Question

because of the low o₂ levels, the fish in the rivers are dying. what effect would the dying fish have?
a as the fish die, they decompose to produce ammonia (nh₃) that is then converted to nitrates (no₃⁻).
b as the fish die, their nitrogen leaves the ecosystem.
c as the fish die, nitrogen - fixing bacteria convert the nitrogen in fish dna to nitrogen gas (n₂).

Explanation:

When fish die, decomposers break down their organic matter. During decomposition, ammonia ($\text{NH}_3$) is produced. Nitrifying bacteria then convert ammonia to nitrates ($\text{NO}_3^-$). Nitrogen - fixing bacteria convert atmospheric nitrogen ($\text{N}_2$) to ammonia (not from fish DNA). When fish die, their nitrogen is recycled in the ecosystem, not just leaving it.

Answer:

A. As the fish die, they decompose to produce ammonia ($\text{NH}_3$) that is then converted to nitrates ($\text{NO}_3^-$)