Christchurch has many natural and manmade waterways. For example there’s natural waterways like lakes, streams, rivers, ponds, springs and wetlands as well as estuaries and tributaries. The man made waterways are the stormwater system, artificial drains, and surface run off.
When it rains there are two ways water can go. If it rains on the grass the soil acts like a sieve. The clean water goes underground and into the aquifers and keeps the dirt on top of the ground. Aquifers are connected to our homes because it comes through the pipes and into our homes for us to drink.
If the rain falls on the concrete, it goes into the drains, through the stormwater pipes then to the rivers and out to the ocean.
A habitat is a place where animals and plants live. Of course a natural habitat could be a birds nest, a cave, or a waterway. A habitat is a place for creatures to live, rest, and feed. Sometimes people wreck natural habitats to make recreational areas like buildings. People sometimes don't realise there is a habitat or a work in progress habitat there, so many animals have no more homes to live in and die. In the end, all wildlife relies on something else so if you take away one thing it will affect everything else. For example, invertebrates need stones because they hide under them, so if stones go, so do the invertebrates.
What is a healthy waterway?
The animals that you find in a habitat can tell you how healthy the waterway is. There are many animals that you will find in an waterway. Some are good for the waterway some aren't. Healthy waterway insects are stonefly,mayfly and caddisfly larvae. These are all called microinvertebrates. There are others that live in polluted ecosystems such as worms and snails.
The water temperature is also very important for some insects. A normal temperature is around eighteen degrees but the best is below fifteen degrees. But water that is warmer than twenty degrees celsius doesn't carry enough oxygen to keep the invertebrates alive.
Have you ever got into a river or a stream and felt beneath your feet a slimy texture on the rocks? It is called algae. If it was a clean river it would have a thin coat on the river rocks. If it wasn't clean it would have a thick sponge layer and may have long strands coming off rocks.
Streamside trees provide shade to keep the water cool, and tree roots and grass that cover the bank also holds the bank together to prevent the soil from eroding. If it was bad ecosystem there will be no trees which will cause the soil to erode because the trees hold the banks together.
It is very important for a river to be clear so you can see the bottom. There should be stones or pebbles to hold the sediment down so it should be reasonably clear. A bad result of water clarity is usually murky water. It is bad because it can clog the gills of fish and it will make it hard for them to see.
Testing our water ways!
We visited lots of waterways. We looked at the health of the river ecosystem using an “In-stream and riparian habitat survey”. We also caught lots of invertebrates. We counted and classified them using the invertebrates survey. We also looked at the turbidity of the water either looking at the water or using a turbidity tube. We found out lots of things visiting these waterways so we can learn things that we haven't even heard of to make more and more pathways in our brains.
Dudley creek is a creek that needs to be improved on. There was less than one metre of vegetation on the banks. That is bad because the invertebrates need shade because they like water under 15 degrees celsius and the roots hold the bank together so it can't erode.
The second thing was that about 50% of the stream bank was eroding, broken, or unstable. That is bad because when it erodes the sediment covers the stream bed so the invertebrates can't hide, so they die.
Another thing was that there were a few trees and shrubs, but mainly just long grass. That is bad because it needs trees to hold the bank together and keep the water cool.
The stream flow has some variety in depths, pools and had a few rapids. That is good because deep pools make good fish spawning areas and rapids and riffles help oxygenate the water.
Also we could not find any macroinvertebrates in there so the river is not that healthy. The turbidity was lacking but you could still see the bottom of the stream.
Changes we could make
Face it, Dudley creek is not as healthy as it could be. Just imagine if we could change that. Invertebrates would live there, the water clarity would be more clearer than any other, and the temperature would be below 15 degrees Celsius. But first we need to make it happen. How though?
Planting more trees to create habitats, shade and hold the banks together
Being careful where we put our rubbish
Adding a bench so you can sit down
Making sure you don't fall in the water
Taking out the silt and replacing it with stones for macroinvertebrates to hide under
Adding a log in the river to create riffles and rapids for fish spawning areas
We need to take care of our rivers because we use them to ...
Swim in, fish out of, waterski on, boat on
These changes are important because our ancestors helped take care of our native habitats by taking mahinga Kai(food from nature) in a way that will last. Kaitiakitanga (a maori cultural value) means to care for and protect our land and water. We have a spiritual connection to our ancestors as well.
Even if we take one small gulp of a polluted stream we could get very sick or if we eat something from a polluted water that is sick or ate something bad we can get very sick.