Lyon’s Lake, Hetton-le-Hole, County Durham, May 2015.
After my sojourns in the Lake District and Latvia, I find myself back home in north-east England for a few days. Whilst I was away, a small packet had arrived in the post, containing a sample of algae collected from a local lake. The bottles contained globules of bright green jelly-like material, with enough integrity to pick up with the fingers and they were intriguing enough for me to drive across one lunchtime to take a closer look at the lake where they came from.
Hetton Lyons Country Park is on the Permian Limestone plateau about 10 kilometres from where I live. It is on the site of a former colliery which closed in 1960 and the surrounding land has been reclaimed and partially converted to a country park. The lake – probably a hectare or so in size – is used for angling and water sports, and the paths around the edge were busy with cyclists and dog-walkers. It is on the edge of Hetton-le-Hole, a small town whose odd name refers to its location in one of the more sheltered parts of the plateau.
A mucilaginous colony of Aphanothece stagnina (left) with (right) a microscopic view of the individual cyanobacterial cells embedded in mucilage. Scale bar: 25 micrometres (= 1/40th of a millimetre).
There were plenty of green algae around the margins of the shallow lake but, amidst this in a few locations, I could also see the small globules of the alga resting on the bottom which, like the colonies I had been sent, could easily be picked –up. Under the microscope, these resolved into tiny cyanobacterial cells, mostly oval in outline and about five micrometres in diameter. These belong to Aphanothece stagnina, a relative of the Gloeocapsa alpina, which we have seen in two other recent posts (see “The mysteries of Clapham Junction” and “Poking around amongst sheep’s droppings …”), albeit in very different habitats.
The word “cyanobacteria” alone is usually enough to make the manager of a recreational lake break out in a sweat. Many cyanobacteria produce toxins that can affect the nervous system and the liver. This means that no contact water sports (swimming and canoeing, for example) can take place and dog-owners have to be warned not to let their pets drink from the water. However, as far as I can tell from a brief search on the internet, Aphanothece is not a genus that is often reported in association with toxic blooms. One less excuse, then, not to go wild swimming in a lake in north-east England on a breezy May afternoon …