Managing the Unwanted Organism Sabella spallanzanii (Gmelin, 1791): investigating how desiccation, fragmentation and acetic acid can be used to manage this pest on aquaculture facilities.

Abstract

Human activities have enabled non-indigenous marine species (NIMS) to cross geographic barriers outside their natural dispersal range. As a novel habitat, marine aquaculture facilities often grow NIMS, or are fouled by NIMS and facilities with poor quarantine practice during harvest and through domestic transfers of equipment and product may inadvertently act to vector NIMS. Furthermore, biofouling NIMS can cause significant economic loss to industry by reducing the quality of the farmed product and increasing production costs. The objective of this study was to aid the aquaculture industry with how they manage the marine polychaete pest species Sabella spallanzanii. Specifically, in order to determine the possibility of S. spallanzanii being spread after harvesting, the survivorship of S. spallanzanii to typical mussel farming operations was examined in two experimental procedures: desiccation and fragmentation. An additional experimental procedure examined acetic acid as a potential treatment option that would effectively eliminate S. spallanzanii while having minimal effect on the cultured product. Sabella spallanzanii is highly resilient to the typical re-seeding and harvest operations that occur in mussel aquaculture. Specimens survived upwards of 24 hours air exposure in desiccation treatments: a longer time frame than what would occur during re-seeding or the harvest process and subsequent landing of stock and transport to processing facilities. Long term survival and regeneration of body parts within 28 days was evident following fragmentation: a simulation of the potential disturbance caused by the harvest process. Immersion in a 5% solution of acetic acid for 1 minute killed 75% of S. spallanzanii with no effect on mussel survivorship. This is a promising control method that could contain S. spallanzanii and have minimal impact on harvest production time. The results of these experiments will enable biosecurity and marine farm managers to make informed decisions about the management, containment and treatment of Sabella spallanzanii and prevent its secondary spread to new geographic areas. However, effective mitigation relies on a rapid response and a strong commitment between stakeholders to achieve a common goal.