The infection of tench (Tinca tinca) with Ligula intestinalis plerocercoids in Lake Beysehir (Turkey)

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1 Bull. Eur. Ass. Fish Pthol., 23(5) 2003, 223 The infection of tench (Tinc tinc) with Ligul intestinlis plerocercoids in Lke Beysehir (Turkey) H. Yvuzcn Yıldız*, A. S. Korkmz nd Ö. Zencir Ankr University, Dept.of Fisheries nd Aquculture Dıskpı, Ankr/Turkey Astrct Tench (Tinc tinc) were smpled etween Octoer 2002 nd Ferury 2003 in Lke Beysehir nd exmined for Ligul intestinlis plerocercoid infesttion. Prevlence rnging from 41.66% ± 8.33 to ± 1.19, decresed with incresing fish size. Index of prsitiztion (I p ) did not differ mong the fish length clsses however, monthly flucttions in I p were significnt. Minimum I p vlue ws recorded s 2.72 ± 0.30 in Octoer nd mximum I p 5.55 ± 0.49 in Ferury. There were no consistent trends in plerocercoid weight in reltion to fish weight. Men intensity levels did not vry in the length clsses of fish. No significnt differences were oserved in men intensity levels in the months studied except in Ferury. Introduction Tench (Tinc tinc L.) is of gret economic importnce for the fisheries of Lke Beysehir, Antoli. In Turkey, the domestic consumption of tench is lmost zero, however filleted ctches re exported to the USA nd Europe. Ligul intestinlis is widespred nd common prsite of cyprinid fish in continentl Europe nd North Americ (Kennedy nd Burrough, 1981). It hs lso een isolted from the non-cyprinid stone loch Brtul rtulus (Ben nd Kirkwood, 1997). L. intestinlis is pseudophylliden tpeworm with three-host life cycle involving copepods, fish nd piscivorous irds. In terms of longevity nd host involvement, the plerocercoid occuring in the ody cvity of fish is the dominnt phse of the life cycle (Hoole nd Arme, 1983; Willims et l., 1998). It is known tht lrvl cestode Ligul cuse pressure trophy of ovries nd hevy ectoprsitic lod my inhiit proper mturtion of eggs (Ferguson, 1989). Fish infected with L. intestinlis my therefore e unle to reproduce (Willims et l., 1998). In Turkey, the plerocercoids of L. intestinlis hve een previously recorded for some fish species such s Alurnis orontis nd Leuciscus cephlus in Almus Dm Lke (Cengizler et l.1991) nd Tinc tinc in Lke Mogn (Oge nd Aydin, 1995). Recently in Lke Beysehir, the infesttion of tench with the cestode L.intestinlis ws oserved where there hs een no previous report of the occurrence of L. intestinlis. The purpose of the present study ws to nlyse the ctul prevlence nd intensity of infection with L. intestinlis in tench from Lke Beysehir over period of 5 months.

2 Bull. Eur. Ass. Fish Pthol., 23(5) 2003, 224 clsses (cm) Octoer Novemer Decemer Jnury Ferury N P(% ) P ± S.E ± * ± ± ± c ± c ± d, c 4 Tle 1. Prevlence (P) of L. intestinlis plerocercoids in different length clsses of tench (N=numer of fish exmined). *Vlues with different superscripts in column indicte significnt differences (p<0.05). Mterils nd Methods Tench (T. tinc) in Lke Beysehir were otined monthly from commercil suppliers etween Octoer 2002 nd Ferury Lke Beysehir is one of the lrgest lkes in Antoli with surfce re of 650 km 2. During the study period totl of 203 tench were exmined for length, weight nd presence of L. intestinlis plerocercoids. Dt were lso recorded on the numers nd individul weights of plerocecoids. A feture of infections with ligulid plerocercoids is the lrge reltive weight of prsite to host tissue. This is expressed in the prsitic index s stted y Arme nd Owen (1968). Prsitic index (I p ) ws used in ssessing the intensity of infection for ech fish: I p =100W p. W -1, where W p is the prsite mss nd W is the host mss. Prevlence (%) nd men intensity levels of prsites were determined ccording to Bush et l. (1997). In the presenttion of dt on infections the fish were clssified into groups ccording to their length. Dt otined were nlyzed using G-sttistics for prevlence nd ANOVA for the prsitic index, men intensity levels nd plerocercoid weight within ech of the fish length clsses. The reltionship etween fish weight nd plerocercoid weight ws nlyzed using liner regression. Results The externl ppernce of infected tench ws norml nd showed no distension of the ody. However, the plerocercoids of L. intestinlis ecme coiled round the viscer nd occluded the ody cvity. The prevlence of the plerocercoids in tench were compred within ech length clss nd for the months studied (Tle 1). The prevlence differed significntly mong the length clsses (p<0.05). The prevlence of infection, in generl, decresed with incresing fish size. The mximum prevlence ws recorded s % in the length clsses of cm in Novemer nd cm in Ferury. The minimum prevlence level ws found to e % in the cm length clss in Octoer nd the cm length clss in Decemer. However, when the months were

3 Bull. Eur. Ass. Fish Pthol., 23(5) 2003, 225 clsses (cm) Octoer Novemer compred, no sttisticlly significnt differences in the prevlences etween ech host length clss were oserved (p>0.05). Decemer Jnury Ferury (Min. - Mx.) (Min. - Mx.) (Min. - Mx.) (Min. - Mx.) (Min. - Mx.) ± ± 1.01 ( ) ( ) ± ± ± ± ± 0.91 ( ) ( ) ( ) ( ) ( ) ± ± ± ± ± 0.93 ( ) ( ) ( ) ( ) ( ) ± ± ± ± ± 1.60 ( ) ( ) ( ) ( ) ( ) ± ± 0.06 ( ) ( ) ± 0.53 ( ) - c 2.72 ± 0.30* ( ) 3.57 ± 0.33 ( ) 3.86 ± 0.48 ( ) 3.15 ± 0.44 ( ) 5.55 ± 0.49 ( ) Tle 2. Prsitiztion index (I p ) of L. intestinlis plerocercoids in different length clsses of tench. *Vlues with different superscripts in row indicte significnt differences (p<0.05). Prsitic lod presented s the prsitic index of tench did not differ mong the length clsses of fish (p>0.05) wheres for the months studied there were significnt differences (p<0.05) (Tle 2). The I p vlues recorded for the study period were highest in Ferury. Men weight of L. intestinlis plerocercoids showed significnt vritions mong the length clsses of the hosts (p<0.01) nd were highest in the length clsses of cm (Tle 3). Nevertheless, there ws no cler reltionship etween fish weight nd plerocercoid weight (R 2 =0.44). Men intensity levels showed no significnt differences within the six different length groups (p>0.05) however, in reltion to months studied there were significnt vritions in men intensity levels ( p<0.05) (Tle 4). The mximum men intensity levels were recorded in Ferury. Discussion In this study crried out in Lke Beysehir, the prevlence of infection y plerocercoids of L. intestinlis in tench vrying from 41.66% to 84.52% represents high vlue. Prevlence decresed with incresing fish size, proly due to selective mortlity mong prsitized individuls, s ws oserved y Museth (2001). Alterntively, the lower prevlence of infection in lrger fish my e consequence of reduced consumption of infected copepods in older fish (Kennedy nd Burrough 1981). The index of prsitiztion ws recorded in reltion to the length of their tench host. However, there ws no correltion etween the I p oserved nd length of the host. In ddition, there ws no mrked reltionship etween

4 Bull. Eur. Ass. Fish Pthol., 23(5) 2003, 226 clsses W f ± S Wf W p ± S pf ( cm) ( Min.-Mx. ) ± 4.76 ( ) 1.06 ± 0.08 ( ) ± 3.09 ( ) 1.81 ± 0.07 ( ) ± 7.43 ( ) 2.20 ± 0.08 ( ) ± ( ) 2.70 ± 0.25 ( ) ± ( ) 3.17 ± 0.47 ( ) ± ( ) 2.35 ± 0.61 ( ) Tle 3. Men host (W f, g) nd plerocercoid weight (W p, g) ccording to the length clsses of fish. host weight nd prsite weight. The plerocerciods of L. intestinlis ttin lrge size reltive to the host nd infections frequently comprise more thn single plerocercoid. Thus, the insignificnt vritions in I p irrespective of the length of the hosts re in ccordnce with this concept. Men intensity vlues were similr in ll months studied except Ferury. No previous surveys hve een conducted on the distriution of L. intestinlis in Lke Beysehir. It is not possile, therefore, to compre the dt otined in this study. Furthermore, tench were only introduced into Lke Beysehir in the 1990 s, representing reltively recent ddition to the inhitnts of the lke. clsses (cm) Octoer ± 0.35 (2-5) 4.10 ± 0.46 (2-6) 4.40 ± 0.51 (3-6) Novemer 3.67 ± 0.49 (2-5) 2.78 ± 0.42 (1-7) 4.12 ± 0.51 (2-6) 4.00 ± 1.35 (2-8) 3.00 Decemer 5.20 ± (2-7) 4.38 ± (1-13) 3.14±0.67 (1-6) 2.33 ± 0.82 (1-4) 1.50 ± 0.50 (1-2) (Min. - Mx) 3.96 ± 0.29* (2-8) 3.42 ± 0.29 (1-8) 3.81 ± 0.46 (1-13) Jnury Ferury ± 0.29 (1-5) 7.00 ± 2.80 (2-14) 3.67 ± 1.76 (1-7) 2.50 ± 0.50 (2-3) 4.50 ± 1.50 (3-6) 3.76 ± 0.56 (1-14) 5.75 ± 0.87 (1-10) 6.54 ± 0.76 (5-14) 4.00 ± 0.00 (4-4) ± (1-14) Tle 4. Men intensity levels of L. intestinlis plerocercoids in different length clsses of tench. *Vlues with different superscripts in row indicte significnt differences (p<0.05).

5 Bull. Eur. Ass. Fish Pthol., 23(5) 2003, 227 The plerocercoids of L. intestinlis my normlly e expected to hve negtive influence on tench popultion in Lke Beysehir, nd the prevlence of infection my increse with time. The immedite effects of L. intestinlis infection on tench were not ssessed in the present study. Nevertheless, it is ovious tht L. intestinlis plerocercoids cn hve drmtic effects on somtic nd gondl growth which my influence the popultion dynmics of tench. Hence, Kennedy nd Burrough (1981) stted tht Ligul hs very rpid power of dispersl throughout new host popultion. It cn reduce the popultion density nd llow the resumption of good growth rtes. It my influence the whole lnce of the fish popultion due to impired competitive reltions. This is of importnce for Turkey when the economic spects of fisheries income from tench export re considered. References Arme, C. nd Owen, W. (1968). Occurrence nd pthology of Ligul intestinlis infections in British fishes. J. Prsitol. 54 (2): Ben, C. W. nd Kirkwood, R. C. (1997). First record of Ligul intestinlis from stone loch. J. Fish Biol. 50: Cengizler, I., Srıhn, G. nd Çevik, C. (1991). Almus Brj Gölü nde ysyn cyprinidlerde Ligulosis rstırmsı. Egitiminin 10. Yılınd Su Ürünleri Sempozyumu, Ksım, Izmir, Turkey.(in Turkish). Ferguson, H. W. (1989). Systemic pthology of fish. Iow Stte Univ. Press, 263 p. Hoole, D. nd Arme, C. (1983). Ultrstructurl studies on the cellulr response of fish hosts following experimentl infection with the plerocercoid of Ligul intestinlis (Cestod: Pseudophylide). Prsitology 87: Kennedy, C. R. nd Burrough, R. J. (1981). The estlishment nd susequent history of popultion of Ligul intestinlis in roch Rutilus rutilus (L.). J. Fish Biol. 19: Museth, J. (2001). Effects of Ligul intestinlis on hitt use, predtion risk nd ctchility in Europen minnows. J. Fish Biol. 59: Öge, H. nd Aydın, F. (1995). Ligulose in tench (Tinc tinc). Türkiye Przitoloji Dergisi 19 (2): Willims, M. A., Penlington, M. C., King, J. A., Hoole, D. nd Arme, C. (1998). Ligul intestinlis (Cestod) infections of roch (Rutilus rutilus) (Cyprinide): immunocytochemicl investigtions into the slmon- nd chicken-ii type gondotrophin hormone (GnRH) systems in host rins. Act Prsitol. 43 (4): Bush, A. O., Lfferty, K. D., Lotz, J. M. nd Shostk, A. W. (1997). Prsitology meets ecology on its own terms: Mrgolis et l. Revisited. J. Prsitol. 83 (4):