Suitable Hosts for Glochidia of Four Freshwater

Mark C. Hove, Robin A. Engelking, Margaret E. Peteler, Eric M. Peterson, Anne R. Kapuscinski, Laurie A. Sovell, and Elaine R. Evers University of Minnesota, Department of Fisheries and Wildlife, St. Paul, Minnesota

Abstract. Management of rare freshwater mussels frequently demands knowledge of their fish host(s). We conducted studies during 1993-1995 to determine suitable fish hosts for purple wartyback {Cyclonaias tuberculata), round pigtoe {Pleurobema coccineinu), cylindrical papershell (Anodontoidesferussaciamis), and squawfoot {Strophitiis undulatus). Suitable hosts were determined by artificially exposing glochidia to fish and observing if they developed into juveniles. Of 11 fish species infested with C. tuberculata glochidia, only the yellow bullhead and channel catfish served as hosts. Three cyprinids of eight fish species tested were hosts for P. coccmcum glochidia. Juvenile A. ferussaciamis were collected from aquaria holding spotfin shiner and . Six of eleven species tested were hosts for S. undulatus glochidia. These trials identified several previ ously unknown suitable hosts.

Introduction Materials and Methods

Conservation of North American freshwater Laboratory experiments were conducted during (unionid) diversity is an increasing concern among 1993-1995 to identify suitable hosts for Cyclonaias natural resource managers. The American Fisheries tuberculata, Pleurobema coccineum, Anodontoides Society's (APS) Endangered Species Committee has ferussaciamis, and undulatus. Unionid and announced that 72% of North America's freshwater fish nomenclature follows Turgeon et al. (1988) and mussel fauna is either endangered, threatened, or of Robins et al. (1991), respectively. Test fish were special concern (Williams et al. 1993). Freshwater collected from streams and lakes believed not to mussels are distributed throughout the world but hold the unionids under investigation in order to the greatest diversity occurs in North America. avoid testing fish that had acquired immunity from Many rare unionids are found in the north- prior exposure to glochidia (Neves et al. 1985). central United States (Cummings and Mayer 1992). were collected with a seine, trap net, or Cyclonaias tuberculata (Rafinesque, 1820) is listed as electrofishing equipment. Fishes were held in endangered in Wisconsin, threatened in Iowa, holding tanks (40 1 or 4001) 2-20 days prior to special concern in Michigan, and of special interest glochidia infestation, at temperatures between 18 in Ohio. Cyclonaias tuberculata is also given the and 23°C. conservation status of "special concern" by the AFS Mature glochidia were obtained from gravid Endangered Species Committee (Williams et al. female unionids collected from the St. Croix 1993). Pleurobema coccineum (Conrad, 1834) is listed (Chisago County) and Sandy (Aitkin County) rivers, as endangered in Iowa and of special interest in Minnesota. Females released glochidia while held in Ohio. Anodontoides ferussaciamis (I. Lea, 1834) is beakers in aquaria. After completion of experi listed as endangered in Missouri and threatened in ments, we returned female C. tuberculata and P. Iowa. (Say, 1817) is listed as coccineum to the collection site. Other unionids were threatened in Iowa. deposited at the Bell Museum of Natural History, In most unionids, the larvae must briefly attach University of Minnesota. Glochidia were separated to a fish in order to transform into a juvenile. from conglutinates by gently drawing a conglutinate Management of rare unionids frequently requires in and out of a pipette tube. We retained glochidia knowledge of their fish host requirements. The for host tests if > 70% of individuals closed when purpose of this study was to determine suitable fish- exposed to a 0.1-1% NaCl solution. host(s) for glochidia of purple wartyback {Cyclonaias We attempted to infest fish with glochidia tuberculata), round pigtoe {Pleurobema coccineum), by one of two techniques. All fish species that were cylindrical papershell {Anodontoides ferussaciamis), exposed to P. coccineum, A. ferussaciamis, S. undulatus and squawfoot {Strophitus undulatus). glochidia, and Ictaluriis punctatus, Cyprinus carpio. 22 Conservation and Management of Freshwater Mussels II: Proceedings of a UMRCC Symposium

and Aplodinotus grunniens that were exposed to ids, etheostomids, and catostomids were held in C. tuberculata glochidia were infested by placing suspended nets to prevent them from eating juvenile them in a 1-2 1 bath with several hundred to several mussels on the aquarium floor. Aquaria were thousand glochidia under vigorous aeration. Fish usually siphoned and siphonate checked for pres were exposed to glochidia for 15 minutes to 24 ence of glochidia and juveniles three times a week. hours, depending on the species' susceptibility to A given search for juveniles was usually terminated infestation. Fish species (excluding Ictalurus after three consecutive searches failed to reveal a punctatiis, Cyprimis carpio, and Aplodinotus grunniens) or juvenile mussel. At this termination exposed to C. tuberculata glochidia were infested by point, each fish was anesthetized and searched for directly pipetting glochidia onto one set of fish gill attached glochidia using a dissecting microscope. demibranchs. After direct infestation, fish were held When we found glochidia, the fish was revived and out of the water for 10 to 20 seconds to allow time the experiment continued imtil we no longer ob for glochidia to attach to lamellae. Every two to four served glochidia attached to the fish. A mussel hours after infestation, we checked gills with a was considered a juvenile if foot movement was dissecting microscope and fins by naked eye to observed. A fish was considered a suitable host if determine if infestation was successful. we observed glochidia encystment and metamor After infestation, fish were held in aquaria at phosis to the juvenile stage. 18° ± 2°C and fed frozen brine shrimp or worms at least three times a week. Fathead { promelas) were fed to piscivorous fish Results once a week and removed from aquaria 5-10 min utes after introduction to minimize the possibility of We found two or more suitable host species for each their consuming glochidia or juvenile mussels lying mussel species examined. Our laboratory experi on the aquarium floor. Except for one group of ments identified several previously unknown spiloptera (see footnote in Table 1), cyprin- suitable hosts (Tables 1 and 2).

Table 1. Suitable fish hosts for glochidia of Cyclouaias tuberculata, Pleurobema coccineum, Anodontoides ferussaciamis, and Strophitus undulatus. Fishes are arranged phylogenetically according to Nelson (1994).

N u m b e r D a y s t o N u m b e r o f Species Tested Metamorphosis Juveniles

Cyclouaias tuberculata A m e i u r u s n a t a l i s I 2 2 2 - 2 5 8 A m e i u r u s n a t a l i s I I 2 2 5 - 2 7 4 I c t a l u r u s p u n c t a t u s 2 3 0 - 3 1 7

Pleurobema coccineum 5 16-25 66 P i m e p h a l e s n o t a t u s 6 1 8 - 2 5 1 9 Phoxinuseos 8 18-29 4

Anodontoides ferussaciamis Cyprinella spiloptera 6 12-20 39 Pomoxis nigromaculatus 6 12-15 9

Strophitus undulatus P i m e p h a l e s p r o m e l a s 5 1 4 5 Cyprinella spiloptera 6 11-13 55 Cyprinella spiloptera' 5 10 11 A m e i u r u s m e l a s 3 1 8 - 2 0 3 A m e i u r u s n a t a l i s 2 1 4 - 2 2 6 0 Lepomis macrochiriis 3 10-19 13 Micropterus salmoides 1 13-15 4 Stizostedion vitreum 4 10-29 415

- Not held in suspended net; able to feed off aquarium bottom. Hove et al.: Suitable Fish Hosts for Glochidia of Four Freshwater Mussels 23

Cyclonaias tuberculata (Rafinesque, 1820) Cyprinella spiloptera than from Pomoxis Two of eleven fish species tested were found to be nigromaculatus. No juveniles were collected from suitable hosts for C. tuberculata glochidia. Roughly Pimephales promelas. the same number of juveniles was collected from Ictalurus punctatus and Ameiurus natalis. Ictalurus Strophitus undulatus (Say, 1817) punctatus succumbed to the parasite "Ich" Strophitus undulatus glochidia completed metamor {Ichthyophthirius multifilis) after 31 days. Inspection phosis on a wide variety of fish species. Suitable of their gills soon after expiration revealed heav)' hosts included two cyprinids, two ictalurids, two glochidia infestation. centrarchids, and a percid. Roughly ten times as many juveniles were collected from than Pleurobema coccineum (Conrad, 1834) from any other species tested. Four species were Pleurobema coccineum glochidia successfully trans unsuitable hosts. formed on each cyprinid tested. The greatest number of juveniles was collected from Cyprinella Eleven Cyprinella spiloptera were divided into spiloptera, followed by Pimephales notatus and two groups to determine if preventing fish from Phoxinus eos. Glochidia were sloughed off by the accessing the bottom of the aquarium would in other five species tested. crease the number of juveniles recovered. Eleven juveniles were recovered from the aquarium holding Anodontoides ferussacianus (Lea, 1834) five unrestricted shiners, while fifty-five juveniles Two of three fish species tested facilitated metamor were collected from the aquarium where six shiners phosis of A. ferussacianus glochidia. Roughly four were prevented access to the bottom of the times as many juveniles were collected from aquarium by a plastic screen. We therefore suspect

Table 2. Unsuitable fish hosts for glochidia of Cyclonaias tuberculata, Pleurobema coccineum, Anodontoides ferussacianus, and Strophitus undulatus. Fishes are arranged phylogenetically according to Nelson (1994).

N u m b e r P e r i o d o f Species Tested Attachment (days)

Cyclonaias tuberculata Lepisosteus osseus Scaphirhynchus platorynchus Cyprinus carpio Ameiurus melas I Ameiurus melas II Noturus gyrinus Lota lota Fundulus diaphanus I Fundulus diaphanus II Lepomis gibbosus Aplodinotus grunniens

Pleurobema coccineum E s o x I n d u s Lepomis macrochirus Micropterus dolomieu Micropterus salmoides

Anodontoides ferussacian us Pimephales promelas

Strophitus undulatus Lepisosteus osseus Arnia calva Catostomus commersoni Fundidus diaphanus 24 Conservation and Management of Freshwater Mussels II: Proceedings of a UMRCC Symposium

that the unrestricted shiners consumed juvenile and creek chubs facilitate glochidia S. undulatus although we did not analyze the gas metamorphosis (Howard in Baker 1928). This is the trointestinal tracts of these shiners. first time Pimephales promelas, Cyprinella spiloptera, Ameiurus melas, A. natalis, Lepomis macrochirus, and Stizostedion vitreum have been shown to be suitable Discussion hosts for S. undulatus glochidia. Our results suggest that a wide variety of fish species may serve as This is the first time suitable hosts have been identi suitable hosts for S. undulatus glochidia. fied for Cyclonaias tuberculata glochidia. Use of This study identified suitable hosts for glochidia ictalurids by C. tuberculata glochidia is consistent of Cyclonaias tuberculata, Pleurobema coccineum, with other members of the subfamily Ambleminae. Anodontoides ferussacianus, and Strophitus undulatus Catfishes serve as hosts for a number of unionid but does not provide evidence that glochidia and species in the subfamily Ambleminae. Ameiurus suitable host species encounter one another under melas and Ictalurus punctatus are known to carry natural conditions. Results from this study should Quadrula pustulosa, Q. nodulata, and Q. metanevra be compared with results from a field study de glochidia under natural conditions (Surber 1913; signed to determine the fish species utilized by these Coker et al. 1921). Pylodictis olivaris (flathead catfish) mussels under natural conditions. Molecular is also parasitized by Q. quadrula and Q. pustulosa genetic techniques may be useful in identifying the glochidia under natural conditions. Studies should species of glochidia attached to fish (White et al. be conducted on Pylodictis olivaris using C. tuber 1994). Field research combined with further labora culata glochidia to determine if it is a suitable host. tory transformation studies should lead to the Results from host suitability tests using P. identification of the host(s) of these unionids. coccineum glochidia illustrate the importance of Additional host studies should be conducted on combining field and laboratory research in deter the unionids tested in this study. A relatively small mining glochidia host requirements. This is the first number of fish species and a small number of time cyprinids have been shown to be suitable hosts individuals per trial were tested in this study. Many for P. coccineum glochidia. Round pigtoe glochidia fish families co-occur with these mussels in the are known to naturally infest gills of , but were not tested in this study. Lepomis macrochirus (Surber 1913; Coker et al. 1921). Those trials involving exposure of fewer than six However, L. macrochirus, Micropterus dolomieu, and fish to glochidia should be repeated with larger M. salmoides were unsuitable hosts in this study. numbers of fish in order to verify our results. Only cyprinids and etheostomids are known to facilitate glochidia transformation for members of the genus Pleurobema (Yokley 1972; Weaver et al. Acknowledgments 1991; Hove and Neves 1994). If centrarchids do not facilitate metamorphosis of Pleurobema glochidia, For their assistance in collecting test fish, we thank then listing L. macrochirus as a host for P. coccineum Karl Koller, Steve Pothoven, Tim Essington, and glochidia based solely on observation of natural Jerry Grant of the University of Minnesota; Bruce infestation is premature. Additional studies should Gilbertson, Dave Zappetillo, Audrey Posterick, and be conducted on a larger number of L. macrochirus to Dave McCormack of the Minnesota Department of verify their status as unsuitable host for P. coccineum Natural Resources; and Leslie MacKichan. We also glochidia. thank Dave Heath, Don Hardy, Glen Miller, Daniel A variety of fish species are recorded as hosts Hornbach, Tony Deneka, Robert Bright, Dan Graf, for Anodontoides ferussacianus glochidia, based and Marion Havlik for suggestions on mussel mostly on observations of natural infestations collection sites and fish hosts. We thank the Under (Kakonge 1972; Wilson and Ronald 1967). graduate Research Opportunities Program and Pimephales promelas carry A. ferussacianus glochidia Research Explorations Program, Science Centrum, naturally (Kakonge 1972) although they did not Continuing Education at the University of Minne serve as suitable hosts in this study. To our knowl sota for partial financial support of this project. We edge, this is the first time Pomoxis nigromaculatus and also thank Bruce Vondracek for his helpful critique Cyprinella spiloptera have been shown to be suitable of this paper. This is article number 22,285 of the hosts for A. ferussacianus glochidia. Minnesota Agricultural Experiment Station Scien Little is known of the host requirements for tific Journal Article Series. Strophitus undulatus, whose glochidia are thought to be facultative parasites (Lefevre and Curtis 1911; Howard in Baker 1928). Laboratory tests show that Hove et al.: Suitable Fish Hosts for Glochidia of Four Freshwater Mussels 25

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