Flounder zone

Flounder zone is the zone which is visited by some marine fish species. Namely, unlike the previous higher zones, the water here is richer in salt (this is actually brackish water) so here you can see flatfish such as flounder and sole and species three-spined stickleback, great pipefish and flathead grey mullet.
Rivermouths flowing to the sea, deltas and estuaries are characterised by largest number of plant and animal species among all habitats. Bottoms are sandy or clay, vegetation is exceptionally diverse, and due to changes of high and low tide, there are large fluctuations in temperature and salinity.