Ceratothoa oestroides

Last updated

Ceratothoa oestroides
Fig 1 Ceratothoa oestroides parasite in European sea bass.jpg
Adult female settled in the buccal cavity of a juvenile European sea bass ( Dicentrarchus labrax ).
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Isopoda
Family: Cymothoidae
Genus: Ceratothoa
Species:
C. oestroides
Binomial name
Ceratothoa oestroides
(Risso, 1826)
Synonyms [1]
  • Canolira oestroides Risso, 1826
  • Ceratothoa sargorum Gourret, 1891

Ceratothoa oestroides is a parasitic isopod of the family Cymothoidae, [1] being one of the "tongue biters" which are obligate ectoparasite of marine fish that dwells in the buccal cavity. It causes various pathologies in fish including tissue damage at the parasitisation site (tongue), growth defects, decrease in mean host weight and size, and increases mortalities in farmed and wild fish populations; [2] fish from five different families are confirmed to host this species: Sparidae ( Boops boops , Diplodus annularis , Pagelus erythrinus , Spicara smaris, Sparus aurata ), Carangidae ( Trachurus mediterraneus ), Clupeidae ( Sardina pilchardus ), Scorpaenidae ( Scorpaena notata, Scorpaena porcus ), and Mugilidae ( Liza aurata ). [3] [4]

Contents

Mature individuals mate in the host's buccal cavity, and the resultant embryos develop in the female's marsupium, where offspring pass through different pullus stages until they are released from the marsupium as free swimming manca, ready to infest fish hosts. C. oestroides is one of the most devastating ectoparasites in Mediterranean aquaculture, with an unequal distribution along different geographical areas [5] [6] [7] [8]

Life cycle

Embryos/pulli extracted from an adult female's marsupium. Pulli from adult female of Ceratothoa oestroides.jpg
Embryos/pulli extracted from an adult female's marsupium.

In general cymothoids are protandric hermaphrodites: [9] adults mate in the host's buccal cavity, the embryos develop in the female's marsupium, then moult through the pullus stages. The first pullus (I stage) can be found only in the marsupium where it moults into second pullus (II stage). Although most cymothoids have four pullus stages, only pullus stages I and II seem to exist in Ceratothoa oestroides.[ citation needed ]

Sexual differentiation occurs only after young leave the brood pouch. [10] As free swimming manca (infective stage), the parasite will seek and attach to an appropriate host, initially attaching onto the host's body (flanks, fins), and then crawls towards the operculum, where it enters the buccal cavity and settles on the base of the tongue. Moulting follows, and the isopods lose their swimming setae and becoming sessile. After permanent attachment is completed, another moult follows, where a seventh segment and pair of pereopods appears which is typical for the isopod pre-adult form. C. oestroides in this pre-adult form is functionally male until various conditions induce its transformation to female. After transformation, the isopod is considered to be adult. [11] Individuals that are first to reach the buccal cavity may undergo the full process of sexual differentiation (male puberty, mature male, transitory male stage, female puberty, mature female). Females block the transformation of a second individual parasite within a host. This second individual remains in the mature male stage as long as the female is alive. All the life stages of C. oestroides are found on the fish host, if we also include the pulli that are situated in the female pouch.[ citation needed ]

Pathology and clinical signs

Head of an adult female
Ventral view of the head of the adult female of Ceratothoa oestroides. 01.jpg
Ventral view
Dorsal view of the head of the adult female of Ceratothoa oestroides. 02.jpg
Dorsal view

This parasite causes various pathologies, including tissue damage of the tongue, growth defects, anaemia, decrease in mean host weight and size and increased mortalities in farmed and wild fish populations. [2] It has not been observed to impair feed intake in pre- and harvest-sized fish. Instead, the decrease in fingerlings’ weight is likely attributed to the suspected hematophagous nature of the parasite. Ceratothoa-infected fish may also infected with Rickettsia-like organisms (RLO), and related the latter pathogen to transmission by the isopod. [12] Apparently, infection of RLO is higher in Ceratothoa -highly infected farms. [7] Vagianou and colleagues observed that larval stages of C. oestroides (pulli II) that attack small fish induce the most damage, causing severe ulcers and extensive granulomatous lesions in the eyes that lead to blindness or the total loss of the eyeball. [7] However, this was not reported in other geographic area where the isopod has been found in reared fish. Fish infected with adult parasites did not show serious pathology. Lesions were localized at the upper and lower jaws and the tongue.[ citation needed ]

Relation to humans

Growth of farmed fish may be reduced and fish can suffer from post-haemorrhagic anaemia due to infestation. [13] Growth of caged fish infected with the parasite may be reduced up to 80% of market-sized uninfected fish. [14] For example, parasitised sea bass ( Dicentrarchus labrax ) in the age group of 291–293 days had reduced growth by 20.1% (14 g) and reduced length of 7.1% (12.63 mm) compared to non-parasitised fish. [5]

Diagnosis of C. oestroides infection is performed by examining the buccal cavity and determining the presence of the parasite.[ citation needed ]

Control methods

Treatment of isopod infestations on young fish has been performed using hourly formalin baths and manual removing from the buccal cavity during the vaccination for other diseases.[ citation needed ] Within a fish farm, it is common practice to decrease the number of wild fish population by fish net, as well as periodically cleaning the floating cages nets, depending on the season. Horton and Okamura (2001) suggest grading of smaller and larger fish and their separation, mooring the cages in deeper sites with sufficient currents to disperse the juvenile parasites in a direction away from the cages. [5] Often, in cases of heavy parasitism and mortality, reducing stocking density is enough to remedy the situation.[ citation needed ]

References

  1. 1 2 Schotte M, Boyko CB, Bruce NL, Poore GC, Taiti S, Wilson GD, eds. (2021). "Ceratothoa oestroides (Risso, 1826)". World Marine, Freshwater and Terrestrial Isopod Crustaceans Database. World Register of Marine Species . Retrieved 2 September 2021.
  2. 1 2 Adlard, R. D.; Lester, R. J. G. (September 1994). "Dynamics of the interaction between the parasitic isopod, Anilocra pomacentri, and the coral reef fish, Chromis nitida". Parasitology. 109 (3): 311–324. doi:10.1017/S0031182000078343. PMID   7970888.
  3. ↑ Charfi-Cheikhrouha, F.; Zghidi, W.; Yarba, L. O.; Trilles, J. P. (2000). "Le Cymothoidae (Isopods parasites de poissons) des cotes tunisiennes: ecologie et indices parasitologiques". Systematic Parasitology. 46 (2): 143–150. doi:10.1023/A:1006336516776. PMID   10830837. S2CID   35895535.
  4. ↑ Trilles, J.P.; Radujkovic, B.M. & Romestand, B. (1989). "Parasites des Poissons marins du Montenegro: isopods". Acta Adriatica. 30 (1/2): 279–306.
  5. 1 2 3 Horton, T; Okamura, B (2001). "Cymothoid isopod parasites in aquaculture: a review and case study of a Turkish sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus) farm". Diseases of Aquatic Organisms. 46 (3): 181–188. doi: 10.3354/dao046181 . PMID   11710552.
  6. ↑ Mladineo, I. (2002). "Prevalance of Ceratothoa oestroides (Risso, 1826), a cymothoid isopode parasite, in cultured sea bass Dicentrarchus labrax L. on two farms in middle Adriatic Sea". Acta Adriatica. 43: 97–102.
  7. 1 2 3 Vagianou, S.; Athanassopoulou, F.; Ragias, V.; Di Cave, D.; Leontides, L.; Golomazou, E. (2006). "Prevalence and pathology of ectoparasites of Mediterranean sea bream and sea bass reared under different environmental and aquaculture conditions". Israeli Journal of Aquaculture. 60: 128–133. hdl:10524/19164.
  8. ↑ Čolak, Slavica; Kolega, Matko; Mejdandžić, Danijel; Župan, Ivan; Šarić, Tomislav; Piplović, Edi; Mustać, Bosiljka (February 2018). "Prevalence and effects of the cymothoid isopod (Ceratothoa oestroides, Risso 1816) on cultured meagre (Argyrosomus regius, Asso 1801) in the Eastern Adriatic Sea". Aquaculture Research. 49 (2): 1001–1007. doi: 10.1111/are.13547 .
  9. ↑ Mladineo, Ivona (December 2003). "Life cycle of Ceratothoa oestroides, a cymothoid isopod parasite from sea bass Dicentrarchus labrax and sea bream Sparus aurata". Diseases of Aquatic Organisms. 57 (1–2): 57(1-2):97-101. doi: 10.3354/dao057097 . PMID   14735926.
  10. ↑ Brusca, R.C. (1978). "Studies on the cymothoid fish symbionts of the eastern Pacific (Crustacea: Isopoda: Cymothoidae) I. Biology of Nerocila californica". Crustaceana. 34: 141–154. doi:10.1163/156854078X00718.
  11. ↑ Lincoln, R. J. (1971). "Isopod fish parasites". Marine Observer. 41 (234): 184–186.
  12. ↑ Athanassopoulou F.; Sabatakou O.; Groman D. & A. Prapas (1999). First indices of Rickettsia-like infections in cultured sea bass (D. labrax). 9th Int. Conference, Eur. Assoc. Fish Pathologists. Rhodes, Greece.
  13. ↑ Horton, T.; Okamura, B. (2003). "Post-haemorrhagic anaemia in sea bass, Dicentrarchus labrax (L.), caused by blood feeding of Ceratothoa oestroides (Isopoda: Cymothoidae)". Journal of Fish Diseases. 26 (7): 401–406. Bibcode:2003JFDis..26..401H. doi:10.1046/j.1365-2761.2003.00476.x. PMID   12946009.
  14. ↑ Šarušić, G. (1999). "Preliminary report of infestation by isopod Ceratothoa oestroides (Risso, 1926), in marine cultured fish". Bulletin of the European Association of Fish Pathologists. 19: 110–113.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.