Seasonal abundance ofNeoechinorhynchus cylindratustaken from largemouth bass (Micropterus salmoides) in a heated reservoir

Abstract

Samples of largemouth bass were collected from Par Pond located on the Energy Research and Development Administration's Savannah River Plant in Aiken, South Carolina, from June 1972 to May 1973 inclusive. The sampling stations reflected water temperatures which were both normal and greater than 10°C above normal for the area. The acanthocephalanNeoechinorhynchus cylindratuswas the dominant species found in the bass sampled. Incidences of infection for this parasite were generally greater than 95% regardless of location. A pronounced seasonal cycling pattern in the intensity of infection was noted in both thermal regions. Significant differences, however, in the mean density ofN. cylindratusper host in fish taken from the heated area as compared with unheated areas were noted.Turnover in the acanthocephalan population was measured by following the percentage of individuals less than 2 mm long. Fall proved to be the most intense parasite recruitment season, followed by maturation of the parasite and subsequent loss from the fish host.The principal factors responsible for the seasonal incidence and intensity patterns are considered to be changes in the fish feeding behaviour and annual temperature regimes.