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Regulation of infrapopulations of Cryptocotyle lingua oncod

Published online by Cambridge University Press:  01 February 1997

D. A. LYSNE
Affiliation:
Department of Ecology/Zoology, IBG, University of Tromsø, N-9037 Tromsø, Norway
W. HEMMINGSEN
Affiliation:
Department of Ecology/Zoology, IBG, University of Tromsø, N-9037 Tromsø, Norway
A. SKORPING
Affiliation:
Department of Ecology/Zoology, IBG, University of Tromsø, N-9037 Tromsø, Norway

Abstract

To study the infection dynamics of metacercariae of the digenean Cryptocotyle lingua, wild living Atlantic cod, Gadus morhua, were caged for 18 months close to the shore. Here they were exposed to naturally occurring transmission stages of the parasite. First, both the abundance and the variance to mean ratio of metacercariae increased, but during the second half of the study the abundance levelled out, and the variance to mean ratio showed a significant decrease. Host mortality was negligible throughout the study. Based on the relationship between pigment spots and metacercariae observed by skin digestion, there was no indication of density-dependent parasite mortality. We conclude that the infrapopulations of metacercariae on the caged cod probably were regulated by density-dependent host responses acting against the cercariae.

Type
Research Article
Copyright
© 1997 Cambridge University Press

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