Incidence of imposex and parasite infection in Neptunea arthritica at Saroma Lagoon [Japan] and their relationship
2007
Miranda, R.M.(Hokkaido Univ., Hakodate (Japan)) | Fujinaga, K. | Ilano, A.S. | Nakao, S.
The incidence of imposex and parasite infection, and their relationship with Neptunea arthritica in Saroma Lagoon was evaluated. Imposex occurred in 30.9% of the females examined, and 25.1% of the males and females were infested by parasites. No difference in infection ratio was detected between the sexes, or between mature and immature individuals. The parasite infection index also showed no difference between sexes (male, 0.079 and female 0.074). Parasite infection also showed no temporal pattern, but in general tended to be higher in large individuals than smaller ones in both sexes. A total of 19.3% of the females showed imposex and were infested by parasites. The number of infected whelks with signs of imposex showed a sharp decrease with the increase in imposex degree. This was clearly indicated by the proportion of infected whelks in imposex stage 1 (28.6%), 2 and 3 (7.4 and 10.3%, respectively). The results suggests that the population of N. arthritica in the lagoon continue with the recovering trend based on the decrease of imposex frequency, as refereed in previous works, and parasitism appears to be the most serious disruptive phenomenon to a complete restoration of this population, based on it's proportion.
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