"Social Darwinism<span> is a modern name given to various theories of society that emerged in the United Kingdom, the United States, and Western Europe in the 1870's, and which are claimed to have applied biological concepts of natural selection and survival of the fittest to sociology and politics", so, in therory, it would allow AND promote imperialisim, as many people are not within the same level of society.</span>
Bacteria, hope this helps!
It would lower the pH, raise the acidity of the water, and it would kill off a lot of marine life if it got too high. As species begin to die their predators follow, and this could cause mass extinction.