Macroinvertebrate leaf decomposers in response to organic matter addition to streams in the Welsh uplands (2013)

Each stream was divided into an upstream reference zone and a downstream experimental zone. Deciduous leaves were added directly to the stream and by fixing 'Onion bags' of leaves to the stream bed and bank.

In early November 2012, 48 replicate litter bags (24 per reference zone and 24 per experimental zone) of two mesh types, fine and coarse filled with air dried deciduous leaves were secured in pairs to randomly distributed metal poles each of the study streams. The mesh bags were then covered with cobbles to facilitate biological colonisation. At the end of the 'before' treatment half the litter bags or 6 fine and 6 coarse mesh litter bags were removed gently from both the reference and experimental study zones within each stream. At the same time 6 new fine mesh and 6 new coarse mesh litter bags were added to each pole to measure the decomposition during the 'after' manipulation period. These bags were left until the end the experimental period. At this point all of the remaining litter bags were removed.

Directly upon collection, all litter bags were preserved in 70 per cent ethanol on site, within individual clear polystyrene bags, marked with an identifying code and transported back to the laboratory for processing. Once in the laboratory the leaf material from each litter bag was rinsed carefully under tap water under a fine sieve and air dried at room temperature. All macroinvertebrates were separated from the contents of each litter bag, and identified to species. Data was recorded onto an Excel spreadsheet. Data was exported from the Excel spreadsheet to a comma separated value file for ingestion into the Environmental Information Data Centre (EIDC).

This dataset is included in the following collections

The DURESS project - Diversity of Upland Rivers for Ecosystem Service Sustainability