Explain why estuaries are very productive ecosystems

Estuaries are very biologically productive. The salinity gradient and the changes in tides, fresh water and accompanying flux in nutrients within estuaries create a variety of habitats that support a diverse food web. ... Because these gradients exist, estuaries are transition zones for many species of wildlife and fish.

Explanation:

Estuaries are very productive ecosystems because they constantly receive fresh nutrients from the river; the pollutants that damage estuaries are the same pollutants that damage other aquatic ecosystems: sewage, industrial waste, and agricultural run off.

d concave shape of wave rock

explanation:

the concave shape of wave rock is a very good evidence that supports the evolution of earth due to chemical weathering. if we talk about structure of   wave rock, studies have estimated that it is around 2.7 billion years old. it also serves as the foundation of evidence that it was the place where australian continent began to form.

how the structure of wave rock was created?

studies suggest that structure of wave rock was created when the surrounded area was started to weather due to which deposition of material started on the part of land which now contains wave rock.

the structure of wave rock is considered to be one of the best-known landforms in australia. at the height of around 15 cm, there can be found flared slopes which formulate the margins of hyden rock. it is now assumed by geologists that wave rock was created by subsurface water-induced weathering and not by glaciers, waves or wind.

due to deposition of material over the period of long time, the wave rock became tougher and tougher due to weathering from surrounding terrain. this makes it a physical evidence that supports   the evolution of earth due to chemical weathering.

hope it !