The waterways in Christchurch can be natural or man-made.
When it rains the water sinks down through the soil and goes to aquifers (if you don't know what an aquifer is it's just a river that is underground). If the water lands on concrete it will either evaporate or flow into a stormwater system. If water lands on the roof it goes through a down pipe to the stormwater drains and the storm water drain leads to our waterways so we need to keep all the rubbish away from them.
A habitat is a place where animals and plants live. An example of a habitat is a stream, and sometimes we destroy them by having picnics and leaving the rubbish at a stream. The fish will get caught in the rubbish and if we don't stop littering, the fish will die. So we need to manage our littering so we can save the habitats of animals.
A ideal place for a mud fish is a creek that has a lot of weeds because the mud fish eats submerged plants. The pukeko relies on vegetation because it feeds on it and if there was no vegetation there will be no pukeko any more. The vegetation helps the eels because they need shade to hide and keep cool.
What a healthy waterway is
In New Zealand you will find a lot of waterways some will be healthy and some will be polluted. There are a few signs you can look for to tell. If there is only snails and worms or no invertebrates, that means it isn't healthy. If it is healthy there will be macroinvertebrate such as mayfly and caddisfly
We have visited many rivers to assess the health of the ecosystem. We have used the “In-stream Riparian Habitat Survey” at the waterways, to decide if the river looks healthy. We also used a TRD which is a sieve on a stick technical retriever device, and we used it to catch the invertebrates. If there was invertebrates that will help us see if it was polluted or not. We then used the turbidity tube that is a tube you put water in to see how clear it is and if it's murky it's a sign of bad water for invertebrates.
The Styx river could be more healthy than it is. The water had a lot of sediment on the stream bed which is bad because the invertebrates don't like the sediment; they need the stones to hide from predators and keep cool.
There isn't much algae and we need algae because invertebrates feed on it. The good thing is that there is only a small sign of erosion because the bank was really stable. The vegetation went really far too, there was lots of plants around the area. It's good because it provides shade for the invertebrates and holds the banks steady because of the roots .
This is the results for styx river. Overall the score is 46 so i think Styx river is fairly healthy
We could change the Styx river by:
- digging most of the sediment and replacing it with stones so the invertebrates can hide from predators
- We could also replace some of the trees with other native trees because there were too many of the same trees that weren't native.