Ecology and Environmental Science are not the same. I see the terms used interchangeably all the time, and I thought I’d clear it up!
Ecology is the study of the relationships of organisms to each other and their surroundings. If you were to go to the Everglades in Florida and study Ecology, you could be studying the relationship between fish and the underwater grasses that are there. Additionally, you could be studying how that relationship affects the fish population that the Florida alligators eat.
Environmental Science is a very broad field in which scientists from the Physical Sciences, Earth Sciences, and Biological Sciences work together to solve environmental problems. For a very simple example, to come up with solutions for pollution of an area, Physicists (and Engineers) may look at the how our infrastructure has been engineered and come up with solutions to reduce building byproduct. Geologists and Meteorologists may look at the physical features and weather of an area to determine how that may affect where the pollution goes. Chemists may look at the chemical structures of the byproduct and come up with models on how it could affect living organisms, and Biologists (Ecology is a “branch” of Biology) may look at how the pollution is affecting the organisms and their relationships to each other (like population and health of individual organisms, for example) in that ecosystem. With all of that data from those scientists, they can together figure out what the best approach to solving (or mitigating) that pollution problem in that specific area.