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Threats to Ecology

A Precious Resource
Introduced Weeds and Fish

Ecology is all about living things. Living things can die if their environment is damaged. There are many different types of events that can have a negative impact on freshwater ecology.

Natural disasters

Mount Ruapehu is one of the most active volcanoes in the world. If there was a large eruption, the ash and material ejected into the surrounding Taupō area could get into local waterways. This material could pollute the rivers and lakes and kill the organisms living in them.

Storms and flooding could also affect the quality of the local waterways with large amounts of silt being carried into the rivers and lakes. The silt could make it difficult for water creatures to breathe and hunt for food.

Human impacts

Modification of waterways

One of the biggest threats to freshwater ecology around the world is from water being diverted from its natural course for the purpose of irrigation, water supply and the production of energy.


When it rains in urban areas, the rain that runs off buildings and down gutters is called storm water run-off. Storm water run-off can carry pollutants, either chemical or natural (silts), back into the local waterways. For this reason the management of storm water quality is of great importance for urban development and resource planning.


Over the last fifty years, land and industrial development in the Taupō region has increased the amount of nitrogen in the water. Nitrogen encourages the growth of algae, which makes the water murky. The health of Lake Taupō and its rivers, and the future of the trout fishery, depends upon clean, clear water. The Lake Taupō Protection Project aims to reduce the amount of nitrogen entering the water by 20% over the next 12 years.


Over-fishing can take a species out of the food web. The health of a waterway can be measured by how many different types of living things it contains. If a species is over-fished this will affect other parts of the food web.

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Investigate: Find out if there are any threats to a waterway near you.

A volcanic eruption could pollute Taupō's waterways. Image: LEARNZ.

Changing water from its natural course can affect freshwater habitats. Image: LEARNZ.

In urban areas storm water run-off can carry pollution into local waterways. Image: LEARNZ.

Land development increases nitrogen in the water. Nitrogen makes algae grow faster. Image: The Bushland Trust.

This is a picture of illegally caught trout. Over-fishing can upset the food web. Image: DOC.

A Precious Resource
Introduced Weeds and Fish