Appendix C. A description of the methodologies used to assess environmental parameters of the ponds.
Conductivity, oxygen concentration, pH, and water temperature were measured with a WTW multiline F meter (Geotech). Water transparency was measured with a Snell tube. A Snell tube consists of a hollow black cylinder (length 0.70 m; diameter 55 mm), which is closed at the bottom and filled with sample water. When measuring, a white disc attached at the side on a meter stick is lowered until the disc is not visible anymore, and then the disc is pulled up again until it becomes visible. The Snell depth is determined by averaging these two depths (Louette and De Meester 2005). Chlorophyll a concentrations were measured spectrophotometrically following the procedure of Talling and Driver (1963). Macrophyte cover (%) of Lemna sp., filamentous algae, emergent, floating-leaved, riparian and submersed vegetation, the percentage cover by tree roots and branches, and the percentage open sediment, were monitored along the macroinvertebrate sampling trajectory in all ponds. Shading by riparian trees was estimated as the percentage of the sampling trajectory that had tall trees (>10 m) within 10 m of the parallel shoreline. Relative YOY fish densities in each pond were estimated by the number of YOY fish collected during macroinvertebrate sampling with the D-net.
LITERATURE CITED
Louette, G., and L. De Meester. 2005. High dispersal capacity of cladoceran zooplankton in newly founded communities. Ecology 86:353–359.
Talling, J. F., and D. Driver. 1963. Some problems in the estimation of chlorophyll-a in phytoplankton. Proceedings of a conference on primary productivity measurements. U.S. Atomic energy Communication. TID-7633:142–146.
Savage, A. A. 1989. Adults of the British aquatic Hemiptera – Heteroptera. Freshwater Biological Association, Cumbria, UK.