Download AEBR 353 Environmental Health Measures for Open Ocean Aquaculture – Physiological responses of epifauna to enrichment under laboratory and field studies

Offshore finfish farming is expanding in New Zealand, but we lack knowledge about how seabed habitats and their species will respond to organic enrichment (in the form of faeces and waste feed) from salmon farms. This report, part of the Environmental Health Measures for Open Ocean Aquaculture project, investigates these impacts through laboratory and field experiments on three species: horse mussels, brachiopods, and scallops. Lab trials tested responses to controlled levels of enrichment, while field trials monitored animals near an operational salmon farm in the Marlborough Sounds.

Key Findings
• Fatty acid tests showed that all species absorbed salmon waste, which affected their nutritional health.
• Breathing rates increased with enrichment in horse mussels and brachiopods, suggesting they were using more energy to survive.
• Changes in gene activity were strong in the lab but weaker in the field, potentially showing early warning signs of stress.
• Some animals developed health issues, including parasites in horse mussels and scallops, and tissue changes possibly linked to changes in their diet or normal variations in living functions.
• Overall, the effects did not cause death, with N. lenticularis showing higher tolerance than the two bivalve species.