For the final day of the Natural History Museum postgraduate field trip we were off to look for aquatic invertebrates and algae, first in some freshwater and later at the coast. The first stop of the day was at the Corfe River where we had a great view of the ruins of Corfe Castle, an 11th Century fortification built by William the Conqueror (and popular destination for my childhood holidays).
Eileen and Polly demonstrated the technique of kick-sampling, where you hold a net under the water and kick the sediment for a set amount of time, this dislodges animals living on the river bed and they are then collected in the net. This method is used to test the health of freshwaters, as each animal collected is identified, counted and assigned a score based on how sensitive they are to water pollution.
Despite being the middle of winter there were still plenty of animals living in the river, including snails, freshwater-shrimp (actually a type of amphipod, more closely related to woodlice than the shrimp people eat) assorted insect larvae and we even a Bullhead fish (Cottus gobio).
Next it was off to the River Piddle (*snigger*) in Wareham. A larger river but which had unfortunately recently been partly dredged and had most of the vegetation cut back, but we did find plenty of Minnows (Phoxinus phoxinus) and I had a dig around the banks to find some earthworms to identify later.
After going back to the Old Malthouse to have lunch (and warm up) plus do a little identification of some of the specimens we brought back from the Corfe and the Piddle wet set of to the coast at Swanage to do some rockpooling.
We found two species of limpets, assorted periwinkles and topshells. There were Beadlet Anemones (Actinia equina) in several colours, you can see one below which had ‘babies’ budding off from it. There were also some tiny Shore Crabs (Carcinus maenas). We also recorded many seaweed species which Eileen helped us identify later back in the lab.
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