Abstract
Submesoscale structures, characterized by intense vertical and horizontal velocities, potentially play a crucial role in oceanographic dynamics and pelagic fluxes. Due to their small spatial scale and short temporal persistence, conditions for in situ measurements are challenging and thus the role of such structures for zooplankton distribution is still unclear. During RV Polarstern expedition PS107 to Arctic Fram Strait in July/August 2017, a submesoscale filament was detected, which initiated an ad hoc oceanographic and biological sampling campaign. To determine zooplankton taxonomic composition, horizontal and vertical distribution, abundance and biomass, vertical MultiNet hauls (depth intervals: 300–200–100–50–10–0 m) were taken at four stations across the filament. Zooplankton data were evaluated in context with the physical-oceanographic observations of the filament to assess submesoscale physical-biological interactions. Our data show that submesoscale features considerably impact zooplankton dynamics. While structuring the pelagial with distinct zooplankton communities in a vertical as well as horizontal dimension, they accumulate abundance and biomass of epipelagic species at the site of convergence. Further, high-velocity jets associated with such dynamics are possibly of major importance for species allocation and biological connectivity, accelerating for instance processes such as the ‘Atlantification’ of the Arctic. Thus, submesoscale features affect the surrounding ecosystem in multiple ways with consequences for higher trophic levels and biogeochemical cycles.
Highlights
Mesoscale dynamics, including fronts and eddies, have been studied extensively and, even though still not fully understood, significant knowledge about underlying oceanographic mechanisms as well as their influence on biological and biogeochemical processes has been gained (McWilliams, 2008; McGillicuddy, 2016)
Body size of C. finmarchicus and C. glacialis copepodids CV and adult females increased with increasing depth even on the relatively small vertical scale from 0 to 300 m
Such a body size-dependent habitat partitioning within developmental stages of Calanus has to our knowledge not been published before
Summary
Mesoscale dynamics (horizontal scale of 10–100 km), including fronts and eddies, have been studied extensively and, even though still not fully understood, significant knowledge about underlying oceanographic mechanisms as well as their influence on biological and biogeochemical processes has been gained (McWilliams, 2008; McGillicuddy, 2016). Mesoscale dynamics can act as vectors of transport for organisms in a horizontal direction. Several studies further demonstrate that mesoscale eddies can serve as a vector of transport, dispersing zooplankton and larvae to oceanic regions (Mackas and Galbraith, 2002; Batten and Crawford, 2005), or as a retention mechanism, keeping offspring close to their spawning site (Singh et al, 2018). While mesoscale dynamics play a vital role for such processes, the resolution of empirical studies still seems to be too coarse
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
