Marine dead zones can form when nutrient run-off causes certain types of algae to grow very quickly and then die off. As dead algae decompose, oxygen is removed from the water. With less oxygen available, fish and other marine animals can die. What would be one practical way to reduce marine dead zones? Add bacteria that are able to eat the fast-growing algae.
Harvest marine fish in dead zone areas to reduce oxygen use.
Pump oxygen into the water using equipment on fishing vessels.
Prevent fertilizer and other wastes from entering rivers and streams.

what image you forgot to include it.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.

a bird that nests only in a particular tree species.