At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga.
Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus.
Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.
Its lifestyle would change because the water will not move very fast. Its eating habits might also change.
The flow will stop greatly affecting not only the creature, but the other inhabitants, thus changing lifestyle and probably driving animals to death.
Hmm yes, that sounds about right. It is hard to answer without knowing the types of areas you have been learning about :)
The primary changes that building a dam would be (a) loss in system energy - so less 'power' for erosion, slower water etc.(b) loss in water in general and (c) a loss in the things that water would bring - food and oxgyen.
In a fast flowing river the organism would receive alot of food and the water would be highly oxygenated. When the dam is built it would loose supply of both of these. A negative impact on the organism would definitely be expected.