BISC 204 Lecture Notes - Lecture 20: Nutrient Pollution, Montreal Protocol, Sewage Treatment
12 Dec 2017
School
Department
Course
Professor
Document Summary
Global ecology and global change: ecologists and environmental scientists are focusing much of their attention on trying to understand the ecological processes that regulate the global ecosystem of the earth. These are described briefly here: background extinction rates are ~1000x higher than historic rates, exploitation of top predators. Humans have reduced the densities and prevalence of top predators in many of the world"s ecosystems. Consider what the effects on food webs and communities is because of the loss of top predators. There has been a tendency to remove top predators in the order of their profitability to humans which often scales with their body sizes. This is referred to as serial depletion of top predators. We"ve discussed this before as a fishing down" of marine and freshwater food webs. Development of a global economy has been associated with rapid movement of species beyond their natural ranges. ), they can outcompete or prey on native species and even cause extinctions.
