Downward particulate organic carbon export and jellyfish blooms in southeastern Hudson Bay

A long-term sediment trap was deployed at 100 m (station AN03; 55°24′N; 77°55′W; water depth = 136 m) from October 2005 to August 2007 to monitor downward carbon export in southeastern Hudson Bay in the Canadian subarctic region. Elevated particulate organic carbon (POC) and total fluxes during fall 2005 and 2006 were the result of wind-induced resuspension of settled POC. The absence of a significant increase in POC fluxes in summer 2006 in contrast to summer 2007 suggests variation in the processes regulating carbon export in southeastern Hudson Bay. Large quantities of the holoplanktonic jellyfish Aglantha digitale were collected in the sediment trap during fall 2006 and summer 2007. The large collection of A. digitale during fall 2006 corresponds to the seasonal descent of the population, while the large abundance during summer 2007 remains unexplained. The increased POC fluxes in summer 2007 and the large occurrence of A. digitale in 2006 and 2007 may be early signs of environmental changes in southeastern Hudson Bay, however more sampling is needed to capture the variability of the ecosystem.

Research Highlights► Downward carbon export was measured at 100 m from October 2005 to August 2007 in southeastern Hudson Bay in the Canadian subarctic region. ► Wind-induced resuspension of settled particles caused elevated POC fluxes during fall 2005 and 2006. ► Increased POC fluxes and large occurrence of the jellyfish Aglantha digitale were observed in summer 2007 in southeastern Hudson Bay.