Seasonal mesozooplankton patterns and timing of life history events in high-arctic fjord environments

Seasonal patterns in mesozooplankton composition, vertical distribution, and timing of reproduction are challenging to study the open sea due ocean currents mix populations different origins. Sill fjords, on other hand, with restricted water exchange, ideal locations for studying taxa- community-specific adaptations prevailing environment. Here, we present re-occurring community structure Billefjorden, Svalbard, a high Arctic sill fjord extensive seasonal ice cover, based monthly sampling from 2011 2013. The zooplankton composition confirmed character this fjord. Predominantly herbivorous taxa, such as Calanus glacialis Pseudocalanus spp., showed strong variation abundance depth population minima spring being compensated by rapid recovery during summer. Omnivorous Microcalanus spp. copepods family Aetideidae , largely remained at throughout year had an extended or year-round reproductive period. Deep-dwelling omnivorous/carnivorous species peaked winter–spring when were severely depleted. Taxa seasonally limited occurrences, i.e., meroplankton, summer surface, but absent rest year. life histories, contrasting feeding modes, preferences, lead reduced interspecies competition allow rather stable despite short primary production window latitudes.