'I BULLETIN DE L'INSTITUT ROYAL DES SC IENCES NATURELLES DE BELG IQUE, BIOLOGIE, 68: 47-53, I998 BULLETIN VA N HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWET ENS CHAPP EN, BIOLOGIE, 68: 47-53 , 1998

The Asiatic clam Corbicula (Bivalvia: Corbiculidae) 1n

by F. SWINNEN, M. LEYNEN, R. SABLON, L. DUVIVIER & R. VANMAELE

Abstract Introduction

Over the past few years Corbicula jluminea (MOLLER, 1774) Corbiculajluminea , notorious for biofouling power plant and Corbicula jluminalis (MOLL ER,1774) started colonizing the service systems world wide, has gradually conquered the river Meuse and some major connecting canals in Belgium. river Meuse. ln 1994, DUVIVIER & VANMAELE (LABORELEC) A map with the presently known distribution in Belgi um is identified Corbiculajluminea in the nuclear service water provided. system at Chooz (France) along the river Meuse, which is very close to the Belgian border. In the same period, Key-words: Bivalvia, Corbiculidae, Corb icula, Belgium, Corbicula species including C. jluminea, were also found biofouling, service water system . in the river Meuse on Dutch territory (bij de VAATE, 1994). Hence Corbicula jluminea could be expected also, like the well-settled Dreissena polymorpha (PAL LAS , 1771 ), Resume biofouling service systems along the ri ver Meuse in Au cours des quelques dern ieres annees, Corbicula jluminea Belgium. Subsequently Corbicula jluminea was found (MOLL ER, 1774) et Corbicula jluminalis (MOLL ER, 1774) ont close to power plant service systems at Seraing (river commence a coloniser en Belgique Ia Meuse et ses canaux de Meuse) and Mol (Canal Bocholt-). joncti on . By 1997 Corbicula jluminea was abundantly present in Une carte de repartition actuell e en Belgique est presentee. service water systems at Seraing, Tihange, Langerlo and Mol. We assume that by that time, it became well Mots-clefs: Bivalvia, Corbiculidae, Corbicula, Belgique, salissure established in the Belgian section of the river Meuse and biologique, circuit de refroidissement some of the larger connecting canals and probably is still expand ing. Meanwhile the estuari ne species Corbicula jluminalis ha s been found, albeit less frequent, in samples from , Gee! and Langerlo.

Distribution

Table 1 - presents localities in Belgium known so fa r to be succesfully colonized by Corbicula sp.

Coll ector Date or year Locali ty UTM Corbicula Corbicu/a Other species present jluminea jluminalis DUBR UN * 1992 MEE RHOUT FS46 ? ? not checked Fa ll ow land, covered with slush (I) 0 UVIVIER 1994 CHOOZ (FRANCE) , + - Dreissena polymorpha & VANMA EL E Ri ver Meuse LAB O ECOL . & 1995 SERAl NG FS80 + - Dreissena polymmpha AQUACU LT URE River Meuse Physella acuta KUL AN D MOL FS47 + - Dreissena polym01pha LABORELEC,S PE Canal Bocholt-Herentals DUB RUN * 21-5-1996 MEER HOUT (2) FS46 + - Dreissena polym01pha II

48 F. SWINNEN, M. LEYNEN, R. SABLON, L. DUYlVIER & R. VANMAELE

Collector Date or year Locality UTM Corbicula Corbicula Other species present jluminea j!uminalis LEYNEN & 1997 SERA lNG FS80 + - Dreissena polym01pha LABO RELEC Power plant river Physella acuta Meuse TIHA NGE FS60 + - Dreissena polymorpha Nuclear power plant, river Meuse LANGERLO FS74 + + Dreissena polymorpha Power plant Physella acuta Albertkanaal MOL FS47 + - Dreissena polymotpha Power plant 10-1997 Canal Bocholt-Herentals P. SWINNEN 1997 FS37 + + Lithogliphus naticoides & F. SWINNEN ** Slu ice 7, Canal Bithynia tentaculata Bocholt-Herentals Va lva/a piscinalis DUBRUN * 31- 10-1997 MEERHOUT FS46 + + Dreissena polym01pha 11-12- 1997 Unio pictorum LE YNEN 26-3-1998 SERA ING FS80 + - Dreissena polymorpha & SABLON Power plant Physella acuta river Meuse Bithynia tentaculata Valvata piscinalis Sphaerium rivicola LANGERLO FS74 + + Dreissena polymorpha Power plant Physella acuta Albertkanaal Bithynia tentaculata Potamopyrgus antipodarum Sphaerium corneum MOL FS47 + - Dreissena polym01pha Power plant Physella acuta Canal Bocholt-Herentals Bithynia tentaculata Radix ovata P. JACOBS * May 1998 HERE NTALS FS27 + - ? Canal Bocholt-Herentals FS37 VIERSEL FS 17 + - ? netekanaal FS27 + - ? Albertkanaal

In 1992 it was not sure where the slush came from since it is common practice to transport mud from dredging-works and subsequently dump it in other, often distant, places for various reasons. The collector not being fam il iar with the species m the Belgian fauna, mistook it fo r a marine species. 2 By this time it was confirmed that the slush came from dredging-works at the Albertkanaal in the vicinity. * In collaboration with the RB INS. ** In co ll aboration with KUL.

Taxonomy Over the past decades Corbicula species started conquering Western Europe. To our lmow ledge Corbicula species in Ever since MOLLER described three new species in the Western Europe are present in The genus Tellina LINNE, 1758: T fluminea, T fluminalis and (GITTENBERGER & VAN PEURSEN, 1992; MI EN IS, 1993 ; T fluviatilis, many living species of Corbicula MOHLFELDT, MOOL ENBEEK, 1993), France and Portugal (MOUTI-IO N, 1811 , have been described in freshwater and estuaries 198 1), Spain (ARAUJO et al., 1993) and Germany from Southeast Asia and elsewhere in the world (ARAUJO (KINZELBAC H, 1991) and might be expected in Luxemburg et al., 1993). (DHUR & MASSARO, 1995). I I

Corbicula in Belgium 49

Everywhere Corbicula has frustrated taxonomists because In Belgium, Corbicula can't be mistaken for any of the of its great variation in shell morphology and colour, autochtonous bivalves. The shell is thick and heavy and linked with the wide geographical and ecological range. has two equally sized similarly shaped valves, united by Moreover, according to ARAUJO et a!., 1993, there was a thick external ligament. The shape is oval in juveniles no proper designation of type specimens for the three in and more or less triangular in adult specimens. Hitherto Western Europe living species acknowledged so far, which two Corbicula species have been recorded in Belgium. was adding to the confusion. Therefore ARAUJO et a!., They can be distinguished by to the following characte­ 1993, designated type specimens for the three Corbicula ristics: species. We have adopted this point of view in present publication.

C. jluminea (MOLLER, 1774) C. jluminalis (MOLLER, 1774) Shell moderately triangular. Shell triangular with very pronounced umbos. Size up to 30 mm. Size up to 25 mm. Up to 40 well-marked concentric ridges on the surface Up to 45-55 well-marked concentric ridges on the surface. External surface glossy, dark brown to olive. External surface glossy, dark brown to olive. Internally the shell is white with a blaze of purple Internally the shell has a deep purple blaze. more or less pronounced along the margin and the muscular impressions. Dorsal border thick with strongly developed cardinal Dorsal border very thick, teeth same as C. jluminea. (3) and lateral teeth.

Fig. I. - Presently known distribution of Corbicula species in Belgium. From left to right, top to bottom: Viersel, Grobbendonk, · Herentals, Gee!, Mol, Meerhout, Langerlo, Seraing, Tihange and Chooz (France). II

50 F. SWINNEN, M. LEYNEN, R. SABLON, L. DUVIVIER & R. VANMAELE

Fig. 2. - C. .fluminea (MOLLER, 1774), I. Seraing (27x24 mm), 2. Tihange (22xl9.5 mm); 3. Seraing (3.5x2 mm), (8x4.5 mm), ( 18x ll mm), 4. Mol (8.5x6 mm), ( 11 .5x9.5 mm), 5. Genk (Langerlo) (22xl7.5 mm). I I

Corbicula in Belgi urn 51

Shell size seems to be the most variable feature in Control techniques include mechanical, physical and European Corbicula populations. For that reason, shell chemical controls. In Belgian plants, clams are removed shape rather than size at different locations should be physically on a periodic schedule. Since 1993, different compared (ARAUJO et al. , 1993). control methods such as chlorination and ozonization, are thoroughly studied at the Laboratory for Ecology and Aquaculture (KUL) in collaboration with ELECTRABEL,SPE Cot·bicula as a biofouling organism and LABORELEC . Ecological demands, sexual strategy and life span are The freshwater clam Corbicula jluminea has effectively different in both C. jluminea and C. jluminalis which fouled service water systems in power plants because this certainly has an impact on expansion (MORTON, 1982). The environment fulfils the ecological needs of the species former species is essentially a stream dweller that incubates i.e. temperature over 20°C most of the year, there is suffi­ fertilized eggs and has a life span of approximately 3 years, cient oxygen and food supply and there are no natural the latter prefers lentic estuaries, lives for much longer and enemies. Hence growth and reproduction within these fertilized eggs are usually not retained (MORTON, 1982). systems is considerable (PAGE et al. , 1986). From this perspective, invasion in Belgium is followed at Problems caused by fouling are multifold: I. flow blockage the RBI NS, blending in with the general project on fresh­ at the bottom of the intake structure and intake tunnels; water molluscs which is treating historical as well as recent 2. accumulation in cooling tower bassins, fire protection data on occurrence, loss or expansion of the autochtonous lines and discharge canals; 3. clogging fi lters. malacofauna and its causality. I I 52 F. SWINNEN, M. LEYNEN, R. SABLON, L. DUVJVIER & R. VANMAELE

Fig. 3. - C. jluminalis (MOLLER, 1774), 6. Genk (Langerlo) (12.5xl3 mm), 7. Meerhout (15xl6 mm).

Conclusion in the USA (BRITTON & MORTON, 1982). From North America it was successfully introduced in Europe in the Since the expansion of the Asiatic clam ( Corbicula) across early 1980s. the United States in the late 1950s and early 1960s, people At this moment the knowledge of the extent, let alone became aware of the bivalve mostly in a series of negative of the biological impact, of the invasion on Belgian encounters. The clogging of pipes and vessels in some territory is still in a premature fase. It's evolution in kind of industrial operations has been one of the most Belgium however needs to be followed , preferably from costly ways in which the Asiatic clam has created problems different angles. I I Corbicula in Belgium 53

Acknowledgements MOOLENBEEK, R.G., 1993. Problemen rond de naamgeving van de Aziatische korfmossel, de fijngeribde korfmossel en de toege­ We sincerely wish to thank our field collaborators Philippe knepen korfmossel. Correspondentieblad van de Neder/andse SWINNEN, Norbert DUBRUN and Paul JACOBS for providing Malacologische Vereniging, 270: I 9-2 I. some of the material. Special thanks are due to Thierry MORTO N, B., I 982. Some aspects of the population structure B ACKELJAU, RBINS, for commenting upon the manuscript, and sexual strategy of Corbicula cf. jluminalis (Bivalvia: Corbiculacea) from the Pearl River, People's Republic of China. to Prof. F. OLLEVIER , A. van P EURSEN and C. MASSIN Journal of Molluscan Studies, 48: 1-23. for their kind suggestions. Photographs were taken by T. HUBIN, RBTNS. The illustrations were prepared by H. VAN MoUTHON, J , 198 I. Sur Ia presence en France et au Portugal de Corbicula (Bivalvia, Corbicuiidae) originaire d' Asie. Bas feria, PAESSCHEN, RBINS. 45:I09-I I6. PAGE, T.L., NEITZEL, D.A., SIMMONS, M.A. and HAYES, P.F., I 986. Biofouling of power plant service systems by Corbicu/a. References Proceedings of the Second International Corbicu/a Symposium. American Malacological Bulletin, Special Edition Nr. 2: 4I-45. ARUJO, R., MORENO, D. and RAMOS, M.A., 1993. The Asiatic clam Corbicula jluminea (MOLLER, 1774) (Bivalvia: Corbiculidae) Frank SWINNEN in Europe. Arnerican Malacological Bulle/in , I 0( I): 39-49. Lutlommel I 0 bij de VAATE, A., 1994. Corbicu/a 's in de Maas. B-3920 Lommel, Belgium Correspondentieblad van de Nederlandse Malacologische Vereniging, 278: 73. Michel LEYN EN BRITTON, J.C. & MORTON, B., 1982. A dissection guide, field KULeuven and laboratory manual for the introduced bivalve Corbicula Laboratory of Ecology and Aquaculture jluminea. Malacological Review: supplement 3: 82p. Naamsestraat 59 DI-IUR, G. & MASSARO, JA., 1995. Etude historique et faunis­ B-3000 Leuven, Belgium tique des lnvertebres immigres ou introduits dans Ia Moselle luxembourgeoise et ses aftluents_ Bulletin de Ia Societe des Natura/isles Luxembourgeois, 96: 127-156. Rose SABLON Royal Belgian Institute of Natural Sciences GITTENBERGER, E. & VAN PEURSEN, A.D.P., 1992. Corbicu/a's in Malacology Section Nederland. Corresponc/entieblac/ van de Nec/er/andse Malaco/ogische Veren iging, 268: I 032-1033. Vautierstraat 29 B-1 000 Brussels, Belgium KINZELBACH, R., 1991. Die Korbchenmuscheln Corbicula jlumi­ nalis, Corbicula jluminea und Corbicu/a jluviatilis in Europa (Bivalvia: Corbiculidae). Mainzer Naturwissenschaftliges Archiv, Leon DuviVIER & Ria VANMAELE 29: 215-228. Laborelec MIENIS, H.K., 1993. Een opmerking betreffende de naamgeving Rue de Rhode 125 van de in West-Europa voorkomende Corbicu/a soorten. B-1630 Linkebeek, Belgium Correspondentieblac/ van de Nederlanc/se Malacologische Vereniging, 270: 16-17 _