Experimental infection of the endangered bonytail chub (Gila elegans) with the Asian fish tapeworm (Bothriocephalus acheilognathi): impacts on survival, growth, and condition

Abstract

Bothriocephalus acheilognathi Yamaguti, 1934, a tapeworm known to be pathogenic to some fish species, has become established in the endangered humpback chub ( Gila cypha Miller, 1964) in Grand Canyon, USA, following the tapeworm’s introduction into the Colorado River system. The potential impact of this tapeworm on humpback chub was studied by exposing the closely related bonytail chub ( Gila elegans Baird and Girard, 1853) to the parasite under a range of conditions that included potential stressors of humpback chub in their natal waters, such as abrupt temperature change and a limited food base. Survival of infected fish under low food rations was considerably lower than that of control fish, and mortality of infected fish began 20 days earlier. Growth of infected fish was significantly reduced, and negative changes in health condition indices were found. No significant negative impacts were revealed from the synergistic effects between temperature shock and infection. Bothriocephalus acheilognathi does present a potential threat to humpback chub in Grand Canyon and should be considered, along with conventional concerns involving altered flow regimes and predation, when management decisions are made concerning conservation of this endangered species.

Impact ofBothriocephalus acheilognathi(Cestoda: Pseudophyllidea) onCyprinella lutrensisCondition and Reproduction

“…Although there was a difference in condition between uninfected and infected groups, there was no significant difference in condition among infection intensities. These results suggest that an initial infection by one tapeworm impedes the absorption of nutrients by the host and leads to higher intensities (Brouder 1999, Hansen et al 2006. Hansen et al (2006) also noted that impaired growth might increase risk of predation.…”

“…Cyprinids examined in previous B. acheilognathi studies exhibiting impaired growth were large bodied, long lived fish hatched and reared in the laboratory (Brouder 1999, Hansen et al 2006. This study examined the potential impacts of the tapeworm infections in fish from wild populations.…”

“…Brouder (1999) compared infected and uninfected Gila robusta (maximum length = 43.0 cm total length; Page and Burr 1991) and determined that infected fish were significantly shorter than uninfected fish. Infected Gila elegans (maximum length = 62.0 cm total length; Page and Burr 1991) in a laboratory study grew at a significantly slower rate and weighed less than uninfected fish of the same age class (Hansen et al 2006). The short-bodied and short-lived cyprinid Notropis topeka also exhibited reduced growth in infected fish (Koehle and Adelman 2007) in a laboratory experiment (maximum length = 7.6 cm TL; Page and Burr 1991).…”

RETRACTED ARTICLE: Occurrence, spread and control measures of Bothriocephalus acheilognathi (Bothriocephalidae: Cestoda)

“…The susceptibility of fry is probably because copepods make up a large proportion of the diet of these fish, and the limited space within the intestinal tract to accommodate these large parasites. Heavy tapeworm burdens cause blockage of the intestine and severe pathological changes, leading to reduced growth, condition and survival (Scott and Grizzle 1979;Granath and Esch 1983b;Hoole and Nisan 1994;Hansen et al 2006). The tapeworm has also been the cause of disease problems in ornamental fish farms in Australia and Central Europe, involving Poecilia reticulata and Xiphophorus maculates (Evans and Lester 2001; R. Kuchta, unpublished data) and mortality of koi carp (Han et al 2010).…”

“…These include: (i) protein depletion; (ii) altered digestive enzyme activity; (iii) elevated muscle fatigue in heavily infected hosts; and (iv) mortality of young fishes (Liao and Shih 1956;Davydov 1978;Scott and Grizzle 1979;Granath and Esch 1983b;Brouder 1999;Hansen et al 2006). Bothriocephaliasis also reduces fat content and causes a decrease in kidney, liver and spleen weight (Balakhnin 1979;Zitnan and Hanzelova 1982).…”