Answer:
Thermal energy.
Step-by-step explanation:
Thermal energy can also be referred to as heat energy. It is produced when certain rise in a temperature makes some atoms and molecules to drive faster and hit against each other. The said energy that emanates from the temperature of the heated substance is known to be thermal energy.
In an ecosystem, usually water from a nearby river or lake is pumped in and used for a cooling process. This causes an increase in the temperature of the water, causing less oxygen to dissolve in it. Many types of fishes which have a small tolerance range for oxygen dies off in this process.