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Break-up
and
freeze-up dates.
Hudson
and
James
Bay
(Hochheim,
Barber
&
Lukovich, 2010)
1996–2000
compared
to
1980–1995
Mean break-up dates earlier by
0.4–2.0 weeks. 63 per cent of area
is 0.8 to1.6 weeks earlier
Mean freeze-up dates later by 04–
2.0 weeks. 58 per cent of area is
0.8 to 1.6 weeks later.
5 Contemplating the Future of the Hudson Bay Marine Ecosystem
Predicting the future is not an exact science, but the broad outlines of probable futures for the Hudson
Bay Complex have been emerging for several decades. Some things can be predicted with a high level of
confidence. The concentrations of greenhouse gases in the Earth’s atmosphere will, at least for most of
the next century, continue to increase. This ensures a continuing and increasing upward pressure on
global temperatures, although there is less certainty as to where, and by how much, temperatures will
rise. The increasingly sophisticated global circulation models are generally effective at reconstructing the
climate changes that have occurred in the past, which lends credence to projections that Arctic and
subarctic regions will, as they have in previous decades, warm more rapidly than temperate and tropical
regions. The Arctic Climate Impact Assessment (ACIA, 2005) projected that Hudson Bay and Baffin Island
would warm by 3 to 9ºC over the next century. We can also be sure that significant interannual and
interdecadal variation will continue to be a feature of the regional climate.
Indeed, climate change/warming is the overarching “elephant in the room” that is already having a
marked influence on the region. The seasonal ice cover has changed, with earlier break-up, later freeze-
up, and more open water. Polar bear populations in western and southern Hudson Bay are seen as being
particularly vulnerable because the longer ice-free season prevents them from hunting seals on the ice.
While the uncertain future for the majestic and iconic polar bear has our attention, the changing sea ice
is becoming less safe and less predictable for Inuit hunters and trappers who have relied, for many
generations, on the ice cover to harvest resources from the sea (Laidler et al., 2009). This aspect and its
impact on cultural traditions and community economies are not widely appreciated.
Another critical factor is the role that ice algae has and will likely continue to play in the system. These
tiny plants that are on and imbedded in the lower surface of the sea ice form the base of the food web
associated with the ice pack, yet they are mostly out of sight and out of mind. Less ice cover will inevitably
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shift more of the primary production to phytoplankton living in the water column, with an inevitable
cascade of changes in the food webs of the Hudson Bay Complex.
Recently, Hoover (2010) used a food chain model to simulate what might happen with respect to food
webs. Present and future declines in ice algae are expected to have a strongly negative impact on most
large mammals, although reduced ice cover is also associated with more killer whales and more predation
on seals, bowhead whales, narwhals and belugas. The author estimates that a 50 per cent reduction in ice
algae biomass would lead to an overall decline of 30 per cent in total biomass of marine mammals, a 25
per cent decline in biomass of all fishes, a 40 per cent decline in the biomass of zooplankton, a 20 per cent
decline in biomass of benthic biomass and a 15 per cent increase in pelagic primary production.
This projection might be overly pessimistic. Less ice cover will also mean a greater energy input into the
marine system, and that system is likely to be less stratified with more upwelling of nutrients. The
combination of more light penetration and greater nutrient availability could lead to a substantial increase
in pelagic primary production with a cascading effect that could be of particular benefit to species that
are not dependant on the seasonal ice cover. New species not present in the system could also invade
and flourish in a warming system.
Future changes in the Hudson Bay marine ecosystem will occur within a changing climate system that sets
the boundaries on how the Hudson Bay marine ecosystem will evolve. A changing climate will have a
profound influence on the physical, chemical and biological oceanography of the marine ecosystem to the
advantage of some species and to the detriment of others. Similarly the social, cultural and economic
benefits associated with the system will change and aboriginal communities will likely be called upon to
adapt to the new realities—both positive and negative. A major challenge is to develop an improved
capacity to anticipate and prepare for a future that is likely to be quite different from the past. Ideally this
will involve close cooperation between aboriginal observers, who continue to harvest resources from the
sea, and Western scientists, who seek to understand how this large system functions, especially with
respect to the mammals, fish and waterfowl that are harvested as part of traditional cultures and
economies.
Changes in climate will also have a direct bearing on future development in the region. One must assume
that there will be additional hydroelectricity development. While these developments will not be on the
scale of the James Bay or Nelson River projects, their cumulative impact on the timing and location of
runoff into the Hudson Bay Complex will have a large impact on the freshwater budget and the overall
functioning of the ecosystem. The combined effect of river regulation and a warming climate will likely