TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The feedstock material comprises at least one plant material comprising plant tissue. The feedstock material comprises aquatic plant material. The feedstock material comprises at least one animal material comprising animal tissue. The aquatic plant material in the method (M3) comprises plankton.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred System: The system (S1) is automated. In the system (S1), the first container is supported by at least one of floating in the water body, suspending in the water body, and resting on a floor of the water body. The system (S1) further comprises at least one flexible second container, where the second container is coupled to the first container; the at least one bacterium in the first container produces a quantity of methane in the first container; and the methane produced in the first container is transported to, and purified in, the second container. In the system (S1), the methane is purified using at least one differential dissolution property of methane with respect to at least one other gas. The system (S1) further comprises at least one flexible third container, where the third container is coupled to the first container; the bacterium produces a quantity of carbon dioxide in the first container; and some or all of the carbon dioxide in the first container is transported to the third container. In the system (S1), the carbon dioxide transported to the third container is purified by separating a quantity of a liquid phase of the carbon dioxide from at least one other liquid. In the system (S1), the purified liquid phase carbon dioxide is sequestered by collecting a quantity of liquid phase carbon dioxide and transporting the collected liquid to a position on or near a floor of the water body. The system (S1) further comprises at least one fourth container, where the purified liquid phase carbon dioxide is sequestered by collecting the quantity of liquid phase carbon dioxide and placing the quantity of collected liquid in the fourth container. Preferred Components: The first container comprises at least one of a gas, a liquid, and a solid. The first container comprises at least one bacterium, where a quantity of nutrients in the first container is transported to the surface. The porous container in the method (M3) comprises at least one of a tube and a bag.