Polar bears are at the top of the food chain and have an important role in the overall health of the marine environment. Over thousands of years, polar bears have also been an important part of the cultures and economies of Arctic peoples. Polar bears depend on sea ice for their existence and are directly impacted by climate change—serving as an important indicator species.
If linchens or lemmings for example go extint. It will efect all the other animals in the ecosystem. An ecosystem is made of many organisms. Organisms are linked together by what they eat. Organism’s depend on each other for nourishment to survive. An example of this would be plant plankton being eaten shrimp, and a shrimp being eaten by fish which are eating by larger shrimp, and which are eaten by Bears. "A change in a plant can affect the largest predator". This quote is trying to explain that if you get rid of the producer at the bottom of the food web all the other consumer's status will start to go more towards extinction. Once the producer goes extinct the primary consumer's status will start to move more towards extinction. Then once the primary consumer goes extinct, the secondary consumer will run out of food and its status will move more towards extinction. once the Secondary consumer goes extinct all the top predator would start to die off from food shortage,too. Then it would do the same to the whole food web. It’s kind of like dominos, one organism goes extinct, and there goes the rest of the food chain. Theres no more ecosystem after that. So if once organism goes extinct it will affect the top predator by all of the rest of the organisms will start to die off, since there is no more food for them to eat.