Studying invertebrates in the River Plym

Luke getting stuck in...
[Photo: Paul Ramsay]

The new conservation biologists at Plymouth University are doing an intensive Introduction to Biology module. It includes regular field trips.

Last week, we were at the Eden Project in Cornwall and collected our own data there to compare with a recently published global study on leaf venation.

This week we were looking at stream invertebrates at various points along the River Plym. We were interested in how freshwater invertebrate composition might reflect the surrounding habitat: for example, the river inside woodland versus in moorland.







To do this, we sampled the river invertebrates in faster-flowing "riffles" and slower-flowing pools in each of the sites we visited. The invertebrates were identified and assigned to functional feeding groups (such as shredders, scrapers, predators) and lifestyle groups (such as swimmers, crawlers, burrowers). The animals were returned to the river once we had looked at them.

Apart from seeing flattened mayfly nymphs and stonefly larvae up close, there was also the chance to try on some very lovely rubber waders. And we had a few water chemistry probes, tape measures and highly scientific oranges to play with.

Next comes the data analysis and report-writing. Not quite so much fun, but just as important...

The River Plym flows through some wonderful oak woodland.
Does the addition of all those leaves in autumn change the kinds
of invertebrates that live in the river? [Photo: Paul Ramsay]

Not far away, the Plym flows through open moorland on Dartmoor.
[Photo: Paul Ramsay]

 

One of the group heads out into the water and vigorously
kick around the substrate to dislodge the invertebrates.
[Photo: Paul Ramsay]