Physicochemical influences on parasites of age-0 largemouth bass in the atchafalaya river basin, louisiana

Abstract

We investigated prevalence and intensity patterns of nine parasite taxa in 244 age-0 largemouth bass (Micropterus salmoides) collected from lake (high dissolved oxygen levels), riverine (high current velocities), and swamp (hypoxic canals and bayous) sites (N=6) in the Atchafalaya River Basin during the 1996 flood pulse. Ectoparasites were dominated by monogenetic trematodes (prevalence=100%; median intensities 27–91 per host) and glochidia (prevalence > 96% at all sites, median intensities 47–148 per host), whereas Posthodiplostomum minimum (Trematoda), Caecincola spp. (Trematoda; C. parvulus and perhaps C. latostoma), Neoechinorhynchus cylindratus (Acanthocephala), and Proteocephalus ambloplitis (Cestoda) accounted for 94.6% of bass endoparasites. Overall, lake sites supported the highest median parasite intensities in bass and most highly parasitized individuals. P. minimum was prevalent in bass collected from all sites, but intensities were highest in bass from lake habitats. In contrast, P. ambloplitis exhibited lower than expected prevalence in bass from lake sites (P. < 0.05) and higher intensity (P < 0.02) in bass from riverine sites. Patterns of parasite abundance appeared to be related to habitat effects on intermediate host and parasite life-cycle dynamics rather than hypoxia-related suppression of bass immune responses. © 1999, Copyright Taylor & Francis Group, LLC.