Using Monogenoids (Phylum Platyhelminthes) as Indicators of Aquatic Ecosystem Health

Abstract

Environmental parasitology encompasses studies on parasites as (bio)indicators of environmental health. A bioindicator is a species or group of species that can respond to specific changes in the environment caused by anthropogenic or natural stressors. Monogenoids (phylum Platyhelminthes) are ectoparasites that usually infect the gills and/or skin of fish. There is growing evidence that monogenoids can act as reliable bioindicators due to the variety of ways they respond to environmental variables. This chapter reviewed the published literature on monogenoids’ responses to environmental changes and concluded that monogenoids can provide valuable information for two major environmental factors: 1) physicochemical parameters of water and 2) aquatic pollutants, particularly metals. However, due to the complexities of parasite–environment relationships, monogenoid species may sometimes produce conflicting results regarding environmental changes. Nonetheless, the intimate linkage between monogenoids and their aquatic habitats, combined with their ability to cause disease outbreaks in specific conditions, makes them potentially useful indicators of ecosystem health and a viable alternative in environmental parasitology.