Copepod diversity in a subtropical bay based on a fragment of the mitochondrial COI gene

Abstract

Copepod communities in lagoons and embayments on subtropical islands in the Pacific Ocean are geographically isolated from other populations along continents and other islands. Nevertheless, taxonomic identifications suggest that many of these species are cosmopolitan. The genetic diversity of planktonic copepod species in a subtropical embayment, Kaneohe Bay, Hawaii, was investigated by pairing morphological identification of the species with sequencing a 710 bp fragment of the mitochondrial cytochrome oxidase c subunit I (mtCOI) gene. DNA sequences were obtained for six calanoid and three cyclopoid copepod species. The sequences of two oceanic species found in the bay, Undinula vulgaris and Paracalanus parvus, were ≤3.0% divergent from conspecifics in the coastal western Pacific Ocean. In contrast, sequences from the more estuarine, Parvocalanus crassirostris and Bestiolina similis specimens were ≥16.0% divergent from conspecifics of the western Pacific Ocean. The Labidocera sp. and Acartia sp. were ≥16.0% divergent from all congeners, while three Oithona species differed by ≥26.5% from congeners. These results suggest significant genetic isolation of the more estuarine species, although more sequence data for Hawaii and elsewhere will be needed to understand the population and genetic structure of coastal island copepod populations.