Is our coastal water suitable for plants and animals?
Our Region’s coastal water quality is well suited for our marine plants and animals to live in. It is well oxygenated and contaminant levels are generally low.
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What lives in our coastal water?
Our coastal waters are home to a wide variety of plants and animals including:
- seaweeds
- plankton
- barnacles
- shellfish
- crustaceans such as crabs and koura (crayfish)
- fish
- marine mammals (such as dolphins).
They need good water quality to survive.
Water quality monitoring
There have been no detailed studies to see how suitable our coastal water is for plants and animals. But over the past 25 years we have collected water quality samples at about 40 sites around the Region.
Samples were collected between 1973 – 1997 from both open coast and enclosed waters (such as harbours and estuaries). The water quality variables measured include:
We can use these samples to draw some broad conclusions about the health of our coastal water and the ability of plants and animals to live in it.
How healthy is our coastal water?
- There is little sign of increasing plant nutrient levels (such as frequent algal blooms or the growth of sea lettuce) from land-based activities.
- Water clarity in estuarine water is often low. In some areas, high turbidity prevents light from travelling through the water. This lack of light restricts the growth of some underwater plants.
- Water clarity around our open coasts varies. Rocky shores have good water clarity. But the surf zone on open coast beaches usually has low water clarity because the wave action stirs up the sand. Water clarity in the open ocean is excellent (up to 50m visibility).
- Levels of phytoplankton are generally low, although blooms or ‘red tides’ are occasionally reported in summer. Many conspicuous blooms are harmless and do not affect human health. But sometimes the ammonia released when large numbers of cells in the blooms die and decay can kill fish.
- Conditions in the open coast and enclosed water are similar, although levels of bacteria and ammonia tend to be higher in enclosed water.
Our Region’s coastal waters are well suited for coastal plants and animals to live in. There is no evidence that average water conditions have changed since samples were first collected in the 1970s.