A Global Assessment of Parasite Diversity in Galaxiid Fishes

Abstract

Free-living species often receive greater conservation attention than the parasites they support, with parasite conservation often being hindered by a lack of parasite biodiversity knowledge. This study aimed to determine the current state of knowledge regarding parasites of the Southern Hemisphere freshwater fish family Galaxiidae, in order to identify knowledge gaps to focus future research attention. Specifically, we assessed how galaxiid–parasite knowledge differs among geographic regions in relation to research effort (i.e., number of studies or fish individuals examined, extent of tissue examination, taxonomic resolution), in addition to ecological traits known to influence parasite richness. To date, ~50% of galaxiid species have been examined for parasites, though the majority of studies have focused on single parasite taxa rather than assessing the full diversity of macro- and microparasites. The highest number of parasites were observed from Argentinean galaxiids, and studies in all geographic regions were biased towards the highly abundant and most widely distributed galaxiid species, Galaxias maculatus. Parasite diversity generally increased with the number of studies and individual fish examined, however studies which examined parasites from all body tissues could overcome the effects of low study effort. In order to promote further understanding of galaxiid–parasite biodiversity, we provide a series of recommendations, including the use of molecular techniques to verify parasite identity, and highlight the future roles both fish biologists and parasitologists can play.

Helminth Communities of Common Fish Species in the Coastal Zone off Crimea: Species Composition, Diversity, and Structure

“…Thus, despite the substantial difference in species richness, other diversity indices of the helminth infracommunities were comparable in both aquatic areas. These comparisons confirm the opinion that species richness and the diversity of infra- and component communities are uncorrelated with each other [ 1 , 101 ]. This result, however, contradicts some previous data.…”

“…The helminth fish fauna is being recognized as an important field for parasitological research because of their major impact on the fish industry [ 1 , 2 , 3 , 4 , 5 ]. Several helminth species are known to affect the growth, reproduction, and survival of the hosts [ 6 , 7 ] and cause morbidity and mortality, thus reducing important fish stocks [ 8 , 9 ].…”

Geographic range, distribution patterns and interactions of Monogenea Van Beneden 1858, with species of native host freshwater fishes from Brazil

“…Understanding which factors drive observed differences in monogenean diversity in Brazilian fishes is of great interest in fish parasitology. At the geographic regional scale, diversity of parasites may be strongly linked to the number of potential host fish species, which in turn is associated to a region's size, because larger geographical regions supporting a greater number of both host and parasite species (Paterson et al, 2021). Geographical distribution of monogenean species in fish from Brazil may provide insights into the evolution and diversity of parasitic communities.…”

“…Historical host-parasite associations between monogeneans and freshwater Neotropical fishes are fascinating due to the host's geographic isolation in hydrographic basins, which have complex biogeographical histories (Wendt et al, 2022). Parasites are strictly dependent on their hosts for essential resources as nutrients and attachment; thus, their geographical distribution, biodiversity and evolutionary history must, in part, be influenced by the history of their hosts (Reverter et al, 2017;Paterson et al, 2021). For the most Brazilian hydrographic basins there is a lack of knowledge regarding diversity of monogeneans parasitizing host fish species, in contrast to other basins as such Amazon River and Paraná River, which concentrate the most of studies.…”

Freshwater fish as hosts for parasites in Australia: How much do we really know?

“…Many introduced species, for example, often have a reduction in their parasite fauna following release, leading to an increased body size, greater population densities and enhanced competitive ability (see Torchin et al, 2002, 2003), which can exacerbate their potential impact upon native fish. Native freshwater fish in Australia are considered to have a diverse, but largely undescribed, parasite fauna (Kaminskas, 2021; Lymbery et al, 2010; Paterson et al, 2021). Introduced fish also have parasites and a number of these co‐invading parasites, such as the Asian tapeworm, Schyzocotyle acheilognathi , anchor worm, Lernaea cyprinacea, and the protozoan Chilodonella spp., have established and subsequently spread to native species, with some causing significant epizootics among native fish populations (Dove & Fletcher, 2000; Gomes et al, 2017; Kaminskas, 2021; Lymbery et al, 2014; Whittington & Chong, 2007; Zhu et al, 2021).…”