Define an ecosystem's carrying capacity.

The carrying capacity of an ecosystem refers to the maximum population of a species that the environment can sustainably support over time. This concept encompasses not just the availability of resources like food, water, and shelter, but also the interactions with other species and the effects of environmental conditions. When a population reaches its carrying capacity, it means that the reproductive rates and mortality rates balance out, leading to a stable population size unless impacted by changes in resources or external factors. This understanding is crucial for managing wildlife, agriculture, and conservation efforts, as it helps predict how an ecosystem can maintain its health and stability over time.

The other choices focus on different aspects of ecosystem dynamics. Total biomass refers to the mass of living biological organisms in a given area, while the resources available pertain to the materials needed for survival, but they do not directly define carrying capacity. The minimum population needed for survival reflects a population's viability, not the maximum sustainable level that an ecosystem can support.