Friday, 30 May 2014
What exactly do you do in that field? Sampling Hauxley's ponds
The experimental ponds at Hauxley have proved a revealing time machine. Since they were dug out in the autumn of 1994 their animals and plants have been monitored, allowing the changing communities to be tracked in detail. For the first ten years all thirty ponds were sampled in January and early summer (late April to early June, depending on how fast they were drying out). Since 2004 the animal life has only been checked in five of the ponds, simply because of the logistics, although it is a race between the science and my knees giving out. The sampling is used to record the presence and absence of taxa, first of all using a small, fine meshed aquarium net to sweep the open water, then a stout pond net to rake round the edges and through the plants. Each pond is sampled for between 2-3 minutes. I keep on doing this until no new taxa turn up in the white trays. Here I am crouched over the trays checking all the creatures wriggling and crawling.
As I do each tray I pour the contents into the blue box to hold the animals until I can put them back alive into their home pond. Presence/absence is very basic but I like the idea of putting back the animals rather than killing them all in samples, though I suspect they are not keen on being dredged out in the first place. Many of the animals are small, but a hand-lens works well for identification although I do keep some beetles, Chironomid midges and Ostracods (pea shrimps)to check. All of the ponds are now choked with mosses and grass. The animals of the bare, raw ponds of 1995 and 1996 are largely gone and overall species richness has declined, probably a mix of predictable changes as ponds age but also degradation from increasing drying out after two very wet years early on in 1997 and 1998. Hunched over the trays has some benefits. Inquisitive stoats have crept up, perhaps wondering if I'd make a suitable meal. A local fox took to lying up next to the hedge to watch me with, I'd swear, an amused smirk on its face. In winter geese wheel away horrified to find a human crouched under their flyway. I probably miss even more wildlife baffled by this strange performance but those trays of animals do not sort themselves.