IN THE FIELD
There are two components of the Ghost Ponds Project which are being carried out in the field. Firstly, we have the re-creation of the six study ponds (for details on each individual pond, see the resurrections & restorations drop-down menu). This involved the re-excavation of three ghost ponds (ponds which had been filled-in for land reclamation), and the restoration of three highly overgrown ponds (sites which still just about qualified as a ‘pond’, as they contained a small amount of water, but which were very species poor and highly terrestrialised). The ponds form three pairs of study sites; at each of the three farms involved in the Ghost Ponds Project, a ghost pond and a restored pond have been dug close together (usually in the same field).
In addition, a series of microcosms – or ‘mini ponds’ designed to replicate different pond conditions – have been dug at each site. These are being monitored along-side the study ponds, and give us the opportunity to investigate the pond colonisation mechanisms under more controlled experimental conditions. The microcosms variously exclude organisms from dispersing into them (fine netting), or exclude the sediment bank (plastic lining and sterile soil), allowing us to identify whether plants and invertebrates appearing in the study ponds are likely to be from the sediment bank, or to have arrived by wind or animal dispersal. For each study pond there are 16 mini ponds;
4 x resurrection conditions – lined mini-ponds filled with sediment taken from the study pond, and covered with fine netting to prevent organisms entering from outside. Any plants / invertebrates appearing in these ponds should only have come from the sediment bank.
4 x dispersal conditions – lined mini-ponds filled with sterile soil, open to the environment to allow organisms to enter. Any plants / invertebrates appearing in these ponds should only have arrived by dispersal.
4 x pond replicates – lined mini-ponds filled with sediment taken from the study pond, and open to the environment. These should behave in the same manor as the study pond.
4 x controls – lined mini-ponds filled with sterile soil, and covered with fine netting to prevent organisms entering from outside. These are to check that the experimental design is working, and should not contain any plants / invertebrates.
Microcosms being dug alongside Swift pond.
IN THE GREENHOUSE
In addition to the field experiments, a greenhouse study is also underway, investigating the viability of the seeds and eggs stored within the ghost pond and restored pond sediments. This provides us with a more controlled environment in which to test the viability of the sediments. For each of the six study ponds, sediments from the older pond layers (just above the marl base), were collected during pond excavation. These contain the seeds laid down by plant communities when the ponds were at their peak. The sediments were then stored (refrigerated), until the greenhouse was set-up, before being divided into replicate aquaria for each pond.
It is hoped that at least some of the seeds will still be viable, and will germinate over the next 12 months. This will help us identify which species found in the ponds are likely to have come back from the sediment, and which are not seen in the sediment and are therefor likely to have arrived by dispersal. After 12 months, the aquaria will be drained and the sediments sieved to remove all non-viable seeds (those which did not germinate), giving us a measure of what proportion of the historic seeds remain viable, and which pond species are best adapted for long-term seed dormancy.
IN THE LAB
As part of the aim of the Ghost Ponds Project is to establish what role the historic pond sediments can have in returning lost communities, it is important to have a good grasp of what these historic communities were like. Macrofossil analysis – analysis of preserved plant and animal remains – can tell us not only about the plant communities which used to fill the pond, but also give us clues as to the past invertebrate assemblage (zooplankton eggs, beetle wing cases and hard mouth parts all preserve well). In addition, finding fish bones provides a wealth of information on past pond ecology, as ponds with and without fish differ in many aspects. Already we have identified a number of aquatic plant and zooplankton species, as well as gaining insights into what the surrounding terrestrial vegetation was like in the early years of the ponds. We have even found stickle-back vertebrae in the sediments of one of the ghost sites (Original ghost) – a particularly curious finding as this pond had always been isolated in the middle of a field, with no connections to other ponds or ditches.