Which one of the following statements is $NOT$ correct?

• A
  The amount of some toxic substances of industrial waste water increases in the organisms at successive trophic levels.
• B
  The micro-organisms involved in biodegradation of organic matter in a sewage polluted water body consume a lot of oxygen causing the death of aquatic organisms.
• C
  Algal blooms caused by excess of organic matter in water improve water quality and promote fisheries.
• D
  Water hyacinth grows abundantly in eutrophic water bodies and leads to an imbalance in the ecosystem dynamics of the water body.