"Field data shows correlation — nitrogen and algae rise together. But does nitrogen CAUSE the algae? To answer that, you have to manipulate it. That's what experiments are for."
Why Experiments? From Observation to Manipulation
Observational data reveals correlation; manipulative experiments establish causation. By controlling all variables except the one we change, an experiment isolates cause and effect. In lagoon science, the central causal question is nutrient limitation: does added nitrogen, added phosphorus, or both actually stimulate algal growth in a given segment and season? You cannot answer this from monitoring alone — co-variation of N, P, temperature, and light confounds any observational analysis. A controlled nutrient-enrichment bioassay removes the confounders: same lagoon water, same light, same temperature, only the nutrient treatment differs. This is the experiment that underpins every load-reduction management decision: if we cut nitrogen, will chlorophyll actually fall?
