Effect of hydrogen peroxide as treatment for amoebic gill disease in Atlantic salmon (Salmo salarL.) in different temperatures

Abstract

Amoebic gill disease (AGD) is a pathogenic disease in salmonids caused by Neoparamoeba perurans. Treatment of AGD infection has been through freshwater bathing of the fish. However, as the availability of fresh water is often limited, hydrogen peroxide has been introduced as an alternative treatment. This study investigated the effect of hydrogen peroxide as treatment for AGD-infected salmon (Salmo salar L.,) at different seawater temperatures and hydrogen peroxide dosages. In total, 600 fish were challenged with N. perurans and the severity of the AGD infection was measured using a gill score scale. After challenge and disease development, the fish were distributed into 12 tanks. The treatment was performed at different seawater temperatures (8°C, 12°C, 17°C) using different hydrogen peroxide doses. Each temperature included an untreated control group. Linear models were used to analyse gill score. A significant effect of treatment was found (À0.68 AE 0.05) regardless of dose and temperature, suggesting that hydrogen peroxide was effective in treating AGD. When the model included dose, a negative linear relationship between dose and gill score was found. The study proved that treatment of AGD with hydrogen peroxide was successful, as gills partially recovered following treatment and further disease development was delayed.

The interaction between temperature and dose on the efficacy and biochemical response of Atlantic salmon to hydrogen peroxide treatment for amoebic gill disease

“…Tasmania is recognized as a global warming hotspot (Oliver et al, ), thus further limiting the potential use of H 2 O 2 in this region with current technologies. While the ability of H 2 O 2 to reduce both gross and histological AGD lesions has been demonstrated previously (Adams et al, ; Martinsen et al, ), the present study provides further evidence that H 2 O 2 does not only reduce AGD pathology, but also significantly reduces the load of N. perurans on the gills. We also demonstrate that clearance of amoeba is optimal at a treatment temperature–H 2 O 2 dose combination that does not cause significant gill damage.…”

“…Indeed, the ability to reduce the temperature of the bathing treatment is one major advantage of wellboats over liner-based treatments. However, it must also be acknowledged that in both our study and those by others (Adams et al, 2012;Martinsen et al, 2018), H 2 O 2 does not completely resolve AGD lesions or remove all amoeba on the gill surface. Therefore, compared to freshwater bathing, H 2 O 2 is less effective.…”

“…Indeed, histological studies have demonstrated a significant reduction in amoeba and resolving hyperplastic lesions 7 days post-treatment with 1,250 mg/L H 2 O 2 (Adams et al, 2012). Similar in vivo studies have also demonstrated that H 2 O 2 treatments can effectively reduce the gross gill pathology and delay-but not eliminate-further progression of AGD (Martinsen, Thorisdottir, & Lillehammer, 2018).…”

A comparison of the use of different swab materials for optimal diagnosis of amoebic gill disease (AGD) in Atlantic salmon (Salmo salar L.)

“…However, this latter treatment has a reduced safety margin at higher temperatures (Adams, Crosbie & Nowak, 2012) or where fish are compromised by advanced‐stage AGD (McCarthy et al., 2015). Overall, AGD‐related mortality is increasing, causing major economic losses in regions of Atlantic salmon aquaculture, including Tasmania, Norway and Scotland (Martinsen, Thorisdottir, & Lillehammer, 2018; Oldham et al., 2016; Shinn et al., 2015).…”

Evaluation of sodium percarbonate as a bath treatment for amoebic gill disease in Atlantic salmon

“…H 2 O 2 is increasingly being used at concentrations of 800-1,250 mg/L as a means of controlling AGD in Scotland and Norway (Adams, Crosbie, & Nowak, 2012;McCarthy et al, 2015;Overton, Samsing, Oppedal, Stien, & Dempster, 2018;Powell et al, 2015). However, while the 20-to 30-min treatment is much shorter than freshwater bathing (Hytterød et al, 2017;Powell, Attard, Harris, Roberts, & Leef, 2005), there is an elevated risk of chemical toxicity to Atlantic salmon at temperatures above 12-14°C (Bowers, Speare, & Burka, 2002;Cameron, 1993;Martinsen, Thorisdottir, & Lillehammer, 2018;Overton et al, 2018Overton et al, , 2019Wynne et al, 2020) which limits the safe use of H 2 O 2 to higher latitudes and cooler seasons.…”