<span>One can infer from this situation the following things: first, the fertilizers used in the farm eventually get to the adjacent river. Second, these fertilizers may be providing some benefitial conditions to the algae, allowing it to grow exponentially and strongly.</span>
Oxygen can get into the water in several ways: Oxygen from the atmosphere dissolves and mixes into the water's surface. Algae and underwater grasses release oxygen during photosynthesis.
