From MarineSpecies Introduced Traits Wiki
Carrying capacity usually refers to the biological carrying capacity of a population level that can be supported for an organism, given the quantity of food, habitat, water and other life infrastructure present. For the human population other variables such as sanitation and medical care are sometimes considered as infrastructure. As population density increases, birth rates often decrease and death rates typically increase. Carrying capacity is the point at which these two rates are equal. [This last sentence is not true. The difference between the birth rate and the death rate is the "natural increase." The carrying capacity could support a positive natural increase, or could require a negative natural increase.] Carrying capacity is thus the number of individuals an environment can support without significant negative impacts to the given organism and its environment.
The concept of 'carrying capacity' incorporates:
- physical space,
- food and/or nutrient availability,
- waste removal/recycling,
- mortality factors,
- time or temporal factors,
- other factors.