Monitoring macroinvertebrates and diatom populations in East Stoke, Dorset
As part of a long term, collaborative research project between BU and the FBA, PhD researcher
Tadhg Carrol and BU research assistant Jack Dazley have been assisting freshwater biologist John
Davy-Bowker in sampling two rivers in East Stoke, Dorset for aquatic macroinvertebrates (such as
insect larvae, aquatic worms and water beetles) and diatoms (microscopic plants with a glass-like
‘shell’). The research aims to understand how environmental changes, such as increased
temperature and altered riverbed composition, affect the abundance and species diversity of these
groups.
Samples were collected from 5 sites at each river – the Frome and the Piddle, where a square
sampling area 10m wide was set up from each bank. Macroinvertebrates were collected using the
kick sampling method (pictured), whereby the person sampling would rigorously kick the river bed,
exposing mud and stones, and with them the invertebrates, which flow into the net. Environmental
measurements were also taken, and included width and depth of the site, percentage cover of each
species of aquatic plant, and substrate composition of the riverbed (i.e. what types of rocks/stones
are present). Once collected, the samples were preserved to allow identification at a later date.
Diatoms were also collected from each site, and were done so by collecting 5 large stones (one from
each corner of the site and one from the centre) which had clearly visible signs of algae growing on
them, such as green mats on the surface. Using a toothbrush, a section of the green mat was
scrubbed off into a plastic tray to collect the diatoms, and to work out the abundance the scrubbed
area was traced onto acetate. The diatoms were preserved to be analysed at the lab.
Alongside collecting macroinvertebrates and diatoms, careful note was taken in the Piddle upon the
capture and rerelease of protected species, including bullhead fish and white clawed crayfish. These
native crayfish are particularly monitored as they are susceptible to diseases carried by the non-
native signal crayfish. Infact, the Piddle is thought to be one of the only sites in Dorset where the
white clawed crayfish is relatively abundant.
This project is incredibly important to understanding the future of river communities from a bottom
up perspective – diatoms and macroinvertebrates form the basis of the food chain in river
ecosystems, and so support larger freshwater organisms such as fish and birds.
As part of a long term, collaborative research project between BU and the FBA, PhD researcher
Tadhg Carrol and BU research assistant Jack Dazley have been assisting freshwater biologist John
Davy-Bowker in sampling two rivers in East Stoke, Dorset for aquatic macroinvertebrates (such as
insect larvae, aquatic worms and water beetles) and diatoms (microscopic plants with a glass-like
‘shell’). The research aims to understand how environmental changes, such as increased
temperature and altered riverbed composition, affect the abundance and species diversity of these
groups.
Samples were collected from 5 sites at each river – the Frome and the Piddle, where a square
sampling area 10m wide was set up from each bank. Macroinvertebrates were collected using the
kick sampling method (pictured), whereby the person sampling would rigorously kick the river bed,
exposing mud and stones, and with them the invertebrates, which flow into the net. Environmental
measurements were also taken, and included width and depth of the site, percentage cover of each
species of aquatic plant, and substrate composition of the riverbed (i.e. what types of rocks/stones
are present). Once collected, the samples were preserved to allow identification at a later date.
Diatoms were also collected from each site, and were done so by collecting 5 large stones (one from
each corner of the site and one from the centre) which had clearly visible signs of algae growing on
them, such as green mats on the surface. Using a toothbrush, a section of the green mat was
scrubbed off into a plastic tray to collect the diatoms, and to work out the abundance the scrubbed
area was traced onto acetate. The diatoms were preserved to be analysed at the lab.
Alongside collecting macroinvertebrates and diatoms, careful note was taken in the Piddle upon the
capture and rerelease of protected species, including bullhead fish and white clawed crayfish. These
native crayfish are particularly monitored as they are susceptible to diseases carried by the non-
native signal crayfish. Infact, the Piddle is thought to be one of the only sites in Dorset where the
white clawed crayfish is relatively abundant.
This project is incredibly important to understanding the future of river communities from a bottom
up perspective – diatoms and macroinvertebrates form the basis of the food chain in river
ecosystems, and so support larger freshwater organisms such as fish and birds.
