Physiological stress associated with mechanical harvesting and transport of cultured mussels (Perna canaliculus): A metabolomics approach

Harvest and transport of farmed mussels are known to impose stress on the crop species. However, not much is known about molecular pathways underlying these physiological stresses. The present study investigated the effects of harvesting on the metabolome of the haemolymph and hepatopancreas of green-lipped mussels (Perna canaliculus), complemented by assessments of behaviour and survival under simulated dry and re-immersion live shipment scenarios. The gas chromatography–mass spectrometry (GC–MS)-based metabolomics approach was used to compare the metabolite profiles of control mussels (sampled directly from growing lines) with mechanically harvested mussels and post-transport mussels (after 3 h transport in water). The results showed differences in a large number of metabolites in both haemolymph and hepatopancreas of post-harvest and post-transport mussels when compared to the control state. These metabolites are generally involved in energy metabolism, amino acid metabolism, protein degradation and fatty acid metabolism. Mechanical harvesting induced metabolite changes typically associated with increased energy demand and a rapid transition to anaerobic glycolysis. Some metabolites began to return to baseline levels following a subsequent 3 h immersion during transportation. Re-immersion was also effective in prolonging life in mussels emersed in 9 °C air for three days. However, after six days emersion the mussels were moribund, dying after a total of 7.8 ± 1.0 days in air or in the re-immersion tank. The findings highlight the importance of acute metabolic trauma in determining post-harvest outcomes and the potential role for transient recovery systems.

Keywords: Greenshell mussels; Live transport; Survival; Physiological stress; Metabolic profiles