Sea otter populations along the Pacific Coast of North America declined as a result of hunting. Sea urchins are a favoured food of sea otters. When the sea otter numbers declined, sea urchin populations increased. Sea urchin are herbivorous and feed on kelp. As a result, vast tracts of kelp forests were consumed by the urchins.Which one of the following statements is TRUE?

Question

BlackTom AI · Accepted Answer

The question presents a classic trophic cascade example where changes at one level of the ecosystem propagate to others. 
Option a: 'The sea otter and sea urchin have a symbiotic relationship that was disrupted by sea otter declines, which then resulted in the decline of the kelp.' This misstates the ecology: sea otters and urchins have a predator–prey interaction, not a symbiotic one, and the kelp decline followed the urchin boom caused by fewer otters, not a direct decline of kelp due to disrupted symbiosis. 
Option b: 'The sea otter and kelp have a symbiotic relationship that was disrupted by sea otter declines, which then resulted in the decline of the kelp.' Here again the assumption of a direct symbiotic relationship between otters and kelp is incorrect; kelp forests are affected indirectly through urchin grazing, not via a mutualistic or symbiotic link with otters. 
Option c: 'The sea urchin is a keystone species, the proliferation of which had a disproportionate impact on the entire kelp forest community.' This reverses the focus: while urchins exert strong influence on kelp by grazing, they are not the keystone species in this system; the keystone species is the sea otter, whose predation on urchins maintains kelp forest health. The misidentification of the keystone species undermines the causal explanation. 
Option d: 'The sea otter is a keystone species, the loss of which had a disproportionate impact on the entire kelp forest community.' This captures the core idea of a trophic cascade: otters suppress herbivorous urchins, which allows kelp forests to thrive; without otters, urchins overgraze kelp, leading to widespread kelp loss and ecosystem disruption. The statement aligns with ecological theory about keystone species and cascade effects. 
In summary, the other options either misrepresent the type of species interactions (symbiosis vs predation), misidentify the keystone species, or misunderstand the causal chain from otter decline to kelp forest decline. The true interpretation emphasizes the otter’s pivotal role in maintaining the kelp forest through controlling urchin populations, illustrating a disproportionate impact characteristic of keystone species dynamics.

类似问题

What type of species loss results in the greatest decline in ecosystem function?

Given that grey wolves are a keystone species in North America, after their reintroduction into the Yellowstone ecosystem, which of the following events occurred?

Which from below are keystone species? Mark all that apply, but remember wrong answers penalize your score.

A species that has a disproportionately large effect on its community is called a(n) species.

The passenger pigeon, like the American beaver, was a _______________ species -- i.e., a species that profoundly affects the environment and the success of plants and animals within its sphere.

Given that grey wolves are a keystone species in North America, after their reintroduction into the Yellowstone ecosystem, which of the following events occurred?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单