Diversity and Life-cycle Analysis of Pacific Ocean Zooplankton by Videomicroscopy and DNA Barcoding. I. Cnidaria

Abstract

AbstractMost, but not all cnidarian species in the classes Hydrozoa, Scyphozoa and Anthozoa have a life cycle in which a colonial, asexually reproducing hydroid phase alternates with a free-swimming, sexually reproducing medusa phase that, in the hydrozoans, is usually microscopic. Hydrozoan medusae were collected by zooplankton tows in Newport Bay and the Pacific Ocean near Newport Beach, California, and hydroid colonies were collected from solid substrates in the same areas. Specimens were documented by videomicroscopy, preserved in ethanol, and sent to the Canadian Centre for DNA Barcoding at the University of Guelph, Ontario, Canada for DNA barcoding.Among the order Anthomedusae (athecate hydroids), DNA barcoding allowed for the discrimination between the medusae of eight putative species of Bougainvillia, and the hydroid stages were documented for two of these. The medusae of three putative species of Amphinema were identified, and the hydroid stages were identified for two of them. DNA barcodes were obtained from medusae of one species of Cladonema, one adult of the By-the wind Sailor, Velella Velella, five putative species of Corymorpha with the matching hydroid phase for one; and Coryne eximia, Turritopsis dohrnii and Turritopsis nutricula with the corresponding hydroid phases. The actinula larvae and hydroid for the pink-hearted hydroid Ectopleura crocea were identified and linked by DNA barcoding.Among the order Leptomedusae (thecate hydroids) medusae were identified for Clytia elsaeoswaldae, Clytia gracilis and Clytia sp. 701 AC and matched with the hydroid phases for the latter two species. Medusae were matched with the hydroid phases for two species of Obelia (including O. dichotoma) and Eucheilota bakeri. Obelia geniculata was collected as a single hydroid. DNA barcodes were obtained for hydroids of Orthopyxis everta and three other species of Orthopyxis.The medusa of one member of the family Solmarisidae, representing the order Narcomedusae, and one member (Liriope tetraphylla) of the order Trachymedusae were recognized as medusae.In the Scyphozoa, DNA barcoding confirmed the planktonic larval stage (ephyra) of the Moon Jelly, Aurelia aurita, the adult medusa of which is occasionally common in and around Newport Bay. In the Anthozoa, antipathula larvae were identified from the Onion Anemone, Paranthus rapiformis and a cerinula larva was identified from the Tube-dwelling Anemone, Isarachnanthus nocturnus. We have yet to find the adults of these species locally.