Physical, chemical and biological data from peatland ponds, Pennines, UK, 2012-2014

Macroinvertebrate samples were collected using a long-handled net (250 µm mesh). Two minute samples were collected from across all mesohabitats (i.e. open water, floating vegetation, littoral vegetation, bottom sediments) and then an additional one minute was spent searching for surface dwelling taxa. Percent vegetation coverage in each pond (primarily Sphagnum growth) was estimated visually on site prior to sampling.

Samples were preserved in 70 % methylated spirits and transported to the laboratory. After sorting, macroinvertebrates were identified to species level (where possible) under a light microscope (up to x40 magnification) using standard keys. Where Chironomidae abundance totalled >50 individuals, sub-samples were extracted (n=50) for identification to the lowest possible taxonomic resolution. Individuals were immersed in a solution of 10% potassium hydroxide and heated to 70°C for 10 minutes. The chironomids were then transferred into a solution of 95% glacial acetic acid for five minutes, then 80% methylated spirits for five minutes before being stored 100% methylated spirits. Individuals were mounted on slides using Euparal and identified using a compound microscope.

For each pond, the altitude (m) and location were recorded using a Garmin eTrex Handheld GPS Navigator. Aspect was later calculated by cross-referencing co-ordinates with the Ordnance Survey Terrain50 grid. Pond long axes, short axes and perimeters were measured on site with a tape measure. A minimum of 40 depth measurements were taken in each pond, with more measurements in larger ponds. The approximate water volume was estimated by multiplying the surface area (calculated by multiplying long and short axes) by mean depth.

Dissolved oxygen (DO), water temperature and pH were measured on site using a portable HACH HQ30d meter, with the sensor placed in the upper 10cm of the water column. The pH sensor failed during month 12 sampling, therefore missing values were determined using the relationship between pH~[Mg] across all other samples (r=0.81). A 50 mL water sample was filtered on site (0.45-µm filter) and subsequently analysed for total nitrogen (TN), total phosphorus (TP), dissolved organic carbon (DOC), aluminium (Al), iron (Fe) and Silica (Si) using an Analytikjena multi N/C(R) 2100, a San++ Automated Continuous Flow Analyzer and a Thermo Fisher Scientific iCAP7600 Duo ICP-OES.