Seasonality of occurrence and recruitment of Arctic marine benthic invertebrate larvae in relation to environmental variables

Abstract

The Arctic system is one of the regions most influenced by ongoing global climate change, but there are still critical gaps in our knowledge regarding a substantial number of biological processes. This is especially true for processes taking place during the Arctic winter but also for seasonal processes, such as the dynamics of intra-annual meroplankton occurrence. Here, we report on a 1-year study of meroplankton seasonal variability from a fjordic system in the Arctic Archipelago of Svalbard. The study combines an examination of phytoplankton, zooplankton, and hard bottom benthic settlement with measurements of environmental parameters (e.g., water temperature, particulate organic matter, and dissolved organic carbon).Samples were taken on a bi-weekly or monthly basis, and a total of 11 taxa representing six phyla of meroplankton were recorded over a 1-year period from January to December 2007. The occurrence of benthic larvae varied between the seasons, reaching a maximum in both abundance and taxon richness in late spring through early summer. Meroplanktonic larvae were absent in winter. However, settlement of benthic organisms was also recorded during the winter months (February and March), which indicates individual trade-offs related to timing of reproduction and competition. In addition, it suggests that these larvae are not relying on higher summer nutrient concentrations, but instead are dependent on alternative food sources. In parallel with meroplankton abundance, all other measured parameters, both biological (e.g., phyto-and zooplankton abundance and diversity) and physical (e.g., particulate organic matter), exhibited seasonal variability with peaks in the warmer months of the year.

Seasonality of bivalve larvae within a high Arctic fjord

“…Thorson 1936;Norden-Andersen 1984;Weslawski et al 1988;Fetzer 2004;Kuklinski et al 2013). In accordance with our results, meroplankton occurrences have earlier been shown to exhibit a strong seasonal pattern at polar latitudes, with highest abundances of bivalve larvae in summer (Weslawski et al 1988;Stanwell-Smith et al1999;Bowden et al 2009;Kuklinski et al 2013; Fig. 3).…”

“…Pelagic larval stages are a vector for dispersal and therefore 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, however, remains scarcely known (Kuklinski et al 2013). …”

Do benthic meiofaunal and macrofaunal communities respond to seasonality in pelagial processes in an Arctic fjord (Kongsfjorden, Spitsbergen)?

“…The decline in oweniid size in May (station B) and August (station C) may also be related to the oweniid life cycle with maximum of larval occurrence in Arctic waters in spring (Fetzer and Arntz 2008) and recruitment of juvenile forms soon after. Kukliński et al (2013) who studied the occurrence and abundance of benthic larvae in water column as well as the timing of recruitment in a yearround study in Adventfjorden reported that in general, the benthic larvae were not synchronized in their occurrence in their response to organic matter production peaks in the water column, and benthic recruitment was observed yearround with some groups (e.g., spirorbid polychaetes) recruiting preferably in winter season (Kukliński et al 2013). Ambrose and Renaud (1997) found no obvious link between phytodetrital pulses and recruitment of polychaete species in the northwest polynyas.…”

Species pool structure explains patterns of Antarctic rock-encrusting organism recruitment

“…We are aware of plankton patchiness and that the sampling interval may not accurately estimate the overall larval species richness and abundance at our study sites (Pineda et al 2010). However, in general, other studies on larvae or plankton from polar seas and elsewhere have also revealed very few, if any, larvae of encrusting fauna (especially bryozoans and spirorbid polychaetes), which dominate newly recruited faunal assemblages (Bowden et al 2009;Kuklinski et al 2013). As many of these studies involve annual sampling or even sampling over longer periods, this suggests that the majority of encrusting fauna larvae are simply not present in the water column in the zone covered by the sampling techniques, which are usually conducted metres above the sea bottom.…”