AEI 11:1-17 (2019)  -  DOI: https://doi.org/10.3354/aei00292

ABSTRACT: Sugar kelp Saccharina latissima is one of the dominating kelp species on sheltered sublittoral sites along the Norwegian coastline, providing important habitats and ecosystem services. In finfish aquaculture in Norway, infections caused by salmon lice Lepeophtheirus salmonis are one of the biggest challenges the industry is currently facing, and presently the most-used therapeutant is hydrogen peroxide (H₂O₂). Commonly, this treatment involves bathing the fish in a solution of approximately 1700 mg H₂O₂ l^-1 seawater before releasing the solution into the surrounding waters. The present study was conducted to increase the knowledge on how these H₂O₂ emissions from farm operations could impact juvenile S. latissima. This was achieved by determining the effects of a 1 h exposure to realistic H₂O₂ levels on S. latissima mortality and photosynthesis. Effects on photosynthesis were determined by incubating plants at 3 time intervals post-exposure. Toxicity potentials including lethal concentration for 50% of the population (LC₅₀) and effective concentration (EC₅₀) for photosynthetic capacity (P_MAX) and efficiency (α) were determined based on these data. Juvenile S. latissima was highly sensitive, having an LC₅₀ of 80.7 mg H₂O₂ l^-1, which is less than 5% of the dose commonly used at farms and emitted to the environment. A concentration of 85 mg l^-1 caused an immediate 90% reduction in both P_MAX and α. The EC₅₀ was found to be 27.8 and 35.4 mg l^-1 for P_MAX and α, respectively. This may indicate that natural S. latissima populations in the vicinity of fish farms can be negatively affected by H₂O₂ bath treatments.

KEY WORDS: Kelp mortality · Kelp photosynthesis · Aquaculture effluents

Full text in pdf format

Cite this article as: Haugland BT, Rastrick SPS, Agnalt AL, Husa V, Kutti T, Samuelsen OB (2019) Mortality and reduced photosynthetic performance in sugar kelp Saccharina latissima caused by the salmon-lice therapeutant hydrogen peroxide. Aquacult Environ Interact 11:1-17. https://doi.org/10.3354/aei00292 Export citation Share:    Facebook - - linkedIn