Abstract
The temporal and spatial distribution of larval plankton of high latitudes is poorly understood. The objective of this work is to identify the occurrence and abundance of pelagic bivalve larvae within a high Arctic fjord (Adventfjorden, Svalbard) and to reveal their seasonal dynamics in relation to environmental variables—temperature, salinity and chlorophyll a—between December 2011 and January 2013. We applied a combination of DNA barcoding of mitochondrial 16S ribosomal RNA and morphological analysis to identify the bivalve larvae found within the plankton and demonstrate a strong seasonality in the occurrence of bivalve larvae, largely coinciding with periods of primary productivity. Seasonal occurrences of bivalve larval species differ from those known for other populations across species’ biogeographic distribution ranges. Serripes groenlandicus, which is of circum-Arctic distribution, demonstrated a later occurrence than Mya truncata or Hiatella arctica, which are of predominantly boreal or cosmopolitan distribution, respectively. S. groenlandicus larvae demonstrate the most pronounced response to seasonality, with the shortest presence in the water column. Establishing latitudinal differences in the occurrence of bivalve larvae enhances our understanding of how reproductive traits of marine invertebrates may respond to climate-driven seasonal shifts in the occurrence of primary productivity.
Highlights
Strong seasonality shapes high latitude environments, with intra-annual changes in solar irradiance, ice cover, glacial melt water and mixed layer depth, influencing seasonal changes in marine benthic fauna (Wlodarska-Kowalczuk and Pearson 2004)
We applied a combination of DNA barcoding of mitochondrial 16S ribosomal RNA and morphological analysis to identify the bivalve larvae found within the plankton and demonstrate a strong seasonality in the occurrence of bivalve larvae, largely coinciding with periods of primary productivity
Identify reproductive patterns of bivalve larval species in Arctic coastal areas, we present data on the occurrence of bivalve larvae from a study carried out in Adventfjorden, Svalbard (78°1506000N 15°3108000E), over a 14-month time period (December 2011 to January 2013)
Summary
Strong seasonality shapes high latitude environments, with intra-annual changes in solar irradiance, ice cover, glacial melt water and mixed layer depth, influencing seasonal changes in marine benthic fauna (Wlodarska-Kowalczuk and Pearson 2004). It has been suggested that local environmental variables have a direct effect on the timing, occurrence and duration of larval stages of marine benthic invertebrate species (Fetzer and Arntz 2008). Pelagic larval stages are a vector for dispersal and have the capability to alter the abundance and distribution of benthic invertebrate species at a given site (Mileikovsky 1968; Thatje 2012). The role of seasonality on the occurrence and distribution of invertebrate larval plankton in the Arctic, remains scarcely known (Kuklinski et al 2013). An important Arctic keystone group is the bivalve molluscs, which contribute significantly to benthic biomass in some areas; e.g. in Svalbard molluscs contribute between 10 and 110 g ww m-2 to benthic biomass
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