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<br />214 . PROCEEDINGS OF THE HELMINTHOLOGICAL SOCIETY
<br />Table 3, Mean density of Bothriocephalus acheilognathi from three size classes of mosquitofish
<br />collected from the thermally altered site (HA 1) from March 1980 to March 1981. (Each mean is
<br />based on N = 20 unless otherwise noted.)
<br /> Size class (mm) (x :t SE)t
<br /> "
<br /> Dale 530 31-40 ~41 F:\: (df ~ 2,57)
<br /> 3/80 0,5 :t 0,2 4,0 :t 1.5 2,2 :t 0,7 8,13*
<br /> 4/80 1.4 :t 0,7 5,7:t 1.9 3,6 :t 1.8 10,12* -'
<br /> 4/80 2,1 :t 0,8 2,9 :t 1.1 2,2 :t 0,7 0,16"'
<br /> 5/80 1.7 :t 0,7 2,8 :t 0,9 2,1 :t 0,7 1.11 "'
<br /> 5/80 2,2 :t 0,8 2,1 :t 1.4 0,8 :t 0.4 3,29"'
<br /> 6/80 6,6 :t 1.6 4,7 :t 1.8 1.0 :t 0,3 13,62*
<br /> 6/80 5,9 :t 1.9 5,8 :t 2,0 3,8 :t 1.3 8,29*
<br /> 7/80 4,O:t 1.4 5,0 :t 1.5 4,3 :t 0,5 1. 56"'
<br /> 7/80 1.0:tO,7 2,0 :t 0,8 1.4 :t 0,8 1.98"'
<br /> 8/80 0,5 :t 0,2 1.2 :t 0.4 4,0 :t 1.2 12,01*
<br /> 8/80 1.0 :t 0,3 1.1 :t 0,3 ~O,2 :t 0,2 2,06"'
<br /> 9/80 0,5 :t 0,3 0,1 :t 0,1 1.2 :t 0,6 3,16"'
<br /> 9/80 0.4 :t 0,3 0,3 :t 0,1 0,3 :t 0,1 0,05"'
<br /> 10/80 0,9 :t 0,3 1.9 :t 0,5 1.4 :t 0.4 1.09"'
<br /> 10/80 5,2 :t 1.2 4,9 :t 1.2 3,1:tO,7 5,31 "'
<br /> 11/80 6,3 :t 1.3 6,0 :t 0,9 5,1 :t 0,7 4,53"'
<br /> 11/80 9,6 :t 1.7 9,2 :t 1.6 3,1 :t 0,6 17,16*
<br /> 12/80 5,7:t 1.4 7,8 :t 1.9 5,0 :t 0,8 5,05"'
<br /> 12/80 4,5 :t 1.3 5,3 :t 1.2 4.4 :t 0,9 4,96"'
<br /> 1/81 3,1:tO,7 3,9 :t 0,9 3,9 :t 1.0 1,03"'
<br /> 1/81 3,5 :t 1.3 4,7 :t 0,8 3,0 :t 0,5 1.96"'
<br /> 2/81 2,5 :t 1.1 4,1:tO,9 2,1:t0.4 4,89"'
<br /> 2/81 1.2 :t 0.4 3,5 :t 0,6 2,1 :t 0,6 5,12"'
<br /> 3/81 2,3 :t 0,9 2,7 :t 0,9 3,0 :t 0,8 0,96"'
<br />F( df) 7,82* 7,03* 5,61*
<br /> (23,456) (23,456) (23,421)
<br />t Underscored means are not significantly different as determined by Duncan's multiple range test.
<br />:\: . ~ significant at P < 0,005, ", ~ not significant at P > 0,005,
<br />~ Entry based on N ~ 6, df ~ 2,43,
<br />
<br />Normal changes in host foraging strategies with increasing age and/or size may
<br />also affect the population biology of helminth parasites (Kennedy, 1977; Chubb,
<br />1980; Esch, 1983) and appear to playa significant role for the mosquitofish-B,
<br />acheilognathi system in Belews Lake. A recently completed, but as yet unpub-
<br />lished, study of the stomach contents of mosquitofish in Belews Lake strongly
<br />suggests definite changes in foraging and prey preference within and between
<br />various size classes of G, affinis throughout the year (M. R, Riggs, pers, comm.).
<br />During those months when water temperatures were high (late spring through
<br />fall), stomachs were full, reflecting higher feeding intensity or, perhaps, greater
<br />prey availability. This time period corresponds to those parts of the year when
<br />recruitment of B, acheilognathi was occurring.
<br />
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