Potential Parasite-Induced Mortality in Age-0 Bluegills in a Floodplain Pond of the Lower Mississippi River

Abstract

Abstract We assessed seasonal variations in endoparasite intensity (number per host) for six 1986 cohorts of age-0 bluegill Lepomis macrochirus collected from an overflow pond of the lower Mississippi River during March–December 1986. Allacanthochasmus sp. (Trematoda) was the predominate endoparasitic taxon infecting bluegills. We noted peaked intensity curves and declines in variance-to-mean ratios for total endoparasites and Allacanthochasmus sp. for three cohorts during pond flooding in October. Although changes in the distribution of parasite intensities during this period may have reflected bluegill mortality, declines in variance-to-mean ratios of parasite intensities were smaller than those predicted by theories of parasite-induced host mortality. We also examined bluegills of the previous (1985) year class in spring 1986; their endoparasite intensities and variance-to-mean ratios were substantially lower than those of 1986 cohorts in fall 1986. Because these data are from two year classes, they ma...