UV AS AN ECOLOGICAL INVASION BARRIER:UV INACTIVATION OF Myxobolus cerebralis, VHSV,AND MARINE PHYTOPLANKTON

摘要

UV has been successfully applied to the inactivation of viruses, bacteria and protozoans in municipal drinking water, wastewater and reuse applications, and much is known about its effectiveness for inactivating pathogens in these classes. UV is now being used in other applications with similar and new classes of pathogens.We have been investigating the effectiveness for UV to inactivate a variety of new pathogens, that could be classed together as ecological invaders. They cause harm to natural aquatic populations, or to the ecology of aquatic ecosystems, and are often spread anthropogenically. This paper will show examples of our studies, also highlighting the need for understanding the proper metrics of inactivation of new pathogens, as demonstrated in the evolution of knowledge of UV inactivation of Oyptosporidium.Whirling disease of salmonid fish is caused by Myxobolus cerebralis, a myxozoan parasite with a two host life cycle. Through infectivity studies of the different spore forms with their respective hosts, we demonstrated the effectiveness for UV to inactivate them and prevent the spread of whirling disease to and from hatcheries. This work superseded earlier work that had much higher UV dose requirements because vital stain methods overestimated the UV requirements. VHSV is a virus that infects a broad range of fish species, and was recently introduced to the Great Lakes where it caused numerous fish kills of many species. We demonstrated the UV dose-response characteristics of VHSV. We also examined the UV dose-response characteristics of a number of marine phytoplankton, possible candidates for spreading by ballast water. We compared a number of methods to demonstrate the effects of UV. Together these studies show the wide applicability of UV to inactivate many pathogens in many applications, but reinforces the need for using the correct metrics.