Impact of tidal dynamics on diel vertical migration of zooplankton in Hudson Bay

• Main Authors: Petrusevich, Vladislav Y., Dmitrenko, Igor A., Niemi, Andrea, Kirillov, Sergey A., Kamula, Christina Michelle, Kuzyk, Zou Zou A., Barber, David G., Ehn, Jens K.
• Format: Text
• Language: English
• Published: 2019
• Subjects: Arctic; Arctic Ocean; Foxe Basin; Hudson; Hudson Bay; Hudson Strait; North Atlantic; Sea ice; Zooplankton
• Online Access: https://doi.org/10.5194/os-2019-107; https://www.ocean-sci-discuss.net/os-2019-107/

Hudson Bay is a large, seasonally-ice covered Canadian inland sea, connected to the Arctic Ocean and North Atlantic through Foxe Basin and Hudson Strait. This study investigates zooplankton distribution, dynamics and factors controlling them during open water and ice cover periods (from September 2016 to October 2017) in Hudson Bay. A mooring equipped with two Acoustic Doppler Current Profilers (ADCP) and a sediment trap was deployed in September 2016 in Hudson Bay ~ 190 km north-east from the port of Churchill. The backscatter intensity and vertical velocity time series showed a pattern typical for the zooplankton diel vertical migration (DVM). Zooplankton collected by the sediment trap allowed for the identification of migrating scatters during the study period. From the acquired acoustic data we observed the interaction of DVM with multiple factors including lunar light, tides, as well as water and sea ice dynamics. Solar illuminance was the major factor determining migration pattern, but unlike at some other polar and sub-polar regions, moonlight had a little effect on DVM, while tidal dynamics is important. The presented data constitutes a first-ever observed presence of DVM in Hudson Bay during winter as well as its interaction with the tidal dynamics.