The effect of the isopod parasite Ceratothoa gaudichaudii on the body weight of farmed Salmo salar in southern Chile

doi:10.1016/0044-8486(96)01262-8

Aquaculture

Volume 143, Issue 1, 15 July 1996, Pages 1-6

https://doi.org/10.1016/0044-8486(96)01262-8 Get rights and content

Abstract

A study of the isopod Ceratothoa gaudichaudii, a parasite on farmed Atlantic salmon was carried out on Guar island, Chile, between May 1993 and August 1994. A total of 671 salmon, with an initial body weight of 0.9 kg to 1.1 kg, was selected; one third were naturally infected with one or two growing parasites. The fish were kept in a separate cage and were examined individually, under anaesthesia, five times during the study. On each occasion, the weight and number of the parasites on each fish was recorded.

There was an increase in the prevalence of the parasitosis from 33.4% to 98.2%; concurrently, the total number of parasites on salmon rose from 309 to 3987 with an increase of infestation intensity from 1.4 to 6.1 parasites per fish. No adult females with eggs or larvae were found. At the end of the study, salmon with less than three parasites weighed 4428 ± 949 g; those with three to eight parasites weighed 4151 ± 983 g, and those with more than eight parasites weighed 3763 ± 1056 g. A significant difference in weight (P < 0.05) among the three groups was detected.

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Marine fish are a nutritious and high-value food commodity, but many wild-capture fisheries are in decline. Thus, marine fish culture is expected to expand greatly in coming years. Management of disease is a major problem in this industry, and metazoan parasites are among the most significant disease agents in terms of economic loss and animal welfare. Current methods for controlling metazoan parasites are mostly reactionary and rely on chemical treatment. Such methods are ultimately unsustainable. Here, we summarise the life cycles of marine metazoan parasites and how this knowledge can be used for nonchemical management and control. To aid the sustainable growth of marine fish culture, we advocate for a renewed research focus on the basic life history characteristics of parasites.
Parasitic isopods Ceratothoa banksii (Leach, 1818) and Nerocila orbignyi (Guérin-Méneville, 1832) of farmed Atlantic salmon and their potential as vectors of Neoparamoeba perurans (Young et al. 2007) in Tasmania
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Adult female N. orbignyi and some larger adult males were located adjacent to or on the caudal fin. The prevalence and intensity of C. banksii found in the present study are similar to the prevalence of 98.8–100% (mean intensity 3–5) of C. gaudichaudii previously reported for farmed Atlantic salmon in Chile, (Inostroza et al., 1993; González and Carvajal, 1994; Sievers et al., 1996; Sievers et al., 1997). In the Chilean studies, parasitised fish with a higher intensity of isopods were of a smaller size than fish without isopods (Sievers et al., 1996).
Reiterative freshwater bathing is the main treatment to control amoebic gill disease (AGD) of farmed Atlantic salmon in Tasmania, Australia. Regular freshwater exposure appears to control ectoparasitic cymothoid isopods, which were only seen at high prevalence and intensity in summer when fish had not been treated for over 100 days. With the potential advent of non-freshwater AGD treatments or increased periods between freshwater bathing due to selective breeding for AGD resistance, it is possible that cymothoid parasitism will become an increasing threat on Tasmanian salmon farms. In order to establish whether isopods could be vectors of Neoparamoeba perurans Young et al. 2007 (the causative agent of AGD), gill isopods were collected from salmon that had not been bathed for seven months and carried a 95% prevalence of isopods, including Ceratothoa banksii (Leach, 1818) and Nerocila orbignyi (Guérin-Méneville, 1832). PCR analyses of gill swabs indicated that 82% of salmon were positive for N. perurans while 41% of the sampled isopods were positive for N. perurans on external surfaces. When internal material was analysed, only 9% of the isopods were positive for the amoeba, but in very low concentration. Quantitative analysis showed no correlation between the concentrations of N. perurans from gill swabs and the isopods from the same individual fish. Thus, it is unlikely that these isopods act as a significant reservoir or vector for N. perurans.
Physiological effects of cymothoid parasitization in the fish host Pomatoschistus microps (Krøyer, 1838) under increasing ocean temperatures
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Adlard and Lester (1994) and Fogelman et al. (2009) have seen that Cymothoid parasitisation significantly decrease fish condition. On the other hand, in Lanzing and O'Connor (1975) and Sievers et al., (1996) it was observed that, for the species they tested, only when fishes were host for multiple parasites did their condition decreased. In the case of P. microps more than one parasite per fish seems rare in nature since all fish caught for both this work and a previous work by Cereja et al. (2017) had only one single parasite (direct observation).
Currently, the effects of global warming on marine organisms are widely recognized by the scientific community. However, studies that relate the increase in ocean temperature with other stress factors are still scarce. The main aim of this study was to evaluate the effects of water temperature increase on the parasite Anilocra frontalis, the parasite’s effects over its host Pomatoschistus microps. Therefore, P. microps were subjected to A. frontalis parasitization and both species were then exposed to two different temperatures, 22 °C (control) and 26 °C (experimental temperature). Critical Thermal Maxima (CTMax), antioxidant enzyme activity (glutathione-S-transferase, catalase and superoxide dismutase), Heat Shock Protein 70 and Lipid peroxidation (MDA content) were analysed for both species. Anilocra frontalis CTMax raised 1 °C between animals acclimated to 22 and acclimated at 26 °C (CTMax was 32 °C in animals acclimated to 22 °C and 33 °C in animals acclimated to 26 °C). Additionally, the parasites acclimated to higher temperatures showed higher release rates from their hosts. Although the parasitization did not influence P. microps’ condition, when combined with temperature it increased fish mortality rate and stress levels. The results show that temperature only influenced HSP70 values, presenting higher levels in fish acclimated to 26 °C.
Global diversity of fish parasitic isopod crustaceans of the family Cymothoidae
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Of the 95 known families of Isopoda only a few are parasitic namely, Bopyridae, Cryptoniscidae, Cymothoidae, Dajidae, Entoniscidae, Gnathiidae and Tridentellidae. Representatives from the family Cymothoidae are obligate parasites of both marine and freshwater fishes and there are currently 40 recognised cymothoid genera worldwide. These isopods are large (>6 mm) parasites, thus easy to observe and collect, yet many aspects of their biodiversity and biology are still unknown. They are widely distributed around the world and occur in many different habitats, but mostly in shallow waters in tropical or subtropical areas. A number of adaptations to an obligatory parasitic existence have been observed, such as the body shape, which is influenced by the attachment site on the host. Cymothoids generally have a long, slender body tapering towards the ends and the efficient contour of the body offers minimum resistance to the water flow and can withstand the forces of this particular habitat. Other adaptations to this lifestyle include small sensory antennae and eyes; a very heavily thickened and calcified cuticle for protection; and sharply curved hooks on the ends of the pereopods which allows these parasites to attach to the host. Most cymothoids are highly site and host specific. Some of these parasitic cymothoids have been reported to parasitise the same host fish species for over 100 years, showing this species specificity. The site of attachment on the host (gills, mouth, external surfaces or inside the host flesh) can also be genus or species specific. This paper aims to provide a summary of our current knowledge of cymothoid biodiversity and will highlight their history of discovery, morphology, relationships and classification, taxonomic diversity and ecology.
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2013, Aquaculture
Citation Excerpt :
This allows different species of wild fish infected with isopods to be the source of mancae which then can infect farmed fish, which is relatively simple where many wild fish occur in the vicinity of sea cages (Lester and Hayward, 2006). A similar scenario was reported from Chile, where farmed Atlantic salmon were parasitized by Ceratothoa gaudichaudii Milne Edwards, 1840 (see Sievers et al., 1996). The infective mancae did not reach reproductive maturity on Atlantic salmon and were believed to have come from an environment outside the cages.
Cultured striped trumpeter Latris lineata was held in sea cage systems or a land-based facility in south-eastern Tasmania. Visual checks of metazoan ectoparasites were conducted on six cohorts (T1 to T6) in the land-based facility from 2006 to 2007, and three cohorts (C1 to C3) held in cages from 2007 to 2008. Three parasite species were recorded; a cymothoid Ceratothoa banksii; a chondracanthid Chondracanthus goldsmidi; and a caligid Caligus nuenonnae. All three parasite species were present on the striped trumpeter in the sea cages with C. nuenonnae and C. goldsmidi found in very low prevalence on all cohorts. There was no significant effect of cohort or season on the parasites' prevalence or intensity. Cohort C1 had the highest numbers of C. nuenonnae with prevalence of 2.5% (intensity 1.0 ± 0.0 parasites fish^− 1), whilst cohort C3 had the highest prevalence of C. goldsmidi (3.3%, intensity 1.0 ± 0.0). The isopod C. banksii was recorded in increasing prevalence in cohorts C1 and C2 during 2008, cohort C1 had a prevalence ranging from 9.8% (intensity 1.0 ± 0.0) to 17.5% (intensity 1 ± 0.0) whereas prevalence in cohort C2 ranged from 27.7% (intensity 1.21 ± 0.1) to 67.2% (intensity 1.8 ± 0.1). The two copepod species were recorded on the fish held in the land-based facility. C. nuenonnae was found on fish from two cohorts at a prevalence of 22.3% (intensity 1.4 ± 0.1 parasites) in cohort T1 and 4.3% (1.0 ± 0.0) in cohort T2. In contrast, C. goldsmidi was present during all parasite checks of cohorts T2 to T6 with the percentage of infected fish ranging from 27.2% (intensity 1.3 ± 0.1) in cohort T2 to 100% (intensity 32.8 ± 1.9) in cohort T4. Treatments against C. goldsmidi were conducted on cohorts T2 to T6 including manual removal of adult parasites and Neguvon baths. There was no apparent reduction in the parasite prevalence within season during follow-up surveys after ~ 6 months. An eleven month re-infection experiment was conducted with C. goldsmidi; striped trumpeter from which parasites were removed showed significantly lower prevalence (F = 161.8, df _1,20, P < 0.001) than those fish from which parasites were not removed. The study suggests that effective control of parasitic crustaceans is likely to be an important factor in the successful culture of sea-caged striped trumpeter.
The occurrence, distribution and pathology associated with gnathiid isopod larvae infecting the epaulette shark, Hemiscyllium ocellatum
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Gnathiid isopod praniza larvae were found to infect the epaulette shark Hemiscyllium ocellatum. All sharks carried larvae on their external body surface, with the preferred attachment site in both sexes around the cloaca (P<0.05). The claspers were the second site of preference in male sharks. Within the buccal and branchial cavities, about 16% of larvae were attached to the roof and floor of the mouth and 84% attached to the gills. A significant positive correlation existed between larval number and fish size. Histological examination showed that larval attachment in the buccal cavity elicited variable responses, the most severe being a loss of epithelium and compression of underlying tissue. No host cellular response or tissue proliferation was observed. Praniza attached preferentially to the efferent side of gill filaments (relative to blood flow), and caused loss of epithelium, compression of tissue, and a small amount of connective tissue proliferation. Attachment to the gill septum or to the afferent side of the gill filament caused lamellar disruption, a cellular inflammatory response, and connective tissue proliferation. Scanning electron microscopy showed little obvious praniza-induced gill damage, other than localised tissue distortion to form pockets around larvae attached between filaments. The results suggest that praniza larvae do not cause sufficient tissue damage to adversely affect the health of this shark species.

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Aquaculture

Abstract

References (11)

Salmonicultura en Chile, estado actual, proyecciones y estado sanitario

Medio Ambiente

Registro de parásitos detectados en salmónidos de cultivo en la X Región

Boletín de Informaciones Actualizadas Pfizer

Studies on the cymothoid fish symbionts of the eastern Pacific (Crustacea: Isopoda: Cymothoidae). II. Biology and systematics of Lironeca vulgaris

Occasional Papers of the Allan Hancock Foundation (NS)

A monograph on the Isopoda Cymothoidae (Crustacea) of the eastern Pacific

Zool.J. Linn. Soc.

Prevalencia e intensidad de infección estacional por Ceratothoa gaudichaudii en salmones Salmo salar cultivados en agua de mar en el sur de Chile

Arch. Med. Vet.

Cited by (32)

Metazoan Parasite Life Cycles: Significance for Fish Mariculture

Parasitic isopods Ceratothoa banksii (Leach, 1818) and Nerocila orbignyi (Guérin-Méneville, 1832) of farmed Atlantic salmon and their potential as vectors of Neoparamoeba perurans (Young et al. 2007) in Tasmania

Physiological effects of cymothoid parasitization in the fish host Pomatoschistus microps (Krøyer, 1838) under increasing ocean temperatures

Global diversity of fish parasitic isopod crustaceans of the family Cymothoidae

Parasitic crustaceans infecting cultured striped trumpeter Latris lineata

The occurrence, distribution and pathology associated with gnathiid isopod larvae infecting the epaulette shark, Hemiscyllium ocellatum