Final answer:
Increased competition for water as population density rises is a density-dependent factor causing an increase in mortality and potentially lowering birth rates.
Step-by-step explanation:
Increased mortality in a population due to increased competition for water is the effect of a density-dependent factor.
Density-dependent factors are biotic elements that impact a population based on its size. For example, as the population density rises, natural resources such as water become scarcer, leading to heightened competition which can cause an increase in mortality. This scenario packs a double punch; not only can mortality rise, but the birth rate may also decline if individuals have less access to the resources required for raising offspring.
This concept speaks to the importance of managing population growth and resource utilization, especially in light of expanding human populations in environmentally vulnerable areas and increasing instances of natural disasters, both of which intensify competition for essential resources like water.