That's a wonderful question. I'm glad you asked that, because I think it's a source of confusion. The answer is it's all of those. For example, I can study a kelp forest the size of this room. An ecosystem, by definition, is simply the living and the non-living parts of that environment and their interactions, which means that the decision on the spatial scale that you apply to that is essentially arbitrary. For example, the largest, or what we refer to as large marine ecosystems, encompass the entire coast of British Columbia, but also go down to the size of individual ecosystems like kelp forests or an estuary. An individual estuary in a fjord is also a single ecosystem. So when I say multiple ecosystems, it's those smaller units that connect to one another in an area.
Evidence of meeting #66 for Fisheries and Oceans in the 42nd Parliament, 1st Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was process.
A recording is available from Parliament.