Arctic zooplankton do not perform diel vertical migration (DVM) during periods of midnight sun

Abstract

Diel vertical distribution patterns of dominant zooplankton taxa were studied during a period of midnight sun (May 1999) in the Marginal Ice Zone (MIZ) of the Barents Sea along 2 transects across the ice edge. Eight stations were sampled every 6 h over 24 h at 5 depth intervals. Our study confirmed that copepod nauplii (most probably Calanus hyperboreus and C. glacialis) together with Pseudocalanus spp. preferred the surface water layer. The herbivores C. finmarchicus, C. glacialis, and C. hyperboreus concentrated in the upper 50 m depth interval, whereas the omnivores Metridia longa and Microcalanus spp. were generally found in deeper waters. As a result of vertical distribution patterns of the numerically abundant taxa, a bulk of zooplankton was concentrated within the 0-50 m layer. Vertical distribution patterns of all examined taxa/groups varied in time as a result of habitat changes (with respect to water mass distribution and sea depth) as well as random patchiness. Based on our data and on a comprehensive literature survey on Arctic zooplankton diel vertical migration (DVM), we postulate that common zooplankton taxa in the MIZ of the Barents Sea do not perform DVM under the midnight sun. Arctic C. glacialis in May 1999 occupied deeper layers at stations with more ice cover and less melt water. This distribution pattern was probably related to the species' reproduction. At the same time, Atlantic C. finmarchicus was concentrated further away from the ice edge and chlorophyll a maximum, and presumably had not begun its seasonal reproduction. KEY WORDS: Zooplankton · Calanus · Diel vertical migration (DVM) · Marginal Ice Zone · Barents SeaResale or republication not permitted without written consent of the publisher

Seasonal variation of diel vertical migration of zooplankton from ADCP backscatter time series data in the Lazarev Sea, Antarctica

“…Bogorov, 1946;Buchanan and Haney, 1980;Blachowiak-Samolyk et al, 2006). This view is corroborated by our results for the early summer period, November-mid-December (Figs.…”

“…While most studies of DVM at higher latitudes have focussed on the period of midnight sun or the transition between Arctic summer and autumn (Fortier et al, 2001;Blachowiak-Samolyk et al, 2006;Cottier et al, 2006;Falk-Petersen et al, 2008), Berge et al (2009) presented acoustic data from two coastal locations in Svalbard (Kongsfjorden and Rijpfjorden at 791N and 801N, respectively), which demonstrate a synchronized DVM behaviour of zooplankton that continues throughout Arctic winter. Their findings are corroborated by our results from the Southern Hemisphere, where synchronous DVM continued at 691S throughout austral winter and thus disproves the classic paradigm of Arctic and Antarctic marine ecosystems that DVM slows down or ceases during the polar night.…”

Evidence of Diel Vertical Migration of Mesopelagic Sound-Scattering Organisms in the Arctic

“…A diel light cycle was clearly observed despite midnight-sun conditions, and while net-determined depthstratified abundance did not reveal any significant difference between day and night, acoustic data with 25 m vertical resolution resulted in significant differences between day and night backscatter strength vs. depth across all stations. In contrast, Blachowiak-Samolyk et al (2006) postulated, based on their studies in the Barents Sea marginal ice zone (latitudes 76-77 • N) and a comprehensive literature survey, that common zooplankton taxa do not perform diel vertical migration under the midnight sun. Neither study area was deep enough to have a DSL, and consequently cannot be directly compared to the present study.…”

Sensitivity to ocean acidification parallels natural pCO 2 gradients experienced by Arctic copepods under winter sea ice

“…However, knowledge of current seasonal and interannual variability in carbonate system parameters for the Arctic Ocean, particularly under winter sea ice, remains limited. Furthermore, information about the ecology of organisms that live in Arctic waters is primarily restricted to summer studies, with only a few investigations being conducted during the ice-covered winter period (5). Hence, predicting how organisms and ecosystems respond to OA is currently restricted to studies from subarctic and/or icefree Arctic systems because of the technical difficulties and costs involved in sampling remote ice-associated Arctic locations.…”