Fluorescent in situ hybridisation assay as a species‐specific identifier of the northern Pacific seastar, Asterias amurensis

Abstract

A fluorescent in situ hybridisation assay has been developed to detect a high profile marine pest in ships’ ballast water, namely the northern Pacific seastar, Asterias amurensis. This organism has not been detected in New Zealand waters, but is seen as a high risk to marine values, including economic resources, should it become established. The fluorescein‐labelled species‐specific probe construct, coded AM2F, scored positive against A. amurensis larvae. The probe was tested for cross‐reactivity against larvae of the starfish Patiriella mortenseni, Coscinasterias muricata, and Sclerasterias mollis. The signal given by the probe against these species was either absent or extremely weak, indicating minimal or no cross‐reactivity The assay detects at the organism level and, because the method involves microscopy, it has potential for enumerating detected species. Additionally, by meeting several criteria for viability assessment (i.e., degree of body wall and organelle integrity as well as fluorescence), the assay can provide indicative counts of viable larvae.