New Zealand Journal of Marine and Freshwater Research abstracts

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Distribution of helminths in the digestive tracts of New Zealand freshwater eels *3. Interspecific associations and conclusions

P. M. Hine

and

R. I. C. C. Francis

Fisheries Research Division, Ministry of Agriculture and Fisheries, P.O. Box 19062, Wellington, New Zealand

Abstract Pairs of helminths from the alimentary tracts of Anguilla dieffenbachii and A. australis were tested for association. After the variable of host size had been eliminated from the data, three significant associations were indicated. A positive association between the digeneans Stegodexamene anguillae and Telogaster opisthorchis in both eel hosts is attributed to the use of the same intermediate hosts, resulting in concurrent infections at all stages of the life cycles. Competition in the eel host has been reduced by selective site segregation, modified by interactive site segregation. A strong negative association between the nematodes Spirocamallanus sp. and Paraquimperia sp. in A. dieffenbachii is proposed as the reason for the relative occurrence of each nematode in each host. Paraquimperia infects both hosts, but is rapidly excluded if Spirocamallanus enters the host (usually A. dieffenbachii). As Spirocamallanus infections decline in older hosts Paraquimperia may establish again. There was no apparent segregation of the nematodes to reduce competition and avoid competitive exclusion. The cause of an apparent negative association between the flukes Stegodexamene anguillae and Coitocaecum anaspidis is unknown, but may be fortuitous.

Keywords Anguilla australis; Anguilla dieffenbachii; gut helminths; parasite associations; segregation; exclusion; competition; digeneans; nematodes.

New Zealand Journal of Marine & Freshwater Research, 1980, 14(4): 349-356
Received 27 February 1980; revision received 6 October 1980 Fisheries Research Division Publication 422

PDF file of entire paper: medium quality (631K); (scanned from paper original: notes about this process)

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