Impact of Antiparasitic Treatments on Aquatic Ecosystems

Antiparasitic compounds are indispensable in modern aquaculture for the control of ectoparasites such as sea lice, but their use has raised concerns over unintended consequences for non-target species and broader ecosystem function. Treatments administered via in-feed medication, immersion baths or direct chemical discharge introduce active substances—ranging from macrocyclic lactones and organophosphates to synthetic pyrethroids—into water columns and sediments. Persistence and bioaccumulation of these compounds can induce acute toxicity, physiological stress and behavioural impairments in crustaceans, molluscs and other invertebrates. Sublethal effects, including oxidative damage, enzyme inhibition and immune disruption, may compromise reproduction and larval development. Benthic community structure often responds to gradients of antiparasitic residues, with declines in abundance and diversity of sensitive taxa. Such impacts can propagate through food webs and alter nutrient cycling, posing challenges for ecosystem resilience. Emerging approaches aim to refine treatment protocols, reduce environmental loading through integrated pest management and develop low-impact therapeutants that safeguard both production and environmental welfare.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Impact of Antiparasitic Treatments on Aquatic Ecosystems publication trend

The graph below shows the total number of articles in impact of antiparasitic treatments on aquatic ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Emamectin benzoate: A macrocyclic lactone administered in fish feed to control sea lice, noted for persistence in sediments.

Deltamethrin: A synthetic pyrethroid applied in bath treatments for ectoparasites; highly toxic to non-target crustaceans at low concentrations.

Azamethiphos: An organophosphate pesticide used in delousing procedures; can induce oxidative damage in bivalves.

Benthic communities: Assemblages of organisms living on or in sediments, whose composition reflects environmental stressors.

LC50: The concentration of a substance that causes 50% mortality in a test population over a specified period.

Oxidative damage: Cellular injury resulting from reactive oxygen species attacking lipids, proteins and DNA, often used as an indicator of sublethal stress.

References

1. Acute and Sublethal Effects of Deltamethrin Discharges from the Aquaculture Industry on Northern Shrimp (Pandalus borealis Krøyer, 1838): Dispersal Modeling and Field Investigations. Environmental Science and Technology (2023).
2. Negative effects of the sea lice therapeutant emamectin benzoate at low concentrations on benthic communities around Scottish fish farms. The Science of The Total Environment (2019).
3. The Interactive Effects of the Anti-Sea Lice Pesticide Azamethiphos and Temperature on Oxidative Damage and Antioxidant Responses in the Oyster Ostrea chilensis. Antioxidants (2024).