New Zealand's Sea Shore

Key ideas about coastal areas

• New Zealand's coastline is more than 15,134 kilometres long. This measurement is not very exact. The more detailed the measurement, the longer the coastline gets! If someone could measure every single little indentation and every edge of every rock of every size, the coastline of New Zealand would be millions of kilometres long. The coastline includes a large variety of coastal environments including estuaries, bays, beaches, sand flats, and rocky shores.
  
  
• In an ecological sense, the edge of the sea goes into bays and estuaries and even up rivers to little creeks high in the mountains. The water flow is unbroken from mountain to ocean and anything put into the water winds up in the sea.
  
  
• While the coastline is very long, it is not very wide. On a vertical shore, it is only a few metres wide, extending from the lowest low tide line to the highest tide line. There is a spray zone above the high tide line where waves spray salt water and a surge zone below low tide where strong wave action scours the bottom.
  
  
• Where the slope of the shore is gradual, as on a gently sloping beach or tidal flat, the width of the coastal area is broader, but not often more than a few hundred metres.
  
  
• Tides are caused by the gravitational pull of the moon and the sun. They are highest (spring tides) when the moon and sun are working together and lowest (neap tides) when the sun and moon are at right angles to each other.
  
  
• Many thousands of plants and animals live on the land, and many thousands more live in the sea. Only a small number of creatures can live in the coastal zone where the environment changes from land to sea twice a day.
  
  
• Animals that live in the intertidal zone time their lives to the tides. They continue to behave as if they can feel the tides even when they are put into an aquarium far from the sea were there are no tides. Birds, fish, oysters, sea shells, starfish, crabs living on the sea shore know all about tidal cycles.
  
  
• The edge of the sea is also important for people. People came to New Zealand on boats. To get on and off the boats, they need places where the coast was protected from waves and deep near the shore. These places are called harbours. All of New Zealand's cities were built where they are because of the harbours.
  
  
• Beaches and rocky coastlines also attract people for recreation and fishing. 85% of all the people in New Zealand live in cities near to the coast and nobody lives very far from it.
  
  
• Harbours are special to wildlife because the protected waters are where many sea creatures live when they are very young. The water in harbours is rich in food and has many places for small sea creatures to hide. The food comes from the many plants that live on the land, from the soil, and animals that live in the edges of the rivers and shallow wetlands.
  
  
• Look at a watershed on a map and compare this to the branches and roots of a tree. Both are branched again and again until there are very small branches. In These branches are like fingers reaching out to gather food and minerals from the land. This branching pattern is very common in nature where materials are carried from one system to another. The lungs, which exchange gasses between the air and the blood are also branched the same way. Blood vessels that carry food and wastes to and from the cells are branched the same way.
  
  
• People, farm animals, and industry produce waste products and these are sometimes washed into the water by heavy rains or dumped into the water through pipes. Often these wastes are contaminated with molecules that are poisonous to life. These wastes stop natural cycles, often killing the eggs or very young sea creatures in the estuaries and harbours.
  
  
• Other wastes, such as sewage, may contain good nutrients, but they are put into the water too fast for the natural cycles to process. This harms the natural cycles by overloading them. Bacteria and other disease organisms may become very numerous and cause more sensitive creatures to die.
  
  
• Other wastes, like plastic bags and fishing rubbish, plug up the natural cycles and tangle sea creatures. Whales have died from swallowing plastic bags.
  
  
• People also damage delicate natural cycles by filling in wetlands. More than 95% of New Zealand's wetlands have been filled in. Other areas are destroyed by dredging or by being smothered in mud eroded from the land. Loss of these valuable biological filters introduces dangerous silt, toxins, and excessive nutrients into the marine environment.
  
  
• Sally Carson, Gael Arnold, Bob Drey, and other sea keepers, understand that people can stop harming this delicate coastal area if they are more careful about what they do. To be more careful, people have to learn how they harm the sea and then work out ways to help, and not hurt, the natural cycles.

Resources to use

Microsoft CD The Magic School Bus Explores the Ocean

Microsoft CD Oceans

Starters and Strategies Magazine. No. 20 Feb. 1996. p. 32-33.

A guide to New Zealand Seashore Dave Gunson Penguin. 1993.

Between the Tides, Mike Bradstock, Reed Methuen, 158pp. 1985

Margins of the Sea, Exploring New Zealand's Coastlines. Professor John Morton. 1985.

Nature Watching on the Beach John Walsby, Wilson and Horton, 144pp.

New Zealand Sea Shores by Professor John Morton is a classic reference book on the sea life of New Zealand's coastal areas, with information on the condition of the sea shore around the coastline dating back over twenty years.

Seashore Life of New Zealand by Erick Heath and R.K. Dell. Reed Publishers

Seashore Secrets. by Sally Carson 1995

Aerial photographs and maps of a study area.

Field identification guides for shells, sea birds, algae, and other shore creatures.