Describe two ways to protect the biodiversity of local fresh water ecosystems

1. Not cutting down plants carelessly

fresh water ecosystems rely on Plants' roots to protect its soil. Cutting down plants carelessly will destroy the soil's strength around the fresh water ecosystem

2. Not using too many chemical fertilizers

Chemical fertilizers will provide unnatural source of nutrients which will caused abnormal growth of several organisms (such as algae) which will destroy the water ecosystem

hope this helps

C. gemstones they are the only non metallic mineral from the list.