How food chain is disrupted through water pollution?

Water pollution offsets the nutrient balance in the water, disturbing microscopic life as well as aquatic plant life. These organisms are at the bottom of the food chains, which means that they sustain the entire food chain. 
When these organisms begin to die out, the higher levels of the food chain do not have sufficient food and the organisms at these levels begin to die out. Thus, the entire food chain is disrupted due water pollution.