"Studies on Ligula intestinalis (Linnaeus, 1758)"
by T.S.C.Orr, B.Sc., A.R.C.S.
A thesis submitted for the Degree of Doctor of Philosophy in the Faculty of Science of the University of London.
APRIL 1967
Imperial College Field Wellcome Laboratories for Station, Experimental Parasitology, Ashurst Lodge, University of Glasgow, Sunninghill, and Beareden Road, ASCOT, Bearsden, Berks. GLASGOW. 1. ABSTRACT
The pseudophyllidean cestode Ligula intestinalis (Lin. 1758) was studied in order to reach a fuller understanding of its biology and life cycle in a natural environment. The plerocercoid larva in rudd, Scardinius erythrophthalmus, was intensively studied by sampling the fish population of the reservoir. Environmental factors affecting the plerocercoid directly and also mediated through the host's physiology were studied in one generation of rudd sampled during a period of two years. The site of the plerocercoid in the fish was accurately determined by dissection and by sectioning of infected fish. Morphological changes during the development of the plerocercoid were investigated together with accompanying changes in nitrogen, glycogen and lipid content. Changes associated with senescence of the plerocercoid were observed from sections. Stunting of the rudd and changes in its behaviour were observed to result from infection with the plero- cercoid. Final hosts in the life cycle were observed on the reservoir and the size of infected fish eaten by these 2. birds* The adult phaoo of the lifo cycle use obtainod in the laboratory by in vitro culture and, by experimental infection of ducks* Eggs obtained from ip vivo culture in ducks were used to determine the effort of light on the hatching of the coracidia* Fish of various families harbour plorocercoids of Idatiajouleatialla and a hoot-lief was compiled showing the distribution and specie° of fish infected* Evolutionary dovolopment of the oestodo in several fish families le discussed*
ACKITOWLEDGEMENTS 1 should like to thank Professor 0.W. Richards in whose Department the work was carried out and the Agricultural Research Council for financial support. should also like to thrink Dr. June Mahon for the helpful supervision extended during this work and Professor B.G. Peters for many useful discussions. I am indebted to Dr. P. Call for advice on the biochemical sections and to Dr. C.A. Hopkins for comments on this section. My thanks extended to all the personnel of the Mid-MorthamDton- shire Water Board, particularly those at Ravansthorpe reservoir, who gave help so willingly during the collection of fish and, lastly, to all my colleagues at Ashurst for assistance in various ways. CONJJ,NT5.
Abotract Aelztawledgementa Contents . Introduction •Vcole4 of -the life ole Licitla autina •SECTION _ I: . . Chapter I. Itothado of fiat or d examination 18* introduction 18 Sampling raothodo , 20 Seine netting 21 nod and 'him Eishing 24 , • Tranoport ot, live tiah to laboratory 25 Data rzlcorded in laboratory • 26 ticanurcrient of i'ioh cncliplorocerceids • 20
C41113) Or ko2.oh.. ,-,4.41,1. intectinalin 29 • - , . . . . Introduction • 29- A. Phyoical -2eatniroa of ilavenot.l.lorpa rociervair 'end influence of climatic almageri on the zuld: 30 1. Ohara li ao and changes in water • . level 35 2.. 17a-tor zaveraento: 39 3. two action. 40 • 44, Teraporatnro 41 5 Might i'..i.tti.roct o Itavonothorpo ronertolr 43 1., '21-Jakton 43 2„ Bon-thou 45 30 Aquatio plan.tg 45 4, rich fatula of Itzwenat orp 1962-65 46 5, Birr.l. fauna
ont lifo hi,ttory 50 1ho ruddy Soard±n ,orlithroyhthalmus 50.. ..2 Distributioti-'. of. rudd'vrithit t roctorvoir 51 3, Abundnitioo of tudd; • • 53 4.,Groith ofru- dd.. .55 • • 5. Braloaing.-habits tuld bo.hhiour 56 .6, ilierb.fion "Of.' 50, 7,tpngavttiy - of 58:- 8, Dioonsos ctrul..othOr Dartioltoo of mill 53 Diott oorrpotitovi anti prociatorn zttdd Itatp?nr.t-thorpo. 60 1, :Diot radd 67 2, Cormo-bi-ie*,16n 63 3. Pish prodatora of mid 64 III 'Lao greater Crested grebe • 65 5*
Chapter III. IlcolOg or tho llorocorooid'in fho 69 oropipaiimmakrearrouto Intwaduction 69 noological • Tactors-irigluencing..host .. and praoito 74 • tffoct o soo:r3onal variations in • climatic and 'physical raptors. on . 75 2* Seasonal variation in food' supply or. =dd. and • °greet on ..- • . - intontinalio • - 81.: 3* Seasonal 'voliiation in distribution '• cf rudd the r000rvoir and egiloot on T.t3gt4a, ingestatiOns 87 Scazonal vztviation abtindanco or radd and effect on Mr iritOStatiOnd' H • • .93 5 i,13casouril variationo in raitgration . og rudd arid orfoot on Zif-,:tAlq • .-"infostationd „ . • • .• . 100 6a. poaconal variations' in activity Or . rudd and' orgoct on. - • • • . infontationS-- . - '103. • Ago and roproductiva condition rudd and ege.00ta_on44.0.422. • . infontations Introduction . 104 •• •14 Ohangon in footling habits. ox' mid - and ogre...ot onLiaula -311-ficstational.05 2*. Distribution of mid ai difforont 043 -mid affect .on Mauls • infestations - 108 3i- Abundance of radd at ditgoront ' agar, ond: offoct o.n I in:CO at ati Oh a 111
72,;.17.)..ing migration not ofloct on, ineo,ntationn = 112 -ahariGoa -in away/ V . ci4 =cid with : ago rma offoot,oar21..upaz InZeotationD FI~c o2 plorociorcoido =tad and ofxpo -on .clubsotraont infoutationd 114 : , • .1%ectliriet;-11abitte.:of., ingectod' and 6froot on. ' • t 1v .z?fosto:.ltd.. 011101•••••=111111111ft• .• _ Diatribution 1:rrrocimd -• and off ect on oubcoripout 'intoatatione" • /16: infooted7.i.add,and •ofroot on aubcoquent , ingoata.tiona, _ : 117 . . Spawning migration' of Lru.dd and: offoo• o aubrioquent . . 117 5 Activity of in..VoO bod' cfroat subaostont - inter:Ito:tam:La
Charter IV. S to of do-vc-Aorimont ottto.,122.f.a.6orcold IntroductiOn 119 119 SitO of dovoloyment of tho' p1ol?ocoracid iVit.,iripatttra and adult mad ,'• 121 •
hantor wr Growth era tiovaici mont 1orocorcoi1 iltbrOdUC'1032, - • 3.30,
1, Dovoictmont of tho pionnoroolil, 131
t" • 2, Sille tho plor000rocid 136 - 3. Ra• .z. grmrth of nlo.rocercolds _138 Si r,6 ploroceroniels i L ;iit1tiple infestations - / 5.1 Deformed growth 144 6. Chemical Changes associated vrith rowth rind develorrinnt cr.!: Van plerocerceid 145 a. nitrogen- content 145' b. lipid content. 149 0. Glycogen content - . 154 Charter VT, nffeot of :tai z1a 1nte6tinells ostau ens 1...... 411MIP.11 •1•1011406
In 158. 1. Susceptibility of :rudd: 'infoStatien,:159 ' 2. Direct effect ofpioteocercoia on the ru.dd . 160: Grolith- 0f infrmted rudd 151. 4. Effect 'of plerocercoid infoutationo. ' on the -behaviour of the....t.iurld hoot • 170 rortaity of infested' .7.1.1dd 172 . Chapter VII .Diecussiont Section It Ileols.4=1...." the e7olt., intectineain 1..Ilost of plerOccrooici of allsal1.11tInt.....13.2.1 • . 174 2, Distribution O tho'plerodoreoid of' lica/a intestinalis in the Uorthamptonf- kaltAxo 44.4.o4 - . 176 3.Changoa in ruddta'diot and effort on Lifsla infostationa 177
- 4. Effect of infontations onriAd anc . ausceJitibxiity to furthar . teOstation vith Lictulti • .78 - • - 5, d6hriona1 variatioh- lh plorocereold - nfostationsfltnd in- dovololpontof: egg and.Droceroold 3-34 6. Water .t3vel in RavonStb.orpo:reserioir and: incidence' of 1ifialta 2 tho rrtdd . -1,S3 a , . .7. In of riew3onal changes• on:growth -, of .tho plerocercoldt its deirelomo:dtal 't3tagari and-.aqsociated hiochendoal.•.- changes,: . • . a, Inc• of seasonal. ohot -tea. tin ercrath• tInd development of, the plerocorcold 191 Staz-Hes 'in . e.ovelopment o Ll.gul ploroo:szcaidu -- • • 193. . c. Bionhoiee.1 ehanseS dovolopment . of tho plerocoreoid Glycogen. content Iiitrogen content . . Tripid Suriatiry o Discuss mit SY:CT./02i It 'Culturo or rldnl:t ni7laa-intectinAilA rm 1141221aJg.s.01. vivo . 206 1, not:hode a, nifeetiaa or duckd 207 ColVle.!tioli of eggs 208 2..gesults 210 . 3. Discussion 211 4. sc ary of In Vto culture 214 Che..ptozb IX. ntvitrc cultivier 216 216 Intro4uction .3 •. Methods of in vitro aultaxo 217 2a nosalts 219' Bicehenital sway 221 4, Dineussiaft 230' 5# St m 253
Chapter " The influenen of light on the hatch!.lw .2Lighgl=a1 Introduction 234 1.Uothoda 234 2.Res ulta 236
3. DIOCUD3i021 237
4. auM3 r2
OECTTOIT Int
Chapter XI. Distribution of Liimln intostimlis 244
• rtraeronAlos • 251
Anpondiz 264 INTRODUCTION New field.. studies hive :been undertaken.'in Britain on the life cyclo of cootodea Whieh are ''not .of .irmediate, . economic 'importance. -In 1962 numbirs'..of =dd. =so were reMoved. froM Ravensthorim reservoir in Northamiton# . oh .Which..the • incidence of plerocereoide of . ' . was. high. It wan 'ideoided-lo, study the - parasite in •the field in an enVironment, which was not • fished ter coarse', fish and to.. °implement' field work, with laborato0_ observationa. Prequently'..; life: cyciled are. do9o2Abfad Eta • .. • • continuous proc000 which proceeds: ineVitably. ...In order • - to roach a 'real underatendind of .factore which Control the-life .oyelef observatione.Muot .be carried= out .in the field and. in the laboratory'..:. Pield 'Studien are governed by .the. availability' -of : material. fin which Several staaeo occur ,the .life eyole. from which the "tarasitelogiet obtains .his material* Habitats sr centinualli,influeneed "by' man whose-.. influence punt. teldiatinguiehed from other environmental • . :factors. The:' lilsciatinuoud' and - limited availability ;of Daiasitoo, in the field haa. stimulated the. culture of the pramoites in the laboratory under defined oenditione in Ardor to acquire valuable physiological evidenoo concernitig conditions necessary for .survival.,... The ocolcigy. of stages in the .life cyclic Shoed be. observed both in the flold..and in the labortito*7 under Controlled conditions.. - • Thore- are-.many methods of studying parasites, oh an culture.. electron stoma eoixy and•biochemical assity Methods,. all of which, contribute , informatiO4 'relelient to: the conditiOns under'.Which the parasite
. Zito cycle of Xieu,/a 4itetkAinsAlls, (Ida. 1759). Until recently regarded as a monetypic speoies (Smyth,. 19474 two further species of the genus amaja 13loch, 1182 Moo, bOubinina, 1950), and Tai, 1:mm1078104 '040). 1111=4 .1950 is have been described, and Dingy anti pottiai(ocievhaNtr were grouped into a proposed new -Bally of the Steudephyllidea the ;#1,0411dae' (Dubinina, 1050. The adult ikuilp,"*:esitiing/is is found in the intestine of piscivorcus birds (Ceeier, 1918) :altheugh .• Weralo end Nerieedt• (1052) state that the adult to found . only in, livit'9fi op. in North America, but in diving "endWtaing birds in, Europe. Recent evidence (crier* 1955) indicates that Magi may mature , in aquatic pikicivfarous • Ate, but in Europeit has only boo reccivered from pisoivorons•.and scavengirig birds (Brauer. 1910). Ormanlate .eggs laid by the adult pass, out with:-: the host faeces. and-can oar develop ,in water ". tpc.b.annislandif , 1980s *Min the egg, the heraoenth • embryo dovoiapa, surraUnded by a eiliated, eabrycphoro and hatches tau the. egg as a ahortabliliedo- tree-esitstEng . -corints*m:d (Sohitunialende 1865), The CoraeidiuM'iS ingestettilby 'a oopepodo firet intornodiato hest. and penotrateti into the haemeaoel where it, develops into the, i.roCceroold or that stage.- The procercoid a . 6 • of ',the cycle (rigs „ :_ps13) oas the last to be found and wad:revealed in 1919 by, Becton who truedeeded in recovering an early; pleracereeid by. feeding- copeiode to . gudgeons he: pleroceroold or- seoond larval sta&J 'develops the body cavity: of the fish intermediate boat and has• been Observed. by- many workers and reviewed by Octhper (1918). •• The' speoiee of fish. infected by jIntiexatknalsaheuld oritiCally appraised in the light of b.teAninitte and i.959) and Breitengs ;1943 works. oundi:: that' itistula intestinalip occurred the Cypr*id fieho pi;:ilttilsytibi% in the body cavity of ,013bitii fish an Liz.TMlovatti in the ,body, cavity of 'ilobiees
13.
Fig. 1. Life Cycle of Ligula intestinalis
Piscivorous bird
Infected fish / oral infection ADULT pisciverous bird intestine 045 -70),i 2-7days En passed out \ in faeces 6-2Idays Cyprinid Plerocercoid fish Cyprinid fish Coracidium body cavity free 350 days+ swimming 50p 2days Infected copepod Procercoid oral infection haemocoel of copepod 7-I6days ae/
In Cyclopoid copepods 14. After a period - of diffrelopmerit during. Which the. primOrdia cif the, reprOductive organs- deVelopp. the plerecerceid bootlace inteetive to :'the- final host.; .betwtien the form in the fish and that in the inteiitlne- of.birda were .notad by ..Bloch (1782) mid Benederi.-(185d). who unsucceitsfully attempted. to ebtain .by feeding infect0d4ish to duc*s. - The first succooiltul ilttottipts, to ebtain.--the adult .wert Duchemp: (1870' and Donuadidu. (1877). who': developed' the what :in. ate* and- found, deielopmenti maturity and • death to- be voz7, The wheiii of the- life cycle was finaUy::reVealed by Roden (1919). . Thisee. intereei ing aspecitto, have boon studied; 0.10-Urfa. cultures; of the adult; • the economic effect of e- plirai3ite' end_ onetration of': the fish :host. The adVandrit State of development. of the,. plere— corooid i'(1938b) an d then • *th - • • (1947) to • attempt yid.. Culture of the adult. Smyth (1941), ';.euctiO4sfully: obtained a :few fertile egg's. Techui‘ee doyaloped by: snytek (1.9544) have been used.
• in thei. culture .of tAlSi o 21400: (Mueller) (Piteedlo. 19ct-6)* cultur!id.s-by theati methods
itt!" 2 0i:duce- eggs in media .:other' than he ri 130/11111* The IWO. freohirater fiah:as. a feed *aurae in; • • • 3- . :jhas: resulted in the .stUdY of ;Maga from an •, 15. economic point of view/ The paraoite causes stunting of fish growth .(Pitt anti Orundmanna. 1957) and. changes in the bioahenical oceposition of the boatl observations have been- made on the life cycle,-(Dublixthas 1950 andTibova. 1957) but itt moat cases these - observations are restricted to • small. numbers of. fish* PahrmannJ1934) nOted that the presence .of, UAW& cdused castration of the, fish boat -and Kerr (1940 emonstrated thcLeffeet..,of the presence of•idtialk ans the basophil. °Glob of -the pitultew in the roachi' and the. =natant effect on the zonado• -• Rocentlyi Armoiand.Otion (1965):hateshown a. similar effect in ._ other: Oyprinids poranitieod b him*" .1711e rderecercold phase. 'of AtiviA in the firith host is the longest' in•the life history, Infected' fieh act naturalli as a reservoir of infestation for the final host and aloe for. the parasitologists. . • liltirocercoid batori al. at different ,stagos of development can' ho obtained and, used 'as a..source of mateiial .1:or. culture -of -the 64444.: However, the material required was . often diffi,oult. to obtain da mud,prevented access to :.tionorvoli'during• certain periods*, *a:greater part of this thesis concerns the.. plerooercoidistago and sampling ‘was.--carried outwhen••' • over 'possible at monthly. intervals. /t is demonstrated s 1V that tho ini'ection.• Of. rudd tuxd dovelopment'of the plerocorcoid depends on a complex of Influences rather than on a single sot. of 'factora• An ecological study ,damands. observations:not, only on the parasite but on the hostvo habits m oee/oggi both rudd and:final•hostia'ectiloict ex,ePoorly 'documented* Therefore. bath infeeted and uninfected, rudd were investigated in order to 'determine diet, chances. aVorwintoring habitar feeding sativityp distribution in•.the reservoir' and Seaming, '‘.These habits changod not, only with .the ai?;e of the ,radd and itt reproduetiVe condition but al do with sontional. Tho• incidence 'of .pleroaercoide in tile' fiat the intensity. of infestation and the- parasite' burden wore correlated-, with changes in ,the envireortent end .' ph.yeiological cendition of the host* The effect of Li Rla infeatationi 'Oil the fish population, includ the stunting effect on growth and the aitoration in'the r..haviour, of the infooted fish. were studied. The morphologioal dovelopthent of the plorecercold Wan. observed togother with the biochemical changed related to the, stage of development and info etivity to the final hoot. The position of tho plorocercoid was recorded In all. else groups of fish obtained, Adults tZ/03:0 tkantailleid.lazitta during a brief 17. series a experiments and AR vivo in ducks. Ems obtained f.rom i t, Aye mid 41 vAtro vfork.previded material 2or experiments an the hatching or the eggs. The free-oliving stages are direetlY-affeeted by - • ! • • ' changes but little ia know or *totem affectinc development :. WAlua is a coomopolit l`p site with a work-. wide distribution-awl liet4or counti4ea and flay - / - bests in vzhich the ,plereeereeid ooeurs has. been compiled* end the validity of Dubininats apoeies oelivilbt and 14..Ea,v2....oveatt. is disouneed. le.
SECTION 1. ECOLOGr OP THE rays arm Or rfuntrA AVVSTICS MOTU I f Methces of fish spimp;in4` anit exeimintykion for fish ignites. Introduction. In order to obtain and examine as many apecimens of the rudd Soardinius errtiptiphthalmtle (L) from the reservoir, the following methods were used: Two methods of sampling were employed; rod and line fishing and notting'with - two sizes of seine net • with different meshes. in practice, no one net proved • „ suitable to catch the complete ,sise and age range of rudd present' and, • therefore,., two nets , designed specifically-. farcertain :slide of ' rudd were: used, - The frequenCY of 'the; size' groups captured, which becausie: of the correlation betweew idea and,.age' of-they fish can be used as an indicatitin of .age,•aepends. on the length of the,tithe spent theeff*oitincy• Of the apparatus and the way in which it is need. At . certain times it was impossible to use allthree. methods of sampling because of the conditions prevailing. The main hasard was the severe drop in water .level, exposing areas of mud impossible to cross on foot and preventing launching of the boat. Therefore the figures • available for rad abundsnoe of the fish of di:Cforent AP00103 Crab(10 Iv* p,49) trtist be considered -In relation - ' • . to those conditions, .. • Mon' observations. wore carried out, Ustlany between -the 33t and 25th daj of tio'nekath► tlie plaoon iSdicatett on the map (Pig, 2, p,51), Observations and amp: u13 ware ulislertakenap,'rudd 'bornin the Swatter a ac 9G as • ri.4 ..the . eau° tine. observations and easoling V40::a - also o;Irried out on •4110 other. ace groups,' after eaptt'iro Tz'ore. hoid. in 6 Itzioiv etzo is the 'resetevoir.Ver.orslY vrozoport to the. ittbare,tOrs• , .' •ohrosologica ; itorico•ef data''vre,0 • aeouraulated, /ieldi*3 . - - • . information . ore;the be tutit diatribUtion Of • the . acid..1xed the. incidence, in and -parasite .boon
.ef mad,' eell:eollecti*; tr.p the whole roservoir was . ..ebserVed- in the •earliacit. and.ladt Izours - ofdavlight, At :these tines tho.1otribition and Itkovera&rts of the uc:ellia be cbservelL chaal was cas,7 to ace-. bootnizie e its'Poeition cleae'to the lank in • water,. The *ositicd -of t#e elder' soup of ruckd could - .")e 0.)cc.ii-Titid. surfaao mom:tents -cf. the fish at:earl/ .- and 'late, hours, If the age ximulis ot.the fish vero indou'1,1,t, netting wais•parried out, .At first it was 20. diffloult to distinguish thospeoles of fiah hy their surface novaaant. bat this vas rapidly molved as rudd exhibit charaotoristio movenenta which aro easily rocognised. Thoporohprosont(PernAuvhrkill,01 DA) seldom exhibited any ourfaco movemout, other than inshore whore they aro =oily distinguishablo. rho nontblz sampling of the rued try revealed important information on the movement ana habits of both infected and uninfooted fish. Uottina and rod and lino fishingrovcaled information on tho fiett of Oronp 1 ana older gleh up to Group 10.
Sampling mothOds.. ronthly sampling:vas earriodeut i t a.11.010014. special cases in the area around tho'beat..house (Pig. 2 p.31). Pry 14mm taken with the amall'seine. close to too shore, than- the_loror fish vero taken with thaw for soino further out. The Older fish (Group 5 and older) Dan ht with rod :7,4.aa lifts were all taken in an aroa mono 50 yds out from the, boat-house (Mg.' 2 p.31). Opoolal cases of sampling did arise. either (1) to identify fish or (ii) to catch courtinO fish or WO Wii01% the fry shoal movcd.
The shoal eghibiting courting behaviour during ' - April was notted with the seine at the position shown 210 144,0 7 x.67) on the north aide of tho embankment* Other rudd were aloe nottod at' various' poaitidis' during thititivo over the Whole area, of.the reservoir* :dry wore &florally sampled from the boatwihouse position' with twcyJxceptions.(i) a:sample was taken i tho main. feed stream tai sue, 7,;' p.67)_because the fry had moved into- the' stream (ii) p aortae of samples were taken at - the- feeder stream, the embanLmont bridge and tho boat houoo, in ordor:to dotermino differoneoa in incidence of infection and parasite burden in the rudd fry in different irate of the reservoir*
Seine netting* Two specially constructed seine nets wero used in the reservoir, the long mine being used from a boat* The long:wino was manufaetured to tho aboeifications given below,by Itridport and Oundry/td*,'Dorsot* Thin not was 50 yds long and 10 tt deep, beNing a 1" mesh or 31/2n knot to knot, with tapered ends* It was , conatructod of synthetic) materials except for the load weights. the floats boins, of expanded polystyrene and the not of nylon* This not woo deaigned for and fulfilled throe main requiremontat (a)it was light and could be handled by one person (b)it wan extremely otrong and rot...proof* and 22, thorotoro special storago aonditions word nOt requized,- • (e)-. tizas atittla, tttvioti'X'to toko.1`.1att tit tvo-vars enti tutm's* onouOt to .so thifootigh tho middy i)ottiorzei„ -.7.146 -min dravibatilko wozio.totrad tritl . thiri not* Zirotly* had..no tho rIttiac, cap. 1:112,54/1...-Vottifl_havo bocli• oostly#- - , areas cone:146mM° liottorlif.4*Gatatio4, to lower parta- of the .r,ot- t‘ndod .to docapos under tho nett .f.t *4111. iAth obinos# Coiorul haullpg or the_ bottom 1144 itottivitoro'.proveritod' rolling or the batto odgo* iocaiso at larto Size or the reservoir, tho nettled:IA-riot bo uosd aroma' givo a- good, yiaid, dna undorviatir olvtaoloo:rootriotod tit° arOa ttiri Th64O- obstaoloS 000drrod particularly Ion the is ):113,4111 " Catat (?ig, • 2 2431) , Other. limitations a tai}• utrt; wome.ovidoa 1.; with firstly* 06tio• plates woro. ino,Otoisaiblo cor.taizt tizoo Lu to biali.•4 0,:evtat or. the boats • %Awn ..t116 roaivvoir wad :Lori Lind' and. 'lilt 'provozi:tdd .tho.uotsiolne, haulea in* ho' bast adoOrtca oldo fish. -obtainod th‘ not wore toad takort ' tho tirst two Iii .Or, daylight* kb titio tiro 23. ofrudd could, to noon by:eurtace movement due , to 'their Teeding activities, Mon the ilsh iioro on'
-the Ourraoe - the seine_ not could be laid, around theme' Tile road tended to come 'In eeparate-eirlo Groupo p.7*- ittatittait i - And adizItite '15115 nhoals, of fry.
6110taa tre- £LD2 and- echoole of aults were normally all naperatow The long noint• normally.- todic.ianatuve alt he mature Titih wove occat-dirially *an* filo cinch., the 1%toya, G. mad upto one your oaa credal seine not wao nada o" towylaaa. Tiao net T. 15 7.1.4o 'long otir 4 tt deep nth- n =4. mime o 1/8,1 which enabled. a'0n rita1a,y bat al4otttia.11. at 'avor 2. cm leds to So 4okon•
:41.pno1 .t; it7an oucceontal in ."44.at.it could bo lined e; t:: quickly. o tho tho once the wore faoen 'Zvfo appodoheo ;707:40 116d to, catch tho Zvi/. .• The net cailld,eithor be need ae a1.4ottarl uoino. 1•0-•, ix an arcs, Whoa the wore plentiZtili or it could, be
'mud ala,t3htly ire4d4 allra Q-370),14 elms tho bunko oC -Vac roomnroL7 wheten 37glki' wore scaroo, Who diap.dvvzi • c tho liV4ter x13,9-411041 was taut iiloit o.eighth off:' the cat ;ht woro loot ovei. the top o.tho not during weeping, h3 a not would have ion more ouccosetulwith a bita. but iagaiii uoot was Liatting Enotor• tod mid ,Line -At core' stages' it was deSirable to catch oldor tish which wore not. takon , in numbers in eithor the two seine neta, duo probably to their ripoett and. tower numbers* Methoda such as Gill netting and elootric tishiri,1 wore considered but rojooted because (i) .46111- net ft 443ploying, 10414 note of. Lino zlaterial - entanc-,710' 1.4)4.113h ao _theyblundar into them' would intertere with trout t G i 14 to an extent. that lmed. not be tolerated 4, the at 20=4 and'Ziobizt aosociations •t;u41 (II) electric tiating. b,y otunning the tioh with a oUrrent passing batmen two eloctrodos eubmorged the water. woad nectiositato a large conorator =Ha etaaued Ash would not be many retrieved espocial4 izt doopor part+ o tho reserveir• 10 rod misl. Zinc dohing wao ch000n as boinc` tho =oat expedient in me although probably not -the
1/1001: OgnoielIts :`41.ho alvantago et uoine coarse tiohing techniques in a roservoir which had previously been only oily' tishod soon bac= apparent* I was ublo to catch 15 or 26 rudd o Group 4 and OV6.1." in about tour hours by using tho 2onovrlag technique:0. he boat wao takon out to rb.are the water 1470.9 1540017 dooP (rig. 2 P*31), Thin arca woo heavily ground baited with anaguatjamMI by aoattering 200 254 opeoinens ovor .110 area, in tho evening, The position Mar.lrfarl 4421 a polystweto btioy, to nort 'rod end lino flehin/ was started at (Immo MO bait ttaod ritao azoin ab:Lssztomaj onr me 6,U - 11,strxidard book# 7tith 5 lb 131.iettkinc;- ceacain zonofilazent nylon lines The 'bait wari odlusted to at.10-12 ;nit. this" dep.% :ins fey d ztiold, most fish,
Tranoovt Of. Zive 'ieh to laboratory. It was neceseary to maintain the fish Olive while coaapling continued. as thin' coilid. to up to 2 days. cago wad bit, .t irith 'a frame of and a zino bat toy. The .sidee end, teirf woro covered . 'with plott,bie tygen. oe_:el.no;mosh. , „..., TaotOrarovi 5 'ft: ton 117.dace by 2 ft ride and 'was vrelettcd by the'. zinc bottom .se thct it floatod 17.1.th- its-top' level with. the *ter* The ooze, ti.37Eld the boot while sotpling 'and the captured fish rep plactid ineide artor 'their doreal fin was clipped. for 4"-soozAtitioni, and the:pia:coo', tiie* date avl- peSition of capture 'xiecordods - , The rudd wore carriod from the reserve .r to the laliomtery at'Asbuist in, ttr e large plastic dtlet each of 16 canon' capacity* In the winter months '
2S 0 . with laia,, tomporatureo the bins 0,16no wore satisfactory Cala tal0 f.1011 crixteitod. pante,iided tho journey tine did - not mooed vat. Mum and micvided there ,trere not too' • alrov lage:ThstiidUnin., In tite et=rto Mattis,- howevort with .1.11dhor tezperaturcsit the fish died rapid unless the l'ellot/Lng precautions wore token; , the bine were ho.avily lagged vita glass fibre to a dopth;i. of 3" - on the slits:Moo the sidetti1/4-,,thottem an& lid of the bin all beingId. 2ofero placinc,,,the fish in the b:int bbo bottoil was covered to a'depth of 5" with ordshed.loei mad the bin two-thirds •filled with reservoir water. It moll- cylinder of orm,on (20 ett•ft0) Was co tot to a V.ore•as diffuSer mael this was placed in,th6 watorit the bin., In this way 'the viatr,sr 1,7a • otreenated for Several mbiutes. Duririg this period the 'fish were placed' carefully in the 5n 'with a hand not. 'T.he diffuser vtt313 then ronered and the lid looked in, position.' This method enablet. larger ratabells or. fish to be transported in 7.•arnor teraperaturoa• Data "Accorded in /laboratory1i it.zo of .fish. - There arc soveral methods of eatitaating the age of fish. The most accurate is to nark the fish at on early stage and then to recapture at intervals (Rtunsefali and Everhart, 1962). The method chosen in this study was to count the number of growth rings on fish soales removed just dorsal to the'lateral line. The age eitimated from the scale was oonsidered together with information of-sige and weight gained from the fry of 1963. - The scale method is prone to error, because breeding checks to the growth of the scale:may occur in older fish, and, the resulting' additional rings cam► confuse the correct. count. . The terminology of Bplitsefall andlverhart U962) was adopted, i.e. fish Owl years of age compose Group 11 fish 1.2 years old compose Group 2, eta. It was . difficult to decipher the first three annual rings on the scales therefore scales were taken at intervals from the, fry of 1962 'and 1963 of known age and these scales were unod tor reference. All scales collected wore mounted. Each scale was washed in water and mounted between two microscope slides held together with 'araldito' (an ester, glue). The slides could then be eitami►ned under a binocular microscope, or the image projected 'on to a screen in order to determine the growth rings, 28, Measurements of Fish and PlerocercoldSi All'fish'colledted, both infected and uninfected, were blotted, weighed and the length measured along a .straight line from the,tip of' the enout.to the:tip-a_ the oloeed tail fin. ,:licalesuied.for-eetimating age Were rano-tied from a position just derail of amid lateral line, about 'half.WaY4Ilang the length of the fish* By means of a ventral median longitudinal incision. the body cavity was opened and the pleroCercoids - examined in situ. they wore 'then removed, counted and placed into '70A'alcohol'a-t.room temperature for 24 hours. Vhe- Olerocerceids were' then rapidly removed, quicklysuzfice dried with fiiter'paper'and weighed , wiii4m10'seoonds*'. The'length of the, plerocercoid,was _then measured, 'ftighing after immersion in 700 alcohol allowed-even Small plerocerceids to be handled without damage whereas fresh worms were easily broken. . 294 CHAPTER It.
EcoloO. at hosts of iintestiritge•
Xn,troduoticill has three-hosts' in the life cyole (Rosen, 1919).4'. The adult occurs In a piscivorous bird. the procerooid in a cyclopoid Copepod and the plereceroold in' a fish4 In Ravensthorpe. reserioir the p.le_rodertfOid is found in the body cavity of the rude SeWiniuS ermihroviatpalruls (04 and the adult is believed to emir in--the intestine of the., greater crested grebe Pop:Oils -,44.4tAtAo oristatup (l1)4. only two per-s of • which are usually found on the reservoir. Befori,conoidering the ecology of the parasite. it is important-to Imow the 13,fe history and habits of the hosts-and the-normal behaviour and condition of the host without parasites. Thiti knowledge should include the effect on, .the hosts of:environmental conditions and the direct or indirect effect on parasitic phases. mediated through the host. The relationship of the hosts and parasite can be underatoOd only in the light of this knowledge, • The aaii of this chapter is to give a pieture of the rotor-var. the physical and biotici changes which can normally occur in it and the effect of these changes on. 30. the rudd and the grebe. Similer environmental studies on different localities have been carried out by fish and bird ecologists. More recent surveys of Ltaula iktesti‘alis have been carried out by Nikailov (1957)* Bence (1958),Nitnan (1964) and Ruculele! (1980)* but do not inolude infestation in the • rudd. There is scant information available on the rudd as an intermediate host and there are few records of final hosts. The following observations made over a period of four years on the second intermediate host* the rudd* and the final host* the grebe* are therefore of importance.
A. Physical features of Uavensthorpe reservoir and' influenoe of climatic changei on the rudd. The unspoiled condition of the reservoir has been. important in this study. Trout fishing only is permitted and this is limited to the area S.L. of the road embankment lice Map p.31). Large numbers of trout are introduced each year. . Nome netting of rudd takes place intermittently* Plainly for fry* 'rarely for adults* in order to reduce,the numbers of coarse fish present. Ravensthorpe reservoir was constructed during the latter part of the 19th century. The reservoir is situated in a natural valley in Nbrthamptonshire some 31. Fig. 2. Sampling areas Ravensthorpe Reservoir',
4—Trout fishing /limit
______Sampling areas ______
Fry and immature fish Scale 1/2500 x- obstacle O 500 1000feet 32. - eleven miles north.-a eet of Northampton itself* The shape of the reservoir is shown in Pig. 2, p.31, the length from N.A. to 8.B* being approximately one mile and the width at the widest point approximately half a mile* The reservoir wan formet-by the building of a - dam at the 8.14, end. , The small stream whit*, is =melee° provides the ivater'supply from the NA, end. .The road level at the NO..-end was-raised on to an embankment .which. divides the reservoir into two Pula which join under. the bridge., The surrounding land -has about 18* of .topsoil -, under _which is an iron rich'` sub.4soi1. Ottaraatekstio , or the Northamptonahirereion* The :division of the reservoir into two Parts 'has resulted in the deposition of _silt in the LW. end and to some, extent along the 'southerly shore of the main part of the reservoir*, The main water supply to :the reservoir 'is froM three streams. (111`8i 83# rig..30 p033)0 . of. there 81 is the major contributor, S2 aid 83 being no piers , than', ditches. • In recent years the demand for iwater, has exceeded the resources 'of the resertfoir'azit its catch.. !lent tea„- and an emergency source has ben, provided by 33.
Fig . 3. RAVENSTHORPE RESERVOIR
5-3
S-2
, SCALE 1/2500
X\ 0 500 1000 fest 54. pipe line from a tributary of the river 'Nene.. Nene water in used only in emergencies and ,with. due respect for .the level of the river iteelfe. = The pipe ,entere the reservoir after, linking. with it pipe from Hollowell reservoir. This latter reservoir ie nearby and slightly higher than Ravonsthorpe and. water , from Hollowell dine is used for topping up the reservoir. - Both these alternative' soUririen .cif supply have the disadvantage that they allow fish to -be pumped Up from the Nene, and other species of fish to enter from Hollowell. The outflow of water from the reservoir is at the. end approximately 30 yds 'out from the embankMent' as ',hewn On Pig. 3. p.33 at G1. The pipe id 'tit a . of 28 -ft below water at overflow level, - The form of the. baoin is important as shillew waters have ,a high produotivity. Noble and Noble (1961) and others have expressed the view that adense . population' or aquatic organisms increases the incidence' and; infestation by parasitoe in fishes., _.• tavenethorpo reservoir is a shallow reservoir. as was olearly revealed in 1965 when the water level .dropped to 165" below overflow level, ' At this' level the whole North-west end of the. reservoir was drained and large areas along the shore up to 75.7de Wide were 3 was estimated - "e need, It , that the stirface,area of water was reduced by 450.550,0,, This iziolicates that a- large percentage reservoir: is shallow and -that - the, photosynthetic) some is superimposed on, the.' - decomposition sone* . There is oonseqUently„a high populatien of, aquatic:: orgatiamsable,,ta, provide food for .a dense poptilation ' of fishi" which can in tiara support a population. of . piseivorous birds* .. OhOgei3 in' climate. affect the phySical featitres of., the reservoir* la }There :line end chimes ix .w0er level* - The southerly aide. of Baverititherpe'reservair hao irregilar shore', line, with two main biro 33. ,and,t2 (Pig* 3, Paj”; whichtend to be well•10412111:60a =add ,beoause .theie bayed, are shallew and Mimi 'tiense Plant '6rovrth ' The north-we St. end of ,tie reservoir is also shallow but silting inhibits grovith of plants and - is in. consequence norMally, poorly populated by fish.-: The two- bays and B2 ialtwayis yielded mere fieh. per unit use, of the not « Bmtill Chingos 'in.yirater level 'are' known to inoreaoo • the produativity of Waters* The level 'of Bavonsthetrpe reservoir from Noveiber 1963" until 8eptembor 1965 was
36. averaged for each. month (11g, 414384: sample data being, given in the appendix p$2614, !igurea for, earlier, irears ,are given. in. the Ilid—Worthamptonehire Water Board reoorde(sicid 'these show that the water Shortage in the early iart -of 1965 Caused the,mork sevore-drop,in the reservoir'., for. over t!eity years. - The - effect of the loin water- level on .the rudd wan most pronounded:in 196541'- spittri. at the NO* end of the reservoir and.along the oholterod southerly ,shorei. and- bOth:these areas, are shallow with aburidant week cover. „ In the nrrisz of 1965 the nerrial, littorJ.. Pt xi 4-• was short-lived due to' the'rapid.,rise' and, fall of `the water ass shown in graph.7ig. 4. p.38. During -these- violent fluctuations the fish did. not show the*. nOrmaii,lv 'obvious' courting be ha ?Jour; Only 15 'rU4d. fry were taken in' the summerOf:1965 'compared With appreatinatelY 51000 in a ‘nornal siTsrmer4; in' 1965 mature female rtidd with eggs Were, ecoasionaily; taken in July and August Which is unusually late* . • It appears that 'destruction of normal spawn.ing ,-.‘ grounds by fliterisuations in water level' bad a serious- effect either on the ability of . the, fish 'to spawn or the survival of -6* fry at a very 'early stage-4, The only effect of ,the fluetuatione in ,water level 37e on the grebes rts to limit them to the matm part of the reservoir* However, =indirect effect maY become apparent in 1966 and 1567'as a, shortage of fish food due, to the destruction of the 1965 rudd fry* Rainfall vitally affects the water level of the 'reservoir and a steady level is necessary to the rudd for ita normal behaviour -in Spawning rad movement of the fry* . Water is-continually being drawn from the reservoir in nn' annual cycle by the Water Board* The water-level drops through the summer and aut.= and Alm again in. early epring,' ROnTall has to ba supplementoa by frequent topping up from the riVerSenegi During periods of low rainfall, as- in the autumn of 1964, the water level in the reservoir is not ' maintained but drops rapidly, see chart pig* 4, p* 39 The amount of water which may be pumped from the Nene' is strictly defined to prevent pollution of the river by its level dropping too Ica* Topping up from the None may raise the'level or , may contain a steady drop in level* The effect of a given period of rainfall o the level of water in the' reservoir is delayed, depending on the degree of aaturatiam of the catchment area* .A drop in water level in the reservoir affects the 38.
Fig. 4. WATER LEVEL OF RAVENSTHORPE RESERVOIR, RAINFALL AND TOPPING UP
•2 .1 RAINFALL 0 in inches
20
WATER LEVEL 40 down in inches
60
80
100
120
140 30 20 TOPPING UP 10 days per month 0 H NJ M M J 5 NJ M M J S 1963 1964 1965 390
spawning of the rudd, availability of food for the young and- immature fish and cover available for the fry. ?law fish become stranded in shallow pools and examination of the fish in theSopoolo revealed that .many trout-and perch died but that rudd survived these conditions*
Water mevogents . Itammerton (1959) worked on biochemical stratification in lakos and'showed that thin decroasco with increasod water movement, and that sovoro otraulficatiOn. loads to poor growth and productivity*, It id imirobable that oovero stratification can occur in. Ravenothorpo recorvoir becaum of ito - olulllowneso* Any tendency to.biochemioal stratification,' hammer, would be offset by the provalling bar. wind which swoops =row the deopoot • part of the roservoir (.Rammortono 1959). _ The HO. end of the r000rvoir# duo to ito sheltered position. has little movemont. Slating up of this area has occurred from the main food otroan 1. During the oummer this otroam s from 2..3 ft deep until the autumn whon it rapidlyri000 to approxibatoly 5 ft. The stream lo usually inhabited by rudd fry and a • 40.
Tow oidor tioh. • nonwoven,' with, the ride in,wator lovel "t ho frY loavo the stream. The prof:wilco of trout moving back up. the °tread at this of yeti to . , opc,Thi. may alxio-'eauco frj t;ii,novo., •
Vave aotlarl. - , •- • • Mao action has a -sked effect on the grebes. Ait4ouij1 probes ceUld woathor:,oUt u itouun° daY. :in the middle, o$ 'the rosorvolrt, whore ti•ley r.liniectred .never to _ • rood, ,when,thet7ater, rae rough 'the: grebes wero coon fooding, only,• in:the criall baps' on the,aelither17 ahem. 17a/ie •action 'also:affects ,the calM • riater in, the surnor months fry more . uottally,within five yards' of 'the 'shore4 but moved furt'her,,out in .-. rough'' wea- her. InWinter they rry•wore normally' in deeper water bUt` in rough pea ther moved. avori further out., The- elder fish• t7hich word more evenly dioporsed- throughout the wator .ahoWod, surface. novor!cnt in calm el="1107; conditiond and ezooptinnally mild winter onoe. All surface movement redoes with tho onset of rounh weather. . The firj were alwaya found on 'the sholtored southorly cido of tho rosorvoir and only rarely were they found, on the northorly oxp000d side. Surface movonante of older raid wore oleo litaited, to aholterod nreao.' 41.
♦ Tomporatcro Tempera:taro and light were shotn -by Ilrown (1957) to exert an impoxlant- influoxico ''on -the spawning of fish. Thc . roproducttvo cycle ilYnormally govoined by tho onVirOnment. ,,T;ao'difZerent,times of courting-and sziawning_behaviourwero obsorvod'in rudd tn 1963 and: 1964.rho lovel, of tho roserVoir soverolyfluotuating at both of:theito timos In the spring:of 196'3 the fish oxhibited courting behaVionr_ in oarly tho first fry werotakon in Juno. , In-th&spring of 1964., tbe fish'showodnti- courting behaviour until.lato April and fry were not, ,soon 'until July. Tho airerago water tomporatUrea,for Mhrekand April 1963 and'1964'aro'givon in Table 14 p.41'. The avorage toMporature for April 196310 considerably. hiahor than that :of April 1964. TABTM 1., Month 1966 narch' 6°C .5*G. ' April 12°C . 8°0 Table 1 shawing avorago water to:Sporatures in 1963 and 1964, The affect of tomporaturo on. a fish is complex and often Indirect Ono/Maio 1963). The most obvious offoets aro thono, on growth and metaboilon• In the rudd 42. in Ravonothorpo tho mont intonnivo notabolinm only • -mourn at the higher summor tomporaturon. The rudd or tho oarliont ago groupsi 1.5, grow MOM rapidly in:Ravonnthorpo than in tholocalition inventigatod - ato by Hartloy (194T). A Ilaximum growth occurs in tho at or months and them in little or no growth in tho wintor. Tho fry ohow:no inoroaao in weight over tho first winter. Tho graph on page -rAA- nhown tho rotation of dish weight to water tomporature. Tho averago water temporaturo in'the ronervoir for each Month in Given for November 1963 until Septomber 1965." The growth of the ris h. is roprenented by incroane in might of uninfoctod nobs Tho dovolopmont or the fry shoal born in the curt or of 1963 wan'falowed rightthrough until September 1965. The £iah ropronontod on the graph are tharoioro or ono gonoration and of Islam age.. It nay bo noon iron the graph that inorcaoo in might and thoroforo pis° occurs with:inereano totiporaturo. In the spring of 1964 the fry do not sho7 en inoroano in, might in the earlier menthn in rolation to tho tomporaturo. Other duplicate data for fry of provioun yoarn in not available but it nay be that thin dolaj before increase ilfvoight occurs, at thin otacco in normal. The npring of 1964 wan colder 43*
than• 'in 1965 and thin could have affoct,ed the rudd fry- and their food supply* ,In thc' spring of 1965 the fish incroasedrapidly in 'night with inereaso in temporaturo•
• • -
, readings- were made of light, intensities, at the :-,surfaes or at dopths beoause, of lack'-of time. •Ittavenothorpo -is- a r ha 3or rodorvoir and ponotration, • • of' light gives rise to a dense . flora.; Diurnal - movements of -rudd were observed while samPlirig‘in the spring of 1966, using gill. nets* "When'4the nets' wore: placed at r4sht angles to the shore and examined in, the eveninc • and felloming morning, ,relativoly few fish were caught* Iterievar, when' the nets wore placed about 30 yds out • 271,1.0.M1 the shore and parallel to it.faw fish worn: °might' :in the daYtimobut,many wore caught at night. _those reaultst as the, ilea' wore enrnedhoci on the • outer side. , indicate a movement of fish inshore. in the spring at night*
Biotic feattiros of,llavonathorpo reservoir.* 1. planktea .<, 'Plankton forms an important part, in, the _diet, of yoim ridds 'especially in *0.6 first".year* • some of the • • cyclopeid copepods ,which harbour the procorcdoi of nla _intostimliep aro planktonic* Innis the plankton 44.
Fig. 5 .WATER TEMPERATURE MONTHLY AVERAGES RAVENSTHORPE RESERVOIR
20 d
18 .... '1/4.2 yrs. old 1 30 --- I HSI
16 J 26 EM DI U I H o 14 i 22 I 1
12 II 18
TURE 1 V219 N
RA 10 14 / SVV t MPE i 8 / -I 10 TE i I / •• I 6 I 6 ,'S I yr. old I 4 , 1 2 . . . . . J...... ---.---.—.--7 7— trY64 ...... , J NJ M M J S NJ M M J S N 1963 1964 1965 43.
is vitally important no rood and as a source of plerocercold infestation. y nandom =plan Of plankton wore taken, with plankton nets and several hundrod oopopods examined Tor procercoids, but none yoro found. Thung no rocord of the incidonco of procorcoids in - crustacoa in navensthorpe roservoir is available*
2. Donthod. The bottom fauna and flora of the resorvoir is conoidorable both in range of cynics and density.* Elora and TaUna providing food for the fish aro listed in Table I/ below*
Bottom fauna no neuron of food for rudd
Pry I yr and under Cructaeog Immaturo 1-3 years Inscta Crustacea ae Adult 3 yrs and above nollueca Moneta J,1211
3. ilamitic There in normally a good growth of aquatic plants during 'the slimmer months in the shallow water of Pmenotherpe. Seasonal growth of algao, followed by incronson in the planIctonle orustaceat occurs in spring and early autumns and may block, the water filtors of the 456 reservoir* The aquatic vdgetation is important'to the hosts of Lizi.3Alatatinalio in four ways: . . (1)Spawning of- tho rudd in severely restricted whcrn there is no aquatic vegetation* , The rapid fluctuation of the water level in the sprinG of 1965 prevented Growth of vegetation and spawning was prevented* (2)_Aquatic plants provide sufficient cover for t10 first' year. rudd*, In 1955 an abnormal littoral ficira developed ,duo to the fluctuating water level givirit; , little cover .to tho few rudd present. -(3) -Groberolormally nest in roods in the water a few yards from,,tho Water's edgo and they did so in Anril 1953. In 1964- the grobeso'r.ost was left hi ;h.. and dry by the drop in wator lovol and was thaa' abandoned by the grobes* ,In 1965o'bocauso'thero was no aquatic vegetation with and :upon which to build the nest, no nest vat built* in 1954 and 1965 there were no offdpring from oithor pair of grebes* Tso fluctuatins pater lovol in 1955 may havo dotorred tfie Grebes from, nosting6
46...... A.TnxtvlataslItmensI...... harlynpsamlajakatka6 Throe species of fieh were found only in 1965, viz. :.oath, nillorts thumb and gudgeon (Table III, p6 47 )
47.
TABLE III
Presence of Presence of Presence of fish Species Family copepods m pkrocercoids diet of Lintestinalis 1962 1963 1964 1965
Rudd Scardinius erythrophthalmuskiCyprinidae + +
Roach
Rutilus rutilus (L). Cyprinidae + 4. + + + +
Dace
Leuci scus leuc i scus (L). Cyprinidae + + + + + +
Gudgeon
Gobio gobio (L). Cyprinidae + + o o o +
Brown trout
0 + + + + Salmo fario L. Salmonidae o? adults fry Rainbow trout o adults Salmo irideus, Gibbons Salmonidae 0 + + + + ? fry Miller's thumb
Cottus gobio L. Cottidae ? 0 o o 0 +
Loach
Nemacheilus barbatula(L). Gobitidae ? 0 o o 0 +
Three -spined stick! ebadc
Gasterosteus aculeatus L. Gasterosteidae + 0 + + + +
Perch
Perca fluviatilis L. Percidae + 0 + + + +
Table" /I shows the species present, years when present, presence of copepods in diet and whether infected with the plerocer cold of L.intestinalis. 4S• • These, .re essentially Ivor or:streara fish and proenlitilbly entered frori‘tho rivor None durilz7 r.?Icten ct -pun. pine_• Carried out .in 190. Two other species, dace and roach, oxiet,in ema11: numbers only and aro,alse.bolieved to,hemo entered the resorveirAuring pmping in 1961.or 1962. —Presence of copepods in tho diet of I. inteetlnnlia Dieroceraoids aro shown in Tablo /I/101447 • Although -the porch' and tho throespired.oticklebaelt feed,en copepods they, do,net bocone infested with Ligula• The infection is'lithited to members or the family - eyprinidae• The density of the fish poPulation'was not estimated accurately, since this: requires,nothods which: muld neeessitate'a"whole'studiin. themselves,. However, a reurjh,ostimato wae.obtainod for the three species Dresent in arcatost numberswhioh mro trout, perdh and rued (Table 114- p. 49 )0 -Picurso for rain— bow trout are -included with those for bra= trout.- Tho threespined stichlobac% inhabitina-stroam Bit =Jets in amall numbers and will be disrecarded, Porch first.appoared in 1960 in Ravonsthorpo reservoir when it was topped up from Hollowell tnd they have since become established' in Ravonsthorpe reservoir• 49.
TAD MI IV
itntr=inate 1 62 '63 , 65 Sane - Coon amnion,- . Common, Common Po•vc.- Rare Conen -. dornion Coon SoordiniuO,ovthrophtlialraus Alsttadant Ablindan Abundant Abundant
The .numboro, ot: trout have roraiinod f.o.irly constant duo to at:coking but the numbers of' In tad ohowad, a.- notable drop in./964. and 1965.
•
Of the bird fauna, frac) once:too ol" pioeivorouo, biras: .and one noavongor were oboorved on the reervoiro. rho5:eater ()rooted Grob° Podiaorm3 orlotatud cristatuo Z. and the heron A722as3at....Iroa aro ;both ploolvorouo ithodion.. • The horono wore soon only' at trio ITO. end • of the reservoirs usually near tho main btroan al* uo nor° 'than two ‘"(Airclo wore over oboor.vod. The two, or grobes which Wore prose' t on the, r000rvotr.* ror moot or. tho year aaouned EfOrve 'ao rho .final hoot Xor
ro
‘1*
Presence ai 4.;?;bos Ita o sae o r
Wintor Sumer - Winter Suramor Vintor - 63/64 64 64165 -.65 ‘_ 65/66
0 0
Though. the, grobos usua13.y leave tho rosorveir • •in the winter, both pe..drri re:mined during the vrinto ei 1964/65 ClAbloV't P#50). Attempts teeapturc twebos. n. ordor to tal:o gaccal swrig.oci wort iinsucooss:itila
,1321.0thor bird spOoirm proserrt 11,7,0 observed to' :Coed
Intdd; _ this was the cs.rriim or= Corms eovirm 74. sumner crows odeurred in 2=se numbers. around tisn, mtorts etio but in win• or. were varely rio.on in, the. prol,-.ini.ty of. the r.ozervoiro
0. Host life history*
X. 10 ' 'ho mid • Sectrdin.....us
In navenothorparose:rya1r,- 'tho giali•Darrisitisod vith piers:Rio:molds tern identiCied as rudda no othsr three ilaitetod speoiesp
the dace. rocs and rradcoontp• only aeour.tving man numbors. , ' nhnrnc~oro usod ror idontification w~ro ph~goal colou",~; tenth, :fin poo1·tion of {lo,rnal.'. and. llalvJ.o fin , . (Ji:lkols1;:1i, 1961) M ~1thtn ~ho r6norvof~. niotrlbution of rudd• • pm. I • ~o.blo 1,11 f p~ 52' t ind1.oO,'tDfJ.' tho' 1'00:1"trion of .throo, aze erOUl'lJ .of 'lioh.tlmoughol.t't the: year an.c1 t;lhotllcr ohcnling ocourxed. ·A ohoal io dofjn~d 'ao a 'group of . , nol"O than ~o, i!la:t~dun1 :1::1011. . !nllc:t'o a..t'c nbou.t fivo lnrt;tJ' 011003.0 oi ma'~~o i":1.oh; ..,thi.*~o oS: i~'tuito,. and - ' , thrCIJ of £ri1 :t.n 'tho' roo():\.~oir -111 tho, mu:ntn.... A ochool ' , ' of £'10h io do£:l1l0cl 'ao 'n ,g:r.-c.mp OO:lvoOgtl ot leon tll..."\."'l ;SO ,~.n(U.i,..iu.nal0. i'Jld" OaOt'l'ro ai:·tor, and t)ol'o:ra ohoi:tlil1E;. I , • • I. ~ " 52. 7,..A13/0E ri th inicirl within rosortroiv ho t tho ear aloo ••••••••••••••••.•••••••••••••••• ••••••••••••••••••••••• riiiltor I,____ ; 'armor .Autrain- 2.-RY Pooition' rosOrvoir. Sgt =actor l • 51."-b 13of n 3-5Zt . Shoraboniult- Ohohlinz Mioaling Oohoolo O'hdalo • 1 •••••••41.••••••••• . • • . Position in y.tocorvoir 16-15t:e va td.z. , 10:in 6,.a.t 54g0t, Ohorobound-1 to • otenhoro i • , 5110021.1-1G ' kno1.721, ShoA11.41 Ohdal ,_ into oohoolo , ! , , T- •tlitilM117; • •••••%••••••••‘ Pooition rosovvoi.i_ 5-25:et, - 10-25f t Oteritioro-"; - i040 Shoaling Stall cciidola School° •••••-••-••• •••••••• !33. Abv~danoo :;i. .:1 d ;pxzaca; I• I ofq rudd r:;~tiM~fon of nu.nbQl"o or i':ttlh "Dt'co(.'7J.:~ in,'bho ' • w - : , ' ~oocr'loi:t' o.t' t;....n:;J ono t:lln~) is (1:!.!£:tcul'G, but ;to ·1!?-~ol'to.nt 'r/~'lOn. oonoitlol"ing tho' cif£cc,t er a p~oo:J.tio :i,;'li'~ot~.<):tlt " !t ~ns not ~¢solblo,to' omploy n ta~,~~~ ~ccaptl1rO'mO~lOa (Rounn~~cll and Evcrh~~, 19GZ), All. OriD'tured f'::y \101'0 oxnmiriou 'lor! th~J pl:aroccl'oo1u.\ ill'l;cstine.lis~ oX LirtttlnI 1 ... ,. uouall'\1'11 in Ga.'1lploD.,. of- 2;:1-;50•. n~t?lt'vor•."the' llUI:lbcl' of· t:lbh CXUt1:l.:uClC! ,'Q.Q.tlnot bo nocll, ·to . '. , . ' ~ octi~n.tc .'bhc.l!onai'ty ot "the- j)ODulo:t:tOl1 '!:Hlonu:JC OOVOl':.:w. : , -, '. . ,- ( , . ' of' tho':.rich c~uGh'fr worn. pr6oorvod ·~cxn..'1inod o~·. l~el"t , . , ~ Q~:pczsimontal t';o:r.~:. .. oJ.:tvo fox·; , . . Al'l .:111aicction oi" 'hho- abu.naw"6~·O;{, f:tol1 v-as ghinou. .. .' £rorJ o~;iJorvC\t1ono r.I~lOtlh:i.i.o-oUPt't1..rinr; fl!.'Jh' (T:'lbloo ,'lIII, 'VII! nnel IX). ". " M~ .\' .. l.t)~J"!"'l:'r1:-~ 'T1IT, .....Ii: .1'l.1)'pro~it1P.tc i.t:Lnbun{,10,nco: 19G2 ,- 19G!!.~ •I r ...... ~ IT. If. .-s a ... • "S11 ~ Att:.1ttrra .AEll£..OWll1iE.l1":..,,'2Q;,!:~)1$1\11_at. fp;z. tz9in..Q. '1962 'Vory alnmdcn:t;· . s,nOO"::tntliv:i.urH~lo' ", , , t:\~~ _.~v,,;l Alm.'"1.(Jant 1,000 do. 19G..1 Corrl1cn 50-100 do. 1965 Rare a do.' ," ..,t;.1..• . . q1.\Sc.l~ ~~ hD.J~_lp.rfj,o ,.oo.:1Jltt 19132, Ro.ro Si."'lGo :1ncl~:'rldnnlo 196:;> qomon 50-100- - do. j~95t~ C0m.r;10ll. . SO~lOO do. 19G5 ',hbununn,t; -1.000 do~ "'~ , . -', . 196:1. 30'ina1Viuu~~o.~ 14 do. ~ 6 do~' ]- . . ' rolo·tho~ d;1tfo:l;'~~nt oarr~rl'ro u-.1.th ono '0.0 , tlotllodri, of. ... U04"O O:.t.:':lJ... -1P..:;."4 "VO.'t'Ut1Q o~.... ,J;..r.o.aL.'.J .. •. Iu. 19G2 ana 19G;i fl~' \1Q:t'!C! C\bunc1m.\t i.md bu.:cvivocl to' g:b;o OOmlJOn nnct o.btul(lmt-:; 11'ld!v1du.t.1lrs' i.~ 19Sc~ and 19G~f tho populntion in 1965 ha7L~Z c e~eetc~ proportion of :1.I:''1lcrl,uro 1mlividuolo. e5 Growth or ryld Groff of rudd in affocted by onvironmontal conditions 1963)e and, in Ilavonsthorpo roservoir those condition° appear to be favourablo as then) is- a via° also =Igo- of Tien* . rho sbapo- of tho rude changes durinig booming progressively flattenod laterally. In the • yoar the rudd han an eloncate appearance. then a.ftor tc o yaws the body rapidly doopens.' Growth is, rapid up to the fourth and fifth years aftor which , incroano in length and Weight of tho fir% is alight Comared viith carlior years* Growth of uninfected rudd may bo illustrated by ottitz length, against' might logaritbni.cally; the result is a straight lino (3ig. 6, n.57), rt Joh 'le late7.* comearod with tho lino for,infoctod fioh Patterns of growth are relatod to the seasonal wales, with rapid, growth in the sumer months and relativoly slow or no grovedsh in tho wintor months (Vic* 5, n44)s pioia woighing more ,then 40-50 ga wore either, nature err b000sing mature. Rudd Feighing up to 40 isci and* approzirlately throe gleams old. normally occur in trio typos of shoals; in the fry shoal up to ono year old and in the immalre.ro fish shoal up to three years olds 56. .r.".tho oho too ohcal dopondo oar tllo number o2 .fry and imaturo fichpr000nt• on f.r.y,aro =arca. for q of 1964 captured in tray an4 April 1965, oxtamplo fl - , the yonna firth wbro found with the WO tnro oboaly inoroaoo. i21 Weicht and in, loriarth og - 19G4 contact' in Au not end Soptomber o 195$ Wan loon tbzt in ono goat old tioh oamplod- in proviouo, years* Stun:tins inrowth or firth in 196! Was_ a.rocult o o oot,oro,drop wator lovol which pro venue tho, ootablichmont or a normal littoral fauna: for food•for thoce firih• a. Broodina habits ark bollartour‘ In Aprtl or Nogtho, maturo..rudd congro8ato largo oboa3.o in shallow. 't do arocui• f3hoa1 1:011.00 - placo at tho Mao ond of tho r000rvoir norm, tho Motrth. • of tho otrodm Sip end at the two bays, X31 ad ,132 (71c• 3 i p.'33)• Durins thigi:ohoaling tho dioplay characteriotic molromonto• 17c,co aro laid on and aronnd undonlatoraquatio vogotation and otp.all fry appoar trio to tripod wool,tro lator.• Tho fry 1.:01.10131 no= tho =face of tho orator =ions' the vogotation for' tho first two woo :o. Tho fry vary • connidorably in °loot which ion rofloction of tho oxtont of tho spawning period. 57. Fig. 6. LENGTH: WEIGHT RELATIONSHIP OF UNINFECTED FISH 40 ..-^^'...... dee: • • 20 • ....------• .....*.r1Ple ------. •...... * .• ....'"'• ,------i"----". z 4 I- z w -1 2 1 I 2 4 6 8 10 20 40 70 100 200 400 700 1000 WEIGHT IN GRAMS 58. 1.117otion of =V • nue& do not migrate oxcept at opal- .ntuna. - AccordIng to Nilcolnkii (1963) thin in a movement trjay from the feeding or overa intoring ground!" to the npavning ground°. Nature floh norzinlly 1110170 into °halm, wooded =OW prior to spawning. rid immaturo indi'71duals wore, recovered from, mimics taken during • thin typo of raigration.' 7. Tiontrvity of rude Pro= anti too of the =labor of Lworith rimsin . the cacaos, the oldent rudd in the renervoir 174.,Nro between 11 end 14 yews, old. It in difficult to count the number al' ringo on old °dam; becauno the chectn in the ncalon are alone end there in none iliterforence from brooding °health. The esti...la-toe ago may not be ctlurate Dineanon_and other parstoiton of rudd Pour other speolon of /lame:Ito wore commonly founeinfecting rudd$ I. ArtiRlun toliapoun I. 1750 2, ( 140111711 010)0 3. IoIllhgophlihirlun multifiliin Vougue, 1076. 4 Oarvphyllaoun (rallant 1701). 594._ 1. Arm(luo Zolineourt ivao Found :only on Vic thaaloo O. nature, Zia% avow 40-50 cm, and oolinatay on lartio•rich loo mi to goo cmi og-tho.nott oven. 50,0a. 207.'y . . ioro infootod,:71:411 Ar1r41u® golionwie -.Wad max- irzurt number oil parhoitoo tpund on any ono - i'iott, being ,Z1VO• 2, Dio1ostormIn'tatititocat not000roar ' ladifore goUnd in the /ono ar vho oyo in ,radd ono month- olds., ' Z'artjei faiiaboro a motaao'inairio* up to 120, doair oldor' or ratio, e".;;; ctra' itractado Hatvi* . individurgo !iato p r 1 a Oatoradt dosoislisod 14 D1%104 4'196141 Ioirtivo.AthiVilt rat,,lt.if= oillatO with an =mai oyolo living in tho !Skin o.Z th a and during tho raontho. -of Ilarcht April, ozzia tlay tU fiah caught vier° f.attnil to balini'actade In late airmart autumn caul ivintaii very fcra indiriduaiot- about, 10;10 vtara :fin aotad+~ 4, arasre)?)11,71.1muo laticam• is oastada. oaeurre4 . cia adulta 3Q `c d t t rude in tlio,'onimmora 62 1965: and 1)64. 2wo to Vireo worms wore i'ound in the... ingaotod:individUalo, 60. II* Mot; compotitora and prodatora of, radd at ilavonathorpe• Pool chnino play an important paiit in . tho life hiotory, of, Tairmla Tito Blot a. tho rudd in the firct fo7 montho 4 liro lo rontriotod to. • • ornotaccat followed by progToccivo conmtaption of inaeotat mollusca and pVitt material', , Iz 11,a4TonothorpO ounz,* pe:,,roh c1oo fici.od on cractacoa at a yowls* atatzeik . It 1.e4 irk tidy otago, tho rudd fry during the Eirct month that infection ocourct but not 'in tho. poroh, •Rudd 'aro preyed upon by fioh.'birda and ma. '176 opecios- of fish goad on radd; - Derck taco individUala - up• to 10 on long, and trout oat rudd up to. 25 cm lonc• Tioraor trout, wolishing about 4 kgt- aro' ontiroly carniirorouca Both poroh and trout h,:nrbourod tho pler000rooida - of ilinkla intoctinalic.in -the into-attic., hat1 boon toloacod27..on, infested ivadd• rioithor porch nor trout haw Xi alas intootinalict .olorocerboido tho bady cavitj. Two apocion of birdat herono and groboo food on rzzaa tap to 141 on 3,ongs rho activitiec. of man. havo. introduced a new an unucual rinta hoot into tho oycla o Lirola. CroWn. *food pan tho toodioa o largo, dead rudd loft lying on. tho bank by gichernon• Thom nob, in, tho ciao rat :0 30-35 out 61.' or caurtht by, trout Sichermen using 'Sly. end then thrszu out to the banit* The way in which the aro= l'oed on the 211:311. z omtremely interest-L-1g* _ tale croTla oat only the eyobans L'Lld tp.o oontonta of the 'body cavity and the' root Of the orrimaeo Jo .The eyeballs and body cavity are both sitea o2 ineestation by parasitic larvae, Trith DiTfiestornmf olettthacaeurt metaceroariao in the lens and Iiigulat Atostinalig. in the body cavity* The oroW could, therecre. aerve as a Einal• host 2or both .iii-Pula and Diolostor4w4 and the apporont _wastage of mat,ftre, pie:moor:1°1dt: in largo mad which are not oaten by grebes but which, ore Tod upon by crows, would be loosened* 1, in:. :jLid. The diet or a Sit% boot has a pro:routtd oiTect• on the parasitic sauna of the fien (Do3ica' et ali t 1961)* The early stages; aged 0-6 menthe, feed on . crustacea (Ilikelakiip 1961) boconina oramivorous Inter*- Iludd in Ilaymisthorpo- showed thicripattem of diet cluanr,e., but with sots DICI a11°3,1110n*, thoir f.irat-fyearo ' rudd took orustacen_ together rithlnseet Immature ingest a sinner percentatto o crustatert - . and a hidiez..* percentage a insects, !loll/loos and, plant G2. materita•._ it ie. not until the fourth end fifth years' that a farther change occurs* In the stoma ch ...pxtd intestine of 4.5 year o1d raddi large emanation ofr plant notarial. wore foUnd• Fio1 o thio age. ileup c.100 oh *1170 arc wore cauaht using tworms'im bait* and nhould therefore be regarded ao ormivoresa Theca observations differ :riot Itiltoleklits (1961) but • egiee °lovely 194 oh add. infection. withZirrula intestinnlid by ingeritien copepods 12arbottring precercoide irk tlatto Mere. to' coin= in the early Stages .of •tho ',daft history, in order, to .tomplement the above obserVations% the intos•binal lents.th' Of fry• •and ad'alt fish Was- r•L'ho iength of -rho intentine varies i963) . with tha*dieto - c.8. the intestine of predatory Sash. rneasures:about `2.00'14 or. the body, lengtho tit neanureo up to 1500 of tho body lonGth'in herbivorous fish. It- would, therefor4 , be reasonable to assurie lin increase , percentage- length of the intestine 'of 'the. rudd with increane in. nye ancI annoeiato,d- herbiVoreue diet* The percentalls length of .the rudd gilt* from the junction df the oosophegus. with the buccal cavity* to the anus' tmo, measured (Table z) and does increane with ago. 53. - TAM: Xi Chanre in {out length of fish compared to ago - ric,4r,ht Gut lqaqth ao jwimilUammer - LAimmoifq0 oody vo14au Adult finh over 300 gm Over 5 yrs 125;'of total body, ttry under 2 t7m - 1 yr 6'14 length 12 the adult rudd were, herbivorous, the inereaso in intestinal lcnGth would.bo.greater,o.g. in Trypophthalnichthys nolitri* a phytoplankton'fooder, the gut measures 1,500;!,:of body l'ength4, rurthor oVidenoo of an'omnivonimo by thO type orpharyaocaltoeth,found in ruddo , Pharynseal-tooth, or othor oyprinids, such as carp, Oyprinus ear. go, dovolop serrated grinding aroas, associated, with horbivorous'foeding, tho serrations' serving to.ohe* plant matorial (Nikololdi,-1961)* - The `tginding.aroas on rudd teeth do not develop to tho'samo ortcnt he thoso in horbivorous fish* . The tooth have, •. ,bosidos tho.sorrations, the appoaranco of normal. -aanivoroub pharyn5oal tooth.. Competition domPotition for 'food by &t oront ODOCi00 or fish affoots both growth of Individuals and density of the •64. population. Porch and rudd both pass though stages in which, - they feed on crustaceans. Perch food, on erustaocans for a short period only before becoming diverse,fooders, whereas rudd feed on orustaceans for a lon,5or,poriod. Porah are never foUnd to be infected with Idrultxx_ Intestinalls, although they intermingle with rudd in , which thelnoidonco- of nirmla reached goi;'% Adult porch and trout- In the reservoir become carniVorous and rudd become omnivorous. There lo therefore, ne.direet intraspecific.competition for food between adult fish* 5* Pish predators of radii Rudd up tat -10 on, lona are taken by porch- (p.66) which, until 1965, never attained alarm sloe' (over 25 o) in the reservoir* The" effectof predators on - the ruddIbpulation Is difflOult. to access. trout, which feed On rildd fry -care added :to :tho rosezioir each year,,whereas - porch have beceine eStablishod only recently. Direct 'observation showed.that trout,and verchhave_different ways of taking rudd.- Trout hunt . away* whereas porch attach in cehoola." The floyston _of prodatore ad it is believed' to occur in the rocervoir Is illustrated: in .101.- • OPop TABLB Xi* sSystem of rredatorso Prodtor Perch(uP to 25 cm), rOut(Uir to 35 cm) Trout(00 cm) Proy Rudd Immaturo radA Mauro-mid Trout, .(20 cm)*' o porch woro ovor round in tha stomach contonts of porch and trout czaminod* /forgo trout food on all fish proaont oncopt porckbut the groator proportion of fi:17h takon ly trout comprisos • maturo and irmature rudd* Information on the predator system was collectod by otomadft °nomination and by using spooles of"fish as bait and noting tho prodators* Z11. Tho groat created grobo. Grobos, Po icon, criatatna Ii., were tho only birdo coon to food regularly on rudd and wore thorofore assumed' to ba final hosts in tholiro cyolo honovort no crobos woro ozaminod* The grebe la a c1ivin bird and is aapablo of aocuring and oatin fiah up to 10 cm long* It.nnlks with difficulty and loavoa the watorlraroly and faeces* which would contain eggs in an intocted*individual, aro shod directly into the reservoir* Tho grobea normally leave tbo r000rvofr for till') 66. • vi:atox, =it did co in 1963 and 29.65i rotuining the . raiordna ,Gta, noi-rovor.dttrinz,..'bho 71n.tor ;or ''1964/P thby- clid not loomi too re6orvoira'af €x11, tho .rOaoon •#. not *lthown;- • Groboo food.on 'fish tho are= ' 1 tho ti41) G1. The- dint -.1v3c..7._- • P•65, . , or •*o- &taboo Talii`o Zfl p;e66. (.Afton 20.6)# , I „ . ,- Blot IntiOoto iarvao 35'40;1 • CVuotdoccold 23*5;1 -7#9;j: 116-dt -and tridpo243 1•50 ,Plant 15,55 ()tat 100.0 121/o - avdoieo or ilah gonna. in thO dint of Grob a crc - 0;Flon in Table XIII. p*68 (Attar. Withorby: ot 040)• 67. Fig. 7. Grebe position and other sampling areas Ravensthorpe Reservoir Scale 1/2500 0 500 1000 feet 68. Zarin MX* svocci 0; ,tioh. fat Iris dilet ci 7abati): - floaelv • rtatilitui- rIti;uo -(i.)' -, Ontiriidae Dace ZotiOlootio:leikainene, CL.) -do. Budd ' Soardinkus orytlaropbthalt4t0(Ts.) do. -, - t .- 111=w Ph u© iketinue -(11.) ' , . do. . Tench Firtpa 'afloat (l.)' • :do. Gud'iseca ,Gol4o tr.obi° CIO do.' .Carp OYDAIT* otavio ,(14) -do. Bream, 19.iocia.lvtobr4ka (1.)" do. Trout Galli° ..trutil.' .±A. 'Onamanidee Char ...Salve" iEi-m.,a,..,„ -., . 'dd. Eel AVA11.1aopeida,14 (L.), i.'', Anguiiiiiiao l'ereh ittitasisy9i -till° L. : , Pereidae - Y Stiohleback.:- Gaitorosicits oipiloatuss Ii. ' Gazimrootoida6 larat,2 number o .6110,. zinc:tog tinted above 8.TO membrIzin d2ythe family Cytwitidaof mcmy- of 17111011 0374.7 2,23.0= bocci= infected with the piereeeredid- of Ifir-tania...1 69. CHAPTER ns, Boo10 of.. the nlerooereoid i the _rudd hoot. introduction Tho •plerocereoid of iiipula 'inteatinalia io normally- found in the body cavity Of the iudd1 Scaripiniue er4hronhtkialmaxt. The worse lie in a tangled masa - ouriOunding the' organo- of the body cavity. Hollowell and Pitaford- reaervoira, and, the river :-- Hone Nee: Pig« 0, p.7i) in proximity to Raienathorpe repervoir were purveyed to determine whether Ligula infeatationa. were general throughout the area. resorvoir waa aamp1ed in 1963' and no LL .a ware found ins Piko .13aoz Li HOOaida.0 Porch Peyca, fkkvtatilia L. Poroidao Trout - 041mo truttck Ta. Oalmonidae Ho -ciprinida Wore recovarod from this recorvoir., , Pitaford. reoervoir Was oleo sampled in 1963. Ligula plerocercoido were found , in roach Rutilua rutilua(L). (Cyprinidae),:but ,not in , trout. Salm trut_ta,L. ‘(Elalmonidao). 'rho river. Hone wao sampled at two pladeo and no .Licula wore_ rocovered. Tho following fish were examined* Pike . Esoziucii4 L..* • Ettooidae pthrch- Peres- fluviatiIis Le - Peroidae. ` Roach. -Icutilus 'rutillia t.' Cyprinidae Bream Blioca _bloernka (L)- _ 'do. tench Tiipa- tincq- (L) do.. Gudgeon , ,Gobio 4obiq. ay, i • . do. Chub Smiling oevhAlus (L) do. • The plerotteigeold tiiatta inteetinlis in Variatia epeoiee of 'firth has been Studied -by,_ several workers. Moot work hao been:done in. Eastern Europe becauee of the 'economic, importance- of freshwater fisheries. In- the *. .United States research on Lifula has been stimulated by 'the'Aiierican:approach to fisheries and cniiervati „ KothiCka ,(1963) inirestigated the pathology of fish; in a large number of laken- in Poland.' Iluculak„(1960), . intensively studied fish fromninetY-five lakes in the Vistula river basin in- Pc4and and found lagula-intestinalie - in.‘the 'following apes:ties iof -fish; Gobi° gobio. Itutilna rtitilus. toxicant:dad ok) lineatus. Abrqmith brims and . , Leuciscus cephalus.. IlitkrAlov (1957) worked on mass infestations of iipuiaInteeinnalie, in the` river _Kura' in Aierbaidzhan (USSR) 'and, Zitnan (1964) etudiad , infestations' in roadh. Eutklua rutilue, from a gravel' pit at Koeioe in:dzeclioslovakiao, Deuce (1958) and. -Pitt 'and Grandmas (1957) have dealt' 71. -Position of the three Reservoirs and river samples showing drainage of reservoir overflows to the R.Nene Hollowell Ravensthorpe ... Pitsford Merry Tom IN Scale 2 miles River sample x I R.Nene .-.----.7 Figure 8. 72., with incidonee, intermit" ef-infoetation and parasito ,b on of ligulst plorocorcoidefin tho United States, but did little to dos onotrate corrolations with enmironmontal conditions. Thena'Workors wore primarily, intorostod in. tho afoot 'of the- paramito'ontho fish. Parasites of economic inportanCo'aro frequently studied, with a vio7 tooffectinG control of disoaso. Wrillqis not of urgont oconomic:inportanos at: present in this 'entry and an:plerocorcoldthstorial is abundant - „ lot;;-term work'san bo plannodvand a thorouch'• study is ' possible. Axt ideal..land.terri Study' nada acourate mothodsisuchas.fiSh taggina;, bird marking* otitimation or infootod copepodoli-distribution, position and numbors -Oftho fish hosts.would be roally worthwhile but the problems of'tiMe and. money would be sovore. These problems couldiOloweverip bo-overeoMoo and opportunitios to stuayfreShwater fichos An,cortain.heibitate, not influonood .biman would be realised. - - 'An ON fish," resularly ro.infooted from an,osky eta, nicht be o;pcotod tocarry a largo number. 120 or, morov of plorodorcoidsi but such intones infostations rarely occur in nature. Some of the factors which dtornine.intonsity of infontation nay not Oven ht vo boon reoognisod, but othors have and their influence eon be domonotratod. 73, - In this chapter the ecological conditions necessary for - the establishment* an development of the ploro. coreoid stage of tho life cyolo 'will be described. The incidence , of1 itii-intensity of infestation and parasite• burden of the- fish, aro -related* to a Complex 'of - e factor. inflUonces- than to a sin&/ - . - The following_ charaCteristiee ,of the plerocorcold, and its fish, host must; be borne in mind during a discussion of the effect of environmental factors on them both* , (1) Tho pler000rdoid 13'a larval stage not requiring role:aid to the external environment because the fioh host: is :eaten. whole by the final host which 'is a,- piscivorous bird, - • The pieroceroold is relatively norknotile after entering the body cavity of the fish, in Which it noods ne adhesive mechaniemo to maintain its position. Thus. no. hoot reaction 'is provoked by the action of adhesive orc.,,ans-4; A definite time, which varies with , nvironmental, eonditione. mist elaribe before the plorocorcoid beoones infective 'to the final hoot, (2) finio 'fish:- hoot must bo accesoibloi to the procorooid larva in the copepod- host and therefore the diet-of the fish is important,. The fish nuOt be able to support' 740. the grovrth• and development of the parasite and must live long enoublx, for the- pleroeercoid, to become infective* • • •The- . plerocercoid is inflUenced not only by its. imtediate surroundingi within' the host, but aloe by the -. environment of:the host which-,goVerno changes in the host. 3 physiolOgyi ,The influence of •the environment is doubly ,Importan t in the case ot•oral infection of the, fish hoot; which' can. occur •onlY after ingestion ,of axe opted., copepod* Ecological fe.orp Anibiencing host end parasite*. • • • gcological-faatdrs influence,both rued and-plero.. cercoid• , The plCi.oceroCid /nay' be,-affected .directly or indirebtly, t4.7cough7 changes in.the hoette .physiology Por example, ail 17.03.1 .nri ;the di.reet,Neffodt, of temperature, • the, eifeets otseasonal changes the'hostta diet, pea/tient abundance, migration and activity on- the parasite were stUditid*. The interactions between seasonal changes in the, _ physical and biotio:lOattires -of RaVensthorpe reservoir and the Liquitk found' are summarised' in the diagram on p.76* The diagram p46 Shows the'effect of physical changes' in the biotic featured of the reservoir and the resultant effect :on the three heats of Ligula., ' The features 75 the parasite fauna which reflect these ecologioal influences and whiehcan aloe be 'measured are:, percentage ineidence,of the parasite in the host population; .intensiti of infeitation; i.e. number of worse per individual'hes4 parasite burdens*, i.e. total 'Weight of ParasiteSitilati4e:tobody weight . of: hest:' , iheincidenco, intensity'and paraeite'buidena Were Measured and.ohown to fluatu4te, eee'raPhs.,p.* Effect of seasonal variation° in olimatic and Arden' factors onlithrula The cliMate of the region governs,, 'to an extenti - the flora and- fauna of . the reoorvoir. Situated in the. temperate zone, the reservoir is 'not subjected. to. ' extremes of temperature. Seasonal changes in temperathreaffect - the plero—' cerceld directly and affect the'infeatatien indirectly by influencing the abundance and distribution of eorepods which form. part of the diet of rudd; its abundance and distribUtion in the water; ' its migration and winter inactivity. Another important factor of the climate is rainfall. ,During,winter of l964/65 the- rainTall- was low and Caused a severe drop in the water level in the reservoir. The drop in water evel Was further accentuated by withdrawal of water from the reservoir for 76. Figure 9. SEASON AND YEAR. Spring, Summer, Autumn ,Winter 1963— 1965 1 CLIMATIC AND PHYSICAL FEATURES of Ravensthorpe Reservoir Temperature, Rainfall, Wind, Daylight and Insolation, Water level, Salinity, pH BIOTIC FEATURES of Ravensthorpe Reservoir Copepods Rudd Grebes distribution distribution distribution abundance abundance abundance ir,--- diet predators age movement reproductive shoaling, migration _ condition PARASITIC INFESTATION of Ligula plerocercoids in rudd incidence intensity of infestation parasite burden 2 u 0 o %fishin fe c ted = = 20 80 40 60 Figure 10. 0 0 0 2 4 3 4 2 5 1 3 1963 NJ _...-- Incidence ofLigulaandparasiteburden Parasite burden Intensity ofinfestation Incidence M 1964 of ruddfry1963-1965 M "------"------ J S NJ M 1965 M 77. J 18#' d $ requirements; The , so/ore drop in water. level in, the Winter of 1964 (Pig.1.1 pe79) caused stunting -• of growth in the, ono-year-old fish oe:ntured in August 1965; -. The ft-y" of .1964 Were very Levi and therefore ceitld.:.not be sampled adequately a.fter. January, 1965. Only small numbers of , gi7 were born in the nutaner '.of 1965. The drop in water level during the previous winter destroyed the natural breeding grounds of the ruddsind upeot . the overwintering.'positions: of the fry -of 1964 and Teit individuals ''Survived; Coasona conditions affecit .the abundance end distribUtion.- of _the- grebes, *. • beasenal, or cyclical changes .are normally apparent .throughout 'the year, end are comparable in 'their effect from year -be Year*: Eleasonal effoats comprise a combination- of ph.ysicai'factorei af'fecting ,both flora '' and fauna. 'ideally itaveliathorpo reservoir would. be comnared with 'another reservoir. in- either Colder or •tamer climate*, Temperature and rainfall data for the.liavenethorpo area' during 4unew.1.9:64tCe.Taiiipli) can be found in the appendtip267'. The 'range of temperature which can be tolerated 'by, the, zierocercoid As at least 4°C to 18°C, thc.i.:Axtromes of temperature of water recorded in the' raffe,--,w,i3irt: Fry which remain in shallow water will be Subjected to these 79. Figure 11. WATER LEVEL OF RAVENSTHORPE RESERVOIR AND ITS EFFECT ON SPAWNING O 20 normal spawning 40 WATER LEVEL down in inches 60 80 100 no spawn 120 140 160 4 NJ 1401141.1 S NJ M M J S 1963 1964 1965 ao. =trews of temperature' and conSoquen* se are the' .,,young plerecerctiida. The.upPer' limit of temperature belorance- of the adult and immature fish =7 be lower, so they inhabit deeper and cooler water. The metaboliom- of the' plereCarcoid must be cable to, adapt to these tempercituro variations*, However; from .the..thraph; p.86; medt,rapid'increase in'individual- ,- plerecercoid• icht ocouro when' the water temperatures - i are highest. ' ie.incidence of pleroderooids in the gri'a'1964 wao-:gelloWed for two years (iga0, p1,77).0 'In- lieliember1963:,the number of infected fish dropped,as it did ,also during' tlie.winter'monthei 01964', and as the • fieh•caimot rid itself of the pia.aoite, the lower lncidence,id due to.morttility. of- infected- fish*, Incidence of,plerocercoids therofore'varieo with the season. The presebbe'of•t*finai hoot during the winter,, months' 16 not a.determining fa0;er- in eeasonal variation incidence. . drebed were present during the whole of, iher winter.1964/65, yet the incidence,level drops in ‘e- winter period in all case The low incidonc'e. may be due te'the lowlemperaturo-whicli slowd Amin or, tittipa. development and hatching of the' coracidlit, Ae the intensity of infestation remains comparable'at the E31.. beginning and end :of the winter, months, :the mortality rate is independent of the. riumber of Li .a plorocercoida Drotionts • The parasite.bUrden of the 'fry of 1963' fluctuates and . does .not continuously increase (riga° p.77 ) 4 The pai'a6ito bUrden 5.2719 and in November 1%4 13 2.7;4 (riga° p.77). . , Xn a heavily :Infected s mad* 'the presence plerocercoids lowers the average. weight of Plerocercoido harboured by th© fish _ as thorn in the data for the summer of 1964 (Vigo.O. P.77)• In winter months the' parasite -burden, drops, -although. -net or very little, -increase, in incidence 3a observed. The decrease parariite burden. is due to the mortality of irifootod Tuddt- end those fish with the highest burden die. seas in f© aLEIRtli. pjL.,..,zldVand affect on Li a infestationS. 44 The procercoid of lilula'intestinalis occurs in the body cavity of a copepod'and must be inceated by, . the rudd fog' the life cycle to continue. The diet of the hoot has tlieref ore a' strong influence on the incidenoe of Ligula in the fish: The .abundance ,of copepods is of paramoUnt importance end 'their predordnance in the ruddos dint', as well. as , • ' the actual numboro present in the Meter= vd.11 vary with- 82. the season of the year, The densities of copepods in Havenothorpe reservoir were not determined because of the shortage of time. However, Hikolskiits (1963) data showing relative abundance of copepods throughoUt the year in situations ' similar to those for Ravonsthorpe reservoir are given in Pig.12 p. 83. ' Nikolekiiis-(1963) data indicate a low level of copepods during the winter months and a very high level in the summer. Grebes, the final hoot of Linula, are normally present on the reservoir from April to September, that is to say during the months of high copepod numbers. An abundance of copopode during thesummer months coinoldes with the appearance of the rudd fry, and the fry of 1964 became rapidly infected by procorcoids during the first few. weeks of life, when they were feeding on planktonic crustaceans (Pig.14, p.96). The intensity of infestation remained remarkably steady during winter month periods of 1963/64 and 1964/65, and provides further evidence for the low copepod density. The slight variation in the incidence figures may be due to sampling errors, During the summer months, when the flnal host is present, when high temperatures favour egg development and when there is a high copepod density, the incidence 83. Figure 12. Abundance of Copepods Crustacea wet wt. Kg per hectare at 200 — 160 - 40 - 0 Jan April June July Sept Nov Dec 84. of the plerocerceids rises sharply (Piga° p. 77) while .the intensity of infestation drops and then rises (Pig.10 p. 77). The initial drop in intensity, indicates that fish uninfected the previous year were , becoming infected with single worm in the summor i.e. May, June, July (1964). These newly infested .Fish, as well as those previbusly infected with one plero— eercoid continuo._t6 aeqwtre further plereeercoids until late autumn when the copepod population falls. The: rapid increase in the parasite burden between May and July -1964 and May and July 1965. is. related to abundant food supplies. - The rapid increase in the. size. of i)loroeercoida is concomitant with the increase in the rudd'o notablie rate, In fish the metabolic rate is- seasonal and co3ncid©s with increase in tompercthtre and abundant food. The diet of the rudd fry changes an it becomes older. Young fish feed. on crustacea, but the proportion of cruotacea in the diet decreases with age as other foods are eaten, such as molluscs and insects. However, the quantity of copepods eaten does not decrease but in fact increases to a maximum in group 3fish aged 2 yrs, and thereafter decreases. The actual quantities of copepods eaten by rudd of various ages were not studied quantitatively. 85. The .quantity of food taken by a rudd depends on the availability of the food, which varies with the season. -ImAture fish consume relatively more food for growth and at the same temperatures grow faster than mature fish, which use the food for gonad development and fat deposition around the intestine! (Nikolskii, 1963). The average weight of one generation of infected fish and-the weight of the largest plerooercoid taken from each sample,is shown in Pig0.3.3 14861, together with the water temperature. The proportion of copepods in_ the ruddis diet • varies with the- season'and determines the number of plerocorcoido beooming established. The weight of food ingested by the rudd affects its size, and consequently the size of the plerocercoid. The quantity of food consumed by the rudd and its rhythm of feeding has not been investigated, but pro -t wzbly also shows seasonal variation. The largest plerocercoids in immature fish are found during summer and,autumn. - The apparent decreaae in weight of the largest plorocercoid obtained from fish in. the winter of 1964/65 (rig.13?., p. 86) is further evidence for mortality of fish with heavy parasite burdens. The maximum weight of the largest plerocercoldo in. 1964 occurs in November (Pig.13 , p.86) whereas the 86. Figure 13. Average size rudd-1 water temperature and weight of largest pleiocercoid :1963-1965 18 -Ia o 6n 2 1-8 m E m 1.4 c ; 1.0 m 1). 0.6 EY V 2w 0.2 E. NJ M M J S NJ M M J 1963 1964 1965 87. - parasite burden (Pig.-10, p. 77) is greatest in July The high parasite burden in July comprises a high proportion of freshly acquired plorocercoids, resulting from the ingestion of the abundant copepodo. The number of plerocereoids in eaoi rudd increases up to 4-5 yro of age. -In fish aderthnn 5 yro growth 16 slam, and the proportion of copepods in the diet is extremely long. The effect,of seasonal variations on incidence, intensity of infestation, and. parasite burdenin the 'older fish groups is more difficult to elucidate because of the change in habits of fish during breedimg,andoverwintering., The severe drop in water level in winter of 1964 (Pig. 11 p. 79) probably reduced copepod numbers, but the rate of infestation in the immature fish was again high in the-summar-of 1965 (rig. 10, p.77); ingestion of planktonic copepods by the rudd: was. possibly favoured by destruction of the littoral fauna. 3. Seasonal variation in distribution of rud,4:1 _in the reservoir- and effect on Iligula infestation The distribution of rudd in the reservoir varies throughout the year, the fry, immature fish and mature fish all having different distributions. Light, temperature and rainfall are the important seasonal 88. • factors influencing the fry and'immature rudd (Groups - 1,2,3). The abundance of food in certain areas on the sheltered side of the reservoir'at certain seasons attracts the fry. On the other hand', mature rudd are more dispersed- throughout thereservoir during the whole year because of'their brecding.and overwintoring habits. The distribution of fish within the reservoir is controlled by the food supply,. especially in the younger stages up to 2 yra old.`. The fry remain close to the bank until they are 2 yrs old but their move— ment into deeper water is more closely associated with size than with. ago. rry close, to the bank are in contact with copepods in the summer months.when incidence, intensity of infestation and parasite burden (Pig..10, /3:77) all rise6 In the winter the greatest density of copepods is found in deeper water (Alkolskii,.1963) and fry exposed to low temperature and short daylight in shallow waters food less in winter when the copepod intensity is also low. Growth of fish and parasite is slow and acquisition of new plorocercoido ceases (Pig. 10: p.77). The effect . of the diurnal fluctuation in depth of copepods and its correlation ,with distribution of the rudd has not boon studied. - 89. Pry in shallow water arc exposed to greater seasonal variations in light and temperature than are adults in deeper water. The influence of light intensity on. the fry is not understood. rich in= genera. aro found atsah- optimum light intensity for feeding, and it may well be that fish in the fry stage needia comparatively high light intensity _to feed, compared with, _older, fish.' 'The abundance of food and loiier from predators probably play a more important role than light intensity* Immature fish aged 1-2 yrs may occur in water up to 10 ft deep,- but. are never captured beyond this depth. They are not subjected to the temperature extremes of summer and winter to which the fry are subjected in, shallow water. Immature fish do, however,. still show a period of rapid growth during the summer and little growth during the winter. The distributinn of immature fish varies throughaatthe day.- Mature fish are found near the surface in the first hours and last hours of daylight in the summer months. In the middle of the day mature fish are usually found below a depth of 7 ft; their distribution at night is unknown* The movement between nun 'ace and deeper waters approximates to that of planktonic copepods, but 90. the data are insufficient_ to make a detailed comparison. Surface feeding is more probably associated with insects on _the water than with a light stimulus. - The effect cf. seasonal variations on adult rudd is more' marked. Unin.rected adults move inte.spawning grounds in shallow water in the Spring_and return and disperse to deeper water after spawning; Mature fish- are seldom taken close' to the -shoro, except for heavily,infected individuals. Mature rudd overwintor in deeper water but move into shallow water in the spring and then spawn. : These rudd are therefore not subjected. to large variationscial temperature because they are consistently in deep water. Even when rudd food at the surface, they usually remain in areas of deeper water. Growth of the plerecerceids is slow in adult fish due to lower overall temperatures, overcrowding of plerocercoids. and the fact that many plerocercoids are large by the time the fish is adult. As rudd of yrs of age are still acquiring new infestations the overall.inerease in ineidence in adult fish is slight. The intensity of infestation, however, is- at its highest in rudd aged 4-5 yrs. The parasites provoke sevemeffeets upon the fish (see Ohap.IIpsI58). Seasonal variation in the distribution of the rudd is related to the quality and quantity of food available. , The increase in number of plerocercoids is_ greatest in the summer months in the fry and immature fish, being in shallow water where the copepods are abundant. fry -In. winter, copepods are few and the_ in shallow water are subjected ,to low temperatures. Thus, the growth of.the plerocercoids slows. The shallow water habitats of the fry may well account for their heavy mortality under adverse conditions in the winter months. Rainfall is an important: aimatio factor and the _drop in water level in September 1964 Mg.. 11 o p.79) affected the distribution of rudd- of all age groups. . Mature fish wore unable- to show normal courting behaviour-in the shallow water in the spring of 1965 anctboth-infected and uninfected fish wore taken together, whoread in the spring of 1963 and 1964 :infected -fish never occurred in the courting shoal. AS fish wore unable to spawn normally there were few - fry'ih the'summor of 1965, when only 10 wore captured, - and no large scale infection could oceur.; immature rudd stayed in deeper water at about 10 ft instead of moving into water 5-10 ft deep.: Young. rudd moved into the cleaner and shallower-water by the feed stream. 92. The rapid drop in water level in the reservoir In September of 1964 led to a movement of fry from the southerly side of the reservoir to the north-beet into the shallow area beyond the road embankment (Pig. 7 p. 6', coincident with the algal bloom in the shallow area. A large proportion of rudd Of all other age groups also gathered in this shallow area. In September 1964, frj were sampled from three positions, the boat house (Pig. 7 Bi), the bridge (Pig. 7 , Ei) and the south of the stream Si (SSi Pig.- 7, p. 67). The movement of fish away from their usual areas may have been due to the combination of heavy algal bloom and lou water level. Incidence of Ligula was different for each of the three tread, 'sampled for fry: low incidence at the boat house, high incidence at the bridge, and medium incidence south of the stream (Pig. 22 , pZ43). The fry on which the incidence data are based cannot be guaranteed to have moved there as a result of the drop in water level but may have been in their respective areas for some time before sampling. Because of the low water level, there was no vegetation to provide cover in the boat house area, whereas the opposite end of the reservoir on the other 03. Bide of the embpritment had a-luxuriant growth of aquatic plants Mg. 7 , p. 67) which was unusual for thid area and woo: whore the grebes congregated during the period of low water level during Septembor 1964. - When the water lovol Ia low the boat house area it devoid of static vegetation. but at certain times thick with planktonic algae, and thereforeunsuitable for .rude fry. When the loyal in the rosorvoir le low the atreani.mouth producon foot running water which is unauitablo for copopods. Lioula occurred in rudd caught from the stream to which they must have moved, alroady, harbouring the infection. Conditions around the bridge appeared to be favourable for rudd fry and copepods. The highest Incidence of Ligula in, rudd fry (Fig.10 1477) occurs under optimal condition° for devolopmant of Ligula eggs, for an abundanco of copepods and for the prosonco of rudd fry. 4c Soaoonal variation in *undone° of rudd and effect on,Zigula infesttionq In wintor the numbers of fry and immature rudd decrease by natural death and by mortality duo to Ligula. In winter, incidence in the,fry drops considerably (p2434.10 p p.77), heavily infootod rudd dying. Death of 94. -.•••111.{ •end of 2avonothorpo rr,sorvoir to Soptomber 1964, ohowin the final hooto of Li:1aq, a pair of creator crIzted greboos 95.. the rudd is related to the weight of plorocercoids present but is independent of the miner of plerocercoids. The largest plorocercoids are therefore removed from the Ilopulationby- death. of their hosts in winter. . In unfavourable conditions-of winter, accompanied by natural decline in rudd population; fry and immnture fish with large plerecercoids survive less well than fish with small plerocercoids. Adult fish, which aro no longer acquiring 'new infestations are probably unable to overwinter, and die as their plerocorcoids increase in weight but data are insufficient to demonstrate this. In summer, numbers of :mad are increased by appearance of fry which can become infected within two weeks of being free swimming (pig. l4 P.96). .There Is thus an initial short-term drop in incidence of lalmila in the rudd population. Pry feed on plankton and become infected when the number of corepods is at its optimum. The potential of procercoids for infecting sevdral hundred,young fish is quite astonishing, although large numbers of both unieected and infected fry die. Rudd up to the age of 4-5 yrs all show an increase in numbers of plero- corcoids in summer. Figure 14. u u c. 0 In • O 6 t- et a, w= %fishin fec te d — .c 4 tn a. 9 50 70 30 I0 2 3 1 II. Fry of1964:a)uptakePlerocercoids appearance offry IS June; 1 1 'July SeptNovJan 1 : i 14 %incidence1964—1965 96. 97. In winter, with adverse conditions and few copepods, the numbers of fish decrease and fen* or no new infections, are acquired. In. summer, when the fry are first free sWimming, the number of-now infestations--is high.and . the rudd population is,at-its annual maximum, coinciding with good conditions forcopepedoi.proceroold devolopmont and fast grbwth of young rudd. In. 1963 the climatic conditionsof-the .reserveir were normal, rudd fry wore abundant and incidence of in -the total rudd,population. was at its highest (Pig. 15, P.98) • When the numbers of fry were reduced in. 1964 because of low,water level and dropped to nothing -in 1965 the incidence of ni-rula also dropped.. intensity 'of infestation also decreased durirt the 1.eriod 1963-65 (Pig. 15, p.98). The lowered incidence,and;intensity of infestation nay be related to factors other than scarcity of fry, such as the number of inrective ploro- cercoids available to the final host- and Subsequent egg production and procerooid development.- The absence of fry in 1965 and consequent lack of one complete generation of fish will bring about a ehange in the diet of grebes from 1-2 yr old- fish to older, and therefore more heavily infected fish, and,Ligula infestations would be favoured, or the grebes diet may- change to yoUnger fish with uninfoetive plor000rcoido and 98. Incidence and intensity of infestation of Ligula plerocercoids 30 Infestation 20 10 NS 100 80 Incidence d 60 te fes NS= no sample 40 h in is 20 f t o /0 NS NS NS 0 0 date 1962 63 64 65 1962 63 64 65 1962 63 64 65 age ADULTS IMMATURE FRY Figure 15. 99. • the Liqula infeotation would drop. Ultimatum rudd incidence and intensity of infestations are maintained during 1962, 1963. 1964 and 1965 (Pig. 15, p.98) although they decrease in fry and adult fish over the came period, during which time the nuMbors of fry and adult rudd decrease. The relative numbero of Immature fish in the rudd population have increased during the period 1962-1965. ' The- incidence of p1,7,rocerceido in adult rudd dropped in 1964 (171G.15.p• 98); although parasitised individuals wore.heavily infected (Pig.15, p. 98). Infeotationo were therefore highest in 1962 when the same fish were feeding on clopopods. The severe climatic ehangeo in 1954-55 influenc the water level in the reservoir affected rudd _fry moot, and adulto and immriture fish to a looser ortent. The size of the fish, population is known to affect both the cizo of the fish and the quantity of food eaten by the fish (Nikelskii, 1963)* - In greater concentrationo fry each oat more, than in small concentrations. Poor diet rooults in wider variation in fish size than does abundant diet, and affects also incidence and intensity of infestation of the parasite. Incidence ana intensity of.infestation of Ligula in the rudd born in 1963 and 1964 100. and campled in January 1964 and.Jenuary 1965 roopectivoly wore compared (Table15 p.101). Both samples wore taken. in the boat houco aroa. Although the rudd'born in 1964 wore ocarco in the January 1965 oampl© there io little variation in fich oizo Gable 15p p. 101) linkman the two samploc. litoidonce and intensity of infootation with Li .t ic, hodevor, greator. in the 1965 sample when fry were coarco and' the food supply woo poor but with a yelativoly higher copepod ccimponont than in 1963. However, a rine in incidence of Liqu141prOcerooido in copepods in 1964 would also account for highor incidence and intonoity of infeotation of plerocorcoido in 1965 °ample of rudd. Inoidence of procorcoido in copopodo in 1964 could have boon high as a moult of grebes foeding.on' rudd_born in 1962 and 1963 in',whichthe2!o was'a high incidence of 'plorocorcoida. Seasonal v—iations in mit. at on of rudd and. `foot 'rho movement of individual rudd from ono situation to another in'thereservoir. for an observable roaoon In .rooponse to stimAli 7113 botormed migration, whether in largo or in several small groups. 'Rudd migrate only 101. TABLE XV Date of sample January 1964 January 1965 Rudd born Summor 1963 Smiler 1964 _Abundanoe 'of frY. = Abundant Rare Probable copopod diet component Low., High incidence of ,Ligula plerocerooido 3540- 41.50 Average fish length 5.3 cm 5.4 am Variation,in.fish length 6.5-4.5 CM . 6.6-4.7 CM Average fidh weight 1.2 gm 2.0 gm Variatioa in fioh yeight- 2.10.5 gm 2.6-0.5 gm Intensity of infestation Ilumbor of plerocercoids per infected rued 1.5 2.2 102. in Spring (eec p.56 ), when they move into certain shallow waters to spawn. The initial stimuli to - migration az° gonad, development, daylight and rising, tomnerature (Brown, 1957). Ohangos in the pituitary . . - of roach parasitized rith //Pula pleroceroolde are demonstrated by.Kerr (1948). Castration in certain other cyprinid fish-infected rith LiPula may well bo effected by the influence of the,plerocercoid on the pituitilry of- the =fish ((won and Arm* 1965). letting of courting shoals of fish in n124'111617 water in the Spring in 1963 recovered onlyonly .rtfected fish, whereas random netting recovered infected fish which were distributed throughout the reservoir. The presence of plerocercoide app& to inhibit norMal-courtitg behaviour in rudd prior,to °pawning, and the infected fish-show no movement into shallow areas to nrarn. Infected fish are unable to reproduce because of parasite dantratian and their absence from the courting shoal_ means that only potentially ripe fish pair and no fertilised eggs are produced. Infeoted fish do not interm*te with uninfected fish during spawning and the number of fertilised ogee is therefore not reduced. As the rudd population is under stress of .both natural midisLola. induced 103. mortality a further loss duo to reduction of fertile - eggs might result in the rudd population dropping below a level at which it can support the Liqula infestation« That the population of fish does survive over a period of years with a high incidence of Lipmla* is seen in Eye Brook roservoirin Northamptonshire which has harboured in roach from 1945 to 1965 (G.0.S. Oliver, 1965* personal communication). In 1948 J.D. Smyth expressed the opinion that the 'castration effect of Willa on the roach would have wiped out the population had the infected individuals attempted to spawn with the uninfected with an ensueing drop in egg fertility. It was not then knaan that the castration of the fish affected its behaviour and that only ripe and fertile fish entered the spawning shoal. 6. Seasonal variation in activity of rudd and effect on Ligula infestations Activity of rudd is a complex phenomenon related to metabolism and influenced by intrinsic physiological factors such as gonad development and by extrinsic factors such as temperature and light. Water temperature in Ravensthorpe reservoir therefore influences activity of the rudd whose body temperature, according to Nikolskii (1963), does not differ by more than 0.5-1.000 104. from the ambient-water temperature. As temperature increases- during the summer months (rig.5 • p* 44.) activity and rate of food, intake of- the. fish inereaeos- (Bokove4 1940). Increase- in incidence of plerocercoids ia_the summer months (Pig. 10,- p.77) to in part due to- Abe largenumbers of copepodis present (rig. 12, pi 83). and _tothe position of fry and "immature fish in "shallow water. The increased rate of-feeding on copepods:a2so affects the incidence of probercoids in the Copepod and numbers of.copepods - consumed by the fish at various temperatures. Tho incidence of pler000rceids,- the intensity of infestation and the parasite burden are at their highest however, when the activity of the rttdd to -greatest and copepods are abundant* The converse, to true for low winter temperatues when metabolism is slow and the food intake low, and copepods are sparse. B. Age- and reproductive - condition of rudd and effects on Ligula infestations. Introduction The dietary, physiological and morphological changes associated with ageing of the, fish host and their effects on the LiFula population are important 105. . influences in the ecology of the parasite. The age of a fish can now be accurately estimated and .with the development ,of freshwater fisheries research, moreinformation.io available on the ecology of fish. . An the rudd ages co its dint alters, its distribution and abundance.inthe reservoir varies and its migration and general activity arc affected; With the change of diet with ago of the rudd, the- cwt pattern alters and variations occur in gat depositions. The-rudd matures at the ago of three years and its behavieur.changes. All these changes in the rudd affect the biology or the pierocarooid.. 1. Chan-,e© in feedim habits, of rudd and effect. on Ligula infestations.. 11•1110111INIMINIMIO - - The plerocereoid infestation is acquired by the ruddos feeding on infected copepods. 2rovided that the incidence of procercoids in the copepods remains fairly constant; any 6hange in the rudd1a diet will be reflected in the plerecercoid infestation* During its life history the rudd changes from plankton and insect feeding (p.62.) to omnivorous feeding and ceases to feed on copepods at approzimately five yrs old. After five years, further infestations 106. are acquired by chance ingootion ot infected copepods. During the first three years of the ruddis life it feeds Tex&mistrelz on copepodi., The number of plerocercoids harboured by fish of different age groups during the period 1963-1965 was determined (Pig.16 p.107). The rudd seasonally acquires plerocercoids during its early years until it reaches 5 yrs with en average weight of 200-300g, thereafter the average intensity of infestation decreases (Pig.17 , p.109). In 1965, the highest intensity of infestation occurs in rudd- weighing 400-500g (rig,17 , p.109, histogram A), whereas in a small sample taken in March 1963 (Fig. 17, p.109, histogram B) the highest number of plerocercoids- occurs in rudd weighing 300-400g.- The-roasam for the diltbrant weight range with-the highest-intensity of plerocercoids indifferent years is very important. Heavily infected fish in the 400-•500g group in 1965 are the sand fish which two years before, in 1963, constituted- the 300-400g group. There is, therefore, an abundant ago group_of heaVily infected rudd , increasing in age which, if not observed together with data from other years, would mislead interpretation of figures of intensity of infection.-- Baeh of the samples talon in 1965 was dominated by 107. Incidence and'. intensity r of infiitation of Ligula plerocercoids ' r in rudd age 1-4years h is f 20 er p ids Intensity of infestation erco 10 roc le p no. 0 90 70 Incidence d te 50 fec in h 30 is f /o ° I0 Aug Aug Aug May 1965 0 I 2 3 4 Age of rudd 14 26 38 47 months Figure 16. 108. a particularly heavily infected group of rudd (Pig.17 -10 14109). The dominant weight group of 1965 (Pig. 170 p.109, histogram A) harbours wmany plerocercoide as that of March 1963 (Fig.-17, p.109, histogram B viz. 300.400g). The rudd of 300-400g do not become further infected in next. two years (Pig. 17, p.109) although the potential for infection exists. -After changing to an omnivorous diet at the age of.five, the rudd oats no copepods, which would account.forthe drop in the rate of infection. - Rudd with large numbers of plerocercoide-, decrease-in number and,only.individuals withra fow plerocorecids survive until the age of 11 pie,. Increase in size in prierocorcoida in fish aged 7-11 yrs is slight. The increase,in the number of plorocercoids in immature rudd apparently contradicts theAeorease in,proportion of copepods in the diet, - However, although the proportion of copepods in,the diet-of tho rudd falls the number of copopodo ingested increases. 2. Distribution 'of rudd at different eras and. effect on Isigula infestation. Ae the planktonic diet of the young rudd alters to an omnivorous one with the ago of the fish, the distribution of rudd in the reservoir alters. rood no. plerocercoids per f ish 80 40 20 60 20 30 40 10 0 0 Figure 17. Incidence 0 - - - - - IM. 200 and intensity in i rudd wt.groupsingrams rudd B 400 of infestation A of 1965 600 Incidence Intensity .--- of . highest no.ofplerocercoids Ligula 800 . in March1963 of infestation plerocercoids I 1000 1 109. no. supply and presence of- predators govern distribution. ' The food supply of the rudd must be suitable to its size and the fish is always .found in areas,where such food is available, except under severe climatic changes inducing a drop in water level or temperature. •TABLE Table showing distribution of rudd at different ages, presence of copepods in stomach and incidence of - Ligula plorocercoids. ' JULY 1964 Yearly Copepods = increase , Overall in - , Age in Previous incida stomach - Group yrs Distribution incidence incidence (men Unde r + 1 . 1 yr Close inehprof • + 0 + sheltered areas + 1] tt “ + + + + 3 2] 0 5ftWoheltered + + areas + 4 31 Distributed all over + 0 5 4 -10 ft. :derail 0 0 6 5 0 0 + 0 7 6 ,„ - 0 0 + 0 , 8 7 Q-10ft. 0 0 + o 9 8 Evenly distributed 0 0 + o 10 9 0 0 + 0 11 10 0 0 + Distribution of the rudd particularly young and, immature fish is also governed by predators* Young and immature rudd are commonly situated in shallow water close to the bank, where they come 'more in :contact with• copepods than. in other areas, and also _'where they have. the best cover from 'predators* = As the _rudd 'matures its body changes 'in shape, becoming-'deeper and. leas easily eaten by predators than slimmer-fish of a similar length. This protection from predation will also be conferred on heavily infected fish with distended abdomens,- in contrast to unirfeeted fish of a comparable age* 3# Abundance of rudd at different ado© and effect' on Ligula( iniestations, _ In the summer of every year there are, initially, large numbers of rudd fry* The numbers of fry are subsequently reduced by both natural mortality and mortality due to infestations'of Ligula plerocercoids, and as rudd age their numbers decrease. However, the saws numbers of fry are not born each year (Table 7# p. 53) nor are survival conditions comparable and abundance of fry dropped steadily from 1962-1965 when few rudd were born (Table 7 , p• 53)* The incidence of Ligula plerocercoids in the fry also dropped to zero during 1962-1965 (Pig* 10, p. 77). 112.- As the'rudd age and their numbers decrease, the incidence of Ligula plorocercoide in immature rudd fluctuates between 307; and 70;;, depending on the time of the year, the moat, heavily infected fish dying during the winter. Once rudd have reached 4-5 yrs of age they are much lens abundant and 'incidence is low, no more worms are acquired, and intensity of infestation does not increase. However, Parasite burden increases and causes death of the fish. Heavily infected fish of 4 yrs old and over die, and only those with a low parasite burden attain the age of 9 or 10 yrs, whereas uninfected fish of_the same age are more abundant. Rudd fry become infected while they are abundant; they continue to acquire further plerocercoids until' they reach 4-5 yrs of age, during which time many infeoted and uninfected fish die or are eaten; there— after mortality due to other reasons as well as to Ligula infestation is high, and in contrast to fry and inmPture fish, no novtinfestations are acquired and the incidence and intensity of infestation with Ligula drops. 4. Spawning migration and effect on Ligula infestations The spawning migration of rudd has been deeoribed on p.:;56.1tormally, no migrating rudd are infected with 113: Three-year-old fish are the youngest to migrate in reasonable numbers, although occasionally 2yr olds have been taken from the spawning shoal: Thus, the spawaing migration is governed by ago and reproductive condition of the rudd, and no infected individuals occur in spawning shoals' The- reproductive rate of the rudd host is' maintained (see p:56.) providing more potential hosts for the Ligula plerocercoid. 5: Changes in activity Of- rudd with.ape and effect on Ligula infestations The activity of the fish is related to temperature, food supply and ago. Young fry and immature mid_ romer active throughout the winter and although they are feeding on copepods during the winter there is no increase in the incidence of Ligula plerocercoids (vig._10, p.77 ). Paucity of copepods and low temperatures inhibit any development of egg and procorcoid. At the age of 3-4 yrs rudd become inactive during the winter, feeding less and depending upon fat reserves accumulated during the summer and autumn. In winter growth of young fish andtheir plorocercoido is reduced by poor food supplies and low temperatures: In the older'fish- the growth of the plerocercoid is inhibited by the low temperatures and inactivity of the 114. fish, During summer all rudd ere active, when, with' increase in temperature and abundant food, the metabolic rate of the fish increases, _ Activity of rudd, therefore, alters with age, Increase in incidence, intensity of infestation with Ligula plerocercoids, and in parasite burden is restricted to periods of high activity, Periods of great activity are followed by high-mortality in•heavily paraeitiSed fish which have been unable to build up their fat reserves. 0, Presence of Ligula pleroaercoide in, rudd and effect on subsequent infestations, ' The presence of Litula plerocercoids in the body cavity affects the feedins, habits and the abundance of ruddy its spawning migration and distribution in the reservoir, and its ability for.acttve movement, The presence of an established infestation may also affect the establishment and develoPthant of subsequent infestations, The effect of the presence of plerocercoids on the behaviour of the rudd needs a more thorough study. Rudd infected experimentally by mouth or by direct inocUlation into the body cavity could be marked, returned to the 115. natural habitat and their behaviour compared with that of uniTtfected fish. The threshold value.of the effect of en established or a new.infection could be determined. Although no experimental studies were carried out, certain conclubions may be drawn from field observations. I. Peedin habits of infected rudd d--eft a t on subsoeuent Livia infestations, It was deduced from field observations and from examination of stomach contents that infected rudd of all ages fed on the same dietary constituents as uninfected fish. Infected and uninfected adult rudd maintained at the laboratory fed differently at first, the most heavily infected individuals accepting the artificial diet soonest. In contrast to uninfected individuals, adult rudd infected with plerocercoids do not ace ate fat reserves in the connective tissues around the gut. The observed continual. feeding effect found in adult infected fish throughout the winter would only inorease the intensity of infestation if infected copepods are present. The effect of the feeding habits of infected rudd on future infestations cannot be determined. However, the continual feeding of infected fish aged 116 4 and 5 yrs, might lead to an increase in intensity of • infestation only when infective procercoids are available . 2. Distribution of infected rudd and effect an, eubeeoue4t Ligula'infestaAions. Young infected ruftoccurred in'the fry ehoalo_ and sheet's of immature fish Wandtheir behaviour was not different from that of,the uninfected fish. . Very heavily rarasitized adult rudd have an altered distribution in the reservoir. Adult rudd normally move in schoolei butthe heatily infected individuals occur singly as a result of their altered behaviour. In- summer'the infected adult rudd remain in shallow water about 5 ft deep. Although they spend most of the day feeding they sill engage in: surface feeding at dawn and . dusk like the urirroctod adUlt rudd.- but' appearing to feed for longer- periods than uninfected individuales Infected fish are therefore present in shallow water where copepods are abundant and pieoivoroun.birds are present. conditions which favour the life cycle of Ligula inteetinalis. 117. 3, Abundance of infected rudd and afoot on subsequent Lila infestations. Prom:incidence data it- may be seen that heavily infected individuals have a higher death rate than uninfected- rudd. During the winter of 1963-64 the incidence of plerocercoide in fry born tha previous year decreased (rig. 10 p. 77) accompanied by a rapid drop in weight of the largest plerocercoid recovered (rig. 13 p. 86) indicating that the'moit heavily infected individuals died. The presence of largo nuMbers of plerocercoids in fish of grouts 4, 5 and 6 and the increased feeding effect obsqrved in infected adult fish would lead to an increase of infestation in fish aged 4 and 5 yro. PPawniv migration of infected rudd and effect on subsequent Li hula infestations, The presence of plerocercoido affects the pituitary of the host (ICerr, 1941). and inhibits the normal spawning migration of the fish in Spring.' Mature uninfected fish do not show surface feeding during spawning and their feeding' habits at this time are unknown. Therefore, the effect on Ligula infestations is also unknown. Infected fish remain distributed throughout the roservoir and exhibit normal feeding habits which expose them to further infection. 118. 5,f Activity of infected rudd and effect on subsecuent LiFula infestations. Heavily infected rudd-Of-4 yra or older continuo to feed throughout the winter on tha poor fauna,available, in contrast to uninfected individuals who remain inactive In sunimer months these heavily infected rudd reiain close to thadhoro where they feed. - omnivorously, thus enhancing ingestion- of infected copepods, in contrast, to uninfected rudd which have periods of activity: li9. CHAPTER IV Site of develorment of the plerocercoid IntroductiOn The PrOcercoid larvaiin'itil.copepod host, is ingested by the rudd. In the stomach of the':rudd - the procorcoid larva ldoses its ciliated coat,- penetrates the wail of the alimentary canal and moves into the body cavity where it develops into a plerocercoid (Rosen, 1919). • At this'atage, according to Rdsen (1919), 'the 1 plerocercoids are 2-2,2/ mm long and still'resemble a procercoid.- _ Apart from Rosen's (locisit.) account there are no other descriptions of the early develop— ment of the plerocercoid of . The development - of the plerocercoid stage after its entry'into the- fish intermediate host is discussed in ClihpteieviA VI .The smallestsplerocerdoid found measured only 4 mm but did not resemble a procorcoid, in contrast to - Rosen's material 17 days after infection. Methods Infected fish varying in weight from 0,1g to 960g were examined. This size range includes fish,from a few weeks to 14 years old. The methods employed for' r 1204' measuring the _rudd and the Ligl _plerocercoids have already been described (p. 28). . . . . The plerocercoids andtheir localisation in the host can usually be seen after dissecting the rudd. - Small ruddy 3.0 cm long and-2g in weight, were'- examined in two ways. Half. the,sample of small fish were dissected and half were embedded in' paraffin wax and sections out with a rotary microtome.. •Rudd selected for sectioning were fixed in 10% formalin- for 3 Aays'or-in-Reuinta for 12 hours;- washed in tap water and then immersed in Gooding and, Stewart's decalcifying fluid for 48 hours. Specimens were dehydrated in alcohol; 'bleared in xylene and embedded...in "Paraplast" (Sharidon Scientific Co. Ltd.). To ensure penetration of the swim bladder, the fish were embedded in a vacuum oven, and _the' swim bladder punctured with -a fine needle. Sections 7µ, 10µ and '15µ thiok.were out with a rotary microtome., Sections were stained with: 1.-'Ehrlich's Haematoigiriand 1% Eosin (Alcoholic 90%) 2. Heidienhain's Haematoxylin and-1% Eosin (Alcoholic,90%) 3. Mallory's triple stain 4. Alcoholic Oormino hydrochloride All sections were mounted in Canada Blasam. 121., ' Site of development of thelalerocercoid in fry, immature and adult Cooper (1918), Wardle and_Macleod (1952), Dogiel et al. (1961). and Smyth.(1947),:state that Zigula. plerocercoida develop in the body cavity of the fish . Rudd fry,' immature specimens and adult fish were examined in order to determine- accuratelY:the' position of the' larva in the body cavity, in relation to'the' age of the host and, the ageof'the plerocercoid. In the'rudd fry examined, the method of-, penetration of the hest gut wall by the procercoid- was not' discovered as no penetrating procercoids were seen_in the large number of sections cut.. At the ' earliest'- stages found, plerocerooide ranged upwards in. size from 4 -mm long and 0.0006g in weight. The ' pleroberceid.usuallY lies in the anterior region of the body cavity'(Illus. II, p.I24) and is surrounded by a layer of'connective tissue in which it may be partially enclosed (Pig.I8 , pet23). Although commonly found in the body cavity, very small Taerocorcoidsmay be found in anomalous positions. Of approximately 880 fry examined, plerocercoids were , found in anomalous positions in' only lcio of infected fish and never in double, triple and multiple infections. 122.. In two fish plerocercoids were ptesant in the pericardial.cavity Twenty others occurred in the dokdal muscUlature,(Illus.III,'PwI25) and in.1,,tWo the anterior portion of the worm were, in-the dorsal , musole and the posterior part adjacent to the swim bladder (llus.- IV &,V & 127)-. Plerocercoids removed from anomalous Positionsin.undectioned fish did not exceed 5 tam in length and 04020g. in weight. :.In immature fish aged 2-3 yrs the,plerocerooide . were all_ ound in the body cavity and never elsewhere. - The plerocercoids occupy a:_latger volume of the body cavity than ,they do in the fry, as seen from trans- 'versa sections of the fish. , The plerocercoidd are still embedded in liver tissue at. the anterior end of the- body cavity but also extend to the- posterior limit of the body 'cavity. The positions of the plerocercoids depend on the number of individuals.- - In single infections the plerocercoid usually lies in the ventral part of the body, cavity. As the number of plerocercoido in each fish increases the pleroceicoids are distributed more dorsally and laterally, In severe infestations of 18'or more, the plerocercoids are found adjacent to the swim bladder. Nearly all infested adult fish of 3 yrs and' older, 123 Fig.I8 Rudd fry 1963 TS at middle of liver region TS.at posterior end of liver region Dorsal Ligula plerocercoi .6-- Swim bladder Ligula Gut Liver Gut Liver Ventral Scale 2mm 124, nag* 12. Yount; staCee at Ow ploreeereold embeilled in liver tisane of tbe read soli 3 seeemes I m m 125. ILLUS. III. r. Abnormal positiono of the plerocercoid in the dorsal muzculature. 500p 126. Mil. IT. Young plerocorooid in the dorsal musculature of a young rudd. 500)1 I Y °ling plerocercoid in the dorsal part of the body cavity between the two halves of the swim bladder. 5 0 0 ).1 128: harboured a large number of plerocercoids in the body cavity. No plerocercoids occurred in the'dorsal musculature or pericardial. cavity'but.severai were found encysted under the epithelial tissue of the body cavity, in the regicin of the pelvic girdle. In adult fish with moderate infestations of 15-30 worms, plerocercoids in the body cavity are surrounded by connective tissue but in larg6 infestations of 50-135 plerocercoids per fiSh the connective tissue sheath is,-incomplete. .Plerocercoids in adUlt flah are large (see ,Table XIX • NI46), 3g P.W.,and occupy all 'the' available sPace in the body. cavity. , The larger plerocercoids occur towards the outside of the.body cavity and the smaller specimens are'embedded.in the connective tissue surrounding the gut. ' The connective tissue surrounding the plerocercoids becomes'heavily'dalcified, eSpecially in older fish aged' 9-12 yrs, in Which this calcified' connective tissue completely insheathi several worms (IllusVI, 13.129). Calcification - of connective tissue was 'also observed by Owen and Arme (1965) in infestations of, - LiGula plerocercoido in roach. 129. ILLUS. VI. Rudd aged 10-11 yrs and weighing 960 gm dissected to show the calcareous gutter in the ventral portion of the Jr:7n :?rom which the plerocercoid has been removed. Another plerocercoid lies in the dorsal part of the body cavity and no calcareous depositions arr vtGM11 in the connective tissue surrounding this larva. 130. ©RAPIER V. Growth and development of the plerocercoid. Introduction "Growth is the addition of material to that which .is already organised into a living pattern" (Young, 1950). Regarding the,developmentof an animaluthe equation. • postulated by Nee011sm (1964)-:that Growth + Differentiation = Development must be considered, as it implies that quantitative- and' qualitative changes are-involved in development. Ligula-larvae in the body "cavityof oyprinid fish - develop from the procercoid stage'to the fully infective plerocercoid larva during a period of 12-14 months, during which time the plerocercoid.increases in weight and the primordia of the reproductive organs are formed (Dubinina, 1953). Further development from the plero— cerooid to the sexually mature adult can only proceed when the plerocercoid is ingested by a suitable final host or is bulturedin vitro. During its development in the host, the plerocercoid increases in size,-and size was measured by weight and length. Differentiation of the genital primordia was examined in sections. 'Increase in weight and length of the plerocercoid after entry into the body cavity of 131.: the fish and developmentofthe'genital primordia will be regarded as evidence of growth. Biochemical changes are associated with growth and development of the • .plerocerooid and nitrogen, glycogen and total lipid. fractions were measured. ' There- are four distinct stages in the development. of the-plerocercoid. ; Immediately after entry into the rudd the larva still resembles tvprocercoid,(Rosen, 1919). In the second stage of- development the larva attains the gross structure of a plermeroold but without genital primordia and is unable to mature and produce fertile eggs if ingested by the final host. In the third stage the primordia'of the reproductive organs develop and the plerocercoid'is infective (Cooper, 1918). In its.fourth Stage, the larva exhibits signs of malfunction or senescence. The data which follow were compiled from samples taken iwi„the field. 1. Development of the .gerocercoid. According to Rosen (1920)4 immediately after penetration into the body cavity of"the fish the plero-• cercoid still resembles a procercoid. Rosen (loc.citi) found the procercoid.like first stage in the body cavity 17 days after experimental infection of gudgeon (0obio Cyprinidae). No examples of the procercoid-' 132. stage were found in the fry, immature or adult rudd sampled from Ravonethorpe reservoir. As the first developmental stage was already passed by plerocercoids in ,the rudd: examined it must be of very short duration. Sections of month..old fry taken from the reservoir showed plerocercoids already in the second stage of development. ln the relatively high (18°C) summer water temperatures in Ravenothorpe the first stage .is passed through rapidly. In the second developmental stage the larva develops its characteristic plerocercoid structure (Cooper, 1918) and the genital primordia commence,development, but the plerocercoid is as yet Prinfective. Tha highest number of second stage plerocercoids were found,in rudd fry a few months old. Plerocercoids with differentiating reproductive primordia range in fresh weight from 2.0mg to 40 mg. Larger specimens, ranging from 48.0mg to 146.6 mg and harboured by fish aged 6 months and older, all possessed genital primordia similar to larger infective ilierecercoids.:, The third stage of development is a growth phase immediately following stage two. The genital primordia are present and differentiated and the plerocerdoia is able to reach sexual maturity when ingested by the final host. Stages two and three can only be distinguished 133'. by experimental infestation' of the final hest. 'All the from one' year optrudd0 sampled July 19640 possessed well—developed genital primordia and - some of these worms wore cultured in vitro and produced viable eggs. Third Stage plerocercoids recovered from these fish ranged from 0.2460g to 0.7999g in weight_ although the third stage is known to include plerocercoids of lOg and over. ' Stage four is continuous with and morphologiCally indistinguishable'from stage three. Stage four Plero;.; cercoids are large- with a fresh weight of. at least 3g and 21 cm.long0 and occur in fish over six years old. Plerocereoids remain in the fish host until its death as rudd are unable to eliminate the.infestation. Three types of- abnormality occurred in old infestations with stage.four plerooemoids.- Plero.;- cercoids0 found in seven year eld fish harbouring 3-5 plerocercoids•- were completely ensheathed'in connective tissue; only one or rarely two plerocercoids in each fish were surrounded by'calcified tissue, similar to that referred to by Owen and Arta (1965). Only plero— cercoids of 3g and over Were surrounded by ealeified tissue and the smaller plerocerooids from younger fish never were. Illustration VI p.129 shows a 10 or 11 year - old rudd weighing 965g from which one plerocercoid 134. has been removed from its calcified gutter, the others remaining In situcovered with unealcified connective tissue. The second type of abnormality in .old infestations, the necrotic areas, occur in some worms weighing over 4g (Inns* vIi p.135). As seen in transverse section, these necrotic areas wore confined to the cortical longitudinal muscle layer and the subcutioular layer, and wore largest in the posterior third of the ploro- - cercoid swhoro they reached a diameter of 800p* Necrotic patches wore most dense down the sides of the worm, being less dense and smaller in the anterior third*-, The formation of necrotic areas in plerocercolde was not - associated with heavy calcareous deposition in the eneheathing connective tissue of host origin. The third indication of abnormality was outgrowths from the plerocercoid reaching 10 ma in length and 5 mm in width and height. The cuticle covering the out— Croy/the I31 appeared normal. The structure of these outgrowths was studied in transverse section* al abnormal tissues were found, but there was a large, fluid filled cavity at the site of the lateral longitudinal excretory canal. All these abnormal plerocercoids wore alive at the time of removal from the fish. 135, VU. Lame necrotic lutes. in an old plogg000roside 500p 136. , 2. Size of the plerocercoid„ After entering the, body cavity of the rudd the plerocercoid grows rapidly* attaining an average length of 0.5 cm and an average fresh weight of 1.2 mg within a month and continues to grow thereafter. Increase in size continues and the maximum* for one year old plero— cercoidd in one year old fish* was 10.7° cm in length and 0,7999 gm in weight; for two year old plerocerooids in two year old fish.it was 14.3 cm and .1.89 gm. A10 or 11 yr old fish harbours plerocercoids with an average length of 45.5 cm and 16.5 gm fresh weight. increase in size of the plerocercoid increases as the size of the host increases (Pig.I3 , p.86.) and growth does not_ccase after infectivity to the final host is attained. The. size, attained.by the plerocercoid is limited by the size of the fish. The maximum individual plerocercoid weight attained by plerocercoids for each year's new infestation in one year old* two year old and three year old rudd is shown in Pig. 19 * 124,1 19 • The body cavity of a two year old fish is larger than that of.a one year old and.can support larger ploro— cercoids and also permit more rapid growth of the new infestations. Pig. I9 • PP I393hows that the size of newly acquired plerocercoids depends on the size of fish infected. Ateamalltr good la a plorooaroald rosoved from Maid (Mt yrot 14. 130. 3. ,pt ete of ,7enth of plerocereoids.. The rate of plarocercoid development elsP is influenced by the size of fish into which the plero— coreoid enters, the numbers of worms alrenay present and the tine of entry into the host. Individual plorooarcoids present in mid at 3 months, 15 months, 27 months and 39 months wore neighed Mg. 20 P 142). The radd wore sampled in September or November when the infostatien for the re/avant year rzat3 established and therefore detectable. -The probable year and season when the pler000roold entered the hest sin be estimated from the weight group to which the pletteercoid belongs and the might of the host. Pig. 20 p. 1423hom the weight relationship of the plerecerceids in fish of varying ages with on infestation of one up to thirteen plerecereolds. TablervIrshoz-ta the pesoible times of infeetation over the period gram which the eample was taken.and assumes that infection is ponsanal. TablornIfshd*sthe periods when infection vas possible and an estimation of rrhon infection occurred Car each fish. Maroc:le-zooids increase in might as the fish grows and the average total weight of pler000reolds in ingested fish ranges from 0.0006 gn in vary young fry in Group I to 16.5 gm in older fish of Group 10 and 11. The 139. ,Fig.19. Plerocercold increase in weight Maximum increase in wt Maximum increase in wt Maximum increase in wt of plerocercoids to fry 1963 new intake to fry 1963 new intake to fry 1963 in sample 1963 in sample 1964 in sample 1965 90 80 70 25 60 I0 20 SO 8 40 15 m E 6 30 e 10 .... L 4 20 m V 3 5 2 10 0 r J A S Nov1963 Nov1964 Aug 1965 140. TABLE xvii • Possible times of infection forgroupo of fish sampled at intervals of 3, 15. 27 and 39 months* (see gra)bpi42) SuA W Spsu W SDSuA W 8pSu1t 1 2 3 4 Period(s) for infection Winter = Spring = SP Sumner = Su Autumn = A TAM XVIII Prom Graph p142 Period(s) of infection Estimated Ash Type of infection available period Al 1 Single 1 1 Quadruple 1,2 D Triple 1 Double 1 or 2 1,2 P Single J 1 O Quadruple 3, 1 or 2 Double 3. 1 pr 2 123 Single 3 or 2 3 or 2 Thirteen 1234 4,3, 2 and/or 1 141. largest total weight of plerocortoids occurs in fish of 300-400g (015421i P.143 )4 The intensity of infestation is also highost in the fish of this :might group p.143)• 'The drop in total plerocercoid weight in the 500-600g group (P .2I p0I0) coinaidos with the low intensity Of infestation (PiCiiI7 r P.109) and is due to the loss of heavies infootod individuals Fran the population. 500-600g infected fish carry a Ildshor average total plorocorooid burden than 100-200g group fish and are infested with a comparable =bar of plor000rcoidso Thereforeb'p/orocerooids harboured by 200-600g fish are &Towing with the hoot. Plereeercoids continue to grog as long as they are not ovorcrowded and as long as their host continuos to Vow nonarally• Thus, by a atudj of the paracito burden of infected fish the grmith pattern of the larva oanbe aasossod and this pattern la found to coincide with periods of hoot growth (Fig.I3 # P*86 ). The maximum growth period of the pleracercold in young fish coinoides with the growth period of the fish and this is also true far older fish. 4. Mae of_pl9rocorcaida i e -701 Jo, 0 •Mob, were simultaneously samplod in one weight group pf 350-400 gm and the numbor, weight and length of Plerocercoid weight distribution in rudd at 3months 15months 27 months 39months B 6 O 14 12 10 gOB Q w• 06 2' 0 4 cr) e; f y • 02 0 nr- rL r- IP IP 4P 3P 2P IP 4P 2P IP IP • 13P A B C D E F G H I J Intensity of infestation for fish AfB,CID,etc. II 4.0 4 a 0 C Fresh wt. of 0 plerocercoids 4 . 2"" = - ▪ E 5 0. 0 6.. 4 at Pig.22. 0 VI w 0 Fig, 2I, 30- 50 - 70 - 70 - 10 0 100 boat house bridgestream Variation inincidenceofLigula MO in fry1964atthreepositions R Total wtofLigulaplerocercoids A per weightgroupoffish 200 300400500600 fish groupsingms B C I D i E 143 144. plerocorceido determined. (TableXIX, ped46). , The average weight and length of plerocercoids-deoreapes with increase in number of plerocercoidee .In these • . older fish the average weight is depressed- whether the parasite load comprises several large plerocercoido or a large number of small plerocercoide graded in nine.. Terser plerocercoide presumably .entered the fish and began development before the acquisition of new plero.. cercoldoe. 5, DoformedArowthe Only one deformed pleroceroold was found in elm) contaot with the gall bladder of the rudde A Constriction; occurred in the anterior region of tho worm where it was in contact with the gall bladders., Although genital primordia wore present in the narrow region of the worm they were smaller in size than thee° anterior or posterior to this region. The size. of the testes in section, anteriorly and posterio4y'to this narrow region, me 64p x 66p and 64p x:64p respectively. In the narrow region however the testes measured 40p x 504. . and the vitellaria 10p x 15p, compared to 15p x 19p for normal vitellaria. The constricted region, with its smaller testes and vitollaria. glands, further suggests that the plerecercoid 145. does not move its position in the body cavity of the fish. 6. Chemical changes associated with growth and develop- ment of the ylerocercoid. Biochemical assay methods-can be applied to cestode material in order to determine biochemical oomposition during development. The. degree of development in early stages of Schistocephalus solidus plerocercoids is correlated with the- glycogen content (McCaig and Hopkins, 1965). • Nitrogen, glycogen and lipid contents were assayed in a-series- of plerocercoids, in order to obtain • information on chemical changes during development, a) Nitrogen content of the plerocercoid. The nitrogen content of a plerocercoid is related to the total protein content, which is obtained by multiplying the nitrogen percentages by 6.25 (Von Brand, 1966). Method of Nitrogen determination:- A micro Kjeldahl method was used to determine the percentage nitrogen in the plerocercoids. The method employed by Hopkins and Hutchison (1958) was used with minor alterations. Whole live plerocercoids were obtained-by dissection from freshly killed rudd, washed in Hanks' saline and placed in acid-cleaned specimen tubes. The worms were 146. TABLE XIX Average length and average weight of Dlero- cercoids in fish Weighing 350 to 400g taken in one sample 1965, to show decrease in inwrage weight and length of plerocercoid with increase in infestation. No. of plerocercoids Aver ;o might Averwle length oft 54 1.7 ,., 15.1 37 1.6 13.4 37 1.5 15.1 31 2.2 13.1 22 2.6 14.8, 16 1.7 13.9 15 5.6 16.3 15 3.0 16.0 147., placed in an oven at 105°C for 18 hours to obtaih a constant dry weight, and then removed and ground to a fine powder in a mortar and pestle. The material. was stored in a desiccator, with silioa gel to await' use; . determinations showed, no difference ,up to three,: months storage., 2.0 mg to 10.0 mg samples ,of powdered worm were rapidlk.weighed in-the digestion flask and washed down with-2 ml of nitrogen-free concentrated . analar sulphuric acid. The catalyst used was B.D.H. mercury tablet containing lg of sodium sulphate and the, equivalent of 0.1g 'of mercury. Pour samples .of each plerocercoid and two blanks for each plerocercoid were placed in the rack of six digestion flaSks. The digestion of the material in the apparatus and,' the manner in which it is carried out are particularly important. The digestion mixture was heated slowly for the first 30 minutes in order to avoid charring, and there- after it was heated more quickly. The optimum time, for digestion was found by experiment-to be two hours. - The, solution was allowed to cool and then diluted with 5 ml of distilled water and placed in a Hoskin's still. Each digestion flask was rinsed 5 times, using minimal quantities of distilled water. 10 ml of 40% sodium 148. hydrozido and 7 ml of saturated sodium thiosulphate solution were then added and the still sealed. The sample was steam distilled and the ammonia trapped in boric acid with two parts //ethyl red and one part Methyl blue as en indicator. Distillation was carried out for three minutes after the indicator had changed from purple to green. The tip of the condenser was washed with a small quantity of distilled water after lowering the flask. The distillate was titrated with giloo hydrochloric acid; glycine was used as a standard, from which the results did not differ by more than or —3%. Results The nitrogen content of a wide range of plerocereoid material was determined in order to discover any variation with increase in also of the plerocorcoid. Material' from a known ago group of infected rudd was included in order to compare the biochemical constitution of worms in light and heavy infestations. In order to show the variation in nitrogen content with increase in weight of the plerocercoid, the percentage nitrogen content of plerocercoids was plotted against the dry weight on a log. scale, which ranged from 30 mg to 2,000 En (Pig.23 p.I52). The percentage nitrogen 149. content was the average reading from four determinants. These averages are given in Table XXXIV in the appendix. It can be seen from the graph (Fig.23 , p.152) that there is an apparent decrease in nitrogen content with increase in dry might. Since dry weight is.a function of growth, Growth is accompanied by an apparent decrease in percentage nitrogen content. Average nitrogen contents of plerocercoids comprising different intensities of infestation in rudd are shown in TableXX p.150. The percentage nitrogen is seen to decrease with- decrease in numbers of infestation (Tablopxx., p4a50). It may also to seen that the average dry weight Cif the, plorocercoids in one host decreases as the infestation increases. - This, however, is a reflection of the ago of the plerocercoid as it has already been shown-(Pig.23 p.152) that the nitrogen content decreaseo with increase in dry weight of the plerocercoid. .Therefore as the'plerocercoids grow so the percentage nitrogen decreases. b) Zipid content of the plerocorcoid 01 Tbki amount of lipid occurring'in:Various species of parasites is quite variable and there is no indication that the type of habitat has a significant influence on 150. Info_oted raga. 2 :71*0 old _ 43.31 opaplod_in April 196 Not of ploro— PO'. of boot Aver, D.17. or Averaco ;I, corcoids splerocorcoid nitroden a 28.0 0.0798 , 6.2 7 30.0 0.1123 5,9 5 22.9 0.0936 5.6 3 30.0 0.1899 5.7 2 22,7 0.294 5;4 1 24.0 0.1346 5,3 / 2.31 0.4131 4.4 1 25,0 0.2640 4,9 the des roo or lipid ace ation.n (Von. Brandt 1966). BO quantitative data on the lipid content of ',Apia is available. In order to discover. the lipid content and to demonstrate that lipid accumulation may influence, tho decrease in percentage nitres= content, the following determinations wore carried outs Mothod_of lipid determination, The lipid comment or the plorocorsold vas determined using a sins2e extraction and evaporation process cimilar to that doseribed by Sperry (1955), 151. A dry weight °ample wan prepared an for nitrogen determinations described above* Sample° woighing between 10 mg and 900 mg wore thoroughly mixed. with a 2 to 1 Chloroform, methanol mixture, abaken and allowed to °tend in a otoppered voaaol at room temperature for nix bourse The content° of the flask were then filtered through a foot, hard, (=roe filter Matz= grade 114) with nevem? rinainga of the container, and waehingo of the filter paper with 2.1 ohloroform.mothanol oolution into glans flaoko* The oolution wan evaporated under reduced preaouro at 40°0 and placed over silica gel in a doeiceator at room temperature for 24 hour© and than weighed* Twenty. four hour° wad found, by experiment, to be the minimum period for larle sample° to reach conotant weight. The lipid content of plerecorcoida from rudd born in 1963 and sampled in April 1965 was dotormined• Piero— cercoido of loon than 100 mg dry weight wore combined for determination and all other plorocorcoido were determined individually,' Tao replicate© and ono blank were used in each determination, wherever possible. nooultn In order to ohm the variation in lipid oontora with Imo:come in might or the plor000reoido the lipid 152. PIG.23. %Nitrogen/ Dry Weught Plerocercold 8 • • 7 • • • • • • 6 • •• • • • • . . 5 • • • 4 • . 3 g i 2 at O 20 30 40 50 70 90100 120 iso 200 300 400 600 800 1000 1400 2000 3000 4000 5, Dry wt in mg 153. FIG.24 Lipid / Dry Weight Plerocercoid 14 12 I0 8 • • • • • • * • • • • • • 2 0 0 100 200 300 400 500 Dry wt in mg 154. content was plotted ewainst the, dry weight. Tho results (ria.24 , P.I53 • Tab1oDEXIIN 264) show that tho percontkp lipid content decroascs fran 6.34; at 95.0 ra3 to 4.5';', at 400 mt;. The accuracy or tho earlier part of the craph is doubtful because or the combination of selioral small samples to provide detectable amounts of lipid. Growth Jo therefore accompanied by an apparent decrease in lipid cont nt. and an apparent doCroase in nitrogen content. Crlycoann content of the plorocercoid. 7f7,1:1nt0C e clyecz-:en content were obtmlnera. oraor to =plain tho r,ariaticus in lipid and nitrogon contents durInf Erowth and also to observe whether tile raycozon content is omparabIo to that In SchisteconllaIns vecwded, by n'er3ai7, ana 1101:ins (1955). 711-3on mrIwrs .L =d that a snocific le!vel ef glycoa onists in riehistoorynhnina plcrocerecif2s ,13: a cAven. mint. nethpa offpcorton deteimintAion. he percentage glycogen content vas detormined using the net of- :acian (1953) and Ropkins (ig6o). Complete =traction of glycogen from dried plerocorcoids mith' trichloraentic acid at roan temperature vas not satisfactory and hydrolysis or theMilered =au with potasstun 153.. hydroxide (Hopkins, 1960) was preferred. 30-60 mg samples of dried powdered plerocercold were weighed out and boiled for 10 mins with 2 ml. of 30Vd1 potassium hydroxide. The contents of the boiling tubes were washed out with several rinoinge of distilled water and made up to 250 ml in a volumetric flash, • A . . sample between 1 to 1.5 ml was placed in a boiling tube and made up to 1.5 ml with distilled water. To this was-added 0.5 nil of 1 anthrone in ethyl acetate, followed by careful layering-in of 6.5 ml of concentrated . sulphuric acid. Mixing by shaking wad accomplished - 45 seconds for each sample, which was then boiled for 3 mine. After 25 mine the intensity of the resulting colour was then read at 625 mp on a Unidan S.P. 600 spectrophotometer, using glycogen 04;.D.',H. rabbit liver) .- as -a standard, and the c#4* glicogen in the sample was calculated. Results In order to show the variation in glycogen canton-h . with, growth the ;-,!) glycogen content was plotted against dry weight on a log. scale (Pig.25 p P.157). - The glycogen content of plerocercoids in the dry weight range 30 mg to 3,000 mgincreases from 53 to 630 (Pig.25 'p.157). The apparent decrease in percentage lipid and 156. peweentage nitrocoa (ris.23., p.152) may uell,be due to the increase in pereentage- glycoGen as the plorecoreold increases in also. The Table below shows the composition of plorocorpoido of, 100 ma dry weight nnd 400mg dry weight. Tau xxi ampsaal...inwo l./foo lia.daman kataaimSem...42121 ' 11.4 32.5 5.8 6.25 32.8, as protein ri5 glycogen 57•7 lipid 4.5 The glyeocon content of the plereocreeid therefoxe innzlnees as the plereeereoid craws. This is fUrther disevssed- with reference to zulat=lawall42 on p.196 • 15 7 . FIG.25. /e Glycogen/Dry Weight Plerocerc old 70 • . - . 60 • SO 40 5 30 3. V 20 dt I0 i O 20 30 40 50 70 9 0 100 120 ISO 200 300 400 600 500 1000 1400 2000 3000 4000 Dry wt in mg 158. CHAPZER VI. Moot. atitisulu 1ptestinalts ixfest01511 ga the .r4d4A • Introduotion. The pleroceroold larva of 1.1fultt ipteatinaliq in cyprinid fishes has been studied wherever the fidh are of econemicimportance. Paotore concerning the growth: of infected fish, their mortality and general condition have boon studied. , Pitt and 4r adman (1957) working.onantntestation of gtztila intestinaliris in yellow perch (pevaq pip/omens, Mitch.) showed that parasitism by the plerocercoM caused stunting in the fish which was most pronounced in three and four year old fiat. The plerocerooid. also affoota the chemicalcompoeition of the fish, lowerig the glycogen content in the liver (Kooheva, 1961) and reducing the fat and protein content (Shpayonskaya. 1953a). Shpolyanskaya (195313 studied changes in the blood composition assoolated with Itiflula. inteetations and found that in Car#spige opMeelim the polymer leucocyte count increased. This work waa . oonfirmed 11,y Oadkovskara (1953) but Obpolyanekayn (1953b) further showed that the haemoglobin content decreaned and the monooyte count increased. Castration of the gudgeon by the plerocorooids of 15% IdigNaMi was noted by Puhrmann (1934) but it was not until Urea (1948) work on roach that the effect of the pler000reold on the pituitary resulting in reduction of gonad stimulating hormone and consequent castration, was diocovored. Korrts (1948) work was confirmed by rirshonblat (1951) in Russia, working on roach, and later by Jaen (1953) who pointed out, as did Kerr, that castration did not occur to the same extent in atioklobaoka parasitised with popkatooptilallis soligas, as in roach parasitioed withaaga• Recently, Arme and Ovon (1965) investigated other British oyprinids infected withIda& and also found imprecision of gonad development« Observations on the behaviour of adult infected fish at spawning time are included in this Chapter together with the effect of Lima on the growth of rued and mortality in rudd. 1. Sunce*AbMityptput% tq. infeettlAionot • In certain parasitio infectations e.g* those With RimpqsArowlqq, the proaonoo of the parasite, or the Moat_ reaction induced by the permit°, reduces susceptibility to further infection. The average number of plerecercoide in adult rudd is high (Pig415 p1098 ).' 160. No adult rudd harboured only one or two plerocercoidep although ouch a low intensity of infestation would best favour survival of the fish host; rudd of 4*7 years old harbour either a multiple infestation or they harbour no worms at all. However, no conclueions on susceptibility to infestation can be drawn without knowing the infection rate of the fish at various stages in the life history., Kosheva (1936) and Shpolyanskaya (1953a) state that the intestinal wall of infeoted fish becomes thinner. This may facilitate entry of the procercold, which would otherwise not be able to penetrate. The problems of susceptibility can only be resolved experimentally and at the moment must remain hypothetical. 2. Direct effect ofplerocersjad_on Ahe rud4,. The presence of plerocercoids in the body cavity of the rudd leads to distension of the abdomen in immature and mature rudd. The abdomen is not distended in the fry because of the email mass of worms present. Distension of the abdomen leads to compreeeion of the viscera in heavily infected immature and adult fish. The livers wore small and dOngate. The swim bladders however wore not comproseed. 1614 Pat is deposited around the intestine of uninfeoted adult fish during the summer months- and is used during overwintering and gonad development. . Pat deposition does not occur in heavily infected adult rudd. In low infestations of up 'to 10 plerooercoids in immature and, adult fidh, the 'worms are enmeshed in host connective tissue, whereas in, high infestations of 30 or more worms the connective tissue covering is incomplete. In olderrud4 aged 10 and 11 years, the connective tissue around the plerocercoid becomes calcified; ultimately.producing a bard, stony encrustation in the body cavity of the 3. Growth of in footed rude. The effect of ,fibula plerocercoids on the growth of perch was studied by Pitt and 0rundman (1957) mho found that the uninfected fish of comparable ages were longer than infected fish. The length of the infected year.old perch was 37,9A less than uninfected fish; in two year old fish' 47.041 less; three year olds 4940 loss; , four year old 5544% less, and in five year Olds 58400 leas, Studies on stunting of growth in other species of fish infected by parasites have been carried out by 162. Hunter and Hunter (1938), Cross (1935) and Hubbs (1927). They conclude that the parasites modify the infected fish's characteristics by increase in number of scales (Hubbst 1927) or by stunting of growth (Crosst, 1935); (Hunter. and Hunter, 1938). There is no major disturbance in the growth pattern of rudd infected with Iligula plerocercoids (Pig. 260 P.I6 , compared, with uninfected fish (Pig. 66 0 1457 )4b Average weights of the uninfected fry born in 1963 and sampled during the period November 1963 to August 1965 range between 1.2g to 30.7g (Pig.26100 p.165), whereas the average weights of infected fish during the same period range, from 1.2g to 31.5g (7ig.2013. p.165). The average weight• of infected fish with its plerocercoids is always greater than that of the uninfected fish (Pig$2.6by P.I65). During the winter of 1964-65, heavily infected fish died and the average, weight of infected fry dropped to aweight,similar to that of, uninfected fry. which suggests'that the weight of the infected fish , without the weight of the plerocercoids is lees than the average weight of uninfected, fish. The difference between the average weights of,infected and Uninfected fry born in 1964 becomes evident within one month of the fish becoming free-swimming in July (104,40p.I66: FIG.2ia. 163. LENGTH :WEIGHT RELATIONSHIP OF INFECTED FISH 40 0 0.,0 8'88 20 ...... „... 0 0' 0 10 090 I I 5 10 50 100 500 1000 WEIGHT IN GRAMS 164 Salo difference. in welzht of infooted cza uninfected zrada roaches a =dram then, pl.orocorooid growth. and fish crowt.b. aro both at a rani= at tho end of tho first ono-ozd-a-half years of tho fishes life (ic•26b • Pi165)• In two and a half years old fish tho woich-b difference la not co pronotnood becalm uninfootod rich otart their gonad development wheroao 3- t: onus do not. r2lto differonco irelength of. mooted =A infected rich in. less•raarkod than tho 'might difference. raw difforonco in lonocith botwoon tho infected and uninfected floh occurn in ono and a half years old rich 671 X27 • P.167). Infected fish up to the ozo of 27 noutho avo conerally hoarier 4.3nd lonie: 4 V uninfectod floh. The larcor weight of the infocted ruddri_aty be duo to voicht or tie plerecorcoldo prosont, but tho myosoneo of tho worrio. dorm not orIplain, the Te.oator 2ongth of infected rad* It lo p000lblo that only tho fish of tho Disc of infected fiat aro capable or supporting thin bu.1.-tion of pernaitoo and onaller fish clio• Pitt and Grunanann 4957) obotriod an opposito of` oot whore tho growth of young porob infootod with riimula plorocercoido vac otuntod. Growth of older infootod flab is more affected than that of yotuig fish. In order to mamma the growth of FIG. 2611. 16:7 . Infected and uninfected rudd average weight over period Nov 1963 to Aug 1965 of rudd fry of 1963 32 28 24 Infected ---- uninfected 20 16 E crt 12 .c rn To 8 4 0 NJ M M J S NJ M M J S 1963 1964 1965 FIG. 26c. 166. Infected and uninfected rudd average weights for fry 1964 sampled 1964 21 1.9 1.7 infected - - uninfected 1.5 1.3 1.1 In E CP •9 ao...... C ...... AO' .... ••• ... I .0 cm .7 I to i 3 •S i 1 i .3 .1 0 1 July Aug Sept Oct Nov 1964 FIG,27 Average length of infected and uninfected fish 167. Nov 1963 — Aug1965 14 12 10 in 8 E co c 6 .c ... a) c 4 — -- uninfected to infected 2 0 I I o I I I I I I I I NJ MM J S NJ M M J 1963 1964 1965 168. older fish,- they were divided- into weight groups -instead of age groups because the number of' annual rings on'the. scale is obscured by breeding 'cheeks. • Pultonss (1902). coefficient of condition (Q) - can be used to compare • the condition-of individual fish in the population. Tbo , better -the condition of the fish the higher is the value of Qt.' Q As a measure of 'plumpness,' mid is - =pressed au I A inhere Q to coefficient of condition :4 W l'fresh weight in grams, and L iss the length in centimetres. Portion's coefficient (K) (1950), tisitedfby Pitt' and;. • 05. -4 Grinidinann (1957).' states X. where W = fresh Weight L in grams and L is the length 'in ' Vatonts • values for Q and Pitt'and Grandma 'la values for X are. not direetly comparable because of 'the different coefficients used and because different species of fish were stddied• Neither of the coeffioients takes' into account variable faotorri such ae weight of gut contents, site of gonads and- weight of fat deposition. Pitt and Grundmanntel (,957) calou3.ation of the coefficient X for all perch ranging in ago from one to five yenta did not' distinguish between immature, mature and spent fish, which grouped separately would have different coefficients. 4 1690' n ardor to reduce. variability to a minizugn,170- rudd,- which were captured' on the owe day 3n Auguet 1965# Were weighed ancVmeasured and sorted into'welzhi group's* Pultonlio Coefficient Q was- then. calculated from the average weights and lengths 'of- each weight group. In uninfected fish ranging from 60 to 600 on l'ultcaxia 'coefficient 1:1 ,ranges from 009' to 24, whereas • in infected' fish in the same• weight range, Q ranges 'from 0.8 to 107trig., 28 • P.I7I)40 The rapid rise in the coefficient for untnfeoted fish from 0.9 to 200 in the 0.200g range is caused by the deepening of the body and development of gonads. Infected fish do not dhow such an, increase at' .this otage because'of stunting of. growth and 410Abition of gonad development due to the pier°. . °arcade* , In the 500.700g.rangeo 'inteeted fish again have a lower coefficient of condition than uninfected rudd* aomparioons of the coefficient of condition Q in :infested and uninfected fish is a measure of the gross effect of the infestation' The reproductive organs., do not develop fully in infected rudd# nor does seasonal deposition of fat occur In the body cavity.. The lower Q value for infested fish than for uninfected fish indicates a smaller weight per unit length, i.e. ected 3.70* rudd weigh anome per unit length- than infected rudd. The coefficient of condition for the infested older rudd are* however* comparable to -that , found by, Pitt, and 4rinidroarY, (1957) in the yellow perch. Nowe'crer* sttuithi of growth does occur in older infested:, rudd.. as indicated by the, coefficient of condition Q (see P.169 )* The- actual, pattern of growth obtained by plotting the, , length-against the weight of infected fish logarith- mipally-is ahotn. in Irti,7-.12ea PE63 and is .similar, to ' that for uninfected fish 6(?: t Ps' 57 .., In order to, obtain more -accurate. ooefficients*' weights of irritn-Pected fish less gOnads and with .fat 'removed* should be. compared with weight„ of .infected fish with gonads and fat removed.-, , . . 4. Effect of 216roceraoid infeatatien - on-the . - Of the rudd hoot. , _ The behaviour of infected fry and immature fish is not different.from that of uninfected fish* all of . which remain in the same shoal. The behaviour of infected adult fish alters, in three ways; . infeeted rudd leave, the school of,- adult fish;„ do not exhibit normal courting :and spawning. .beliavioury and. do not shovic- normal ,feeding behaviour. Adult fish infected with 30 or more plerocercoidls , .4 were captured away from the main shoals of rudd in th4 171. FIG,28Ftilton's coefficient for rudd sample 2.4 2.0 IM /' / ‘ N / - / N Mr .." t 1.6 N N .00' ien t t ic 1.2 MI ff 1 e 00" 0.0 co 0.8 i — — — uninfected infected 0.4 NO I I I I o 1 1 I 0 0 10 100 200 300 400 500 600 -10 -100 -200 -300 -400 -500 -600 -700 -, weight groups in gms 172. summer and do not have the same distribution in the, reservoir, throughout the rest of the year as the? uninfected counterparts. The, feeding habits of adult infected rudd are altered, (see NILO. In summer • months' with high water temperatures of. 15,0 to 343!0 infected adult rudd are to be seen in shallow water and exhibiting a curious pattern of movement in which the fish swims up to the surface and rolls over bringing its underside to the surface« The altered behaviour of adult infeated rudd at spawning"-time has already been discussed. On P.102 5* IdartgAtr. o infecited'rvAd. 4 Death of infected fish is common during' the winter - months although it also' occurs in the summer. The incidence of Air ula in fry and immature fish drops from 6954 .to .37;' during the winter months (Pig.I0 # •P•77 ) 1 It has been shown -that the life cycle is not continuous (p•82 ) during the winter months and the drop in incidence is caused by, mortality 'of those rudd with the heaviest plorecereoid barden, (Pig. I3' • P.86 ).' The seasonal mortality of infected adult fish is difficult to estimate because no large samples of the adult • population were taken each month over the winter period.. Mortality does, however, increase with agog , sincith: few 3.73. heavily infected fish are found above 500g and only those with TEM' plerocercoida survive ('ig. I7 p I09ti - The heaviest infestations occurred in adult rudd- ia 1962 VI. 98) and fish which would in 1965 have fallen into the 600.800g category are almost absent from the 1965 samples and there is a'consistent drop in; incidence. Death of infected rudd is either seasonal or due to heavy parasite burdens. Seasonal mortality is most important in fry and immature fish acquiring new intsctions, but probably occurs also in adults acquiring further infections. Mortality in adult fish results from growth of the plerocerceide in existing infestations and few infected fish roach a weight of 800g.' . 174: VII. Discussion: Section It Ecolo17 of th© life °pie of Ligula intecatinalie, ' 1. Host sreoificitv of the plerocerceid of Eljall 31111=11111111111111111111111111111intestinalicv„. The results show that in three reservoirs sampled,. Havensthorpo, 2itsford- and Hollowell, only oyprinid fish - were infested with the plerocercoid of Limla inteittistalis. No fish from the river Rene was infected,: . Owen and !trite (1965) also found that only oyprinida were infected_in Britain, and Huoulak (1960) found that only cyprinids were infected in Poland -- However, Pitt and Grunartann (1957) working 'in the U.S.A. found the'plerocereoid of Ligula, ape in Percidae: — Esxlier Work in the surmnrised'by Cooper (1918)„ also recorded Ligula intestinalio from, several families of fish, although some of theSe records are open to doubt, particularly those referring to fish of tho families ialmonidae, OaStorosteidae and Ommeridae. Moro recently, Wardle (1932), Hadorlie (1953) and Deuce (1950'have_reported intos:binalis from Percidaec Cyprinida© and Catestomidaet Dubinina (1950) was of-the opinion, as was Wardle (1932), that several species are probably lumped together under the name Li .a intestinalis, The existence of several species of Ligula or of distinct biological ro'.6es of L. intestinalis would account for the fact that the plerocercoid,of Ligula,does not becomo'established in Perca,fluviatilis, in Ravensthorpe reservoir, although perch fry feed on copepods. In the U.S.A. Perm flavescenS, whiOh also feeds on copepods when young, harbours, Ligula intestinalis plerocercoids (Pycha and Smith, 1954), which appear to be physiologically distinct from the European form occurring in Cyprinidae. The plerocercold found in P. flavescens in the U.S.A. may _be distinct also from that foUnd in certain ayprinids,' such as Notropis cornutigs frontalis and Catastomus commarsonii utawara, in Lower Ohateaugay Lake in the St. Lawrence Watershed, because P. flavescens occurs, I • in the same.lake_and is ,uninfected filunter and Hunter, 1930). Li Lila, like SchistOcerhalus, is not a monotypic genus and more detailed examination may Dhow morphological differences, such as Dubinina (1959b) has found for Schistoceohalus. :C.t may be that worms from different families of fish are distinct, and it would be interesting to apply Bratenls (1966) techniques to Ligula. Braten (1966) implanted plerocerooids of Schistocerhalus solidus into the body cavity of various fish and found develop, ment occurred in only one species, Gasterosteus vulleatus, its natural host. 176. Only theform of lit ula intostinalls which is restricted to cyprinids occurs in Ravenstb.orpe reservoir and Ltaneighbouring waters, 2. DistAbutiop of the ylerocercoa lutestinalis in the Nerthamtenshire area. The distribution of Ligula, plorocerceide is of necessity governed by the presence of suitable inter— mediate and final hosts. Because of the longevity of the plerocercoid, infested fish may be found for some years after transmission to the fish host has ceased. , In Piteford and navensthorpe reeervoirs, rudd became infested each year and thus the LiPula life cycle was completed each year. Fish in Hollowell reservoir were not infested with Ligula, presumably because cyprinids, were absent from the reservoir. Although mu/table cyprinids were present in the river Nene, no Liqula, occurred. Insufficient time was available to observe the bird fauna of the river Nene, but it may be that the lack of Licula was due to the absence of suitable final hosts. Huculek (1960), Donee (1958), Pitt and Grundmann (1957), Zitnan (1964) and Mikallov (1957), demonstrated that infestation of fish with Lioula occurred mainly in lakes and reservoirs. No analysis to determine the 177. cause-has been,carried oat, but there are oeveral stages at which traneminsion of Meu1a may be _favoured by lake rather than river conditions. Moot probably a much smaller number of copepods become infected in a river and of tliothe that do become, infected, fewer are eaten by fish. Hartley (1947) has shamithat the proportion of copepods in the diet of rudd- a Donde and lakes is, greater than rudd inmovinewaters, such as the Nerfak, Broads, The propertiorvof copopoda in the diet-of roach in the Norfolk Broads is greater.than in the roach in the river Cam. 3; Changes in rudder diet and effect on Ligula infestation. AINIMPUMMINSIMINNIP Changes in the diet, are associated with age, distribution, and activity of the rudd. The rudd attar ass second intermediate host to Ligula,intestinaliO. Rudd live in static water with a large copepod population and feed on varying proportion° of copepods during the first five years of life. Copepods serve as first intermediate hoots harbouring the procercoid'in the haemocoel* The diet of a three year old rudd contains the greatest quantity of copepOdo; Kosheva (1956) found a high , Incidence of Litiulaiplerocercoids in the bream fry, and Veer° (1950) in bream aged two to four years. Donee 178. (1950 found a high incidence of Licula in young non— breeding porch. As a general rule thenvinfection occurs at en early stage when the, fish are feeding on copopodu.. Rudd at Ravennthorpe become omnivorous in their fifth year, after whiCh adult, fish aro found in deep,water and infected copepods are ingested .only by chance. Rudd can, therefore, acquire 3i .a infestations during these five years. The plerocercoid becomes infective in approximately 6 months. Orel= prefer static watern (Weatherby et al. 1940) and atRavensthorpe feed eagerly- on infested immature rudd in shallow water and the adult worm develops in the intestine of the bird* Rudd have pr6viou61y been recorded ac hosts of ,Lii7Ula in Britain by Owen and Arm° (1965) and in Vurepo' by Brauer (1910., The incidence of Lip at plerecercoids, is highest in fry and Immature fish, whereas the intensity of infestation is. lowent in these fish (Pig.I5 , P.98 ). In adults, .the incidence was low and the Intensity of infestation high and rudd therefore accumulate ploro— corcoidn with increasing age. 4. Bffeot of Lipla infestations on, rudd arkd ausceptibilitt to further infestation with iiiVact. 24resence of the plerocorcoid in tho body cavity of 179. rudd has been shown to have nOt'only localised effects on the tissues. of the fish but also to alter feeding habits, distribution, spawning migration, abundance and activity.. of the host. Lirula infestations can affect growth, pituitary function and cause physiological and biochemical - abnormalities*, castration and- alteration in spawning behaviour (see Chapter 171), The role of nataral stimuli ouch as light, water temperaturo and water level in. the stimulation of spawning is not understood, but an important role,is played by store-hormones (Nikolskii, /963); secreted Into the water by maze fieh to stimulate spawning :. The male secretes oopulin which brings females into a state of readiaess:to spawn. The presence of the plerocercoid of Liman through its effect on the pituitary may inhibit the ability of the male.to produce the hormone and the ability of the female to be stimulated by th.-- hormone. Growth of the yellow perdh (Perca flavescansi is stunted by the presence of the plerocercoid of Itta. (Pitt and Grundman, 1957, p.161), but in young rudd from Ravensthorpe examined over a two-year period caused no stunting in length or weight. On the contrary, it-wab the larger fish which her worms, 180s. - Physiological oh eat including depletion of host fat, protein and glycogen 6.158) awe dasociated with Li .a. infestations but wore not inveatigated in rudd from Ravenathorpes There are fey invootigationo on the mortality caused by the plorocercoids in fish. Although death of fiches infected with Itiitula plero— cercoids did not 000ur on a large scale (itozicka, 1963), winter drop in maximum weight of individual plorocorcoido in rudd from Ravansthorpe is difficult to explaia except by death of the host. Incidence in rudd Over five years old falls due to death of heavilyinfected iadividuals. Adult fish normally build up fat reserves to overwinter but are unable to do so when infeated with Iigula (p.16I)s Xesheva (1956) states the contrary view, that the plerocercoids-themselves die after two, years in,the host. Rudd frY,.althoUal they continue to Teed throughout the winter are unable to support plerocorcoids in conditions of a heavy parasite burdens The high natural mortality of fry in the,first year emerges only from sampling and does not appear- do large quantities of dead' fish, and therefore, mortality due to_Ligulqwould'net be observedwMeut,thorough, sampling. Boos the presence of Lip .a in the body cavity 181. . make rudd more'likely to acquire infections by altering its feeding habits; distribution, spawning migration and abundance, and does the plerocercold act directly on the host tissues to increase the susceptibility of the rudd to infestation? Prooercoid penetration may be facilitated in both young rudd and older cemnivoraue fish. The intestinal walls of fish infested with 41/z41a are described as transparent (Koeheva, 1956) and Shpolyanakaya (1953a) confirms that the intestinal wall becomes changed, possibly facilitating the penetration into the body cavity. Facilitated penetration has not however boon verified experimentally. Infested rudd differed in their activity and feeding habits from unirfested rudd, although the diet remained the same. Infected rudd maintained at the laboratory feed continuously, in contrast to uninfested fish which feed at intervals. Infested. adults in the reservoir fed throughout the winter months, in- contrast to unipfeeted Fish which fed little* Adult, infested fish tend to stay in shallop water throughout the year in contrast to =infested fish which go into deeper water in the winter and this altered . distribution is probably closely linked with continuous feeding of infested rudd during the winter. Infested fry and irmiture stagec dhow A nee al. distribution. 1820 . The altered activity, feeding habits and distribution of adult infested rudd may lead to the ingestion of more food, which if it comprided infested copepods, would load to an increase in infestation, -This lends further support to the proposed theory of susceptibility but from'the ecological point of view. The abundance of rudd id closely related to the number of potential spawners, As the rudd become mature some 30 of potential spawners are lost because the infected adults do not enter the courting shoalsw infested fish are castrated and thus do not contribute to the rudd population. Noi do the nen—fertile infested rudd cause ,a reduction infertility of the eggs produced by unimPosted rudd (p,IO2). Mortality in older fish, due to Z ii ula infestation, may well have contributed to the fast growth rate of both infested and uninfected ruddy by reducing competition for food.- The abundance of infested rudd affects the number of worms which become adult and produce eggs and consequently the number of now infestations in the ruddy providing that. the oopopod population remains stable. An abundance of fish less than two years old harbouring infective plerocercoids and within the correct sloe range to be eaten by grebes would lead to a marked increase in incidence in the fry. 183. The incidence in the Cry in 1962 was the highest, probably ac the moult of heavy infestations in the previous year#s fry. On the other handiantiell number of infested fish of the correct size =age would lead to a decrease in incidence in the total rudd population, and if oven fewer infected fish were then available, the cycle would not be able to continua. The incidence of ploroceraoide in the fry from 1962-1965 dropped as did the abundance of the fry but the incidence did not tho immature fish in 1962 and 1963. The climatic conditions in 1964 and 1965 reduced the fry numbers and incidence to such a low level, that the cycle may not recover. However* atunting of fry in the adverse conditions of 1964, resulting in smaller than normal fish in 19660 would bring two year old rudd into the grebes' diet range, substituting for scarce one year old fish, born in 1964. The incidence and infectivityofj&V.4in small rudd upon which grebes feed therefore influences incidence in the total rudd population. These small fish, in turn, are directly influenced by clirmtic and biotic conditions in the reservoir. In order that the life cycle of the parasite may continue infected 1-3 year old fish must exist. Increase 184. • in the numbers of infected rudd is rapidly offset by, lack of breeding fish and death due to gaga; decrease, in:numbers of infested rudd is offset by otunting of fish and inoreaeed fry in the latter* 5. Seaeonal variation in ActrocercOd infestations, and_ in develvment of egn apd pracercoid. The environment exerts its influence on Ligula plerocorcoide through, Physiological °henget, induced in the host reflected by seasonal.- changes in the feeding habits and composition of the'diet, poeition, activity, abundance and spawning migration of the rudd. The environment influences directly free.living staged of Lidgulq, such as the rate of egg development, and duration of the cereal:die and also influences abundance of copepods* Some environmental factors, such as temperature, imar act directly on the plerocercoid• 'Seasonal frequency of cestodee has boon obeerved by Chubb (1962)• and Hopkins (1959), the latter stating that seasonal occurrence is commonly reported for flat worm parasites of fish in teMperate cliMates. !oblate!. cephal4s solidus plerocereolde in sticklebacks aloe have a seasonal cycle (Walken, 1963), being acquired during the summer and becoming,infeotive the following spring, when sticklebacke are preyed upon by ilecivoroue 185. birds. Adult S. proliclup in the intestine of these birds yroduce eggs which hatch in water releasing coracidia which are ingested by copepods. In Linulas infestations in fish are acquired wasonally and live an long as the rudds and the Infestation in one individual- is therefore'cumulatiVe. However, incidence of plerocercoids of IfigOia in fry and immature fish does exhibit annual fluctuations with an inorease in incidence in summer aecempanied by a rise in intensity of infestation and a decrease in incidence in winter due to death of infested rudd. The percentages of rudd actively feeding were taken; in Pabruary 96.0A in March 780; in April 8740; in Uays Junes July and August 91$; in November and December 45%. No records were taken for Januarys September and October (Hartley, 1947). Although the February figure is high the summer figures show that maximum feeding occurs at this time. In, summer, fish feed more actively than in winter and rudd fry in Ravensthorpe reservoir feeding continually throughout the year feed on a greater quantity of copepods 'in summer. The time taken for the passage of food down the intestine of a fish aid aisinilation of digested: material decreases with decrease in-temperature 186. (ffikolskii,-1963)* . 8oasonal variation in copepod density was also reflected in _the diet of both rudd and perch (Chubb, 1964)* An abundance of copepods,in shallow water inhabited by try and immature fish in summer leads to a rise in the incidence of Iigulqwhan rudd are most abundant* The rapid increase in incidence in fry in duo to the large number of copepods- in the diet_ of fry. The fall in incidence in winter is duo to death of infected rudd and although Dome uninfected individuals' also die there is no increase in incidence, -The - seaeonal spawning migration appears tohave no effect on the *Re% infection, Seadonal changes in the environmant directly-affect numbers of copepods and, development of pre.pleracercoid stages. Summer acquisition of plerocercoids is related to the preeance of eggs, coracidia and procercoids, and the enviranmentakeffects on the free-diving stages on abundance of copepods and on feeding in rudd. The'egg, ooraoidium and procorcoid were not studied in the reservoir. Little work has been done ore seasonal temperature expectations in the field* Lt4,41a eggs develop in 6 days at. 24..28°C but in 8.9 days at l.l8°C Oubininato 1953)* There are no records of egg development at winter temperatures of approximately 4°C. 187.. . Bggo 'ofEichistoCerhaluo 'solids? develop in 56 meat at 5°6 Moon, 1960. t#11,11obothrAmi Acitups eggo do not hatch below 5°C (11ouirdn. 1953), and then dovoloreent is arrooted below 7°C, although the own remain viable for at least a year (Vergoor, 1936)* likaa has, ao ene might expect, similar adaptation° ao it baa eimilikr diotribution to fictigt000rthquat, Largo number° of coracidia would hatch from the ogga at warm Burner temperature°, coinciding with the incroaoo =bora of cOpepodo, and the number° of ooraoidia would be-. at a minimum during winter when copepodo were ocarco. Tinityntophorun noduitoofio oggo, however, can develop at 0°4.29°0 (Schoring, 1930 and are unusual in being able to develop in l% oalino 1939). If amaia, io oimilar to :Zrkorionkwa rather than to Dtph_v4t• bothrium or fie4letocothaltr, emu would be able to develop during winter, and any winter hiatus in the cycle would be due to puuoity of copepod° during tho winter months. ;if procoreoida in the copepod develop in 6 dayo at 24*We (Dabinina, 1953). - There lo little information on development of procercoido of other poeudophyllido but growth is proem:lady at a minimum during winter and at an optimum in ',tom,. 6. Iv I 4 t4.- 4 5 501, 0 im Ahe 3lud4* Variations in the water leVel of Itavonstherpo reservoir produced dramatic changes lathe reeervoir* Ewe directly observed in tho laboratory wore unable to moist deoiccation and way eggs loft as the water level receded would die. The drop inns:tor level in 4 mw .r of 1965 affected the littoral fauna and flora of the reeervoir spoiling the °pawning grounds and thoroby reduoing the number of fry which did not become infected with aagat although fish introduced into the reservoir by pumping did become infected (see p*47)* Thus, a cover° climatic change dramatically reduced the rudd fry and as a =cult tho incidence of kilo wan reduced. - - infected adult fieh =many mingled with vnlrfected adult() which wore not able to spawn, but the effect of the drop in water level on the numbore of adult rudd is not known* intensity of infestation in immature fish increased, indicating that trona:at:mien of the life cycle wee still Occurring* In the summer of 1964, when the water level was also loat A-swore considerably fewer than in previous yonro but still became infected with 7imp. Howavart the fry moved with the drop in water level to the etre= 189. Si (coo p.33 ), roculting in difforonces in tho incidence in tho wing woad* 7* 1112.aw;41....A" oe malasigagit pit 7vt1l tho *9;0q0M0011A, lto*TGARFP4N; n741411.An4► 110014484 1454440040/ 9b9A5Pq*' , Vlo plerocorOold of 111211a can V0130,111 in tho body cavity of tho rudd for oovoral yeara* ?To doad ploro- corcoide wore ever found in tho although nohow, (1956) stated that dieappearanco of infestations in brew at 7 yearn was duo to the death of the plero- corcoid The dovolopmont of echistpen144\uct plerocorcoido wan atudiod by Marto (1954) and Vicealg and- ltopldno (1)64)*- Tho plerocercolde of polanocoplvAus :Liko - thous ice, awe progonovic (Smyth. 1947) .and olloWs rapid maturation in the final boot* The longovity of the pleroaercoid in tho body cavity of cyprinid rich enables the, life cycle to Continue when MiGratory plecivorouo birds ore aboont during the motor montho; infected plorocercoido are tam by the final hoot en ito roturn (D)ubininagi 1964)a 7ithir the body cavity of the ruddy tho- plorocorcold is =bloated to conditione brought about by cliangeo in the hootoo phyolology correlated with the distribution, 190 • . activity.. and foodinrs Ti:nbits That not with, changers concomitant with spanning_ migration. The or Influence on rudd of all °goo wan magma end in turn afreoted plerocercoid devolopmont• Paotora determining the location of parasites in .their houta =0 not under.i. stood. Via- plerocercolda wore Occasionally obsorved onomalcurt positions in young rialto lloithor immature-nor adult fish were pler000roolda round in-.the dorsal musculature or pericardial oavity• Thin `tom hays boon dile to mortality of these gerocercolds anoma3.ous positions and the correct location of new infestations in immature riah* Ilithor the body cavity Or very young fish did not furnish a-ratitata° environment or the. location moohanism of the early plerocerceid vat not functioning correctly* Trio partiolto burden of inreated fish Increases with -Inoroace in ago of the flab. • Therms° in puma .to burden. indicated the growth of °slating =1 or now =calved pler000roolds at the eta„goa When rudd wore feeding on copopoda. The parasite burden doors not dooreaeo during winter althouLh* the inoldonce figurers and intensity figures docreacedo A high parasite burden roaalts in the mortality of fiah and only fish 'with. a low paraatto burden reached 10 or 11 years old* The 191 maximum plerocercoid burden of older fish of given weight is' faiily constant although it may be made" up of plerocerooids varying in weight. Fish'die if the maximum parasitticar*Kpm is exceeded. Fish of a given weight have .e; higher _parasite burden in the summer. than in the winter.- The size of the' plerocercoid harboured - by older fish is dependent not only on host-provided factors but on the number of larvae present as a crowding effect has been demonstrated. A givenTarasite burden in a known weight grout- of fish was made up either of several large plerocercoids or- of-may' small plerocercoids, depending onithe rate of infection and on the age,otthe infestation. The growth of the plerocercoid is thUs- affected by the.age_and therefoi,e size of the fish and also by the fish's changing•ecological situationwhichAs governed by feeding habits and activity. a. influence of seasonal changes on growth and develop- ment of the plerocercoid. -The influence of seasonal changes on inf6station of rudd has been discussed. The seasons, hoirever, also ,<41 ^/1 • -influenee the-- growth and develoxient o the plerecercoida. Plereeerceid growth Or ouateut- the year is related to water temperature anti fish mouth* - The growth rate o the glib. hest was greatest with increased temperature. intense feeding activity,. and. shxliew water distribution" The temperature increase aiDo directly influenced the plereoorcolds• The growth et the plerocerceid in winter months:0th for temperatures is much slower' Daring tit, :,. .:1*.7.4er. when the red attempt to lay dawn fat'reserves gor the winter, the fish is able to Support a higher parasite burden than in winters The demands Of tho plorecerceid on the hest are severe and fat reserves are not laid down in ingeoted riad• - Per its own nee the 'fish is able to both reconvort gat - to glycogen and. to coritinnaliq produce glycogen which would otherwise have boon converted to at reserve. There is a glycogen gradient from the plervercoid into the surrounding tissues Which provides nutrient material for the growth a the plerocerdold* The rapid increase in plerocercold weight in optimal 13=1202.1" conditions leads to a photionemon whitth 17ili 'be termed Iplerecercoid overgrew*. • In tvinter the ciotivity and feeding o the fish decreases and it- is. unable to sUppert a very largo plerseercold‘ An increase in ' temperature fl'o 4°.23.0 incroacco the ot-rth qopiciloae04343:ooliduo p1orocercoi4 (Sinha and ilopkins. 19G) and it is reasonable is believe, that iikaaa responds' in a 134rill Pm way* Mom temporaturco are remarkably close to the water temperatures of Ravens-Menlo r000lvoir (PiG, 5 to p.44 ). ' 1atvovt3r1 Davieo and VOII:07* (1966) otatelp. na'plerocer-Coid metabolioes-at the dame rata at 15°C in the summer an it does at_ 10N, ia the winter**. Davies aaet al mcaaured the rate of rocplration at different temperatures and eonsider - reopiratleate be a reflection of motabollon. whormo, to may (WI bo ameaoure- of activity* Purthor, they state, nth° importance of this to the parasite io:loss clew* Significance to the 114stivaraalto rolationohip may lie in.tto relatively lower nutritional demand by the paraoite an the hoot at higher summortemperaturoa0 Miss time of high temperature in the ear, _however. la tho'only timo the hoot has enoudh 'mewl for the- paraoltoto rapid growth and for ite own 'ommtval* ,,The pIerecoreold tovergraScin net oupport©d during the wintermentha and heavily infested Acadia* b. Stagea in development of _plerecoreoldo* definite otegoo, occur in development of the 194. pierocotooDia Sobarztoeci/olus colidup (rfopkine and Wag. 1963); a qualitative phaoo in the 3 mc--20 fresh weight range and a quantitativo phaae 3ntho weight range over 20 mge Merocercoids 170143bitla10rz =I over are ablo in ouitable conditions to produce eggs end. sperm, Tho appooranco a the first genital, primordia and_ the onset of infootivity of tho _poliicrb0002halar nlerocorcoid aro aaaociated with on increaso in pore ettl4o dlycogon content (McCaig and - Hopkinot 1965)• The carlicot atom in the doveloment of MAU plorocereoids waa aeon by Room (2919) immediately atm- Ito entry into the body cavity when it atilt resorabled the precerceide - I could not find this stage • and conclude that it is oxtromelsr abort. Genital pritiordia develop_ when the 116rino, haNto a froah weight of 40-5f mot and at thio weight plerocoroolds rut presumably mature end produce eggs in the final heats S veral Of the plc rocorcoido in, fry born in 1963 reacb.ed, a fresh weielt of 4040 me by tlenuary 1964, c. =tin= period of six nontb.s dovelopmonto This perm differs from that given iv Du W.= (1953) who al.10170- 12.14 montha for gerceercoide to bccono infective. although tho temperature IMO not givene 195. The larzori atmermal plepocercoido mom old fish .were presumabiy sAYille laud malfUnetioning. Calcareous °heaths surrounding worms in older fish may rosu.lt from a Gradual. build.up- rather than , rapid deposition. It waG zlettatItabie:,, that older fish harboured other plerocorcoiit with no calcaroouS sheatbn as well ao wow with oheathei. . Several pler000rcoi4 at leant 5.6 years old, were removed frog fish aged 10441 yearn. and bra o• iil ,ohowinG oigno of novemont and were therefore able 1:1orocoreolds in rudd do not die but live ao long ao tho rub, hoot, althoueh tho contrary view is held byltoohova (19%) for Airoglq plorocercoido in bream. The moot heavily in footed fish of 5 yawn end oldor, aro too large to bo taken by pioeivorouo birds end a potontial of infective larvae in ttagenotherpe rocervoir•woo wasted. Plerooercoido wore?. hovevory eaten' by °zoom 'after tho rudd had boon caught and • di000rded on the bank by fisb.ormen. Orion (1955) hao recorded adult, mailautapjatualla from the otter (Itutra_eanadenqii1). Merge fiob would •to more roadily taken •by ottorj whon ac uatio =main end pinciverous birds occur tegother. tho email fioh aro taken. by tho - birds end the larger by aquatic nannalo. The earlier cluvlitative phaso in the f..trowth of pchinteeenhalus observed by 5e1:1,:ins and LicCaig (1963) ita parallel in the crerith zloaa but the later quantitative phase has not• Two other stager) occur in Itir2.119.. one ayery you stage,'just, atter - entry into 1.,13.o fish host. which-probably also occurs in Sebistonevahalus. and the ether a later etas() in older LI plarooereoids• The latter chaszeso which are probably associatod with the- nee oil- the Lifrula pler000roolds do not occur in- 3e1iisteoe4ia1us .beeatise of the short life of Of.taterootcv aouloatuq.• 0. Bicahanical chanzlon in the develop:tent Of:the ploroca rcold. alvpotifori otuttout or_ t,:f ,alornoo 7:53 o d _ The 1,icellertical content of parzi.eitco a1to3.40 during tlteizb clovolopmarst• Who rise tercentace glycoaen content in tho Oeitietece.nhalue, aorcdercoid (Replcins- riczAic 0450'14) correlated with infeetivity tor the arra host• he unpublishad roc .t5 of Areher and Itopkino: atow: a 3.*1.'4a- in 'a IT/CCgcra oantent ( 6'00 , 1s•20I) in the efattly stages of riliVa plor000roolds iron ninnowni corresponding with the first appearance or genital. priraerdia 02111 directly conparable with the results obtained litCaia llophins (1965) in Sqlliat0004/4110" 1970 !rho glycogen contont Z1,1ulet from Ravonethorre is 57,7r, at 400 mg Dry Wt. (ritS• 250 P*I57 ) is comparable with the porcentago glycogen in the infoctivo otaceo- Sehist_oackhalus• Portunately, Archon! and Hopl-c.inse unpublished results wore made availablo to mo as. my' graph* using only plerocercoidli -trim one ritdd With only a fort readings in the rrtngo boa 100 rle,;* did not indicate an. initial inoroase in elycbgen content. 4.410 unpublishokrosults of Archer and Hopidas give the glYcogon content of plorocercolds removod from minnows* and shovr that the initial increase in glycogon observed in Schist ocophalus occurs in ;Armlet, Glycor,,en oontonto or navonothorpo ulorocercolds 3,nthe upper - weight roma az*e similar to those obtaittod by Archer and Hopld.ns (1957) for pleroeorceids from minnow's. Stunting oz paorocorooldo or.touro in !wavy infestations and the glYco[son cantont of 30-40 n worms nay well be equivalent to that of heavior Worms in oincly 1nfcotod rudd• A "lint poroontago glycogon content it] found in heavy plorocorcoids (Pig.25 • p. 157) :Ind those results sgroo with Archer erg Hopkins' results (Pda., 30 .9* 201) . Nitrorten content of the, ulerocotoold. Me percentage nitrogen in larval :2annia is similar for a von state or devolorcont Hopkins and Hutchison* 1950 porcentago nitrogen content 1980 decreases from 6,4 of the dry weight 42 days -after infeetiont to 4,5at 67daysi possiblydue to the inerease.-inpercantage-glycogen content* no porcontago. nitrogon in the plerocereold of_ deeredees with inerease in size of tho plate. cercold (pi .23 p*I52), Results of unpublished work of Archer and Ilepkina (171g.29 * p.199) expressed ad percentagelmetein (protein nitrogen z 6.4), are comparable with. mine (3 ig*29 PeI99). 7herefore, in its early stages of development the pleroeercoid of Linea has en apparently higher percentage nitrogen content then in its later stages' However. the decrease in percentage nitrogen is due to an Imre lase in-glycogen content which the plerecercold stores awing its development* i id content. tlf /the Dierocerceid • ,2he lipid content of DiTylviAe,bothriutk iatu, between 16.6 mid 17407A Bra d, 3.966). The percentage lipid content of plerocerceids decreases in_worms in 100-400 mg Weight rangei vase probably due to increase in glycogen. content* lipid 'estimation for the lowest' weight range of 'vex= mtv be inaccurate as. plorocercoids =re combined to give a sufficiently large saMple* The figures.for Warne above 100 ms are regarded do accurate* FIG.29. 199. (1/0 Protein Ligula plerocercoids Archer & Hopkins 1957 (unpublished) 0 48 0 0 • 46 0 0 .c al 44 t_ 42 • • • 0 • 40 • • 38 • • 0 • • 0 0 • 36 0 • • • ; 34 0. 32 0 0 f - 30 I f • 0 10 20 30 40 50 60 70 80 90 100 110 120 ;130 Dry weight plerocercoid mg NB dry weight scale linear o T.S.C.Orr's figures Increase in parcontaGe ,,Cogan contont in moot rapid vacti genital prinordia i'irst appear and is coneomitant with inZootivity or the plerocorcoidn• The percentage elyoogen tb.e worm constitutes over. StV ei the -az7 weight and the increase in j1yoogon 1.n:cativo- plerecerceids in accompanied by an apparent doorear.,c in lipid ana nitreen*contente ,FIG.30. 201. °/o Glycogen Ligula plerocercoids Archer & Hopkins 1957 (unpublished) 56 — • 54 • 52 • • • • 50 - •-• ..0 01 01 48 - • ,.. t- • • -0 46 - • C 01 171 44 0 CI ,... 0 42 ...... o 40 - • • 38 II I O 10 20 30 40 50 -60 70 80 90 100 110 120 130 - - Dry weight plerocercoid mg. NB Dry weight scale linear 202s SMART of 11BOMMONO 1. I. In llavensthorpe reservoir the plorooerooid of _iltestineliq is found only in the badtcErvity of cyprinid fishes, namely, add (cetrdiniwt ervtaRoulvt o roach Outlast* rutilu), Dace (zasaipeup ;a:iciness) and gudgeon (Goble piebie). • 2. In the- area atoned in. Northamptonnhlre, RavenstherPs and 2iteford renervoirs bataIkea infected cyprinido, - uhcreas nelloacll 1.:44 no fieh ittOcted with al/1E2Q end no cyprinids. In the riverftne there was no infection although ayprinid fish were precast* 30 The plercoertoid is normally found in the body cavity of the rudd though in very young fioh ofone month old, the plerocercoid was found in the dorsal musculature of the £ieh and the pericardial cavity. 4. After entry into tho rude the plerocercoida develop rapidly. the primordia, of the reproductive organs developing within six months in fry born, in 1963 and sampled in 196, and 1964* 5# Development of the plerocercoid involves 4 stages, three of which were obtained from ru.dd in Ravensthorpo. Li the initial statle, not found at navonstherpot tho 1,1erocerceld reeemblcis a preceroold but it in the 2030. :body cavity o tuo fich. the deeond ihiso 'shows the normal amulature of the plorocercold; whereas the third stage id the infective larvae Toodooding genital prianordiao A, fourth attve, foluld only in older rudd, shown atmoraslitied andociatcd with p013.015.00210p the plerocorooia., 6.- During development the biochemical composition of the plerecercoid alters,' the glyoogen content increases from 5'3.4. to GO;;;, ceicating apparent _decrease, in, nitrogen'. content from 6.4ti, to 4.3, and in lipid content from , _45.3e, to 4.574 - The final high glycogen Collent.is that of, infootive plerocorcoide* 70 Infective plerocercolds were found i rudd or -,4 crs . long aid longer* The Vcater crested exobe, was observed to .feed on fish up to approzinately'10 cii long* 80. Rudd- acquire the Urea plerocercolds by feeding on infected, copepods, whith are found in the diet- up to the fifth year* 9* In isry born in '1963, inferitatton wad found to be aendonta, occurring only when, temeratured 'were eufficiontly high egg do' oloprient and for copepods to ourvivo Infanta-bleu occurred du.--ing, the (rimer nontha and ow.ttonded for, keril to november* 204. 10. Seasonal'itariation 12. Olinstio offeota, roaulting in a -drop in synttor level, prevented normal spanning and thus no fry became infootod in 19651 restricted distribution of rttdd to aroaa vb.ore food wan availablo end whoro tho incidence plorocereoida was high, destroyed tho norms1 littoral flora rooulting in poor food supplies and 'Frew afore stmted fish. 13. Vomit distribution. abundance, spaaaing migration and activity alter with tho ago of tho mid* Iludd become infected When they are moot abundant and sham a littoral diatributienduring tho fry and irmnturo stagos. but also in young aAulto aged 3, 4 an 5 wars. Pry and immlature fioll aro actiye all tho year, iu contrast to 205. older fish which coacs feeding in winter Iwnths, 14• Tho presence off' the Idgu pleroaereetb. alters the feedimg habits of rued over 5 years old, Infected fish feeding during winter, affects the, dictribution or older infected add' whiohbecome littoral, and prevents. the normal spawning migration. ho abundance or- infected rudd--with infective plerocerceids determines the nunberof potential adult worms and therefore the continuity or the, oyolo. .The abundance of infeeted,rudd else affects the,future numbers of fry, since infected fiah are castrated*. 15• The presence a the pleroeetcoid has a direct • effect en the radd and also alters the behaviour of the made The direct offect'is oho= in distension- a ' the abdomen, proliferation 'of connective 'tissue, castration, and compression of the viscera* Behavioural changes are shown at cpawning time when infected ru.dd do= not enter couz•ting shoals, and in the continued feeding ,nnet- littoral distribution of older infected fish*, - 16. Mortality caused by it= was apparent in, the disappearance of heavily infected fish hors in 1963 ,during the mater months, but eccutred oleo in older fish, s/..nce the intensity of Infestation decreased in fish aged 10 and 11 years.. 206.- ' VIII. Section III Culture of adult 4k @a iAIRstinglis and hatching of Iigula eggs. p1,74:7! culAurei The problem of evaluating the 4yo culture of flatworm paraoitot3 necessitates the definition of criteria. in the present work, tho percentage of hatchable eggs produced by the adult ossibede was adopted, The tendency for laboratory workorsi to.use ducats which oan be readily supplied at a given state of development necessitates consideration, In the cape of asta, there are no =cords of the experimental infection of grebes with Lipulq probably because .the birds are protected, difficult to maintain and oven hardee. to capture. Domestic ducks, used as experimental final hosts Joyeaux and Baer (1936), wore used in this study. DuCks present several problems to the establishmentof, artificially.fed plerocercoids. Duelmhave a muscular stomach 'which contains grit for grinding of food, thus any plerecercola passing through the stomach may be severely damaged* - The structure of the stomach also precluded passing a tube to the duo denun down which the plerecorcoid could be passed, to avoid damage in the muscular stomach region* The ducks* feeding habits and requirements change during their life, day.weld ducts 2O7 , • feeding on soft mash and older birds on a grain mixture with grit. Ducks were infected to obtain adult Lila and eggs. - The'adults were required for determination of the nitrogen,' lipid and glycogen changes in in vitro and lax= conditions. Difficulties in establishing the adult both in vivo and in vitro iced to the cultUre methods which are detailed below: Hopkins (1950) determined the glycogen Metabolism of Ochistoceplielus plerocercoids in. vivo in fish, and of the adult under ,ini4tr9 culture conditions (Hopkins, 1952). it was believed that the levels of nitrogen, lipid and glycogen content, and the fertility of the eggs under in vivo and in -vitro aonditions would provide a method of evaluating the mature methods. Although nitrogen determinations were made on,in vitro, - cultured adults, none wore made on the adults recovered from ducks, because in vivo, work became, limited to finding, the most suitable age of hosts and pre infection conditions to give the beet infections. I. Mothodo. a. Infection of ducks. Infective plorocorcoida were removed from rudd and fed to ducks aged 1 day old, 6 weeks old, 3 months old 208. and 6 months old, the duck° being atarved for 24 hours prior to infection. The plerecorceid was held in plastic forcepn, placed in the eenopheaun of the duck, and the duok'o beak eloped until the wera wao.nwallowed. Thin wan, followed by a period of five uten observation to note whether regurgitation occurred. If regurgitation occurred the procedure was repeated. Eno' rimental duoko were fed two dicMild Duck Crumbs" with grit and Chick Nash without grit, for day old ducks. l'he tine of the two different foe, was necennaz7 as the Chick Mph was calcium deficient, no grit being. added, while the Wild tuck Crumbs contained--grit. • l'he ducks were hewed in meta/ cage° with removable tre.ya underneath, which wore partially filled with water in order to keep faeces moint. Every 24 hour° the faecen wore removed and the truer washed and r€ placed. b nags. Ewe were collected from duck faecen by cloying, sedimentation and Vitinilitlz• The faecen were removed from the traye and thoroughly mixed with I litre of water. The faceal mixture wan paneed through a aeries o nna000ttoc tent eleven. The mph else° of the eleven were 250p, 105p, 80p and 32p* 209. The eggs which mcaattee 60p, a 431,f, wore retained in the last sieve. A OWIll quantity of faeces only was sieved each time to prevent the sieves from blocking. , The eggs wore washed through the Blowout% a otroam of tap water. Three wadhings of the small samples was sufficient to wash through to the bottom of the aieve all but approilmately 5) of the eggs. The total contents of the bottom sieve were washed five times and washed out into a beak or and than poured into a urine sedimentation jar. The eggs wore allowed to sediment for 1 hour then decanted on tho jar refined with tap water. This method is not suitable as a quantitative method and failed to give accurate results when a Imo= number of eggs were nixed with known quantities of faeces end the extraction procedure repeated with !mown volumes of water. Quantitative methoda to estimate numbers of viable eggs, such as that used by Brgton(1966a), could not be used ae this method retains the liquid used for washing and large quantities of uric aoid crystals are present in duck faeces. rierocercolds need to infect ducks wore obtained from infected rudd removed from the reservoir but main.» tamed in the laboratory. 210,. • Young rudd under ono year old were kept In glass ac Uaria 101 cm long z 280 cm deep- z 280, oz's high in sun. tap water at 23°C and fed weekly on a diet broad and bemox. The rudd became infected with a proto-sean parasite othv,,q,thtliirius and many fish died. It is believed the conditions of still water and high temperatare allowed Iothiruhthkrius to develop in the fry and kill the rudd. Immature rudd were kept -in larger fibreglass tanks approximately. 67 cm long z 50 cm high z 50 em wide, with a supply of ruining tarn-tater at 16°0 and fed the same diet as the fry. Those fioh survived Wen* Atha t- fish were maintained out of dooro in large, etill water, concrete tank° measuring 250 cm long x 100 cm deep z 184 cm wide and fed on the same diet as younger fish* These fioh also survived well* 2. Results. The highest number of plerecerooida became established in day—old ducks (Table XXII p. 213). Large ploraoeraeido became establiohea more readily than small ones (TableXxiT pX3 )* large' plerocereelds nay however penetrate the gat of the young bird, causing its death. Sixoceek-old ducks and three.menth..old ducks . harboured few experimental infestations and only those 211. ducks which had previously boon starved (Tablexxiip.213)4 The muscular stomach is woll developed in 6—week.00ld ducks and =tains grit from the Wild Tack Crumbs used at this stage and probably dmingod the plorocercolds• Bstablished infoctiona in ducks (war 6 months old wore rare (ablexm Pik213)0 The adult worm 'iv:to for up to 12 dayo in ducks (ab1exxinp02I4) but age production drops after 6 days, 3, ocuot lan. In ordor to obtain.mbabataaak and its eggo, duoko wore infected with the plorocorooid• Thio was attompted in order to provide adults which could be comparod with adults from in. vitro culture. Establiohmont of the infeotiou in older duck°, however, proved unouccoosi. ful in that a oufficiont return was not obtained. The in vivo culture work therefore bocame limited to achieving the oetabliehmont of the adult in ducks. Pioolvorous birdo o.g. groboo, normally taro their pros whole. Exporimentol work requirod the numbor of tt s atm to a duck to be Lmown and thus plorecoreolds with no protective cove- 0 wore fed to the ducks. Little is known, of the pbyolology or the alimentary tract of ducks, and bow it compares with piocivoroue birdo. iho muscular stomach in well developed in duoko and gaoao 212. but is loos well developed in piocivorouo birds (Morahan, 1961). In ducks and scoot), the stomach contains stones and grit in older birdo of 3 tiontho end 6 montho, not found in younger birds' Marshall (1961) otateo thatfood is retained for two hours in the . ducker,- otonach at" a pH of 2.33, which, 'taken toggthbr with the presonce of !Ames, could account for the low rate of infestation in the older birds. In yolAng ducks, however, the moonier otomaoh to not ao well developed; thoro are no atones, provided the bird is Zed on Chick Mach, and the aboenco of otonoo can be corrolated with the high numbor of plerocereoido which become eotablinhod in young, duoko. These results aro comparable nth thorn of Macon (n65) who dovelopod the adult of Schistocophaluo. in ducks and found that ?4 84 of the 11()=13 bocono - oatabliohed in young duck° one week old but that in older dueko the porcentage of worn° producing oggo dooroaced to milder 50;Li Purthormore, longovity of adult t u10 agr000 more closely 'with Ilaeonto (1965) rooulta--for Sobidt000_rhalya than with-Dubininaito (1953) for Lixaila rlaoon (1965) found that 3 out of 6 Schiotocephaluo produced oggo until the tonth day, whoreaa Dubinina (1953) °tote° that ,iii ale, romaine in the bird • hoot for 95-100 hours.' 213. MEE xxii. 0'3 VIVO!! =FM TY110 Ago 3o* of No. No. Approx. Starved of of ducks dying V.W.of or Duck Duel= fed during ted plorc Diet fed plaro oxpt. corcoid cereolda never 1 day 12 1 <1gm Chick =eh fed do. 12 0 A do 12 2 6 do. do. do. A do. 12 1 7 ft* do. do. A do.' 12 0 <0.50gm do. do* '(a 3 month.' 3 0 0 <2gm Wild Tuck Starved Crumbs XC do. 3 0 1 do. do. do. XC do. 3 0 0 do. do. fed XC do. 3 0 do. do. do* HO 6 meta 12 0 3 KO = Khaki Campboll = Ay1eoburj ducklings 214• TABLE xxiii. Duration of adult worm in young Aylesbury ducklings infected at 1 day old, using Chick Mash diet. 22at 0 4 5 6 7 8 z 9 10 11 12 13 1 IP 0 + + + + + + + + + 0 2 IP + + +‘ 0 0 0 0 0 3 IP 0 0 '4 SO It is therefore possible to infect ducks of under a week old and fed on a soft Chick Mash diet. There are, however, slight losses among young'birds due to penetration of the gut by the plerocercold. The, longevity. of plerocercoids that do become established in older, ducks may also be affected perhaps by charges sustained on infection or.in the muscular stomach. Summar:1, of In vivo culture. _ 1, The. adult form of Liquid was established in ducks by .force-feeding infective.pieracercoids dissected from rudd. 2.,The criterion of successful establishment of adult worms Was egg production, which commenced at 48 hours . • after infection and continued in some ducks until the 215 • eleventh do' after infection« 3. Young ducklings which- had never been fed gavo tho boot resulte'with 5am7C0 establiehnent Whon- infected with one plerocereold per duck; ducklings week old became infected only when [starved for 24 hours prior to infeotion« Eatabliehrient in duel= oix months old waa not obtained« 2a6, CHAPTER U. lai vitro culture. Introduction. The primordia of the reproductive organs dovolop during the plorocercold otago of_LiaUla in the body cavity of the fioh but nature only in the adult phaeo in the definitive hoot. - The level of dovelopmont of of the reproductive organs in tho plerocercoid stage in groator than in moot other larval cootodos, and there, is a tendency towards progenesio. The worm la thus ready to mature rapidly and lay ogga when introduced into a auitablo final hoot. Tho rapid production of °ego onablori amoosment of culture methods. Joyeaux and Baor (193S) cultured the adult in a variety of media, including horoe serum and dog aorum, at 33.42°C, but dovdlopmont was abnormal ae the tostoo failed to undergo apormatogoneoia. In 1946 Smyth (1946) obtained dovelopmont of SchiotocepAalus aolidua in poptone broth at 400, but although development vac normal the eggs produced failed to hatch bocauao fertilisation had not taken place. Smyth (1947) then applied tochniqueo and onperionco with Schlotocephalua eolidue to Ydraziat and obtained normal development, but the eggs which were produced did not hatch. The rocoptaculam sominis wao devoid of oporm 217. showing that fertilisation had not taken place. However, in 1948 Smytho -uaing 50 ml of undiluted horse serum per plerocercoid, obtained eggs of which 6 were fertile and gave rise- to normal coracidia. In 1949 a variety of media were tried by Smyth but only those plerooercoids cultured in horse serum produced-fertile eggs. Improved conditions (Smyth, 1954a and 1954b) le/d to the production of fertile eggs by S. soliaua, in culture. _ Culture conditions included dialysis tubing to contain the plerocercold and deep tube culture under anaerobic condition°. Smyth (1955)zuggests that these techniques applied to Ligula, which he could not obtain at the time, - would result in production of a higher percentage of fertile "eggs. . These techniques have boon applied to Linula with some success, by Archer and Hopkins (personal cowmunication). 1. Methods of,in vitro culture. Plerocorooida intended for culture were removed aseptically from infected rudd. The rudd were killed by pithing and'a sharp downward blow at the posterior region of the head to severcthe spinal column. Pithing alone- did not prevent the fish from moving during dissection. The fish were then carefully dried tuing absorbent paper and then painted with a 155 solution of iodine in abooluto alcohol in order to sterilise the "outer surface. ' Infected fish:werethen diceected in a- stern° cabinet, the plerocercoido being handled pith sterile instruments. Arityplerocercoids'which could be disentangled rapidly 'and therefore not diced were used. Metal forceps were covered with-plastic to avoid the poseibility of metal toxicity. _Immediately after removal from the fieh the - plerocercolds were' placed in" cultUre 'mimic! under aseptic conditions. ' Two culture methods were employed; both. using the came culture media. In ono method a hot water bath, maintained at 40°C ± 0.5°C, surmounted by en arn to which culture bottles- could bo'clipped, The ar8. tian rocked backyards and forwards by means of an electric motor and tilted the bottles through an angle of 40°. - The rocking movement, necessary for the diaperdiaa of costode panto products throughout the media, pas controlled between ton to eighty. swings per minute. Pound bottomed- narrow necked flasks with a capacity of ml were used. In the second method plerocercolds wore placed in culture media in 100 ml conical flasks in an incubator at 40°C. The flasks pore not shaken. , Five culture media, wore used (T.ableF70.,2204. I am indebted to Glaze Laboratories, Stoke Pages, for 219. supplying free of charge unlimited quantities- of Eaglets !nedium-and Medium 199. 2. Results* The assessment results of in vitro nature is usually restricted to 1311001300 in maintaining the organism in a viable state. Egg production and per- centage of fertile eggs are taken as criteria of success. The time at which egg production commences is. also important. Early experiments, using 3/4 Locke solution, and 3/4 Locke solution plus calcium carbonate, were not . successful although two worms produced infertile eggs (Tables xxv&XX.V1P4222&22i• It was found that the more rapid rate of rocking at SO swings per minute (nee Table ]CM p. 224 lead to fragmentation of the worms; reduced rocking rate at 10 swings per minute resulted in no fragmentation. When horse serum was used egg =eduction commenced on the third day and continued until the sixth day. The fertility of those eggs was- 17 of all eggs laid during the whole period, since eggs were not ow-mined , from daily samples (Tablenviz P.224. The programme was carried further by copying the experiments of Smyth (19540', using deep culture tubes, 220. TAME XX11t• Oomrinents- of in vitro culture media. Medium Previous use Reference le 3/4 Locke Smyth, 1949 • 'Pauli 1959 3/4 iooke and . • calcium carbonate Smyth. 1949 -Paul. 1959 Horse serum Smytb4- 1948,49s BurroUghs Wellcome No. 2. 4. EaglelS medium Glaxo 54- Medium 199 Glaxo - 12n. 8" for near-anaerobic conditions, and employing dialysis tubing of 7/8" diameter, with two plerocercoido in each. No'egg prodUction occurred and the worms here all died by the third day (TableXXVIIila.225)). Culture in the incubator proved to be the most successful when using'100'horoe serum, but not successful when using Ba0.efs medium and medium 199, in which worms were dead by the third day (TableXXIXB&C p.226). Using 50 co of-100%-horse serum in 100 ml conical flasks, egg production was good (see TableXXIXA pa 226). The most successful results therefore were obtained using horse serum in the incubator at 40°C, whon- fertility of -the- eggs varied from.3-75g.: 3. Biochemical _assay. Biochemical changes in the adult can be used as criteria of development in culture. Lack' of. material and setbacks in in Vivo and in. vitro culture prevented full use of the adult material. Nitrogen determinations were, however, made on worms cultured in vitro in order to determine significant changes during development. No lipid or glycogen determinations were made on worms in either in vitro or in vivo culture. The method used in nitrogen determinations was that 2:22. . TABLE XXV ,111 VitrO culture of one adult Wu* per tube using 3/4 Look° solution. Aerobic,- atarilo conditions at 40°C. 100 ml of Locke per tube, medium changed ovary 24' hours. (a) at 80 40*demree ming() per %maw. Tube Day if r Day 2. Day 3. Day 4. Day 5. .biw. 6. 1 + 410 p4. p.1. PD 2 ' + +P PD 3 + +P VD 4 + -+P + 5 + «r 4. pD = alive D = dead Pa = fertile eggs P = fragmentation B = eggs (b) at 10 40 demo SWiilfte per minute , 1 + D 2 + + D 3 + li 4 + + + + + D 5 + + D No fertile eggs produced. TA1}LE XXVI Uo1ng single- wome, '/4 LocltO + caOo, solution at 40°0. ldodium changed ever:! 24 hours., -Undor aorobic. storilo oonditions at 10 owings POl" minute. A. ~ubo Day 1. Da;y 2. Day' 3.- nt\Y.4. 1· + + + D 2. + + + D, 3 + +. + E D -. 'a - J£e-'=C}.1,i'. 4 + .+ -+ + + D 5 + + + + + 'D D c dond Po a fortilo agee. 224. 241,_Dim xxvii in vitro culture of Limas. Using single worms. in 1oc61 horse serum at 401)0* - 100 ml of medium changed every 24 hours. 'Under aerobic, sterile conditions at 10-swings per minute. Tube Day 1. DV' 3. DV 4'. IV 5. Day 6. 1 RE 2 RB rozirti. RE -+ ICE D = dead B = eggs Ve = batch RB = kil1od and fixed* 225. - Val - Iz culture of Ligula,•' In deep tube culture (a" tubes) with dialyeis tubing of Mr dime at 40°0, an described by Smyth (1954a). D's ing 50 731 100V; horse sot= under anaerobic, sterile conditions : with two worms per diaysis tube. \ Tube Day-l• Day-2, Day 3. D D +- 'P = adult D = dead 225. fi LE- %XIX In vitro culture o tirtaa• Culture of oinslo worms in incubator at 40°C, using 100 121, conical :Matt:a vrith 50 ml of =dim, cbanged ovary 24 houra. Mader acrobici aterilo conditionc; A. 11011311 SERUM 10014 Tube Dv I. •Day 2. Day 3, Day 4. Toy 3,* 3. + + . + . E E ro25 2 + -i- + 13 B Pc3.7 3 + + "14, ri B 1703 4 + + D 5 + + + B B re14 6 + + + B E 1'4°61 7 + + D 3 + + + B B roll 9 + + + B T.1 ro75 10 + + + E E re33 * P.aporiment stopped and edata fixed' nAGIVPS Mantilla 2 3 + + D 4- .1. D C. 7rD1u2 199. 3 D D" D (load = cairn = cti hatch* 2274: _described previously (p.145). At the time the determinations were made plerocercoid material was not abundant: In order to conserve material* portions of adults Were cut off every 24 hours because it is known that LiTaa.fragments can become mature (Smyth* 1948). The fragments were washed in Hanks' saline and desiccated to constant dry weight in an oven at 105°0 for 18 hours prior" to storage over silica gel in a desiccator: Before determinations were attempted on cultured adults, the variation in percentage nitrogen content' along the lnngth of the plerocercoid was measured: The anterior of the plerocercoid has a higher percentage nitrogen content than the posterior region, but with a Variable nitrogen content in the middle region. This variation is shown for three plerocercoids in Pig. 31 , p.228, The higher percentage nitrogen content of the anterior end is due to its high degree of musculature and the middle and posterior regions contain reproductive primordia and less musculature. Adult ;sigula were maintained at 40°0 in Nog horse serum in an incubator. The warms were maintained singly in 50 ml of medium, changed every 24 hours* in 100 ml flasks; five worms . were cultured. The results (Pig. 32, p.231) appear erratic but show that for worms 10 2, 3 and 4 only a FIG.3I. 228. Variation in la nitrogen along length of plerocercoid 6 — AN 5 N 0...... , N ,s. 4 0' ::.> A ..-- 0 oss...... -.41 ...----- , 0 -'---- ° --:- A ----____,.-2 0 3 c • • fresh wt 5.196 gms cs 0 • fresh wt 5.638gms L 2 ••• o fresh wt 7.97Bgms Z ....,.0 o I 0 I 5 3 7 anterior L I 3 I I posterior 8 4 8 2 8 4 8 distance along plerocercoid . -...-... 22.9. plight inoroaso in norcentago nitrogen content occurred during the first 43 hours but that after this there was a rapid rico up to 96 hours when the exporiment was diocoutinued. Egg production started at 72 hours in cache the four warns* Worm five wac considerably smllor with a froth weight of 2.6l7g compared with worm 1 with.a fresh woight of 7.522gs worm 2 woighing 5.284g,' worm 3 voighint5 $.944g and Worm 4 weighing 4•756gs and showed a more rapid increase/ in percentago nitrogen" content although eggs woro firstproducc& at 72 hours. If, an vuopootods the incroase in porcentago nitrogen content in worm 1 fram 4.2 to 5.8 Ss in worm 2 from 4, 41 to 6,1,71 0 in worn 3 from 5,2 to 7.2rAs in worm 4 from 4.0;1 to 5.3 and in worm 5ifrom 5.711 to 04,00 reflects the consumption of glycogen rosorves as culture proceeds, the omalloot worms number Ss my utilise more glycogen per_ unit body weight than tho longer worms. Undor aerobic Culture conditions, tho resulta indicate a riso in the poroentogo nitrogon contont during development of adult Wallas to a level which is variablo at the timo of egg- production. The apparent increaso in nitrogen content is mare likely to bo a reflection of glycogen option by the adult in culture. It is tnfortunatoLtbat witiAlar samplos were availablo from in vivo culture for invootigation of 230. 'biochemical changes in the adult in a Beni host* 4. DAcqs slays. Attempts to culture the plerooercoid of Livia to the adult form in various media wore made for a short period, and although these experiments were curtailed, brief dioeunnion of them le given below. Initially, it was intended to compare the adults obtained from 14 Nitro culture iith those from in vivo, culture.' The media mod (p.220) are 'similar to those used by Smith (1947) with the exceptions of medium 199 and Eat.,1* es medium. Neither of these media support cell growth in Lirula and in both media Worms died on the second city* The 3/4 Locke ()elution with and'without calcium carbonate gave renults 'similar to thoac obtained by Smith (1949). /t in interesting that rapid rocking in the water bath caused the plerocercoldn' to fragment but that 'the fragmento did net die Dime they, were still motile, in one case on Day 5 (see p.222), tine of the deep culture tube doeoribcd b Sprat (1954) gave disappointing moult°, but in the light of recent information (Ilopkine, 1966) thin wan probably due to the else of the worms lined.' The worms used wore all of a large nine with a frooh weight of :1-5 gm and according to FIG.32. 231. °/o Nitrogen content under cultivation in horse serum 8 7 6 — -. 5 c 4 w a, fresh wt I 7.522 gms 0 ... 2 5.824 gms E 3 3 5.944gms ...0 o 4 4-756gms 5 2.617 gms 2 ._. I 0 I I 0 24 48 72 96 ',: hours under incubation 232* Heptins (3)oe. cit.) the moms uaod by arrithwerernaoh manor* The failure of the deep tube method' may be attributed to the inability of waste produOts to diffuse out into the horse serum from the large worms used. , Although the_use of large worms was an apparent- disadvantage in.deep- tube culture, it wae probably the _ reneon.for the sucoeseful culture in'herse serum in flasks in the incubator when up to 7554 of cgge hatched. The - eituation of Ligula adults in the conical flasks may have been comparable to the situation of mall plorocercoids of Schist000thaltr!olidus in dialysis tubing* The buffering gnalities of horse derma prevented an increase in acidity, even though the medium wan changed only every 24 hours* the biochemical enalyeis was not completed but the apparent inoz'oaaci in nitrogen content ie probably duo to a decrease in glyoogen content although the glycogen content was not investigated* Hopkins (1950) demonstrated that the glycogen content of adult $chistocenpalus dropped rapidly in the first Cow hours in the inteatine of the pigeon, .and demonetrated in 1952 that a similar drop in Glycogen content occurred in adults in in 'vitro culture. Purther experimental work is obviouely required 233., before- in yitro, culture in a defined medium in auccesom fully accomplished. However* the principles down by Smyth (1955) for anaerobic conditions and contact in a suitable medium. may well suffice if applied to plerocerceids of reaeonable size. •5* igtaxsglikritalro c itm 1. Linu/a, plorocercoido wore aseptically dissected from rudd and placed in sterile media in either a water bath with a shat in device or an incubator, both at WO, in order to culture the adult stage. 2. The following media were used: 3/4 Locke solution, 3/4 Lecke and calcium carbonate caution, horse serum. Bagleso medium and Medium 199. Horse serum wan the only sodium which gertile eggs wore produced. 3. In the water bath with shalcori:,the average proportion of hatching oggo was 3.75`4 whereas in the incubatoro using SO cc of corwn. the hatching varied 2rom 3.751. 4. Assay of the percentage nitrogen content of the maturinc.adult An, vitro revetidd an apparent Increase in nitrogen content in the five worms studied,. The apparent inoreaso wnn *due to the depletion of glycogen reservers used rapidly as the worm matured. 234, MUTER X. The irtquerice, of Mat op.. the hotohing. of Tii Introduot3.011. Tho eggs of adult azika in the final host must pass out with the faeces of the piscivorouo birds and into water if development in to proceed. Tho conditions necessary to the development of the egg have not been studied, but ouch factors as light. pTl and mgen tenfold= affect the development of other psoudophyllid eggs (Bauer. 1959). ' Tho effect of light on the hatching of pseudophyllid eggs has been otudied by a number of workers. Dubinina (1953) observed hatching of Isipula. eggs when exposed to light, and SinYth (1963) reviewed the effect of light on the h'atehing of eggs a poeudophiliiiIV but not including 1. not-fleas. Ewa were obtained from the faocco of experimentaly infected ducks during the first two days of egg production only' (N214). The eggs =re melted and allowed to oottle. the process of modimentation being repeated silt times before eggs were pipotted into 100 ml conical flasksvrith 90 ml of tap water. The flasks wore wrapped in black paper and placed in itn incubator at 2500. Two 2350 flank() wore .illuminated with daylight in a water bath at 25°C. During recovery and washing of the eggsi which were later placed in blackened conical flasks, exposure to occurred for a maximum tine of twelve hours* -'moo `affect of ordinary tungsten light of varying. inteneities on the hatching process was Inv eatigatod* ht 'into:laity woo measured with a Weston Light Meter Mark Ill* After eight dayS in dark fully embryonaied eggs -wore_pipotted in tho dark into blackened petri diohee, As- a control, and in order to discover whether handling proCedure alone resultedin- hatching of _ egmr an egg 'sample was removed, ,biept in the ,dark while 'experimental samples were illuminated. on then *killed* , with 2er, termini* During the experiment the continually eggs were also fixed and later counted to determine percentage batch. To determine whether any eggs had hatched prior to the experiment a" sample was - *killed* in -the dark at the beginning of the experiment* Samples for illumination were pipette(' into black bottomed Petri diehen and illuminated for set periods at a Imam light intensity* At the end of this period the eggs were skilled* by the addition of 2C0 termini. pipetted into glass apeOirilen tubes,' and allowed to Settle* gaoh sample was pipotted on to a microscope slide marked in half millimetre aegares and_the numbers of hitched and__unliatched_ eggs were r. 236. counted. Eggs were considered to have- thatched` when, the operculum'was open, whether or not the, coracidium had loft the egg. This method gave- repeatable results in replicate samples. Mug. Ix', p. 2411 shows the hatching of Mauls, eggs. 2.. Results. At 24-~28°C eggs develop in 54- days (Dubin/n:1, 1963). In the present studyi coraoidia' hatched from eggs kept for five deiys at 25°C after exposure of the eggs to light. as did those which.were continuallir_illuminated. After, eggs had been kept for-15 days at 25°C, 10% had hatched' in the dark, and after-30 days at 2560, 21g had hatched in the dark.- The latter cultures were heavily cOntaminatkVI with bacteria. _In egg -cultures kept at 25°C In the light approximately 73%,of eggs had hatched on the eighth day. In order to provide material for eight experiments eggs wore- therefore kopt.inethe dark for eight days at 2560 with very few eggs botching. When exposed to high intensity 11127m1Tlatien for two hours 42-A of eggs hatched. A series of experiMente,was then performed with varying periods of illumination at varying light intensities. Bach experiment- was repeated three times and the numbers of eggs hatching was averaged. The proportion of eggs hatching in ouch experiment was expressed as a- percentageof 42; whichis the maximum hatch 2370 underoptimal, gonditiens0- she _highest proportion of edge hatehing (Tablati) p,240), atthase high inbnieities of 200 units and t60.unita was 66rfrand - 687A hereas- st the-lawaightintonsity Of 342 units only Matched mizutecti The proportion of - eggs' ( able±xi4- )4240),hatchind4ncroaad1 with incicaac.ia light intensityi-.but. even at very low. light intensity 342- mi.te hatches 'is stimulated., The samples of eggs tkillodt at the- beginning of each eiiporiment showed that a few egg's had hatched"-, that the control oksza which were'ltopt in the dark and skilled., at the end. of th6 02Tortnalit CheWed n illOroaso in hatch (Tab/aux.-, pe240) throuL.th hendlina Prdeeduro. It in evideivt- pat oggs incubated in the light ohow.a greater pereantage hatch at any given time after embryonation completed. 'The hatching of fully embryeratea eggs 'is thorolore stimulated by light and eggs hatch more rapidly with increneing light intensities*, The hatehing process is; however,:sensitivo to low light intensities 3, Dincuseionk Theeffeot of light on hatching of psoudophyllid 0=n was reviewed by, Smyth (1953) who stresses the dependence" or otherwise(' of the hatching mechanism on lighti The ponnible correlation of light ocnnitive mechanisms in hatching with shallow water, habitats and with an abundance of copepods is a tempting hypothesis. However, thoro in an yet little information on the distribution in the natural habitat of eggs in faeces of the final host, onnhother or not,egga will pink to the batten in certain conditions, of salinity and on the effect of arigon'tension, and salinity on hatching. Many results- on the effeet of light' are indeoistvo.._ ego/ (1929) demonstrated that, light did net affect. ombryonation of pilft'llobothrium 3att eggs- but that in dark Only fen coracidia hatched ilIlrott6 mann hatching is stimulated by light. Smyth (1963) quotes the 1930 article of Vogel inwhich.is described a situation (similar• to that found inTsigula4, and in 1%1(114, after Ot% days, tut increasingsorcentago of ems hatched in the dark althatigh mos-hatching was stimulated by light. The present remit° Indicate that mans hatching of Lf-ul did occur in samples kopt in the dark and then ezponed to the light, but the, percentage 42 of eggs hatching za never as high as in aamplei of the same batch of eggs kept in the light.- It is.sugontod thatjltmaaeggn may develop in the dark at a slower rate. Eggs of Triaenonhorun nodulous 239. show a dolayed devolopmont in tho dark: (Mikhailor, 1951)., • Tho oggs of Mania boar a suporfloial rosomblance in thoirhatobing mechanisms to the eggs or PrIpciolsc hamlica lit which., the miracidium is roleasod from tho operculate in an aquatic environment. ' Recent wort' by Wilson (L965) has nhomm that the °g as of Panniola arc stimulated to hatch not only by //gilt but also by tomporaturofluotuations and by vlbration. Wilson found that tho, hatchinl stimulus aotivates tho ropy= system of the miracidium; it may woll be that a &liar mochanion =iota in ifirmla. • increasing tho light intensity to which dark-inaubatod prxali own aro ozposod inertanos tho rate of hatch, cimi/ar to Pasciola (ilson 1965).1 Willa 0=5, Ilbwover• • 'rote not intlibited from hatohing by a high irchinoity 611 light, as wore Pacciola eggs. It appoars that the pronortioa of Li mAla eggs hatching is increased:by light, agrooing with Dubininat 0 (1955) remits, Um/overt Dubinina (1953) found that tho oggo only hatched in light, in contrast to my results. Dubininafo conclusions may be tho result of delayed devolopmant in the dark and lack of oboorvation at longor intorvals• in ,Ravonsthorpo resorvoir the conditions for egg devolopment and hatching aro good, as large numbers.of giah arc infected =oh year, Tho egg output of at 240. /km% in grebes is not snort. The shallow nature of the reservoir allows both penetration of light through the water and high water temperatures. vihich favour psoudophyllid egg development and hatching. TARO xxx • Percentage of eggs hatching en ezposure to light _or different intensities for different /engthsce - time. _ Eggs obtained fron adults in ducks nee p#214. Zength of mosure to light in minutes Light Voter reading units before killing. 3.2 13 - 00 .206 800 Hatch in dark 3.4- 3.5 7.3 6.4 748' 10 37.5 51.8 50.0 68.7- 66.6 20, 38.0 65.7 76.4 80.0 76.1 30 42411 71.2 78.5 84.6 80.8 40 74.3 79.1 75.0 83.8 86.9 50 72,1 78.6 83.3 86.9 81.8 60 93.0 79.4 84.6 ITmidling control 4.1 3.8 7,9 8.7 3,4 Avor3ge results of three counts each 0 It t error ± 5.47% Boaulto aro =pressed as percentago.of the total hatch of 42.8; after 2...hours illumination at nazimmm light intensity. 247 VMS,. TX. AP: 50y 25).1 ha. 50p 25,u Stages in 1-1c,21,nc of Linula ogge. (r)orcalum open B. ontrcwace of the coracidia °map° of ooraoidia D. ejection of matertai from ocgo 20; Summary. 1, Limp oggo woro obtairiod. from tweets ot- infdatod: d.tioks byivaohiriP: tho faocom thrOugh a rho.: oiovon. of - • _ tho' gollowiMg poro diOnotdri -:25014 10514 88/1 and 237pi Tho-0171s aro.rotalnod-an -f4MaI,oioiroi' Raj unetbryonatod • 2, )7'40 wore allot to . dovolon. tho dark at 256C for citSat avow Coraoidla hatohod froz 10 of tho aga3 ' after 15.(14yo in. thn'dark, mid'fziom 207) of ±ho cogO'aftor' 30 elp„,yri. .- VullY ombryoiaatdoggo- kopt:in'tho. dark 114tohod 023.. ampoaure to light. :5Vof tho- total:44%4o hour 62;87'; of all • oggs) hatchIng-in. 16. aiMixte, at 1144 12ifonoitiOO- of 13' .unit60 80 unite, 200 unita and 8O0 unito, rciad, on, ' tioaton Light Motor 1134/II4 r" 4., 'A irigh proport..On • of ot2go2,dotioloping.: in- +17.o ,11:ch..1, . of ich. ap"; rhOroaa tho proportion of Og80.dovolopin5,3.n 71.Z•42•874 1/,6t' oight days. • 5, Tho rainboro of, ozco .3.6•2ninuto,s-.aftor' c=p6ottra to dopoitdOnt on tho :Licht into anith• 37,5;t, of ogcol Imitohed aftor 18 iiixtutO" at' or. 342 units mid 66.6:4 after 1U: nut at -a lich'intonsity of coo units. 244. r3r,crao3 rat -DxsTrarmxon• o LICTITA 011,11M11 XI* geographical distribution of Tiirpla has not boon rovitraod t.t.,=cept tor sing/0- cotultries O areas (Orton and Arne, 1965) a' nocent redoras it they arc accurate in tho- plerceerceids to intentinralqi indicato that- ths corms un Widt!sprtadt occurring in l rear:rus, iat Elotith Agri cap ana 'Torn. ArrIridd, Tho countries in, t7hich the plorocerocid. distributed aro shown. in pg;248 ; p or tho pasmosom convert:1,mm the gieh lists aro givon gamilicso Tho '7;ith uha nest Species int acted with nri,:tia is tho 0,r:tin:tans with innctod riecies in thl Tie end Old 'vlor3.:do • in no Ancrica only into othor gunnies, 1.,12.6 7.)CX;Cidae (0*.0' xxxi 1o249 ) ezd (latest onidtio (sec Tablo XXXXIo 240 arc also inroctedt but ricrabors or these - rani:Lica racio no ingeotod in the Oid 1,7or110 , the Old world littulti Ivo id a12s' recorded frcu. the dobitidac (sac r2c%b1f.XXXI; p.249) and Goblidae (coo Table till p.249) i vhile . in So Africa the 6.onue Zukta of. the gamily Cyprinidao (rif:3o rya 1e XXXipo 249) Wad EOUna to bo infected* Althoush. 245. Ligula is known in Australia (Smyth, 1965) it is not known what species offish're infected. Only-one_species of marine fish, a pleuroneetid (Tabloxxxgp-.2)),, has been. found harbouring Itgula, captured in tOvackish,bay4n- Germany.. :Triaenephorus nodulosus, a pseudoPhyilid usually associated, with. freshwater fish, is a common parasite of coastal fish in the. Baltic sea, which has a salinity -of:approximately '6%.(Bauei1959)..and,iliustratedthat'a predominantly •1 freshwater parasite may, occur in. marine..conditions Livia :is thUS widely diStributed and - appears not ' to be limited to freshwater fish. but able to, survive in fish in, brackish water.': Dub:4aina (1950 and 1950 was of the opinion that the two forms of-Ligula found id the Oobitidae and Gobiidae are different species and has named these L. colymbi and L. pavlovskii respectively. / have not examinedc worms from Cobitids. an&Gobiids. ,Before any physiological differences in forms in different fame lien of fish can be assessed further, experimental transplantation is required. If physiolOgical differences between LS intestindlis, L. colymbi and 11. pavlovskii are demonstrable then I muld suggest that the N. American forms in cyprinids, percids and catostomids are three, separate species. 246. Tho question moo .arisoa as to vhothor the Europa= form of ift-ul whioh Cooper (19/a) comparod with end found oimilar to the 114 American 11.1_1/1test1=9.0 pbysiologionily..difforent from 'bhp it* American forme - It must bo emohaolood that spocios of oyprinid. fish, pr.L.rtiorlar roaoh1 rudd and bream,. cmf. intorbrood 'and that tho onvironiont in whlahLiti:tula can completo ito •lifo-oycle io provided .by a static lam or rosy: 3r; .Tho intorbroodliv ,ot . f ishi or tho dovelopmont of racer) in may ,load to .nor hoot zi6c ord w1th- 4. conSomitont -comptobilitr botwoon host and parasite. Littlo' Jo imorto, concorning eostedo gonotios but the possibility t'llat_diffoz..ont Ter of Lim occur ,in different races fit.-3h 'in Violator/ habitats' ohauld not bo ,dioregardod. fi.hat ,olight morphological eafgozioncon on their- om. oonstitu.to valid osoolfic diottnotions is opon to doubt. iiovcrAvt l morphologica.1 differences in Lipula • co2:4colC,s; aro allied' with physiological (..incorApatibility. Tithdifforon,t hoot...fish harbouring oirailar formop thon, ha diotit.3.1t1-4- -,-113:-.a valid ono. --gorA0 \Ligula, moot s thorovt6h? reVioion not only o.n,morpholog-lool bit on Actsiologioal our do. The maintent.moe of the life %van. in tho laboratory should ocion bo feasible end with this 'facility the study of various :Zior.n.s' trawl:Atte& through ono typo of fish can t)441, 4.1r(0 artaltOne (1964.) discussoa evolatio-n tha Ilizttlidao and stato,(1. that _the pitlroom.vola pliazo- narrowly spooifisto adapted :66 Cordllon =11 ever. -gondra,- .,. of riches in cle-ztain 'oas.- Dubittind (loot. oit,i) • - ifa tho: ploinooroo3,0,. , 7.‘vvtti7or• , artgex,41.3taIt& imarf,oit:it , • 7 ,,- Aliatt;,,*` baZ, .1./C=ItC=f1 rr- or:thci- o'aristmit mizzation tiao .11:orts-.7411,011 .171.17- t oecurzati. tb,3 !And's., or tiloconO period;-- • .thiS coxinoeltihnI , • 1.5 latareating that ".41,w2P, bc.5,(312 (a14.1.ble 249) S.Z*On3.30,Zii120-ifl• 11,addraa, lidn176rs or 413,b.d. , - na..,71yrts have o:dotoef, siztoc: mut givon riso to tho oyptialm graipa (alloloidit 1951)4 alio gams narlyt,ts maycvlon • b' clarlionil inlidihodiato hosts of ena tt., comparison or pidr000roolds rr this • rttnily vr.t.**1. plo:rodVdoitio'frdii bO t.;:l'oa-11* IntOrosti.LaAii roasibld avolationory tmnas vith3n-t1I4,gehus4 1ABM row 248. Hoot-Lift of Linea sDecies.. 1) c7Prinidao infected with plerecercold of LinuXa op* Ovegies Roferonce Maga Goble, jobio Russia SADKOVSRAYA 1953 Poland num= 1960 Switzerland BAUR 1964 _Cigassius carassius .fluspia SEPOIYARSKAYA 1953 rutilus, • Russia - sinannmAT 1951 Czochoslovakia SIMS 1964 Poland =UL 1960 _Russia - SRPOLYANSIAYA 1953 Ensland OVEN ,a ARNE 1965 England BAYLIS 1930 Russia !MGM= 1957 lhands6 KOGTEVA 1957 OcardiniUs er,throthAhalmutEngland NM& Annn 1965 P oxious vboxiqup Scotland ORR, (present paper) ArliccA_Woorkca *Switzerland ; • Di 1964 Russia gOOTEVA 1957 Russia ARETEROV BOGDANOVA 1957 potroRie borriqtuo Rr Amarioa MENCTI 1958 Laucggipius dolineaVs Poland =MAK 1960 Russia ORPOLYAUBRAYA 1953 Abrams bdralack Poland mann 1960 Switzerland BAER 1964 Russia ' ROGTEVA 1957 Russia TIBOVA 1957 ;Ieuciocuci coritialwal Poland nuaumm 1960 NoIrovis hotel:01°as Anerica nAnano 194/ Srbormpuonotatun N. America BA MAN 1941' Assaa SOUTHWELL 1928 liagwamulitlWatual %neck tiara, Israel P Di; 1964 249. TABLE.XXXI,(tont). - Soo. Noforonco 1) 1:3yprinidao NotroDio blApqntom N. .Amo• rioa - Amnon 1914 01yosomas- 000 . T. AmOrica MGM! a Ural) 1946 Loucogonne carp/malls N. America DAMN= mumb 1946 ,Lotv3ciiiqmit iduo Baia SODA 1957 vimbrk Ruaoia MUM MA 1957 , Pt:nth:11os vromolos . N. America SHINS 1959 parbusj ,paluelippous Scb. Africa:, !Mat= 1960a 304049alida 8. Africa =MD=196110a DEltbito 344101X10123.attla so Africa TETVII0K 1960a 2) Porcidao infootod with plorocercoid of Ligula op. Poro4T1Trodoono N. Amorica •iabott 1964 WARDLE 1932 PITT 4 GRUMMANN -1957 3) Catootomidao infoctod with plorocoroold of Ligula, op. Ogtootortuo vataotomus N. 'Amorica vAltDm 1932 Optoptomuo oommoroanii N. AmorioWl WADDLE 1932 0a/onto hunbold#opo Az orica HAD 1953 4) Coboditidao infootOd with plorocorcold of Igtataa op. - ruti4001R India sourmows 1928 09bitio taonia- Russia ZOGTEVA 1957 with plorocorooid. SCIIMIAN 1957 13 1t~ co1mbi Ruoola Lim an= 1950 5) Gobildso- infeatOd with plorocorooid, of raigula op. Borith'diatliao otollatuo . nuosia =NITTA 1959 with plorodoroold of ids vAy;ovoldi Dan= 1059 250. TABLE.XXXI,(cont). ,Snooiol LIAM Ropioioo 6) Plouronoctidao infootod, with plor000roold of`Zitsula op. _ Plottronootoo plate= Gormaa BNGBIAMORT 1958. Linulct arnica aooribod to ipooios other tWai 251. ES AINEROV, A,Kh. 1957 Bata on tho parasitofauna of fish and BOGDAITOVA B sik f In thezegion of the future Stalingrad water basin (In the region of the flood-land lakes and Bruslan River). Bulletiwof the All-Union ScienMe Research Institute of Lake and River Pisheries, 141-153. v/f ALLISON, L.N. 1964 Personal communication. ARM -G. and 1965 Ziguloeis in oyprinid nohow- a odn, n4m, unicue form of parasite inter- ference with a vertebrate-repro- ductivo cycle (Abstract). Parasit 55 (4). 7p. or 1964 Personal communication. / =GRAM p Ras 1941 - Parasites of fish in Algonquin Park lakes& Trans.AmeraPisheries Soo. 70,161-74 13ANGRA1, R.V. 1945 Parasitos of fish of Algonquin and MAIM, C.E. Park lakes. Univaoronto Studios, BioliSeries No. 65, Public.. Ontario Pieheries Rea, Lab. Univ. Toronto Press., BARYSIWA, A.F. 1957 rich parasites of Late Ladoga. Bulletin of the All-Ton Scientific Research Institute of Lake and River Pishorios, XLII, 171-223. I/ BAYLIS, R.A. 1938 Records of cam par6sitio worms from British vertebrates. Ann, &Meas. natural mat. 1 (3), 329443. BATOR, 0,11,(ridit,t) 1959 The ecology of parasites of fresh- water fish. Bulletin of the State Scientific Research Xnatitate Of Lake and River Pishories, XLIX , 31B9. 252. T. 1966a Studies on the Holminth fauna of Norway* VII. Growth. fecundity and fertility of BlyftlAobqthntwR norseAioura YU. eta soda) 1z tho goldeh hametor. Hytt Magaaun for Zoologio 13, 39.51. =TEN 1966b Host specificity in beidotoeopbaluo solidus. Parasitology. 56, 657-664. - • . EMDEN. P.J. van .105a Memoiro uar los vors intostinuaz. Paris (Quoted Smyth, 1947). moon, H. 3.782 Abhandlung von dor Ersougung der Eingoweidevurmer under den ?AtteIn widor dienelbon. Berlin (Quoted Smyth, 1947). BOKOVA" E 1940 The consumption and assimilation of food-by the roach. 5.1rans. Inst.. Pith. USSR, 11. BuAunno A. 1910 Dian Susswassorfauna Boutschlandc. Parasitische plattwurm, or. Heft 18, Itst Cestodos Iv. 18/19. bi/ 3101717.11*(Eclit.) 1957 The physiolot of fishes. Vol. 1. Metabolisms Vol. 2. Behaviours Academie Prase,, Now York. v 0111113/4 J.C.. 1964 Observations on the occurrence of the plerocercoids of TriaegeDh.erue (142.11a0, 1/81) tObstodai se lidos) in the porch Per9sL fluviatilis L. or. Llyn Togid (Bala take) Merionothshires Paraeit. 54, 481-91. OLAIIKT.31- A.S.- • 1954 Studies on the life cycle of the psoudophyllidean cootodo Schksto. ce2halus sqlidus. Proe.Sool. Soc. Iond. 124 (2)10257- 302r COOPIM, A.R. 1918 North Amorioan Pseudophyllidean cestodes from fishes. Illinois Biol. 110210-gr• 4, 16. 253. --ft crams i.n. 1955 Taar34r food habitant rivor otter in the Thompeon Zakos region,' Northwestern liontana# as indicated by seat analynise Amer. Midland Naturalist* 54 (2)i 299-3134P ‘i MOSS, 56X« 1935 The effect of parasitism on the growth of porch in the Trout Lake J. Parasite 21# 267-273. CROON, t'«11: 1963 Elemontary statistics with applications in medicine and the biological acionces., Boyar Pablleations Inc. Row York. ✓ DAV/ES a 3.P. 1966 Tha effect of bodi aim and'. ' - and VA,1=7 ip tamporature.upon consumption of' ogygon of the costodo. Comp.. Biochom. Physiol.;18#.415..25. -/ MUCE# W.A. 1958 Studios on Il...-infooted common shinors,WWSWElicornatUS froppolitp Agassis) in ilia AdirondaOks. . ffelminthiAbstrs.44 (3), 334•6364, V.A.* ' 1961 Porositology:of - liohos. PENCUSUEITSWE G.I.- t and POLTANSKI, Oliver and Boyd. " DONUADM, .A.L. 1877 Contribution a l'hiatoiro do la ligule. Jo-urn. anot•physioli 13, 321-70. (Quoted from Smyth, .1947). 3}U13 XNA, MU. - 1950 (Row data on the -morphology and biology of representative° of the gonun atalQ..] Zoo/. Zburnal# 29 (5), 417-26. j Min=i p on. 1953 [ 3pocificity-of,&fulaiin voriouo phones of .tho o oyc ea] , Paramitologichoslci Sbornik* 15* 234-251 (In Russian)* 254. DIM/111.11A0 F4•11 1959atrsiimull vlovskii name from Behtho us t3' o1 (Goblidao)03 Zool. Marna, 38 (3)0 378.'384* din Ruasiarts' English summary p•304)*, D'UFITN/ITA• VI•IT• - 1959b Nho'natural. olosoification of the gonua skiehistqcen4g1, us eregin (0estOdsis. itigulidae)*].. -Zool• , Zhurnsl• 38 (3.0)e 1498-1517. -.(in Russian: 1ioh ourmary p•1317) Mk:14111A, Ltar.i*'.' = 1964 Z.igulidde (Costodas Pseddophyllidoa) and their ()Volution* Aosd• Sol* of the USSR. Zool•Inot* 11p• . a. 1076 wiloohorahes anatomiqueo pkysiolcigiquos aux los 144/coon Pis. (Quoted Stay-Ult.:1947) • _ 'ENGITRaMECE51. It. ulinterriuchingen ubor don Paraziton- ✓ bcfall dor Nutzfischo in swaldor. "load= told. Kleiner. Naffs" - 2oitschiift fur ,rischerei and, Ililfqiiissou.schaftorn• Novi oorioo, • 7 _((7/8), 481.5n. trronch and Ilttlrii= suminorios 508.40. 1934 "Castration parasito.iro ohoz Za goujon (Gobi° gobio Itinno)," 13ulletin Wass de Poohe -ift do llocioulture, - 35' (5) 0 7045. • 17173.720170,, 2902_ Kato 'of growth Of• Sea fishes* Soi* Invest' Ptah*. Div. Soot*" Rapt* '20. leriliAl10 R. 1964 Personal communication* 1/ =man, Eta. 1953 Parasites of the freShwator fishos • of Itorthorn Orlifornis• Univ. Calif* Pnblio. Zoo', 570 303-3734 IMITEERT0110 D• 1959 A biological. and chemical otudy of Chow Valley- rialto. Soo. Water riroatment and Ditr...Tit Sept. 255. BART/BY, P.11.5. 1947a Tha Natural history'_of dome British -freshwater-fishes. Zool.Sob. 217 1/), 129-246. -JEMMY, _1947b The coarse_fishos of Britain* Proshwator,Biol,: Assoc. British Maps Sci Publication No. 12. ‘./ ITARTin .1948 Food -dad feeding .rolationahipa in community of 'freshwater fishes. ' Animal Ecology, 17 (1), /950 Studios'on costodo metabolism I. Glycagen Metabolism in Schioto!- celo us- solidus in vivo. 3. Paraoit. 36 (4),* 384-390. 40P1CIN3, O.A. 1952 Studies on.cestode metabolism II. The ntilicationot glycogen by SchistocophEllus ooliduo in vitro,. 3. Rapti. Pardsit.'1 (2), 196-213. HOPK/NS, C.A. - 1958 Studios on cestodo metaboliam IV. and HUTCHISON, W.M.- The nitrogen fractiolvin. the. logo cat tapeworm HydAtigera.(,Tmenia) ' taoniaoormis. - Expe. Parasit« 7,_349-365*, HOPKIld, 1959 Seasonal voriationo in the .incidonco and dovolopmont of the cestodo Proteocenhalus filicalio-(Rudasio) n 4astorosteue aculgatus, " 'Paracit. 49 (3/4), 529-542. • HOPI{/NS, C.A. 1960' Studios on destodo'totabo/imj VI. - Analytical, procodures and their application,toaaatirarataeniae. formio. raptl.Parasit. 9i 159-166. u/ HOPLINS,,C.A. 1963 Studies ron'Schistoceph us solidus and-MeCAIGi U.L.O. - I.'Tho correlation of ovolopmont in the plerodercold with infectivity to the dofinittvo host. Bxptl. Paracit. 13, 235-243. 256. inucurduc, P. 1960 “Lifut la intes,tir Z. bat den Prochen aus den 1:a-1.--pronteichtrirt- schaften londek. Golysz,- Ochaby. Acta Hydrobiologica. Cracow 2 (2), 133-142. (Polish summary 141-142)." v/ BUOGRINS* EX. 1959 Parasites of fishes in South Dakota. South Dakota Dent. of Game, Pioh and Parks. Bulletin 484. nums, 1927 The related offoots of a parasite G.D. on a fish; a retardation of early growth, the rotontion of larval. charaotoristics and the increase in the number of scales. J. Parasit. 14. 75-84. =TER* GO'. and 1930 X. Studios on fish .parasites in the numn, W.S. St. Lawrence Watershed. Biol. Surv. St* Lavrenoe Watershed, State N.Y. Conserv. Dept. (V), 197- 216. j HUNTZR*.G.W* and 1938 Studies on the hoot reaction-to WATER, W.S. parasites 1. The effect on. weight. J. Parasit. 24, 77-483. t/ JAM. Z. 1953 "Schorzonia parozytnicze powodujac nieplodnoac ryb (se Szczegolnym uwzglednieniem ligulozy." Mcdyzyna Weterynaryjnao 9 (5), 205-7. v/ JOYEUX. C. and 19361 ”Recherchos biologiques our la Lig7le BAER, J.G. intestinaie roinfestation'paranita_re O.R. Sod* Biol. 121 (1), 67-68. JOYEUX, Q. and 1938b "Wevolution dos Plerocercoides de BAER, J.G. la LiRula intestinaleen C.R. Soc. Biol. 129 (6), 314.316. JOYEUX, C. 1938a "Sur le development des Pseudo - end BALM* J.G. phyllidoa (Ceotodoo)." 0,R. Soc. Biol. 127 (3). 1265-1266. 257. v7 KAHAff, 1953 A rapid photometric method for the determination of glycogen. Arch. Eiochem, Biopbyo. 47, 4O 418. KERRi T. 1948' The pituitary in normal and parasitised roach (Leucisaus rutilus Ploni.) _ Q.J.U.S. 89 (6) 129-1380 . ICIRSIETIBLAT, 1951 [Effect of the plerocerooids of lipula iiitestinalts on the hypo. physic of the roar.] , Priroda MOSCOW Year 1951 170.3. 67.68 (in Russian). * V v/ROGTEVA,n.P. 1957 Isiah parabites from Pot ov-Ohnd• water reserve. * , All-Union Soi. Research Ins t. Lake and River Fisheries, ZLII0 239-65a • . • • KOSNaRITA, N.A. '1961 Disturbancerof the barbohydrata metabolism of Cyprinidac in Lirula and Diagramma infections.] - Dokladi Akademii Bank.SSSR, 139 (2), 510-512. (In Russian). ,x/ ECSIMA A.F. 1956 DEfect of Limila intestinal is Diagramma interrupta (Vestoda) as - fishsj Zhurnal,, 35 (11),-1629-32. (In Russian). v/ KOZICICA, V J. 1963 "Attempt of'fishery-parasitologic estimation of.tho lakes of Wegorzario Establishmaiit." Acta Parasitol. Polonica, 11 (5/13). 113-31.. (Polish suutntry p.130-131)• MASON, 144111.04; 1965 Development and grigwth. of Schist°. cephalus solidus Miler ii7175,77hd In vitro. Ph.D. Thesis, Glasser/University. 258. TIATISHiT1 g A • ti • 1960 Biology and. Compnrative Physiology of Birds* Academic Press* ar. and London. MARSHAmTi* A.d. 4967 Biology and comparative physiology of birds. Vol.II. Academic Prom* London. . " McCAI0* 141.1.0* and 1965 Studios. on schistMahri140 0 HDX/NST * C.A. 3.,The in vitro cultiva on ofOlia". the. - plerocercold* Parasit. 55* 257-263. =TRICK* D.P. 1960a ContributiOns to the holminth fauna of Central Africa.,/I. Some contodes of the order Psoudophyllidea. Proc. and Transact. of the Rhodesia Sci. Assoc* MICH/MOW* W* 1951 Stadiolnosi rostluju nietorych tasiemoow (Oostoda). Annalco Univ. Uariae Curio v.6 (3), Sect. C. 'AlKAILOV* T.i . 1957 [Some data on the distribution of Ligaids in Asorbaidshan waters.] Izvostiya Akadomii Nauk Azerbaid- mhanskoi SSR. No. 9, 96-101* (In Russian)* NAGIBINA* L.F. 1957' Parasitofauna of fiah'of ”Novoe Vygozeran (New Vygozero Lako)._ Bull. A/1-Union Sci. Research Ins y. of lako and River Fisheries XLII. 127-140* ' A • E • 1964 The growth process in rrilhals. Pitman* London* v OppiN, 1953 ft.Tho effect of external environment factors on the developtant and survival of Broad Tapeworm coracidia." Chteniya Pamyati N.A. Kholodkovolfogo 1952.goda. Izdatol'atvo AN SSSR. 259. 1961. Special Ichthyology. Published for the National Science Foundation, Washington, D.C. and the Smithsonian Institution 'Israel' Program for Scientific Translations. O.V. 1963 The'ecology -Academic Prowl Na. and London. .\/NOB, E.R. 'and 1961 .Parasitalogy . The Biology of NOBLE, G.A. -animal parasites. jionglItimpton, London., OWEN, RO. , and 1965 Some observatibna on the distributbn Anmoire. of Li l.a lorocorcoids in British fres wa or a a met]. Paraatt. 55J44 6i). PAPERITA, 1964- The'metanoanparasite fauna:of- Israel inland-. water fishes, , BAMIDGEH, (Bulletin of Pish Culture in kraal, -16 (1/2)i PARSONS 1966' ,Pdreonal ceibuniontion. \/ PARSONS, L.W. 1950 'MAI history ,of thd:yelow perch, Porca =ayescons- (Zlitchill) of. Ole= loaltos - Iowa State Coll.- J. Sci. 25u83-87.1 'PAUL, J. 1959 0611 and tiosus, culture. Livingstone Ltd. 261p. PITT, C.L. and 1957' A study of the affect of parasitisd GRUMMANN, A.W. on the growth_ of the yellow porch- produced by the -larvae of Li a intostinaliq (Linnaeus, 17► o1in 1710. - Prop. ffelminth. Soc. of .17`ashinct, on, 24 (2), 73-80. PYCHA, R.L. and - 1955 Early life history of the yellow SMITH, D.L. Jr. parch Porca flavescons (ulitchi11) s, in the Rod Lages Ilinneaota. Trans., Amor. Piste. Soc. 841, 249.-260. 260. v/REGAN C.T. 1911- The freohuater fiohoo of the Britioh /sloe. 03.E- Vi London. ,// ROUNSEPELL. G.A. 1962 Pishory Soionoe — Ito method° and - and EVERHART,. 174611. applications.. John Wiley&Sono Inc. Hew York. v. SADKOVSKAYA. O.D. 1953 [Chango in the leucocyte blood formula of the common gudgeon during Lioula,infestation.] Papers- on Helminthology presented to acadomician K.I. Skryabin on hie 75th birthday. .LTooeovn Izdatolstve Akadomii Vault SSSR. 617-6/9. SCHAUINSLAND, Hip 1885 Die ombryonalo Entwickolung dor Bothriocophalen. . - Jona. Z. Natw. 190 520. . SCHEURING L. 1930 "Beobachtungen our Biologio des gonna Triaenophorus and Botrachtin.. :gen utor,damjahrseitliche Auftroton von Bandwurmen." Ztschr. f. Parasitenkunde, Dd.2 11, 2-. SHULIMAV 0,6; 1957 The parasites or Zhushitsa Lakes fioh Loki). Bull. All.Union Goi: Research Inst. Lake- and. Rivor Piohories., XIII, , .334-335, SINHA, D.P. and 1967 Tomporaturo effect on the growth of 942=MaT1141.12.4,— In pross4 MYTH. J.D. 1946 Studios on tapoworm phyoiology. I. ✓ Cultivation of Schintoculala solidus in vitro. J40. Expt1e Biol. 23. 47-70. SMYTH, JO. 1948 Development of cestodos in vitrot ✓ Production of fertile eggs; - Oitiy cultivation of plerocorcoid fragmontc raturd. 161. p4138. 261. - SMYTH, ti.D. 1947 Studios on tapoworra ph oiologr. II. cultivation and development of &i la intentinalis in vitro. Parasit, 3813), 175.181. `-/ SMYTH, J.D. 1949 Studies on tapeworm physioloa Further observations on the dovolop- ment of Ligula intestinalis in vitro. 3. rxntl. Parasit. 26, 1-24. MYTH, J,D. 1954Et Studios" on tapeworm physiology VII. Fertilisation of Schir.3toconhelus solidus ill vitro. Parasit• 3,. , \ -7 MATH J • 1955 , Probloms rolating to theitro i._ cultivation of psoudophy costodos from egg to adult. Rovista Iborica do Parasitologica# Granada, (Espana). T=o Extra., ordinarie. - 11 SMYTH, J.D. 1963 Tho biology of coated° life cycles. Tochnical communication NO. 34, Commonwealth Bureau of Fleltiinthology. Sunlit JO. 1965 Poroonal communication. SCIIPOLYAITSICAYA# 1953a (Change in the chemical composition A.T. and texture of the tissues of fish with ,Tiiitula infootions.} Dokladi Lioekovokaya Ordena Solskokhozyaistvennaya Altademiya im, Timiryazova# 85, 367-370. (In Russian)* SHPOLYANSICATA# 1953b [Influence of Lirula on obangoo A.Y. occurring in faMrito formula for the blood of fiches.] Dokladi Akadomii Nauic =R. 90 (2), 319.320. (In nu5sian). 1,/ BOUM/ELL, T. 1928 Cestedec o2 the order Pseudo.. phy/lidea recorded. from India and Ceylon. Annals of Tropical Medicine and Parasitology, 22, p.433. 262. span, Val. 1955 Lipid° Analysis. Methods of Blochem. Analysis, II. (Edit. D. Glick) S3-111. TIBOVA, S.D. . 1957 The parasitofauna of bream (Abrnmis ✓ 112.00 of Lake Ubinakoo. Bull. All-Union £3o1. Resoarch Incu. of Lake and. Rivor Fisheries, ZLII, 160-170.. VERMER, T. 1936 The eggs and the aoracidia of Dipiralbothrium lotum. Michigan Acad. Sci. Arts &Ilett.v.,21. NJ 'OGEL, H. 1929 Studien zurEntvickelung.von ...D..11=4.Lrethx...... innt 1. • Toy.. "schrift -ft, Pnrasitonkunde# Bd.2# 11.2. N von MUM, T. 1966 Biochemistry of parasites. Academic Press. N.Y. and London. v/ WORE, 7.11. 1950 iTho distributiOn of tapeworms Ligula) in Estonian vaters.] Zool. "hurnal 29 (4), 325-326. (In Russian). ,)/ WALICRY#' V.- 1963 Observations on cm, ain host- paraoite rolationslips in the three. spilled stickleback Gastgresteus aculeatus Linnaeus 1754. Ph.D. Thesis. Univorolty of Durham. WAR LE. R.A. 1932 The cestoda of Canadian fishes I. Hudson Bay drainahe system. Contrib. To Canad. Biol. Rev Scrim, 7# 40, 579-403. WARDLB ncite and 1952 The zoology of tapeworms., MIX ON J.A. University of Minnesota Promo, Minneapolis. - =moat ILA. 2965 The biochcmistry and physiology of Digonetic ava and larvae. Ph.D. Thesis, University of London. 263. +/1ITnE ny, •LI.P. 1940 The handbook of British birds* (Edit.) ot al* wo- Witherby litd* Mondon* Vol IV* Cormorants to Crano* 4 WM, .P*d* 1950 Quoted from Needhem 1964. ZITUAll, R. 1964 "Vokova dynamika pleroeorkoidov Tamils Intostinolis (Ti.) u plotieo obyeajnoj'llutilasj.ratqns) a nelktoro je zv askmodt ." Blologia Bvatinlavat 19 (2), 107.1116' (Got= and Russian sumnoriesi NM). - - 264. APPEITDIX • TABLE XXXII libta/ . , DO., No. ris Mipid , eJorror N0. m5 , ,Aipid IfJorror 3 -7.0.14.8, 0r. a 125.3 5.5 4-.04Y 4. - 5 559.6 5.8 -4,0 23 6.3- 14.8 0 16 359.0 3.7 .4.-1.8 57 82.6 6.7 17 201.3 5.7 0 33 78,5 ,' 5.2 3 3 .t4. sincle sample. 265; t . ... TAD1,T-1 XXXIII •• • .'1 , " , " '\7o:t{~ht 'P~e~ocercoid 'Gle.. _vcoson•• __ ,P0r.... ••dry:::..l. n I .. • ••of: 1 .. :; .. ~ •.1._ I -, ttecI T\.. I••h. %glycogon; , .-'- . 482.4 ' . " , ~,'. 29G.~ ~ : _., I, • 'f· ; c \ 351.3 " '52.0 . 57.S. 1870~2;, ' 65.8 .. , v " '_ ,t . ~ \ ' 2046,5 , .' , " , .. -"'"~ . '. " , -.' , -54.. 0 " . •I ~. .-- l043.a- , .t 60.5'_ , " 1211.2' 56.4' 33.9', " 57.6' ,30.0" . " .: -4G.G . ~ :.. ~ ~ . ..- , ' 29,9 " " ·52.0 o , _~. •• ~,I . . -r 39.9,::' , , , 47.2 " " ;;!-f.l . v : ' ,.' " 51.3 J,;' : 93.4' . -, , "'2::> "v~, ~. , , 'f ~, , , . ' ?11.9 " ' . ,62.8 )-- . , .. .. , , 60.a , 3762.,0 , 1700.0 16S3.0' 266. .!LM XXXII 4":°°t °11°Illat r1:1";1"c71 a.' " #* °±"",MOVIIPATOtill DJ. of plor000rooid nitzoizon inoreago of error 4 dterninationu or - 042795 4.67 . 3.6 0.5422 5.24 9.5 0.6792 5.14 •243:' 0.2253 5.67 9.3 1.0421 4.60 .. 7.3 0.2862 5.06 .3.3 0,3715 4.70 5.7 0.2563 3.75 9.3. 0.2135 5.39 3.27 0.0363 5.04 4.1 0.1229 5.65 9.0 0.1260 5.90 10.6 0.1054 5.55-.., . , 3.7 0.0775 6.46 3.2 0.0398 7445 3.3 0.2416 6.18 2.7 0.0210_ 5.77 , 0.0443 5.20 '2.6 0.2072 5.01 ' 2.9 0.3395 5.28 2.0 0.1947 6.30 -9.5 0.0357 5.63 3.0 0.3350 9.12 ' 2.5' 0.2558 -5476 1.7 0.4131 4.44 ' 2,9 0.2787 6.16 7.6 0.1346 5.95 . 0.5138 5.35 11.4 0,3827 5.32 3.1 0.0607 7.77 _5.1 0.0478 5.04 . 0.0770 7.10 0.1 0.3100 5.06 3.1 0.1052 4.60 , 4.7 0.0692 9.03 11.3 4f0410 6.50 6.9 0.0914 7.18 2.7 0.1420 6.55 7.9 0.0602 6.12 042 0.1892 6.08 11.4 0.1776 7,22 2.9 0.0347 6.96 2.0957 4.30 4,3 24270 4.50 2,8 1.1149 4.78 3.4 44543 3.18 1.9 267. TABLE LXXV •ant...2.16A • il000rvoir level rtotoi, temp. -Ii.an.r..lir ton!". l'inin .thatmingkm• oo.110o9n, Morr3r Tom. down in.• inolloo ' - °C. . -, °Cr* • : 1n 1 14 - 16' 52 ' -...... i ' ,14 . 15 ' .. 42 0.41 . 3 - 14 =15-- - - ' . . 43 0,06 . 4 15_ • , 16 46 . ,.. - . 5' ,15 , 15. .' , 50 0.15 6 .- 15 .. 15 - 44''' ' .0.22 . . : 7 ..15:• 16. - 55 _ 042 8 . 14- 15 ..: 50 . 0.73.• 9 ,-,- • '. 14 . '16 . 46 .110 10 15 ' 15 , 54 - ' 0.0 far • •S11 ' - 15 :16. 48 •' ..- ''.4.2 -;:..15 - • 16 ''50'. . lie ,. . : 13 , 15 16 ;56- - .0 46- ...... 14 16 • ', 17 ,52 ,16 ,'52 0,03 .-.. 416 15 • • 17 - I.6. , . 1'7 48 -. ;.1.7i 51. .- 17, %." :.:1.7 '4.a. . "ia :,• .17 51; 0.18 19 ' 3.6 . . 18 ' • 50 . 0.19, 20 :1 -•'• - 16: •. 39. .0.32 21 .'1a 3.6 43 . 22 • -16.-. .. It; . 47 0.01 ,23, 19, ; 16 43 et^ , a 24. •rp S. • 1:2. a ' 25 io 04, ..5 '. , 47 •26 21 • '15: - 53 . 27 • , 31, . 3.p • , 52 a 29.- 22 • ' 16 - 59 . 29 22 . 16 '48 gel* 30. • 23 16 ' 49 . • 268. nartn-xxxvi Salmi° data of fry COMpl#1/,,t. atAnplo tOlton. Jtzly 15-th" 1064 oit, fry born :Ln. 1064. Itudd lash Ptah _ , rTo.of Lonctlt of Volcht 02 icatrt.li wolzfat itiltirgla aiililastr.... 111 . ofi a 3.1 0.2 1 04 0«0006 1 3.1 0.2 41.114. IA* • 3.2 O*2 0.4 0.0006 3.1. 0.2 • 441. Via 5 3.0 0.2 WOO we* 6 3.4 0.3 wr 7 3.2 0.2 Mit 8 3.5 0.3 9 3.2 0.2 0.7 , • 0.0006 10 3.0 0.2 1.10 11 3.3 0.3 0*4 0.0012 12 2.9 042 _ 13. A 13 L.. 4e 0.1 1 14 2.3 0.1 16 2.9 0.2 0.5 0.0005. 17 5,0 0.2 0.4) 0. ) , 0.0007 18 3.0 0.3 dm. 19 3,4 0.2 adi 20 - 36. 0.5 21 5.2 0.2 as 22 3.0 0.3.• 0.5 0.0004 41_ 2,9 0.2 24 2.0 0.1 25 249 0.3 FIN