Abstract
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 2 months for B. balanus and at least 1 month 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.
Highlights
Marine sessile benthic invertebrates often have a pelagic larvae phase in their life cycle to be able to spread to new areas (Mileikovsky, 1971)
At the IsA station in Adventfjorden zooplankton samples were collected throughout the entire year in 2012 (Stubner et al, 2016), but Cirripedia nauplii were only found during the period from 27th April to 6th July with the exception of 1–2 occurrences outside this 10-week time period (Fig. 2)
Based on BLAST analysis Cirripedia larvae were assigned into two species: B. balanus (n = 156) and S. balanoides (n = 12)
Summary
Marine sessile benthic invertebrates often have a pelagic larvae phase in their life cycle to be able to spread to new areas (Mileikovsky, 1971). Planktonic development is crucial for survivorship of benthic sessile populations, as larvae may colonize new territories and reduce intra-specific food competition. These larvae may temporarily comprise a significant part of the zooplankton community. In the Svalbard Archipelago, only three species are reported in shallow waters: the arctic-boreal Balanus balanus (Linnaeus, 1758), the boreo-arctic Semibalanus balanoides (Linnaeus, 1767), and in a few occasions the boreal Balanus crenatus (Bruguiere, 1789) (Anisimova et al, 2010). The release of Cirripedia larvae is timed to the spring bloom and [ 30,000 individuals per m3 can be found in Svalbard fjords when algal food is plentiful (Kuklinski et al, 2013; Stubner et al, 2016)
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