine organisms. IV All-Union Symposium. Abstarcts of communications (A.V. Gaevskaya, ed.), AtlantNIRO Press, Kaliningrad: 17-18 (In Russian).

Nigmatullin, Ch.M., Parfenjuk, A.V. and Nikolsky, V.N. 1991. Ecology and resources of epipelagic nektonic squids of the Atlantic and southeastern Pacific oceans. In: State of the Fishing Industry's Biological Resources in the Central and South Atlantic and East Pacific. Trudy AtlantNIRO (Sushin, V.A., ed.), Kaliningrad: 142-177 (In Russian, English abstract).

Nigmatullin, Ch.M., Sabirov, R.M. and Shchetinnikov, A.S. 1985. Squids: Dosidicus gigas, Sthenoteuthis oualaniensis, Ommastrephes bartrami, and Thysanoteuthis rhombus. In: Fishery Description of the Region of Southeastern Pacific Ocean. GUNIMO Publishing, Leningrad: 80-88 (In Russian).

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Rohde, K. 1987. Ecology of marine parasites. University of Queensland Press, St. Lucia, 245 pp.

Shukhgalter, O.A., 1988. Helminth fauna of squids from South American oceanic waters. Autoreferat dissertatsii na soiskanie uchenoj stepeni kandidata biologicheskikh nauk. Moscow, 23 p. (In Russian).

Shukhgalter, O.A. 1992. The fauna of cestodes in squids from South American oceanic waters (Southwestern Atlantic and Southeastern Pacific). Parasitologiya, 26 (2): 130-140. (In Russian, English abstract).

Shukhgalter, O.A. and Nigmatullin, Ch.M. 2001. Parasitic helminths of jumbo squid Dosidicus gigas (Cephalopoda: Ommastrephidae) in open waters of the Central East Pacific. Fish. Res. (in press).

Vinogradov, M.E. and Shushkina, E.A. 1987. Functioning of plankton communities in epipelagial of Ocean. Nauka Publishing House, Moscow, 240 pp. (In Russian).

Williams, H.H., Mackenzie, K. and McCarthy, A.M. 1992. Parasites as biological indicators of the population biology, migrations, diet and phylogenetics of fishs. Rev. Fish. Biol. Fish., 2: 144-176.

Zuev, G., Nigmatullin, Ch., Chesalin, M. and Nesis K. 2001. Main results of long-term world wide studies on tropical nektonic oceanic squid genus Sthenoteuthis: an overview the soviet investigations. Bull. Mar. Sci. (in press).

Zuev, G.V., Nigmatullin, Ch.M. and Nikolsky V.N. 1985. Nektonic Oceanic Squids (Genus Sthenoteuthis). Agropromizdat Publishing House, Moscow, 224 pp. (in Russian, English contents).

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Table 1. Data on prevalence (P, %), intensity (I, spec.) and mean intensity (MI, spec.) of infections in squid from Indian Ocean and East Pacific

Samples General samples Equal-sized squid samples Region Indian Ocean Pacific Ocean Indian Ocean Pacific Ocean ML, cm 2-26 7-32 13-26 13-26 N, specimens 303 146 245 115 Parasites P I MI P I MI P (CL)* I MI P (CL) I MI Didymozoidae indet. 95.0 1-2270 97 32.9 1-75 12.1 95.1 (92.3-98.0) 2-2270 106.7 34.7 (24.3-45.0) 1-75 13.2 Hirudinella ventricosa jv. 3.5 1 1 - - - 3.6 ( 1.1-6.2) 1 1.0 - - - Pelichnibothrium speciosum l. + + + 38.4 1-25000 1011.1 + + + 43.1 (32.4-53.9) 1-2050 281.7 Phyllobothrium sp.l. 3.2 1-4 1.5 6.8 1-28 8.5 4.0 (1.4-6.7) 1-4 2.2 6.0 (0.6-11.4) 1-28 8.1 Tentacularia coryphaenae l. 51.0 1-35 3.2 13.0 1-2 1.3 46.6 (40.2-53.0) 1-35 3.3 14.6 (6.9-21.4) 1-2 1.1 Nybelinia yamagutii l. 12.3 1-5 1.9 - - - 13.8 (6.3-21.4) 1-5 1.9 Nybelinia lingualis l. 71.4 1-94 5.6 1.4 1 1 82.9 (77.3-87.1) 1-94 6.0 0.9 (0-3.7) 1 1.0 Anisakis simplex l. 19.9 1-5 1.9 - - - 20.6 (11.8-29.4) 1-5 1.6 Anisakis physeteris .l. 2.5 1-2 1.1 8.2 1-2 1.3 6.1 (2.9-9.2) 1-2 1.3 7.7 (1.8-13.7) 1-2 1.2 Porrocaecum sp.l. 46.0 1-108 5.6 10.3 1-4 1.5 48.6 (42.2-55.0) 1-63 5.7 8.6 (2.4-14.9) 1-4 1.2 Acanthocephala indet. 3.2 1-2 1.4 - - - 2.4 (0.3-4.5) 1-2 1.3 - - - (long worms) Acanthocephala indet. 0.6 12-18 16 - - - 0.8 (0-2.2) 12-18 16.0 - - - (from stomach) Total infection 98.4 74,0 100,0 76,7 * CL - confidence limits

Fig. 1 The range of squid Stenoteuthis oualaniensis (1) and the position of sampling stations (2)

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Fig.2 Data on prevalence of infections in ontogeny of squid from Indian Ocean and East Pacific

Didymozoidae indet. Nybelinia lingualis l.

100 100 80 80 60 60

P, % 40 40 20 20 0 0 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32

25/6 26/16 79/41 88/39 80/35 /9 25/6 26/16 79/41 88/39 80/35 /9

Pelichnibothrium speciosum l. Anisakis simplex l.

80 3 60 2 1 P 40 , % 0 20 5-8 9-12 13-16 17-20 21-26 27-32 0 25/6 26/16 79/41 88/39 80/35 /9 5-8 9-12 13-16 17-20 21-26 27-32 /6 /1 6 /4 1 /3 9 /3 5 /9

Phyllobothrium sp.l. Anisakis physeteris l.

40 40 30 30 20 20 P, % 10 10 0 0 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32

25/6 26/16 79/41 88/39 80/35 /9 25/6 26/16 79/41 88/39 80/35 /9

T entacul ar i a cor yphaenae l . P or r ocaecum s p.l.

80 80 60 60 40 40 P, % P, 20 20 0 0 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32 25/6 26/16 79/41 88/39 80/35 /9 25/6 26/16 79/41 88/39 80/35 /9

Nybelinia yamagutii l. Acant hocephal a indet. (long

30 wor ms ) 20 30 10 20 P, % 0 10 0 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32 25/6 26/16 79/41 88/39 80/35 /9 25/6 26/16 79/41 88/39 80/35 /9 ML, cm; N ( Indian squid/Pacific squid) ML, cm; N (Indian squid/Pacific squid)

Indian Ocean Pacific Ocean

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Fig.3. Data on mean intensity of infections in ontogeny of squid from Indian Ocean and East Pacific

Didymozoidae indet. Nybelinia lingualis l.

200 10 150 8 100 6 4 50 2 MI, spec. 0 0 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32

25/6 26/16 79/41 88/39 80/35 /9 25/6 26/16 79/41 88/39 80/35 /9

Pelichnibothrium speciosum l. Anisakis simplex l.

10000 3 8000 6000 2 4000 2000 1 MI, spec. 0 0 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32

/6 /16 /41 /39 /35 /9 25/6 26/16 79/41 88/39 80/35 /9

Phyllobothrium sp.l. Anisakis physeteris l.

15 3 10 2 5 1 MI, spec. 0 0 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32

25/6 26/16 79/41 88/39 80/35 /9 25/626/16 79/41 88/39 80/35 /9

T ent acu l ar i a cor yph aenae l . P or r ocaecum s p.l .

6 10

4 5 2 MI, spec. 0 0 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32

25/6 26/16 79/41 88/39 80/35 /9 25/6 26/16 79/41 88/39 80/35 /9

Nybelinia yamagutii l. Acant hocephal a indet. (long wor ms )

3 3 2 2 1 1 0 0 MI, spec. 5-8 9-12 13-16 17-20 21-26 27-32 5-8 9-12 13-16 17-20 21-26 27-32

25/6 26/16 79/41 88/39 80/35 /9 25/6 26/16 79/41 88/39 80/35 /9 LM (cm), N (Indian Ocean/P acific Ocean) ML (cm), N ( Indian Ocean/Pacific Ocean) Indian Ocean Pacific Ocean