Aquatic ecology and Biodiversity

Unit 6- Biogeochemical cycles

6.6. Limiting factors and governing laws
Limiting factors are environmental factors that limit the productivity of organisms, populations, or communities and thereby prevent them from achieving their full biological potential under optimal conditions. Limiting factors can be single element or a group of related factors.
Environmental factors must satisfy minimum and maximum criteria for life. For example, temperature cannot be too cold or hot and the availability of nutrients cannot be too small or too large. The minimal criteria for metabolically essential environmental factors represent the least availability that will sustain organisms or ecological processes, while the maxima represent toxicity or other biological damages. The minimum and maximum levels of environmental factors bound a relatively broad range within which there are optimal levels at which factors exert no constraints on biological productivity.
The principle of limiting factors is an ecological generalization that suggests that, at any given time in a particular ecosystem, productivity is limited by an essential factor that is present in least supply relative to the potential biological demand. This limiting factor could be climatic or the factor could involve an insufficient supply of a particular nutrient, or an excessive, toxic availability of chemical. In this sense, the limiting factor represents a type of ecological stress which if alleviated will result in greater productivity and development of the ecosystem.
Any environmental factor that can influence, decrease, increase, absence, or presence – limits the growth, metabolic processes, or distribution of organisms or populations. In a desert ecosystem, for example, low rainfall and high temperature will be factors limiting colonization. When a metabolic process is affected by more than one factor, the law of limiting factors states that its rate is limited by the factor that is nearest its minimum value. For example, photosynthesis is affected by many factors, such as light, temperature and carbon dioxide concentration, but on a warm sunny day, carbon dioxide concentration will be the limiting factor as light and temperature will be at optimum levels.