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The mean chain length of an entire web is the arithmetic average of the lengths of all chains in a food web. [ 42 ] [ 14 ] In a simple predator-prey example, a deer is one step removed from the plants it eats (chain length = 1) and a wolf that eats the deer is two steps removed from the plants (chain length = 2).
Acidification threatens to destroy Arctic food webs from the base up. Arctic waters are changing rapidly and are advanced in the process of becoming undersaturated with aragonite. [202] Arctic food webs are considered simple, meaning there are few steps in the food chain from small organisms to larger predators.
Food chain in a Swedish lake. Osprey feed on northern pike, which in turn feed on perch which eat bleak which eat crustaceans.. A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as earthworms and woodlice ...
But the tertiary consumer, or top predator, in the Arctic is the polar bear, feeding mostly on seals, including the ringed seal. Yet through further exploration, the potential fates of this Arctic food web seem to be ambiguous, leading to a very important trade off of polar bear mortality and ringed seal sustenance. [21]
With wildfires and increased warming, scientists say the Arctic’s tundra is now a carbon source. The region had been a carbon sink for thousands of years (NOAA Climate.gov; Arctic Report)
Tundra ecosystems developed in the Northern Hemisphere toward the end of the Pliocene (3.6 ma), prior to this point the Arctic was predominantly covered with forests and shrublands which extended northward to the coastline of the Arctic Ocean. However, during the middle Pleistocene this vegetation pattern shifted to a graminoid tundra steppe. [18]
A focus of the latest Arctic evaluation was the effects of warmer weather and wildfires on the tundra, a far-northern biome that's typically known for extreme cold, little precipitation and a ...
According to the US Energy Information Administration, the arctic tundra holds an estimated 13% or 90 billion barrels of the world's undiscovered conventional oil sources. However, there are a number of challenges to oil exploration, drilling, and transportation in an arctic tundra environment that limits the profitability of the venture. [15]