Confronting Physical, Chemical and Temporal Biases in Experimental Algal Biology.

Selective bias in algal research often leads to proposals of what are often unreliable causal relationships. Systematic errors mainly arise from ignoring chemical and physical environmental changes along with increased algal biomass during cultures. This paper examines three interacting bias dimensions using hypothetical cultures and literature examples. Selective bias in choosing basic parameters to measure cell properties, such as using chlorophyll as a biomass proxy, or over-reliance on genomics or proteomics without integrating physiological processes can lead to misinterpretation of cellular processes. Temporal selective bias emerges from sampling windows that ignore phased physiological demands, including marked daytime changes in photosynthesis and molecular signatures even under constant light. Physical bias arises from poorly controlled experimental conditions such as unstandardized hydrodynamics, altering diffusion boundary layers, gas/nutrient delivery and self-shading. Chemical bias stems from uncontrolled carbonate chemistry (pH, pCO