Geoscience Reference
In-Depth Information
Table A1. (continued)
Node
Name
Node Title
Node Description
States
T2
Predation
Predation on polar bears by other species is very uncommon partly because bears
spend almost all of their time on the ice. With more time on land, polar bears, espe-
cially young, will be subject to increased levels of predation from wolves, and perhaps
grizzly bears.
This will vary by region as some regions where polar bears occur have few other
predators.
Intraspecific predation is one behavior which is known to occur in bears. It has rarely
been observed in polar bears and historically is not thought to have been influential.
Recent observations of predation on other bears by large males, in regions where it has
not been observed before, are consistent with the hypothesis that this sort of behavior
may increase in frequency if polar bears are nutritionally stressed. At present, intraspe-
cific predation is not thought to be influential at the population level anywhere in the
polar bear range. It appears, however, that its frequency may be on the increase. At
some point, it therefore could become influential. At very low population levels, even a
minor increase in predation could be influential.
influential
not
E
Intentional
Takes
This node represents direct mortalities including hunting, and collection for zoos,
and management actions. It also includes research deaths even though they are not
intentional.
These are mortality sources that are very much controllable by regulation.
increased
same_as_now
decreased
T1
Contaminants
Increased precipitation and glacial melt have recently resulted in greater influx of
contaminants into the Arctic region from the interior of Eurasia via the large northward
flowing rivers. Similarly, differing atmospheric circulation patterns have altered po-
tential pathways for contaminants from lower latitudes. This node reflects the possible
increase or decrease of contamination in the Arctic as a result of modified pathways.
These contaminants can act to make habitat less suitable and directly affect things like
survival and reproduction.
The greatest likelihood seems to be that such contaminants will increase in Arctic
regions (and indeed worldwide) as increasing numbers of chemicals are developed and
as their persistence in the environment is belatedly determined. Some contaminants
have been reduced and we have the ability to reduce others, but the record of reduction
and the persistence of many of these chemicals in the environment suggests the great-
est likelihood is for elevated levels in the short to medium term with some probability
of stability or even declines far in the future.
elevated
same_as_now
reduced
R4
hydrocarbons /
Oil Spill
This refers to the release of oil or oil related products into polar bear habitat. Such ac-
tion would result in direct mortality of bears, direct mortality of prey, and could result
in displacement of bears from areas they formerly occupied. Hence, it has ramifica-
tions for both habitat quality and population dynamics directly.
hydrocarbon exploration and development are expanding and proposed to expand
farther in the Arctic. Greater levels of such activity are most likely to increase the
probability of oil spills.
Also, increased shipping will result in higher levels of hydrocarbon release into Arctic
waters.
increased_occurrence
same_as_now
decreased_occurrence
J1
Tourism
As sea ice extent declines spatially and temporally, access and opportunities for Arctic
tourism also will increase. Increased tourism could lead to direct disturbances of
polar bears as well as to increased levels of contamination. here, we address only the
physical presence of more tourism and the conveyances used by tourists (vessels, land
vehicles, aircraft).
The greatest likelihood seems to be that tourism will increase. It could decline,
however, if governments take actions to reduce interactions with increasingly stressed
polar bears. however, as tourism currently accounts for essentially no limitation to
polar bears this effect only comes into play when it is noted to increase.
I believe that tourism will increase in all areas of the Arctic until such time as fuel
increased
same_as_now
decreased
 
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