Polar zooplankton are particularly sensitive to climate change,and have been applied asrapid-respondersof climate-induced change in this fragile ecosystem.DNA barcoding provides an alternative approach for rapid species identification of zooplankton in the Southern Ocean,which will accelerate the routine monitoring of zooplankton community structure.Ninety-four specimens belonging to 32 Antarctic zooplankton were barcoded to provide a more comprehensive reference library.An 830 to 1 050 base-pair region of the mitochondrial cytochrome c oxidase subunit I (mtCOI)gene was obtained as a DNA barcode.The intraspecific variation of the gene ranged from 0 to 2.6%(p-distance),with an average of 0.67%(SD=0.67%).The counterpart between species within the same genera ranged from 0.1% (Calanus)to 29.3%,with an average of 1 5.3% (SD =8.4%).The morphological and genetic similarities between C.propinquus and C.simillimus raise new questions about the status of C.simillimus as a different species.With the exception of the two Calanus species (C.propinquus and C.simillimus),the intraspecific genetic divergence was much smaller than interspecific divergence among the congenus species, confirming the existence of a barcode gap for Antarctic zooplankton.In addition,all species clustered into a monophyletic clade except for Calanus species.Hence,DNA barcoding is confirmed as an accurate and efficient approach for zooplankton identification in the Southern Ocean (species belonging to jellyfish and doliolum were not tested).Confirming evidence was also provided by indicator vector analysis.The new primer sets issued here will facilitate study of the species composition of Antarctic marine zooplankton by single-gene based environmental metagenomic analysis.