TEMPERATURE EFFECTS ON AGE CHANGES OF DACE (LEUCISCUS
LEUCISCUS (L.)) PARASITE IN RIVERS
Ivashevsky
George A.
Institute
of Biology Komi Science Centre
One of the greatest particularities of
young fish ecology in rivers is the presence of their drift. This drift as
biological phenomenon characterizes both migratory fish and local fish (Pavlov
et al.,1981).
The aim of this report is to show drift,
age and temperature effects on changes of the young dace parasite fauna. For
this purpose we investigated the parasite fauna in 138 individuals of young
dace in the Northern Dvina in June 1995 and from June to August in 1996. As a
result we found 17 parasite species. The greatest invasion of the parasites is
marked among monogeneans.
A peritrichous ciliates were the first
parasites of dace larvas (in June). Myxobolus muelleri, Diplostomum spathaceum
and 5 speceis of monogeneans were added to them later (03.07.96). After that
there appeared Rhipidocotile campanula and larvas of mollusces and Diplozoid monogeneans (06.07.96). Increase
of ivasion coincided with the host size, but later the parasite fauna became
poorer. This fact can be explained by the high temperature of water at this
time (26° C). After a temperature
fall (16.07.96) some parasite speceis became richer.
Thus we have found major differenses in age
changes of dace parasite fauna in rivers out of those of fish parasite fauna in
lakes. Invasion increase depends on the host age, but the temperature effect is
not less important. Thanks to the young fish drift the increas of some species
invasion is observed down-stream of the rivers.
