Friday, 21 February 2014

Ecological Characteristics of Streams.

Today we went to Brecon (near Pen y Fan) to collect some invertebrate specimens from a stream; as well as looking at the physical and biological characteristics of the stream.

Typical Welsh weather; it was raining and even hailing for almost the entire duration of our time there. It was bitterly cold, made worse by the fact that we needed to get our hands wet (and for me, my feet). 

We took measurements of the stream:  width of the stream, bank heights, water heights and stone composition at different intervals across the stream. we also measured the speed of the current by using a leaf and a metre ruler. 

As well as the measurements we had to look at potential sources of pollution and how the area was managed. A lot of trees had been cut down near the stream and water ran through that area into the stream we were on.
Spaghum moss which is on the hill to the right of the stream is acidic and so this can wash down to the river. The red sandstone (mudstone) which is in the river, is also acidic (and contains silica). This all means that the stream will be slightly acidic. 

The area around the stream was sued for grazing of sheep, this means that along the hillside was a field. If the sheep did not graze her it would most likely be an oak forest. If it were than the stream may be different (for example what lives in it).

We looked for signs of flooding, for example plants had been pushed over. It seemed as though the stream had not flooded for a while, although some of the embankment had fallen in, but this could be due to general erosion.

We used nets to gather some invertebrates which we then put into a pot, ready to take back to the lab. 
These included web spinning caddis, cased caddis and large stoneflies.

 By this point the hail had really started to pick up and was starting to hurt as it hit and I knew that my wellies were definitely leaking now due to the lack of feeling in my toes. (The photos really don't show just how miserable the weather really was).

When we got back to the lab we had to pickle the specimens ready for our lab session next week. The water in the jar was emptied as much as possible (without loosing anything) and then methanol was added a 20% water to 80% methanol ratio.

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