Occurrence of Conchophthirus acuminatus (Protista: Ciliophora) in Dreissena polymorpha (Mollusca: Bivalvia) along the River Shannon, Ireland |
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Authors: | David Bruce Conn Sarah E Simpson Dan Minchin Frances E Lucy |
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Institution: | (1) School of Mathematical & Natural Sciences, Berry College, Mount Berry, GA 30149-5036, USA;(2) Marine Organism Investigations, 3 Marina Village, Ballina, Killaloe, Co. Clare, Ireland;(3) School of Science, Institute of Technology, Sligo, Ireland |
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Abstract: | Samples of Dreissena polymorpha were collected at several sites along the River Shannon navigation in Ireland, to determine the occurrence and distribution
of their obligate host-specific commensalistic ciliate, Conchophthirus acuminatus, in this newly invaded region. Mussels collected by various methods were fixed immediately in 75% ethanol, in which they
were later dissected under a stereoscopic microscope, beginning with thorough flushing of the mantle cavity and removal of
the gills. One ml of sediment flushed from the mantle cavity and dissection residue of each mussel was examined under a compound
light microscope using brightfield, phase-contrast, and differential-interference-contrast optics. Of 180 mussels examined,
125 (69.44%) harbored C. acuminatus. The ciliates were invariably well fixed and easily identifiable in all preparations. Mean sampling intensity for infected
mussels was 8.47 ciliates per ml of sediment. Both prevalence and sampling intensity varied between sites, but no pattern
was discernible. The present results are consistent with other reports of C. acuminatus being the most widespread and abundant symbiont of D. polymorpha throughout Europe, often occurring where no other symbionts occur. Its occurrence in Ireland indicates introduction of the
mussels as adults, since planktonic veliger larvae are not known to harbor ciliates. Following similar reasoning, it is possible
that the earlier North American invasion by D. polymorpha included only veligers, since C. acuminatus has not been found on that continent. Using these simple and quick methods, the ciliates could be easily identified and counted
to give general comparative data among sites regarding intensity and prevalence. Thus, this method has promise for future
efforts to obtain basic information rapidly in newly invaded systems. |
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Keywords: | Commensal Invasive Ciliate Mollusk Conchophthirus Dreissena Ireland Symbiotic Zebra mussel |
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