DNA barcoding of Cirripedia larvae reveals new knowledge on their biology in Arctic coastal ecosystems

Pelagic larvae of benthic organisms comprise a substantial part of the coastal Arctic zooplankton community in spring-summer. We studied the timing, growth, and pelagic duration of Cirripedia larvae in Adventfjorden, a high-Arctic fjord in Spitsbergen, Svalbard. Two distinct abundance peaks were found: one in early May (25.000 ind. m(-3)) and another one in late May (35,580 ind m(-3)). DNA barcoding based on the COI gene was used to identify the barnacle larvae to species. Whereas both Balanus balanus and Semibalanus balanoides were present, the first one dominated (50-100%) the barnacle abundance. High resolution sampling and size measurements of Cirripedia larvae revealed that these larvae most likely originated from a single spawning event. Development of the larvae suggested a pelagic residence time of roughly 2months for B. balanus and at least 1month for S. balanoides in the Arctic. Long pelagic residence time, large potential for biofouling on ships and larger plastic debris, combined with the disappearance of landfast sea ice and less ice scouring opens up new opportunities for barnacles to colonize the high-Arctic littoral zone. In a future warmer Arctic, we therefore expect establishment of new, more temperate Cirripedia species in Svalbard.