# 3 Causes and mechanisms of eutrophication

## 3.1 Agents of eutrophication

Light availability, water availability, temperature and the supply of plant nutrients are the four most important factors determining NPP. Altered availability of nutrients affects the rate of primary production in all ecosystems, which in turn changes the biomass and the species composition of communities.

## SAQ 15a

> Which two elements most often limit NPP?

### Answer

Phosphorus and nitrogen are the main limiting nutrients.

Compounds containing these elements are therefore the causal agents of eutrophication in both aquatic and terrestrial systems. Let us consider them in turn.

OpenLearn - Eutrophication
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