Effects of Season, Host Age, and Sex on Endohelminths of Catostomus commersoni

Abstract

Two hundred seventy-nine white suckers (Catostomus commersoni) were collected from June 1966 through May 1968 from Pushaw Lake, Penobscot County, Maine. Data were collected on 3 caryophyllaeid cestodes (Glaridacris laruei, G. catostomi, and Isoglaridacris bulbocirrus), 1 digenetic trematode (Triganodistomum attenuatum), and 1 acanthocephalan (Pomphorhynchus bulbocolli). The data were analyzed using a 2-factor ANOVA, Duncan's Multiple Range Test, and where applicable, correlation coefficients. Effects of season, host age, and sex on parasite burden were noted. Host sex was found to have only slight significance (P < 0.10) on three species (G. laruei, P. bulbocolli, and T. attenuatum). No effect was noted for the other species. Infection was found to increase with increased host age for both G. catostomi (P < 0.05) and I. bulbocirrus (P < 0.025). Infections of T. attenuatum tended to decrease with increased host age (P < 0.01). No age effects were noted for the other species. Marked seasonal effects were noted for G. catostomi, G. laruei, and I. bulbocirrus (P < 0.005), all three being most abundant during the period January to April. T. attenuatum and P. bulbocolli were most abundant in the summer (P < 0.005 and 0.05, respectively). The parasite fauna of Catostomus commersoni Lacepede (white sucker) is well documented, with 11 species of protozoa, 75 helminths, one mollusk, and seven crustaceans being listed by Hoffman (1967). There are, however, few seasonal studies on the parasite fauna of this host. For this reason a 2-year study was undertaken, part of which is presented here. The number of studies extending over comparable periods and including winter samples is limited. Fried, Kitchen, and Koplin (1964) discussed the seasonal distribution of Triganodistomum sp. and Fessisentis sp. in C. commersoni and included a very brief note on caryophyllaeid infection. Calentine and Fredrickson (1965) described the periodicity of five species of caryophyllaeids in C. commersoni and gave information as to the intermediate hosts of Glaridacris catostomi Cooper and periods of oncosphere viability. Chaicharn and Bullock (1967) studied the histopathology of acanthocephalan infections in the suckers C. commersoni and Erimyzon oblongus (Mitchill). It is hoped that the present study will help further elucidate the host-parasite relationship in C. commersoni. Received for publication 25 September 1969. * Part of a doctoral dissertation completed under the direction of Dr. Marvin C. Meyer, University of Maine, Orono, Maine. The study was supported in part by USPHS Grant AI-02759 from NIAID, NIH. MATERIALS AND METHODS Two hundred seventy-nine fish were collected by gill nets from June 1966 through May 1968 from Pushaw Lake, Penobscot County, Maine. Divided by months the numbers were as follows: 1-20; 2-21; 3-10; 4-6; 5-17; 6-67; 7-46; 8-22; 9-26; 10-19; 11-25. Collections were not made in December of either year owing to ice formation. Fish were weighed, measured, and scale samples taken from the left dorsolateral surface just below the dorsal fin and above the lateral line. The entire intestine including the stomach was examined and the position of each helminth recorded. Worms were killed in water heated to approximately 80 C and fixed in AFA. Specimens were either stained in Semichon's acetocarmine and cleared, or cleared directly, without staining. Seasonal divisions were established as follows: January through April, or the period of solid ice cover to the time ice is out; May through August; September through November. Host age groups were set up as follows: (2) 2 and 2+; (3) 3 and 3+; (4) 4 and 4+; and (5) 5 and 5+. Age was used as an indicator of length effects since a significant correlation was found between these two parameters (0.44078; P < 0.005). A 2-factor analysis of variance was run to test the effects of season, host age, and sex on each of the endohelminths. Significance was noted at the 0.05, 0.025, and 0.005 levels to indicate degree of effect. An F value significant at the 0.10 level was noted only as an indicator that some sort of relationship might exist. When effects were noted, Duncan's Multiple Range Test was employed (P < 0.05) to determine more specifically where the significance lay. When correlation coefficients were desired, significance was noted at the 0.05 and 0.01 levels. The terms mean intensity of infection and incidence of infection indicate average number of