Helminth parasites of alien freshwater fishes in Patagonia (Argentina)

Abstract

A survey of the helminth parasites of alien freshwater fishes from Argentinean Patagonia is presented, based on samples taken from 2010 to 2017 and including previous published records. A total of 1129 fishes were collected, belonging to 11 species from 7 families. We surveyed 34 localities in 12 river basins, and found 43 parasite taxa (15 digeneans, 14 monogeneans, 5 cestodes, 5 nematodes, and 4 acanthocephalans), belonging to 22 families. Data are presented as a parasite/host list with information on host species and localities, site of infection, parasite life–history stage, origin, previous records in Patagonia, and accession numbers to vouchers. The most frequently found helminths were monogeneans and digeneans. Our data suggest that invading fish in Patagonia have transmitted fewer parasite species than they have received by spillback. Twenty–three (53%) of the parasites seem to be acquired by the exotic fishes from native hosts, while 15 helminths were co–introduced along with their exotic fish host and continue to parasitize these alien fish but did not invade native hosts; 4 of these species were introduced with carp, 3 with Cheirodon interruptus, 3 with Corydoras paleatus, 3 with Cnesterodon decemmaculatus, 1 with Oncorhynchus tshawytscha, and 1 with Jenynsia multidentata. The majority of these co–introduced parasites came from the Brazilic ichthyogeographic region (10 species). This is the first review of helminth parasites of alien fishes in Argentina; in total 12 new records of parasites for Argentina, 6 new records of parasites for Patagonia, and 29 new host–parasite records are presented here. This list is far from complete, however, given that some basins in southern Patagonia remain unexplored in terms of parasite detection.

First report of post-cyclic transmission in trematodes: Derogenes lacustris (Digenea: Hemiuroidea) in Patagonian freshwater fishes

“…In this regard, Rauque et al . (2018) suggested that exotic salmonids stand out as hosts which are highly susceptible to infection by the parasites of Patagonian native fish; this leads to an increase in native parasite populations, as observed for A. tumescens (Rauque et al ., 2003). The rate of experimental transmission of D. lacustris (19.2%) was lower than that registered for A. tumescens transmitted between G. maculatus and O. mykiss in Patagonia (37% in Rauque et al ., 2002; 21.8% in Paterson et al ., 2013).…”

“…The following native fishes have been reported as definitive hosts: Galaxias maculatus (Jenyns, 1842), Galaxias platei Steindachner, 1898 (Galaxiidae), Olivaichthys viedmensis (MacDonagh, 1931) (Diplomystidae) and Percichthys trucha (Valenciennes, 1833) (Percichthyidae) (Shimazu et al ., 2000; Tsuchida et al ., 2021 a ). The following introduced fishes have also been reported as definitive hosts: Oncorhynchus mykiss (Walbaum, 1792), Salmo salar Linnaeus, 1758, Salmo trutta Linnaeus, 1758, and Salvelinus fontinalis (Mitchill, 1814) (Salmonidae) (Shimazu et al ., 2000; Rauque et al ., 2018; Tsuchida et al ., 2021 a ). Salmonids were introduced from the USA into Patagonian freshwater environments as embryonated eggs at the beginning of the 20th century (Tulián, 1908).…”

“…Acanthocephalus tumescens is widely distributed throughout Andean lakes and parasitizes various species of native and introduced fishes in northwestern Patagonia (e.g. Ortubay et al ., 1994; Semenas and Trejo, 1997; Viozzi et al ., 2009; Rauque et al ., 2018); post-cyclic transmission from G. maculatus to O. mykiss has been proved through experimental infection (Rauque et al ., 2002).…”

Cleaner fish in aquaculture: review on diseases and vaccination

“…(2016), Eiras (2016), Rauque et al . (2018)). These are larger internal parasites, of which several can be observed with the naked eye in infected fish (Jansson & Vennerström, 2014).…”

“…Known parasitic helminths of fish are different species of nematodes (roundworms), flukes and cestodes (tapeworms) (e.g. see Bristow (1993), Jyrwa et al (2016), Eiras (2016), Rauque et al (2018)). These are larger internal parasites, of which several can be observed with the naked eye in infected fish (Jansson & Vennerstr€ om, 2014).…”