Ceratonova shasta
Ceratonova shasta spores
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Cnidaria
Class: Myxosporea
Order: Bivalvulida
Family: Ceratomyxidae
Genus: Ceratonova
Species:
C. shasta
Binomial name
Ceratonova shasta
Noble, 1950[1]
Synonyms
  • Ceratomyxa shasta

Ceratonova shasta (syn. Ceratomyxa shasta) is a myxosporean parasite that infects salmonid fish on the Pacific coast of North America. It was first observed at the Crystal Lake Hatchery, Shasta County, California, and has now been reported from Idaho, Oregon, Washington, British Columbia and Alaska.[2]

Life history

In addition to the fish host, C. shasta infects a freshwater polychaete worm.[3] Actinospores are released from the worm, and infect fish, on contact, in the water column. Neither horizontal (fish to fish), nor vertical (fish to egg) transmissions have been documented under laboratory conditions, suggesting that the worm host is necessary for completion of the life cycle.

Spores are released back into freshwater system after its fish host dies, however the complete life cycle, host and vector interaction is not fully understood (especially the ecology of the polychaete host).[2]

Research indicates that the potential for infection is enhanced when water temperatures are high, water flow is low, or numbers of infectious C. shasta are relatively high. Infection rates appear to be higher in or below still water environments than riverine ones.

Pathology of infection

Clinical indications of infection in salmons include lethargy, loss of body mass, darkening of the skin, ascites, exophthalmia and kidney pustules, These symptoms vary from one salmonid species to another, and also depend on life stage of the host.[2][4]

Internally, infection with C. shasta affects entire digestive tract, liver, gall bladder, spleen, gonads, kidney, heart, gills, and muscle tissues. Infection with C. shasta in adult chinook salmon causes mortality through intestinal perforations and co-occurring bacterial infections.[2]

Cold temperatures and salinity may reduce progress of disease, but do not eliminate infection. Progression of infection and mortality is temperature dependent, with higher temperature increasing disease progression and resulting in quicker mortality.[2]

Disease resistance

Salmonid stocks exhibit variable resistance to C. shasta.[5] Resistance is variable and may be compromised by environmental conditions which enhance infectivity. Salmonid stocks which are resistant to C. shasta are not necessarily resistant to other myxosporean infections, such as Myxobolus cerebralis.

Dams and proliferation

Dammed rivers are associated with the proliferation of C. shasta.[6] The dams on the river Klamath resulted in the colonization of large areas with polychaete worms which are a secondary host of C. shasta. Dammed areas tend to cause overcrowding of fishes which is associated with C. shasta infection. Plans for the removal of the dams on the Klamath are underway.[6]

References

  1. ^ Noble, Elmer R. (October 1950). "On a myxosporidian (protozoan) parasite of California trout". The Journal of Parasitology. 36 (5): 457–60. doi:10.2307/3273172. JSTOR 3273172. PMID 14795328.
  2. ^ a b c d e Bartholomew, J.L.; Rohovec, J.S.; Fryer, J.L. (1989). Fish Disease Leaflet 80 | Ceratomyxa shasta, a Myxosporean Parasite of Salmonids. U.S. Fish and Wildlife Service (Report). Retrieved 17 November 2020.
  3. ^ Bartholomew, J.L.; Whipple, M.J.; Stevens, D.G.; Fryer, J.L. (October 1997). "The life cycle of Ceratomyxa shasta, a myxosporean parasite of salmonids, requires a freshwater polychaete as an alternate host". The Journal of Parasitology. 83 (5): 859–68. doi:10.2307/3284281. JSTOR 3284281. PMID 9379291.
  4. ^ "Ceratonova shasta". Oregon State University. Retrieved 1 May 2021.
  5. ^ Bartholomew, J. L. (1998). "Host Resistance to Infection by the Myxosporean Parasite Ceratomyxa shasta: A Review". Journal of Aquatic Animal Health. 10 (2): 112–120. doi:10.1577/1548-8667(1998)010<0112:HRTIBT>2.0.CO;2.
  6. ^ a b Matthews, Alexander (10 November 2020). "The rebirth of a historic river". Retrieved 11 November 2020.
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