Copepoda (Crustacea) associated with commercial and non-commercial Bivalvia in the East Scheldt, The Netherlands

4 Pages·1993·0.49 MB·English

by  Stock, Jan H

Bijdragentot deDierkunde, 63 (IJ 61-64 (1993)
SPBAcademie Publishingbv, The Hague
Shortnotes andreviews
Copepoda (Crustacea) associated with commercial and non-commercial
Bivalvia in the East Scheldt, The Netherlands
Jan H. Stock
c/o Institute of TaxonomieZoology, University ofAmsterdam, P.O. Box 4766, 1009ATAmsterdam,
The Netherlands
Keywords: Bivalvia, parasitic Copepoda, Netherlands
Abstract Theshellswereopenedand theanimal'ssoftpartsweretaken
outand placedfor some 12hoursinamixtureof95% seawater
Sixspecies ofCopepodaPoecilostomatoida ofthe familiesMyi- and 5%ethylalcohol. Thefluid wasthen filtered througha300
colidae,Sabelliphilidae,Lichomolgidae,and Mytilicolidaeare fimsieve and the copepodswerepickedfrom theretained sedi-
recorded from sixdifferent species ofintertidal bivalves in the mentunder a dissectingmicroscope.Specimenswerestudied in
East Scheldt (TheNetherlands),abranch ofthe southern bight glycerine orlactophenoland dissections were stored as perma-
ofthe North Sea. One bivalvespecies may harbour more than nentmounts in Reyne's modification ofFaure's medium.
Representative sets of each species have been placed in the
onespecies ofcopepod,and onecopepodspeciesmay usemore
than onespecies ofbivalves ashost. Zoölogisch Museum ofthe UniversityofAmsterdam.
Mytilicolaorientalis andMyicolaostreaearenewtotheNorth
Sea,bothbeingundoubtedlycarriedinaccidentallywithoriental
oysters, successfully introduced formariculture. Inthelightof Results
the damagethatwascaused by Mytilicolaintestinalis toDutch
mussel cultures in the past, the acclimatization ofM.orientalis
The following copepods and host molluscs were
is amatterofconcern, the moresosince it infests notonly its
original oriental host, Crassostrea gigas, but also the native found:
Europeanspecies, Ostreaedulisand Mytilusedulis,bothimpor-
tant fisheries resourcesin the East Scheldt region.
Family MYICOLIDAE
Materialand methods
Myicola ostreae Hoshina & Sugiura, 1953
DuringtheperiodMaytoSeptember1992,bivalves wereregu-
larly(3timesaweek) collectedin theEast Scheldt,onthe south Material. — Nine specimens from Crassostrea gigas and two
coastoftheisland ofSchouwen,atalocalitycalledSchelphoek. specimensfromOstreaedulis(collectedoverthe entireperiodof
Thecentre ofthe areabears the coordinates 45.500 x 413.000 observation).
onthe topographicmap of the Netherlands, sheet 42, scale
1:50,000(Topographical Service, Emmen, 1986), which cor- This copepod has no doubt been accidentally in-
responds roughly with 51°33'N 03°36'E. The area is semi-
troducedintoDutch waterswithorientaloysters. It
enclosedbytwodams,fullymarine,butprotectedagainstrough
seas.The tidaldifference duringspringtides may amountto 3 is uncommon, thoughactively reproducing, bothin
mormore.Itswesternpart consistsofgraveland boulders;the C. gigasand O. edulis (the latterbeing anew host
central and eastern parts areintertidal flats ofsandy mud and forthespecies). Theseare thefirst records for Myi-
finesand. Atlowspringtides,extensive oysterbedsareexposed, cola ostreae in the North Sea; the species comes
mainlyinhabited bywild specimensoftheacclimatized oriental
originally from Japanese and Korean waters.
oyster,Crassostrea gigas.
The bivalve species encountered, and their copepod asso- The generic status ofthis copepod hasbeen dis-
ciates, areshown in Table 1. cussed by Humes (1986), whosuggested to remove
62 J.H. Stock - Copepoda infesting Bivalvia in the East Scheldt
M. ostreaeto thegenusOstrincola, butfor themo- Thereal hostof thiscopepod issomewhatofamys-
ment I follow Ho & Kim (1991) and consider the tery; it is supposed to live on (feed on?) brownal-
multiseriate ovisac a key character for Myicola. gae.Atanyrate onlytwo specimens ofthiscopepod
were found in Crassostrea gigas, which seems to
indicate that this occurrence must be considered
Family SABELLIPHILIDAE accidental.
Thespecies was alreadyknownfromTheNether-
Herrmannellarostrata Canu, 1891 lands (Stock, 1957: 380; Stock & De Vos, 1960:
206).
Material. - Five specimensinbranchial chamber ofMyaarena-
ria, many specimens in branchial chamber of Scrobicularia
plana,andmanyspecimensinbranchial chamber ofCerastoder- Family MYTILICOLIDAE
ma(formerlyCardium) edule.
Mytilicola intestinalisSteuer, 1902
Although this copepod is known from at least 11
differentbivalve hosts (Humes & Stock, 1973), it
Material. - Manyspecimensfrom the guts ofMytilusedulis.
was not recordedbefore from Mya arenariaand
Scrobiculariaplana. Avdeev (1987) records a spe- This copepod has been known from The Nether-
ciesofHerrmannella, H. dentata, fromMyajapo-
lands sincetheearly fifties(Korringa, 1950; 1951),
nicaintheSeaof Japan,butIcontentedmyselfthat
whenit causedconsiderabledamage to mussel fish-
theDutchmaterialfrom Mya belongs to H. rostra-
eriesandcultures.Inthecourse oftheyears,thein-
taand not to H. dentata.
tensity of theinfestations declinedto such a level
HerrmannelladugganiHolmes& Minchin, 1991,
thatnoseriousharmoccurs anymore. Atthemaxi-
recently describedfrom Ostreaedulis fromIreland
mum ofthe epidemic, M. intestinaliswas sparingly
andBrittany, has not beenencounteredduring our encounteredin othermollusc hosts as well (Ostrea
study.
edulisandthegastropod Crepidulafornicata (Lin-
In TheNetherlands, H. rostrata occurs predom-
naeus, 1758); Stock, 1965). During our 1992 sur-
inantly in the Cockle, Cerastoderma edule but
, vey no Mytilicola intestinaliswas found in these
hasalso been found (Stock, 1965) in Macoma
two hosts. InMytilus edulisfromSchelphoek, M.
balthica(Linnaeus, 1758) and Spisuta subtruncata
intestinalisis morecommonthanthe following spe-
(Da Costa, 1778).
cies, M. orientalis.
Steuer published the combinationMytilicola in-
Modiolicolainsignis Aurivillius, 1882
testinalisn. gen.,n. sp. twice(1902, 1905);thefirst
yeartakes priorityof course.
Material. - Many specimensfrom thegillsofMytilusedulis.
Mytilicola orientalis Mori, 1935
Thissmallcopepod, withitsdistinctivepinkcolour,
is common in the Borealregion of Europe, and is
Material. - Manyspecimensfrom the gutofGrassostrea gigas;
already knownfrom TheNetherlands(Stock & De manyspecimensfrom the gut ofOstreaedulis; somespecimens
Vos, 1960:206; Stock, 1965: 67). from the gut ofMytilusedulis.
No doubt this species, like Myicola ostreae, has
Family LICHOMOLGIDAE beenintroducedaccidentally intoEurope (andelse-
where, e.g., on the Pacific coast of the U.S.A.,
Macrochironfucicolum Brady, 1872 whereit was at first considereda differentspecies,
M. ostreae Wilson, 1938) with oriental oysters,
Material. —Two females from the gillsofCrassostreagigas. Crassostrea gigas. In Schelphoek, C. gigas nowa-
Bijdragen tot de Dierkunde, 63 (1) - 1993 63
Table I.Commercial (markedwith *) and non-commercial spe- respect is the fact that much of its waters never
cies of Bivalvia encountered at Schelphoek(East Scheldt)and leave the embayment. The water moves seaward
their copepodassociates, ifany. Note thattheclam,Myaarena- during lowtide, inlandagain during high tide, go-
ria, is a commercial species along the North American East
ing forthand back in akind of shuttlemovement.
coast, but is notexploitedin The Netherlands.
Infesting larval stages of parasitic or associated
Host Copepod copepods thusstay insidetheEastScheldt, increas-
ing the chance of finding a suitable host. This
*C<rassostrea gigas Mytilicolaorientalis
(Thunberg,1793) Mori, 1935 makes the EastScheldt vulnerabletobooms in in-
Myicolaostreae Hoshina <S festationrates, but ontheother handvery suitable
Sugiura, 1953 for mariculture, inparticular ofoysters, whoselar-
Macrochiron fucicolum vae settleintheareain whichthey were produced.
Brady, 1872
In the early fifties, an epidemic caused by the
*O1 strea edulisLinnaeus, Mytilicolaorientalis
1758 Myicolaostreae copepod Mytilicola intestinalis caused great
*M¡ ytilusedulis (Linnaeus, Mytilicolaintestinalis damage to the commercial activities around the
1758) Steuer, 1902 catch and production of the blue mussel, Mytilus
Mytilicolaorientalis edulis (see Korringa, 1950; 1951). The discovery,
Modiolicola insignis
Aurivillius, 1882 during the present study, of the presence of an
acclimatized population ofthecopepod Mytilicola
(*)M' ya arenariaLinnaeus, Herrmannella rostrata
1758 Canu, 1891 orientalisin theEastScheldtthereforeis alarming.
*C<erastoderma edule (Linnaeus, Herrmannella rostrata As said above, the copepod was no doubt in-
1758) troduced accidentally inthe East Scheldt, through
Scrobiculariaplana Herrmannella rostrata
importation of theoriental oyster, Crassostrea gi-
(Da Costa, 1778)
Angulustenuis (Da Costa, 1778) nocopepods gas, which "escaped" from mariculture and now
Teredo navalis Linnaeus, 1758 nocopepods forms largebanks inthe wild. Notonly itsoriginal
orientalhost is infested, but the copepod invaded
also the indigenous bivalves, Ostrea edulis and
days outnumbers the indigenous oyster, Ostrea Mytilus edulis. It remains to be seen ifMytilicola
edulis. Both oyster species are heavily infested by orientaliswill turn out tobe as noxious as its con-
M. orientalis; lower infestationpercentages occur gener,M. intestinalis.At anyrate, cautious obser-
inthebluemussel, Mytilusedulis.BothOstreaedu- vations of the development of Mytilicola infesta-
lisandMytilusedulisare newhostsforM. orienta- tions seemjustified.
lis. Moreover, these are the first records of M. Of the other alien copepod introduced with
orientalis for the North Sea area; the species oriental oysters, Myicola ostreae, no harmful
originates fromJapan and Korea. effects areknown, butthisassociate shouldbe fol-
Thedistinctionsbetween M. intestinalisand M. lowedas well, especially sinceit hasproved to infest
orientalisarebest shown by Ho &Kim (1992). M. not only its original host, Crassostrea gigas, but
intestinalis has strongly diverging caudal rami, also indigenous oysters, Ostrea edulis. At present,
shorter ovisacs, and less pointed, less divergent, it occurs in numbers too lowto form aneconomic
lateralbody processes. risk.
Theremaining copepod associates areendemicto
theBorealregion, and are not knownto causeany
Discussion noticeabledamage.
TheEast Scheldtis abranchofthesouthernNorth
Acknowledgments
Seawithseveral peculiar ecological characteristics.
The area is fully marine, with very littleinflowof The author is indebted to Mr. R.G. Moolenbeek,keeper of
fresh water, but more important in parasitological Malacology at the Zoölogisch Museum Amsterdam, for the
64 J.H. Stock - Copepoda infesting Bivalvia in theEast Scheldt
identification of the material of Crassostrea gigas, and for LichomolgidaeKossmann, 1877,cyclopoidcopepodsmainly
nomenclatorial advice ontheactual names ofthebivalve hosts. associated with marine invertebrates. Smithson. Contr.
Zool., 127: i-v, 1-368.
Korringa, P., 1950.De aanval vandeparasietMytilicolaintes-
tinalis op de Zeeuwse mosselcultuur. Visserij-Nieuws, 7
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