Answer:
Excessive synthetic fertilizer that washes into ponds may be the reason for which algae become so abundant.
Step-by-step explanation:
Algal blooms that feed on fertilizers can deplete oxygen in water, thereby producing inhospitable ponds. In this regard, it has been shown that the runoff of fertilizers from farms (which are rich in nitrogenous matter) may cause algae to become abundant in coastal environments, depleting oxygen in the water and killing the living organisms that inhabit these areas.