How/why do shallow estuary waters create unique habitats for organisms living here?

Shallow estuary waters create unique habitats for organisms living there, because of the congregation of unique elements to the habitat. The brackish water is composed of salty sea water and fresh water, usually fed from a stream or river. The mixing of this water, along with the shallowness or lack of depth of water, allows sun light to reach the bottom and thus encourages plant growth. These two elements of brackish water and sunlight create a very unique living condition for plants and animals and thus a unique habitat.

Number one is sinkholes may form from water erosion