Well, the most logical explanation is that the water becomes contaminated, killing the “good” minerals in the water that help smaller organisms to survive. Therefore the food web is in “dissatisfaction” and animals will have to find other alternative ways to satisfy their food cravings.
DNA (deoxyribonucleic acid) The abbreviation for "deoxyribonucleic acid," the primary carrier of genetic information found in the chromosomes of almost all organisms. The entwined double structure allows the chromosomes to be copied exactly during cell division.