The ESTUARY is found at the mouth of the river-where the river meets the sea. It is a significant place for animal life. It is food rich as a result of organic material being brought down river continuously and settling within the estuary area. This debris and nutrient rich water provides food for grazing, burrowing and filtering animals such as shrimps,worms and shellfish. At low tide the mudflats and sandbanks are exposed and are ideal feeding grounds for wading birds.
Below the surface fishes can be found. Probably the most common of which is the thick-lipped grey mullet (Chelon labrosus) (<75cm). This animal has a swollen-looking mouth which rasps off algae growing on submerged rocks. It is often seen too sifting through the mud bottom, relying on it's stomach to digest the beneficial plant & animal life it may hold.
Flatfish such as the flounder (Platichthys flesus) (<50cm) with it's blotchy markings can be spotted blending in perfectly with the sand.
The lesser weever (Echiichthys vipera) (<15cm) too are an illusive predator. These small burrowing fish, with their eyes just above the sand, lie in wait for unsuspecting small fish & shrimps to cruise by. When opportunity arises they lunge forward and seize prey with their upturned mouth. These fish have too an additional defence mechanism in the form of a poisonous dorsal spine. Normally used against predatory flatfish & rays this spine can inflict a painful sting if trodden on.
Estuaries are also ideal habitat for the common shrimp (Crangon crangon) (<10cm). This burrowing animal feeds mainly at night, crawling over the sand using it's stout claws to tackle worms, young fish, small crustaceans, plants and organic remains.