RESEARCH OPPORTUNITY

Do Zebra Mussels Have Parasites?

Part I: An Opinion

If our understanding of subject areas like zebra mussel ecology, systematics, physiology, behavior, etc., seems in its infancy, then the study of zebra mussel parasitology is still in its embryonic, or even conceptual phase. At present, very few papers documenting zebra mussel parasites have been published. Yes, there has been the occasional report of a ciliate here or a trematode there, but relatively little in total. As an invertebrate pathologist with the New York State Museum, I find the scarcity of such parasite records misleading, as it gives the impression that zebra mussels do not have many parasites, especially lethal or debilitating ones. If this were true, and these mussels were really so devoid of parasites, they certainly would be rather unique among members of the animal kingdom. All animal groups have an abundance and variety of parasites. Then, why are there so few reports of zebra mussel parasites? In my opinion, it's simple…. it's mathematical...it's because there have been so few serious, focused investigations. When comprehensive parasite studies are repeatedly carried out on an animal group, multitudes of parasites are uncovered. To provide evidence to support this statement, bear with me as I take you out of malacology and over to entomology (my roots are in insect pathology, and when stuck for an example, I regress). The Culicidae, or mosquitoes, are merely one in over 100 aquatic insect families. A literature survey that I did on fungal parasites of aquatic insects, however, indicated that a very high proportion of the fungal parasites that have been reported from all aquatic insects were from this one family. Why so? Is it because mosquitoes are particularly susceptible to parasites? No. It was because mosquitoes, due to their international medical importance in disease transmission, have been the most intensely investigated of all aquatic insect families. As the proverb says, "When you look hard, you find." Similarly, I submit that zebra mussels actually have a wide variety and number of parasites, ranging from the relatively benign to the lethal. If one assumes this to be true, then there is a great deal of work on zebra mussel parasites that remains to be done.

Part II: An Appeal

If you share my enthusiasm, logic, and bias for parasitological investigations, please get in touch. I am currently putting together a list of scientists/graduate students, etc., with expertise and/or interest in areas relating to zebra mussel pathology. Specialists in the biology, taxonomy, ecology, etc., of parasitic/pathogenic organisms (e.g. protozoans, trematodes, viruses, fungi, bacteria, nematodes, etc.) are encouraged to join this international network (individuals outside the United States are encouraged to participate). Our initial goal will be to increase communication and collaboration, and thereby accelerate progress toward discovering, identifying, and understanding the biology and life cycles of zebra mussel parasites. From this initial goal, we could move on to address other questions, such as: what role do parasites play in regulating zebra mussel population dynamics; will trematodes which parasitize zebra mussels have a significant impact on fish and water fowl populations; could a lethal or debilitating parasite be used for the biological control of zebra mussels? Researchers without a background in parasitology could also be helpful in this effort by reporting mussel population die-offs or crashes, whether observed in the field or laboratory. The mussel population in question could be examined (moribund specimens are actually more valuable than dead ones), and if suspected to harbor parasites, passed on to an appropriate specialist. Similarly, researchers working on zebra mussel viscera for reasons unrelated to parasitology (e.g. reproductive studies) are encouraged to look for and inform us of unusual looking organs which might be parasite infected. The best clues to look for would be discoloration or deformation of mussel tissues or strange looking microbial organisms staring back through the microscope. So I encourage anyone interested in joining this network to get in touch with me. Let me know your interests and expertise, even if they are quite narrow in scope. The cooperation and collaboration that will result will breathe life into a neglected aspect of zebra mussel research. Hoping to hear from you….

Dr. Daniel P. Molloy

New York State Museum Field Research Laboratory

RD I-Box 151 Cambridge, NY 12816 TEL: 518/677-8245

FAX: 518/677-5236

(Dr. Daniel P. Molloy, New York State Museum)