Sunday, 26 May 2013
Students of pond difference
I’ve spent the last week in the Lake District with our first year undergraduates on their annual field trip, a mix of core ecological skills for conservation and landscape in the UK (Phase 1 mapping, National Vegetation Classification), ping pong and stone circles human sacrifice re-enactments. They worked hard, twelve hour days, apart from the final night when they stayed up even longer to craft the data they had been collecting into presentations. Creating a pressed flower collection may not seem the most compelling activity when you are 19, but I am confident those slightly mangled specimens of pignut and pink campion will one day be treasured possessions. Each student had a particular flower to find, hampered a bit by the late spring but also resulting in a bout of botanical blind man’s buff, watching them walk past their quarry. They have to do a group project too. One five-some, Ryan, Chloe, Dylan, Andrew and Jack took up the challenge of comparing the richness of invertebrate in two ponds compared to two streams. We’ve not tried this before but after several days of counting grasses in quadrats you can see the attraction. They took kick samples from two streams coming off the southern slopes of the Blencathra ridge up by Skiddaw, then samples from two nearby ponds. The streams yielded Heptagenidiae and Baetidae Mayflies, Leuctridae and Chloroperlidae stoneflies and a supporting caste of oligochaete worms and cranefly larvae. The two ponds were more of a surprise, both teeming with tadpoles but otherwise rather different, one pinging Copepoda zooplankton and creeping Nemouridae stoneflies, the other with Polycelis flatworms, Pseudocrangonyx gracilis shrimps and the giant Ramshorn snail Planorbis corneus. They used Jaccard’s Index of Similarity to summarise these patterns, essentailly a measure of how many taxa two sampels have in common ranging from none, 0%, to an identical inventory, 100%. The two streams were 50% similar to one another, the two ponds only 17% similar to each other, a neat demonstration of the heterogeneity of ponds in the landscape, and a neat demonstration that students can do good work given the opportunity plus staff suffering from an overdose of Protestant work ethic and slightly sleepless nights.