Geo is a prefix pertaining to geology, or the study of rocks, sediments, and soils. Chemical has to do with chemistry, or the study of elements and molecules. Given these, the first term describes a research program aimed at understanding aspects of algal and bacterial activities which involve chemical transformation of minerals. Eco is for ecology, or the interaction of living things with their environments and with each other.
Physiology is the study of cellular metabolism including growth and biochemical processes.
These latter two add a metabolic bent to the above theme, and open the door to laboratory culture work as well as the vast array of field research implicated in the first term.