Occurrence and Impact of the Asian Fish Tapeworm Bothriocephalus acheilognathi in the Rio Grande (Rio Bravo del Norte)
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Bothriocephalus acheilognathi is native to Asia and was introduced worldwide as an incidental hitchhiker of its native host, Ctenopharyngodon idella (Andrews et al. 1981; Hoffman 1999). It is established in ten states in USA with the most recent discovery in the Rio Grande in Texas (Bean et al. 2007). Occurrence of this exotic tapeworm in the Rio Grande potentially is detrimental to native fishes, causing intestinal blockage and perforation, hemorrhaging, reduced growth, significantly decreased survivorship, and mortality (Scott and Grizzle 1979; Hoffman 1980; Granath and Esch 1983; Hoole and Nisan 1994; Hansen et al. 2006). Endemic fishes of conservation concern in the Rio Grande include Hybognathus amarus, Dionda diaboli, Notropis jemezanus, and Notropis Chihuahua and likely are affected by the tapeworm. The purpose of the first part of this study was to examine the presence and mean intensity of B. acheilognathi in Cyprinella lutrensis to determine spatial and temporal patterns in several reaches of the Rio Grande. The study also examined seasonal trends in tapeworm maturation and intraspecific competition. The second study assessed impacts of B. acheilognathi infection on condition and reproduction in C. lutrensis to make inferences about potential impacts on other endemic cyprinid species.