A guest blog post by Laura
This week marks the start of the ‘spring’ ecology sampling season for my team. Today I was out collecting invertebrates in Upton, Pershore, Evesham and Broadway, in Worcestershire. I catch the creatures using a method called kick sampling.
In a nutshell I kick around in the substrate and search under stones to look for invertebrates, they are collected in the net then transferred to a tray.
I pick out all the leaves, sticks and stones, checking none contain invertebrates. The sample is then tipped back through the net, the water drained off and placed in the container.
Data is then collected on substrate type, surrounding vegetation, width, depth, plant growth etc. All this has an impact on the site and can affect the biological water quality and hence the type of creatures present. Data is automatically uploaded onto a database.
Once back at the lab the sample is preserved in methylated spirit so the it doesn’t degrade.
Each invertebrate has a score; 1 reflects poor (low) water quality and 10 is excellent (high) water quality. The photo below shows leeches, molluscs and shrimp (I won’t bore you with the Latin names) from Mere Brook. This initially tells me the water quality is average as these species can tolerate heavy sedimentation and low water quality.
However, the picture below shows a high scoring cased caddis crawling along the container, its case is made from tiny sand grains.
Its’ presence shows the watercourse must be good quality. Just from poking through the sample in the tray I can see lots of species that indicate good water quality. Once under the microscope our experts can pick out the smaller species, the scores are added up and this gives the site an overall score for biological quality.
In the photo below can you spot the difference between the 2 inverts and the sticks? That is what samplers are trained to do. You need attention to detail in this job!
In Piddle Brook at Pinvin and Seaford there were more high scoring inverts present, mostly different types of cased caddis fly larvae. In photo below you can see the cased caddis fly larvae has crawled out of its case which is made from sand grains. Some make a case out of tiny sticks and leaves.
The caddis fly larvae places 2 stones on either side of their case when constructing it that create ballast so it can crawl along the riverbed. It is able to retreat into its case to prevent fish from eating it. If it didn’t have ballast it would get swept away into the water column.
I finished the day in Broadway kick sampling the Badsey Brook. Once back at the office, all 3 pairs of waders, trays, nets and gloves were disinfected and hung up to dry.
This is what we call biosecurity. We take is very seriously as it can prevent the accidental transfer of diseases and invasive species from one waterbody to another.
They’ll be used in the Sud Brook at Gloucester tomorrow when the monitoring programme continues!