Answer:
Because of the depth that makes it difficult to establish rooted plants.
Step-by-step explanation:
The limnetic zone is the region that goes as far as the light reaches. Their communities are plankton (bacteria, algae and zooplankton) and necton (fish). Unlike the coastal zone where photosynthesis is performed by plants, in this region it is performed by algae. The limnetic zone in lakes and lagoons is very deep and although this region receives sunlight, which would facilitate the existence of plants, the depth hinders the establishment of roots of these plants. For this reason, there are no plants rooted in the limnetic zone of a lake or pond.