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The Application of Hydrogen Peroxide as a Treatment for the Ectoparasite Amyloodinium ocellatum (Brown 1931) on the Pacific Threadfin Polydactylus sexfilis

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  • Hawaii C's Aquaculture Consultant Services

Abstract

Ectoparasite infections can cause death or a decline in the general health of farm-raised finfish. This paper reports the findings from two studies conducted to evaluate the efficacy of hydrogen peroxide as a therapeu-tant for the control of infections of Amyloodinium sp. on cultured Pacific threadfin Polydactylus sexfilis (locally called “moi”). Threadfin with amyloodiniasis collected from a commercial farm were used in both trials. Prior to the trials, and following hydrogen peroxide treatment, the extent of infection was determined by a gill biopsy procedure. An initial trial was conducted in the laboratory to assess the response of juvenile threadfin and Amyloodinium sp. trophonts to hydrogen peroxide exposure at four dosages: 0, 75, 150, or 300 mg/L for 30 min. In a trial on a commercial farm, a hydrogen peroxide treatment at 75 mg/L for 30 min was applied to juvenile threadfin in a grow-out tank. In both trials, hydrogen peroxide was immediately flushed from the culture system with sea-water after the 30 min exposure period. In the laboratory trial, treatment with 300 mg/L hydrogen peroxide resulted in 100% mortality of the exposed group of fish. However, single treatments with hydrogen peroxide at concentrations of 75 or 150 mg/L eliminated Amyloodinium sp. trophonts without causing loss of fish. In the field trial, a single treatment with 75 mg/L hydrogen peroxide greatly reduced levels of Amyloodinium infestation, and a second treatment 6 d later reduced Amyloodinium trophonts to a nondetectable level. These findings suggest that hydrogen peroxide is a suitable chemical for the treatment of amyloodiniasis of cultured, juvenile Pacific threadfin.
... The control of these parasites is problematic and a variety of treatments has been investigated over time (8)(9)(10)(11)(12)(13). ...
... Regarding Amyloodinium, several treatments alternative to copper sulfate have been tested in experimental trials in order to manage amyloodiniosis, but inhibitory effects were not determined and, in some cases, neither fully clarified (9,11). On the other hand, to date there is no available literature information In the present study, the potential antiparasitic effects of 18 plant derived compounds were investigated. ...
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The fish parasites Saprolegnia spp. (Oomycota) and Amyloodinium ocellatum (Dinophyceae) cause important losses in freshwater and marine aquaculture industry, respectively. The possible adverse effects of compounds used to control these parasites in aquaculture resulted in increased interest on the search for natural products with antiparasitic activity. In this work, eighteen plant-derived compounds (2′,4′-Dihydroxychalcone; 7-Hydroxyflavone; Artemisinin; Camphor (1R); Diallyl sulfide; Esculetin; Eucalyptol; Garlicin 80%; Harmalol hydrochloride dihydrate; Palmatine chloride; Piperine; Plumbagin; Resveratrol; Rosmarinic acid; Sclareolide; Tomatine, Umbelliferone, and Usnic Acid) have been tested in vitro. Sixteen of these were used to determine their effects on the gill cell line G1B (ATCC®CRL-2536™) and on the motility of viable dinospores of Amyloodinium ocellatum, and thirteen were screened for inhibitory activity against Saprolegnia spp. The cytotoxicity results on G1B cells determined that only two compounds (2′,4′-Dihydroxychalcone and Tomatine) exhibited dose-dependent toxic effects. The highest surveyed concentrations (0.1 and 0.01 mM) reduced cell viability by 80%. Upon lowering the compound concentration the percentage of dead cells was lower than 20%. The same two compounds revealed to be potential antiparasitics by reducing in a dose-dependent manner the motility of A. ocellatum dinospores up to 100%. With respect to Saprolegnia, a Minimum Inhibitory Concentration was found for Tomatine (0.1 mM), Piperine and Plumbagin (0.25 mM), while 2′,4′-Dihydroxychalcone considerably slowed down mycelial growth for 24 h at a concentration of 0.1 mM. Therefore, this research allowed to identify two compounds, Tomatine and 2′,4′-Dihydroxychalcone, effective against both parasites. These compounds could represent promising candidates for the treatment of amyloodiniosis and saprolegniosis in aquaculture. Nevertheless, further in vitro and in vivo tests are required in order to determine concentrations that are effective against the considered pathogens but at the same time safe for hosts, environment and consumers.
... 1.6 Treatment trials for Amyloodiniosis 1.6.1 Supplemented antiseptic and route and dose of administration The selected antiseptic was hydrogen peroxide H 2 O 2 20%. It was added within a dose and duration according to (Montgomery -Brock et al., 2001). ...
... Also, there was a significant correlation between water temperature levels and parasitic infestation while there was no significant correlation between dissolved oxygen and A. ocellatum Occurrences. Montgomery-Brock et al. (2001) reported that, Treatment with hydrogen peroxide to 75-150 mg/L was effective in eliminating trophontes in Polydactylus sexfilis. ...
... Additionally, subacute hydrogen peroxide toxicity caused anemia by the destruction of the erythrocyte membrane and oxidation of hemoglobin (Metzler, 1977;Newsholme, 1983;Innes Taylor and Ross, 1988). Hydrogen peroxide has also been used in aquaculture as an immersion (bath) treatment against many different disease-causing organisms, including external parasites (Rach et al., 2000a;Montgomery -Brock et al., 2001;Powell and Clark, 2004), bacteria (Speare and Arsenault, 1997;Lumsden et al., 1998;Rach et al., 2000b;Gaikowski et al., 2003) and fungi (Howe et al., 1999;Rach et al., 2004), on different species and life-stages of fish. ...
... Hydrogen peroxide has been used to treat a number of external bacterial and parasitic infections of finfish including sea louse infestation of Atlantic salmon (Overton, Samsing, Oppedal, Dalvin, et al., 2018), monogenean gill flukes in kingfish (Seriola lalandi) (Mansell, Powell, Ernst, & Nowak, 2005), amyloodiniasis of Pacific threadfin (Polydactylus sexjilis) (Montgomery-Brock, Sato, Brock, & Tamaru, 2001) and Tenacibaculum maritimum infection of turbot (Scophthalmus maximus) (Avendano-Herrera, Magarinos, Irgang, & Toranzo, 2006). ...
Article
Hydrogen peroxide (H2O2) is a commonly used treatment for a range of parasitic diseases of marine finfish, including amoebic gill disease (AGD). While this treatment is partially effective at reducing parasite load, H2O2 can have detrimental effects on the host under certain conditions. Treatment temperature and dose concentration are two factors that are known to influence the toxicity of H2O2; however, their impact on the outcome of AGD treatment remains unclear. Here, we investigated the effects of treatment temperature (8, 12 or 16°C) and dose concentration (750, 1,000, 1,250 mg/L) on the efficacy of H2O2 to treat AGD. We demonstrated that a 20‐min bath treatment of H2O2 at all doses reduced both parasite load and gross gill score significantly. Parasite load and gross gill score were lowest in the 1,000 mg/L treatment performed at 12°C. At the high dose and temperature combinations, H2O2 caused moderate gill damage and a significant increase in the plasma concentration of electrolytes (sodium, chloride and potassium). Taken together, our study demonstrates that higher H2O2 treatment temperatures can adversely affect the host and do not improve the effectiveness of the treatment.
... Montgomery-Brock et al. (2001)studied the effect of H 2 O 2 on trophonts of Amylood- inium in cultured Pacific threadfin (Polydactylus sexfilis). Application of 75 and 150 mg L À1 H 2 O 2 for 30 min resulted in a reduced number of parasites. ...
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Many classical therapeutants are going to be banned in Europe, and an urgent need for alternatives is emerging. This issue can be exemplified by one major parasitic disease in aquaculture and ornamental fish breeding: velvet disease. This disease, caused by dinoflagellates of the genera Amyloodinium and Piscinoodinium, is an important infection affecting cultured freshwater and marine ornamental and food fish, and consistently causes great financial loss to the associated industries. Therapeutants available contain copper, malachite green, or methylene blue, and which can be toxic to non-target organisms in the surrounding environment. As a result, these chemicals are banned for use by the aquaculture industry in several countries, and a prohibition for commercial ornamental fishkeeping is likely to follow in most countries. Increasing development of resistance to therapeutants, and growing public awareness for animal welfare and environmental protection, have prompted research in the areas of alternative treatment options and immunostimulants. Hydrogen peroxide and peracetic acid are possible “green” therapeutants which do not contribute residues to the environment. Natural feed supplements such as pre- and probiotics can increase animal welfare and prevent stress and/or infections. Humic substances are another promising, natural immunostimulants which will be considered in depth. The aim of this review is to provide an overview of risks and benefits of current treatment options and new approaches to replace harmful therapeutants and minimize the number of toxic residues discharged into the environment. Treatments will be discussed on various parasitic infections and focus, where available, on Amyloodinium and Piscinoodinium.
... There are several treatments available for amyloodiniosis, especially for the motile infective dinospore [9,10], since the parasitic and encapsulated state of trophont and tomont are difficult to treat and eradicate [1]. These treatments can range from the most classical ones, such as formaldehyde [11]; copper sulphate [1,10,12,13], which can be done in combination with freshwater treatment [14]; or hydrogen peroxide [15,16], to the more atypical ones, such as the addition of larval brine shrimp (Artemia salina) to the tank to prey on A. ocellatum dinospores [17]. However, most of these treatments are highly ineffective or unpractical for earthen pond semi-intensive aquaculture, which is the most common type of aquaculture facility in Southern Europe [1]. ...
Article
Amyloodiniosis is a disease that represents a major bottleneck for semi-intensive aquaculture, especially in Southern Europe. The inefficacy of many of the treatments for this disease on marine fish produced in semi-intensive aquaculture has led to a new welfare approach to amyloodiniosis. There is already some knowledge of several welfare issues that lead to amyloodiniosis as well as the stress, physiological, and immunological responses to the parasite by the host, but no work is available about the influence of fish age on the progression of amyloodiniosis. The objective of this work was to determine if stress, hematological, and histopathological responses are age dependent. For that purpose, we determined the mortality rate, histopathological lesions, hematological indexes, and stress responses (cortisol, glucose, lactate, and total protein) in "Small" (total weight: 50 ± 5.1 g, age: 273 days after eclosion (DAE)) and "Big" (total weight: 101.3 ± 10.4 g, age: 571 DAE) white seabream (Diplodus sargus) subjected to an Amyloodinium ocellatum infestation (8000 dinospores mL −1) during a 24-h period. The results demonstrated a strong stress response to A. ocellatum, with marked differences in histopathological alterations, glucose levels, and some hematological indexes between the fish of the two treatments. This work elucidates the need to take in account the size and age of the fish in the development and establishment of adequate mitigating measures and treatment protocols for amyloodiniosis.
... The selected antiseptic was hydrogen peroxide H 2 O 2 20%. It was added within a dose and duration according to (Montgomery -Brock et al., 2001). ...
Article
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Ichthyophthiriasis is a worldwide fish disease with great financial impact on freshwater fish farming due to its associated high mortality rates. Current study assesses the parasiticidal capacity of hydrogen peroxide (H2O2) and chlorine dioxide (ClO2) against the causative agent, Ichthyophthirius multifiliis, in jundiá. Median lethal concentration (LC50, 96h) of each chemical agent was established, as well as the minimum inhibitory concentration of hydrogen peroxide for the parasite´s infectious larval phase (theront). Products were tested asynchronously in parasitized fingerlings for short and long baths at the following concentrations and exposure times: 1. Hydrogen peroxide: (T1) continuous bath - 30ppm and (T2) 50ppm; (T3) short bath - 150ppm, during 1h and (T4) 250ppm during 1h; control group (without any chemical agent). 2. Chlorine dioxide: (T1) continuous bath - 4ppm and (T2) 20ppm; (T3) short bath - 200ppm, during 1min; (T4) short bath - 400ppm, during 1min and control group. Data analysis demonstrated a concentration of 82.54ppm of the commercial product (or 24.76ppm of the active chemical agent) as LC50, 96h of H2O2 and 38.4ppm product (or 2.68ppm of the active chemical agent) for ClO2. Hydrogen peroxide concentration causing 100% mortality rate of theronts in 1h was 25ppm (product, or 7.5ppm of the active chemical agent). At the end of the fourth day of curative experiment, 98% of the animals died by ichthyophthiriasis. No treatment was effective against the parasite.
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