Answer
Ecology is all about interactions among living things and between living things and the non-living world. If nutrients decline in an aquatic habitat, diatoms would decline since they could not reproduce as quickly. This would, in turn, leave less food for organisms which eat these primary producers, and then less food for the consumers above those primary consumers in the food web. Diatoms would also use less carbon dioxide, leaving more of it to acidify the water, though this could be good for non-diatoms which do photosynthesis by giving them more metabolic raw material. This could lead to an algae bloom. Consumers might then switch away from diatoms to these other photosynthesizes as food sources.
Work Step by Step
They key here is to review the properties of diatoms and of photosynthesis (you’ll need to see an earlier chapter for the latter material) and to use your imagination to see how this would mean less food for other organisms as well as opportunities for other creatures with chloroplasts.
