Week 4a- Water

An estuary is a partly enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.  Estuaries form a transition zone between river environments and maritime environments and are subject to both marine influences, such as tides, waves, and the influx of saline water; and riverine influences, such as flows of fresh water and sediment.

Estuaries can provide areas for the settling of particulate discharges so accumulation of contaminants may be significant in these regions.  Estuaries are varied across New Zealand and their characteristics may depend on many factors including size, depth, type and extent of mixing with seawater.  In the North Island of New Zealand, may estuarine systems contain mangroves (plants which have adapted to living in seawater).