DOI: 10.5285/3e6a9ffd-59f2-48ea-840b-1582dc6c1e3d
title: Macroinvertebrate leaf decomposers in response to organic matter addition to streams in the Welsh uplands (2013)

description: These data are macroinvertebrate composition and abundance in eight Welsh upland rivers with contrasting land-use, moorland and exotic conifer, in response to riparian deciduous leaf addition. Eight sampling reaches were chosen at two sites, Llyn Brianne (4 reaches) and Plynlimon (4 reaches). The experiment consisted of adding deciduous leaves to half of the reaches whilst the other half were maintained as control (no addition). Nylon mesh bags containing deciduous leaves were fixed in both experimental and control reaches to estimate leaf decomposition rates. The macroinvertebrate composition of the nylon mesh bags was surveyed in January 2013 and again in March 2013 in each sampling reach. 

The main goal of this survey was to examine how aquatic biodiversity responds to leaf addition in moorland and conifer forested rivers. Dr Isabelle Durance was responsible for organising the surveys, Dr Hugh Feeley, Dr Dan Perkins and Marian Pye were in charge of collecting, processing and sorting the invertebrate samples. The work was carried out under Diversity in Upland Rivers for Ecosystem Service Sustainability (DURESS) project (Grant reference NERC NE/J014818/1). DURESS was a project funded by the Natural Environment Research Council (NERC) Biodiversity and Ecosystem Service Sustainability (BESS) programme
description: 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).