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Author: Dr. Panos Varvarigos
Freelance Veterinarian - Fish Pathologist, Athens, Greece.

AquaHealthTM Laboratory.

 

THE PARASITIC COPEPOD Lernaeolophus sultanus (Pennellidae) FOUND ON FARMED SEA BASS (Dicentrarchus labrax) AND SHARP SNOUT SEA BREAM (Diplodus puntazzo) IN COASTAL MARINE FISH FARMS IN GREECE.

Poster presented at the 13th International EAFP conference on Fish and Shellfidh Diseases. 17th - 21st September 2007. Grado, Italy.

 

Pathogen (name, taxonomy, description):

Lernaeolophus sultanus

Parasite classification:

Phylum: Arthropoda

Subphylum: Crustacea

Class: Maxillopoda

Subclass: Copepoda

Infraclass: Neocopepoda

Superorder: Podoplea

Order: Siphonostomatoida

Family: Pennellidae

Genus: Lernaeolophus

Species: Lernaeolophus sultanus

Lernaeolophus sultanus (Pennellidae) is a cosmopolitan copepod species parasitizing on marine fish. It has been recorded from the Atlantic, Pacific and Indian Oceans as well as from the Mediterranean Sea.

Frequency of occurrence:

Rare

Economic Implications:

Slight (occasional incidents as yet)

Costs associated with anchor worm (copepod) infestations of farmed fish may be:

1. Rejections at harvest (degraded fish).
2. Extra labour to inspect and grade fish at the packing plant (quality).
3. Chronic stress and high propensity to other diseases (indirect mortality).
4. Growth retardation.

Susceptible farmed species, age/size and regional pertinence:

During the late autumn of the years 2005 and 2006 this "anchor worm" has been observed on caged sea bass (Dicentrarchus labrax) and sharp snout sea bream (Diplodus puntazzo) during routine fish handling, such as vaccination and grading. The fish were 50-150g average body weights and the farms were situated in the Corinthian and Maliakos Gulfs (arrowed areas on the map).

The rate of infection did not exceed 0.1% and the affected fish did not carry more than a single parasite. Mortalities were not evident.

 

Fish lesions and parasite morphology:

The parasites exhibited attachment site specificity. The eye sockets, the mouth bony vault, the tongue and the opercula, comprised the usual sites of attachment. The area around the anus and the anal fin was a less common attachment site.

The visible parts of the anchored parasite comprised its flexed 6-10mm abdomen with its 4-7mm long, straight or branched, caudal processes.

The cephalic part with its branched processes (antlers, or cephalic horns) as well as the 7-10mm long tube-like neck linking it to the abdomen, were invariably found to have burrowed deep into the host tissues, causing damage and deformities to the bone and cartilage, destroying the olphactory epithelium, or the tissues behind the eyeball.

These localized deformities together with inferior body condition and growth retardation characterized the parasitized fish.

The anchor worms could be removed by pulling, but the cephalic processes were cut off and remained embedded in the host tissues.

Bar distance = 1mm.

The caudal processes of the parasite portrayed a strong thick wall and occasionally contained crystallised masses.

Parasites with a developed single spiral egg sack, carrying a row of stacked maturing ova, were found on sharp snout sea bream, but not on sea bass.

This finding may show a case of parasite adaptation to alternative hosts and progressive transfer of the parasitism from wild fish hosts to the farmed fish species due to their relative abundance in the heavily farmed areas. The presence of mature parasites on farmed fish may pose a future threat to marine aquaculture in Greece.

Diagnosis (field, laboratory):

Gross observation of the parasites attached to their most common sites of attachment on the fish skin or mouth with associated localised lesions and deformities as well as poor body condition.

Environmental issues:

The parasitic copepods come from wild fish, although this particular anchor worm has not been observed on the common wild species that are seen around the net pens (Mugil spp., Liza spp., Boops boops, Boops salpa, Lithognathus mormyrus, etc.). However, if Lernaeolophus sultanus manages to mature on the farmed species, then the farms would be expected to amplify further and spread the parasite.

Regulations:

No regulations are in place. Parasitism by anchor worms is limited and poses no risk for the consumer.

Selected Bibliography:

Valdes, P. and Abellan, E. (2004) Prevalence of the parasitic copepod Lernaeolophus sultanus (Pennellidae) in common Pandora (Pagellus erythrinus) from Mazarron Bay (SE Spain). Poster presentation at the EAS conference "Aquaculture Europe 2004" [p.811]

Suarez-Morales, E. and Ho, J.S. (1994) Lernaeolophus sultanus (Nordman, 1864) (Copepoda), a parasite of Lutjanus camperchanus (Poey) in the Gulf of Mexico. Bull. Mar. Sci., 55(1):246-248

Grabda, J. (1991) Marine Fish Parasitology. PWN-Polish Scientific Publishers, Warszawa pp.304

Natarajan, P. and Nair, N.B. (1977) On the Occurrence of Lerneaolophus sultanus (Nordmann) on Priacanthus hamrur (Forskal). Current Science 46(3):93-94

Grabda, J. (1972) Observations on penetration of Lernaeolophus sultanus (Milne Edwards, 1840) (Lernaeoceridae) in organs of Pneumatophorus colias (Gmelin, 1788). Acta Ichthyol. Piscat. 2(1):115-125

Acknowledgements

The personal communications with Dr Angelo Colorni (Eilat, Israel) and Dr Francesc Padros (Barcelona, Spain) are thankfully acknowledged.


       


Author: Dr. Panos Varvarigos
Freelance Veterinarian - Fish Pathologist, Athens, Greece.


AquaHealthTM Laboratory.

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Every effort has been made to ensure that the information is accurate until the date of last editing. It is based upon the accumulated personal experience of applied veterinary work. The author cannot take responsibility for incorrect interpretation or any resulting consequences. The contents may be used as an educational guide and are definitely not meant to become a stand-alone diagnostic tool or operations manual.

 

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