| dc.description.abstract | Certain factors controlling the parasitic phase of some nonspecific
fish ectoparasites were investigated. Studies were made of
the infection patterns exhibited by the branchiuran Argulus foliaceus (L. ), the fish leeches Piscicola geometra (L. ) and Hemiclepsis marginata
(Mull. ) and glochidia larvae of Anodonta cygnea (L. ) on freshwater fish.
Aspects of the parasites life history, survival, development,
seasonal cycles in incidence, dispersion patterns, immigration and site
selection were investigated by field and laboratory studies.
In adult A. foli. aceus and P. geometra, the initial attacking
a
phase onto the fish host does not appear to be influenced by densitydependent
factors. In larval A. foliaceus, infection is also unaffected
by parasite density, but in adults, it is controlled at high parasite
numbers when the carrying capacity of the fish is reached. The infection
patterns of A. foliaceus appear to reflect the heterogeneity of both
host and parasite populations, particularly with respect to variations
in host susceptibility and to parasite searching activity.
In adult P. georn tra, the parasitic phase is influenced by
density-dependent factors with increasing intraspecific competition at
high densities.
The population processes controlling these parasites are
compared to other types of host/parasite systems. | |
