Quahog Parasite Unknown

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With Quahog parasite unknown , shortly QPX , is a single-celled parasite Northern clam ( Mercenaria mercenaria ), respectively. Host and parasite are found on the North American east coast, to the north the unicellular organism is found off New Brunswick , Nova Scotia and Prince Edward Island (Canada) and south to Virginia .

QPX has been the subject of research since the 1990s, as it can economically damage mussel aquacultures through multiple deaths of infected animals.

state of knowledge

In 1959, a first mass death of clams was observed with evidence of QPX-like unicellular parasites. Similar reports were made in 1976 from New Jersey and in 1989 from Prince Edward Island . The living organism QPX appears in many respects to be another - unrelated - parasitic protist, MSX (multinucleated sphere X), which attacks oysters and was first observed in the US northeast between the late 1940s and 1950s.

Based on studies of ribosomal genetic material is assumed since 2000 that it was at QPX a member of the class of labyrinthulomycetes ( Labyrinthulomycetes here) and a relative of pachydermum Thraustochytrium concerns.

A possible sign of a QPX infection damage to the flap edge of the shell, yellow nodules and swelling of the sheath (observations of Smolowitz et al. [1998, 2001]), where other Untersuchunges the presence of these infections characters in affected M. mercenaria could not confirm (observations by Ragone Calvo et al. [1998], Ford et al. [2002], or by MacCallum and McGladdery [2000]). Mainly the tissues of the coat and gills seem to be affected, but pathogens have also been detected in the foot and kidneys. Other clinical signs include a decrease in size and general signs of inflammation.

Based on knowledge from data from the noughties, the range of this parasitic disease is limited to the US states of New Jersey , Massachusetts , Virginia and the neighboring Canadian north-east Atlantic areas. There have been observations that young mussels from a hatchery are not infested, but as soon as these individuals are placed in an open water rearing area, severe losses due to death after about a year of waxing are recorded. The pathogens are regularly found in mussels that are more than a year old and larger than 20 millimeters. There is a correlation with the frequency of the pathogen discovery and the salinity of the seawater biotope at the discovery site.

In order to curb the spread of the disease, the trade in mussel stock between the US states is restricted or prohibited, for example in 2002 the import of stocked animals to Virginia as the receiving state and Florida and South Carolina as regions of origin was prohibited for at least 180 days.

swell

  1. ↑ Lisa M. Ragone Calvo, Juanita G. Walker, Eugene M. Burreson: Prevalence and distribution of QPX, Quahog Parasite Unknown, in hard clams Mercenaria mercenaria in Virginia, USA . (pdf) In: Diseases of Aquatic Organisms . Vol. 33, July 30, 1998, pp. 209-219. doi : 10.3354 / dao033209 . PMID 9745718 .
  2. ↑ a b c d Loren M. Coen, Yvonne Bobo, Donnia Richardson, William D. Anderson: Sheet for QPX (Quahog Parasite Unknown) . (pdf) In: South Carolina Department of Natural Resources, Marine Resources Division . February 2004. "QPX in many ways parallels observations for MSX (multinucleated sphere X), an unrelated protozoan parasite of oysters, first observed in the late 1940-1950s in the northeast."
  3. ↑ Mark A. Ragan, Greg S. MacCallum, Colleen A. Murphy, Jamie J. Cannone, Robin R. Gutell, Sharon E. McGladdery: Protistan parasite QPX of hard-shell clam (Mercenaria mercenaria) is a member of Labyrinthulomycota . (pdf) In: Diseases of Aquatic Organisms . Vol. 42, September 28, 2000, pp. 185-190. doi : 10.3354 / dao042185 .
  4. ↑ a b QPX Disease in Hard Clams. (PDF) New York Sea Grant, 2003, accessed March 6, 2019 .