ISSN 1067-4136, Russian Journal of Ecology, 2008, Vol. 39, No. 3, pp. 215–220. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © G.N. Dorovskikh, V.G. Stepanov, 2008, published in Ekologiya, 2008, No. 3, pp. 227–232.
Studies on the dependence of ﬁsh parasite fauna on
host age were initiated in the 1930s. As a result of gen-
eralization of the data obtained, the rule was formulated
that the intensity and extensiveness of parasite invasion
increase with host age (Dogel’, 1947). The study of
trends in the formation of the structure of parasite com-
munities depending on host age was initiated in the
1990s. It was shown (Pugachev, 1999) that parameters
of parasite communities rather sharply respond to
changes in the host biology.
The purpose of this study was to analyze the devel-
opment of parasite fauna and the structure of the para-
site community in the minnow
in relation to the host age and to determine the moment
of their complete formation.
A total of 105 minnows were caught in the upper
reaches of the Pechora River, near the Garevka River
N), in the summer peri-
ods of 2003 and 2004. The size of each sample was 15
ﬁsh. The dates of catches are indicated in the tables.
The parasitological material was collected accord-
ing to the standard procedure. The order of processing
the data on ﬁsh parasite communities, the essence of the
concepts we used, and the sizes of parasites are
described in our previous publications (Pugachev,
1999; Dorovskikh, 2002).
The dissected ﬁsh were sorted by absolute ages,
which were estimated from the earliest and latest dates
spawning in the sampling area (Korolev,
2000). Average values of ﬁsh body length (with error)
for each age are shown in Table 1.
In ﬁsh aged approximately 1 and 1.5 months, two
and three species of parasites were recorded, respec-
tively. These were larval stages of trematodes and nem-
atodes. In the second year of life, ﬁsh were additionally
infested by Microsporidia, Infusoria, and Monogea.
Thus, the diversity of the parasite fauna increased to
seven–eight species. In ﬁsh of the third year of life stud-
ied on June 18, 2004, 15 parasite species were found
(Table 1), with the diversity of Monogea reaching the
highest level. Apparently, the formation of parasite
is completed at this age, as 15 par-
asite species were also found in ﬁsh aged 3+ on August 15,
2003 (Dorovskikh and Stepanov, 2006).
In August, the number of individuals and biomass of
parasites in ﬁsh aged 0+ and 1+ increased, since para-
sites of the next generation appeared. The parasite com-
munity formed by individuals of the last-year genera-
tion was already in a deﬁnitive state in June and entered
the stage of degradation followed by de novo formation
in July: individuals of the last-year generation gradu-
ally died, being replaced by individuals born in the cur-
rent year. In mid-August, almost the entire parasite
community consisted of individuals belonging to the
new generation, with the previous generation being rep-
resented only by parasites using
as an inter-
mediate host. In this period, the process of host invasion
with parasites continued, and the parasite community
was characterized by the maximum values of the dom-
inance index and the minimum values of the index of
species evenness and the Shannon index. In June of the
next year, the parasite community was again in a deﬁn-
itive state, with lower values of the dominance indices
and higher values of the index of species evenness and
the Shannon index (Table 2).
Parasites from ﬁsh aged 0+ and 0+ to 1 were segre-
gated into two groups with respect to biomass (Table 3).
In July and August, the third group was being formed in
ﬁsh aged 1+. A parasite community consisting of three
groups was found in a ﬁsh aged 1+ to 2 on June 18,
2004 (ﬁgure). Apparently, the formation of community
structure is completed at this time; i.e., it becomes the
same as the deﬁnitive community structure in ﬁsh of
older ages (Dorovskikh, 2002).
Change in the Structure of Component
Parasite Communities with Host Age
G. N. Dorovskikh and V. G. Stepanov
Syktyvkar State University, Oktyabr’skii pr. 55, Syktyvkar, Komi Republic, 167001 Russia;
Received September 14, 2006
: parasites, parasite communities, minnow