Human Influence and Limitting factors
![Picture](/uploads/9/6/2/1/96216132/150915130259-polar-bear-arctic-climate-change-orig-mg-nws-00010716-full-169.jpg?454)
1. Climate Change
· Since polar bears rely on ice to hunt, the melting of the polar ice caps greatly decreases their ability to chase their prey (eg. seals). Without food, there is a decline in their health and the bears cannot survive for long periods of time.
· A decline in bear health reduces their reproduction rates. Unhealthy and malnourished mother bears cannot carry/care for their young. This will lead to a decrease in surviving cub numbers.
· An increase in temperatures also leads to a number of bears drowning. Since the ice is melting, bears are often forced to spend a large amount of time swimming in the water.
2. Overhunting
· The international Agreement on the Conservation of Polar Bears states that the bears are allowed to be sustainably hunted by the indigenous people in order to exercise their traditional rights.
· However, some countries’ polar bear hunting quota is unknown.
3. Oil Exploration (Oil and Gas Businesses)
· Contact with oil spills reduces the insulation abilities of the bears’ fur: oil exposure causes hair loss. In order to keep warm, bears must work harder to increase caloric intake (which is difficult due to other limiting factors).
· Ingesting oil through eating contaminated prey and self-grooming causes liver/kidney damage, toxicity and eventually death.
· Construction and operation of oil facilities is a disruption to the polar bear habitat.
· Oil spills near major areas of polar bear dens are also harmful since there is currently no proven effective method for cleaning/controlling an oil spill in icy waters.
4. Toxic Pollution
· Since polar bears are top of their food chain, they often accumulate toxic chemicals through their food.
· Bears with high levels of POPs (persistent organic pollutants) have low levels of vitamin A, thyroid hormones, and some antibodies. These are important for biological functions, such as growth, reproduction, and the ability to fight off diseases.
· This is also a danger to bear cubs. If a mother bear has high concentration of certain pollutants, they can be transferred through her milk to the cubs (World Wildlife Fund, 2014)
· Since polar bears rely on ice to hunt, the melting of the polar ice caps greatly decreases their ability to chase their prey (eg. seals). Without food, there is a decline in their health and the bears cannot survive for long periods of time.
· A decline in bear health reduces their reproduction rates. Unhealthy and malnourished mother bears cannot carry/care for their young. This will lead to a decrease in surviving cub numbers.
· An increase in temperatures also leads to a number of bears drowning. Since the ice is melting, bears are often forced to spend a large amount of time swimming in the water.
2. Overhunting
· The international Agreement on the Conservation of Polar Bears states that the bears are allowed to be sustainably hunted by the indigenous people in order to exercise their traditional rights.
· However, some countries’ polar bear hunting quota is unknown.
3. Oil Exploration (Oil and Gas Businesses)
· Contact with oil spills reduces the insulation abilities of the bears’ fur: oil exposure causes hair loss. In order to keep warm, bears must work harder to increase caloric intake (which is difficult due to other limiting factors).
· Ingesting oil through eating contaminated prey and self-grooming causes liver/kidney damage, toxicity and eventually death.
· Construction and operation of oil facilities is a disruption to the polar bear habitat.
· Oil spills near major areas of polar bear dens are also harmful since there is currently no proven effective method for cleaning/controlling an oil spill in icy waters.
4. Toxic Pollution
· Since polar bears are top of their food chain, they often accumulate toxic chemicals through their food.
· Bears with high levels of POPs (persistent organic pollutants) have low levels of vitamin A, thyroid hormones, and some antibodies. These are important for biological functions, such as growth, reproduction, and the ability to fight off diseases.
· This is also a danger to bear cubs. If a mother bear has high concentration of certain pollutants, they can be transferred through her milk to the cubs (World Wildlife Fund, 2014)