Whew!
Lots of information. Can be confusing.
Simply stated....carrying capacity is what life a given environment can support at a given time.
Here's an absolute...carrying capacity changes. It has to. Growing season changes, species variety changes (as some creatures eat plants, other creatures eat those creatures), fertility changes, photoperiod changes. Therefore, carrying capacity must change, or it will die. Here's another absolute...carrying capacity cannot be accurately measured. Nutrients feed plankton, which feeds insects and small fish, which feeds larger fish, which feed larger fish, which feed larger fish, and so on.
Each level results in energy conversion, and energy loss, as well as waste, some of which is converted back to plankton...recycled, if you will. This system is dynamic, changing, rolling, molding, onward, downward, upward...all the time. These systems are affected by nutrient load, sunshine, temperature, birth, death, attrition.
So, to keep it simple, fisheries guys like me look at carrying capacity in categories such as bass. Carrying capacity of largemouth bass is different in lakes with no forage, and clear water, than in lakes with a strong plankton bloom and diverse forage fish populations.
Carrying capacity is relative, and relevant for those people trying to monitor and manage growth of particular species of fish. To increase the standing crop of game fish, increase the carrying capacity of the environment that grows their food. And, be sure to use species of fish that fit each practical niche in that environment, to enhance your target species.
In other words, for example, in the south, we use bluegill, threadfin shad and redear sunfish as forage for largemouth bass. Each species fills a different niche in a pond.
But, go north too far, and you can forget threadfins and redear. But, you can have yellow perch with bluegill, if you are feeding the appropriate predator fish with these prolific spawners.
Carrying capacity is a circus...many rings juggling many things.
