The Invertebrate Fauna of the River Spey by Craig Macadam

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The study:

  • Following concerns about changes in the aquatic invertebrate populations of the River Spey, the Spey Fishery Board commissioned an analysis of historical data to determine any trends in species of importance to anglers, and whether there are any indications of changes in water quality or flow.
  • Data collected by SEPA at Spey mainstem sites, over a 39 year period, from 1981 to 2019 were obtained and analysed.
  • Invertebrates are at the heart of freshwater ecosystems. Changes to the invertebrate fauna impacts the food web and can have a detrimental effect on game fisheries.
  • Invertebrates are found in almost all aquatic habitats, they generally have limited mobility and as such are useful indicators of localised environmental conditions.
  • By examining the invertebrate fauna at a site an experienced biologist will be able to determine relatively quickly whether the watercourse is impacted or not.
  • The Author: Craig Macadam

  • Studied invertebrates for over 25 years, specialising in freshwater macroinvertebrates, particularly mayflies, stoneflies and caddisflies.
  • Particular interests are the effects of climate change on riverfly populations, the life histories of mayfly species and various aspects of urban biodiversity.
  • Founder member of the Riverfly Partnership. Chair of the IUCN Species Survival Commission Mayfly, Stonefly and Caddisfly Specialist Group
  • Delivers invertebrate training courses
  • 11 years in the water industry as an Engineering technician, Environmental Policy Officer and Drinking Water Scientist
  • Now Conservation Director with Buglife
  • Responsible for the development of the ‘Strategy for the Conservation of Scottish Invertebrates’
  • Sits on national policy fora including the Wildlife and Countryside Link and Scottish Environment Link (Deputy convenor of the Wildlife Forum) and the Scottish Biodiversity Strategy Habitats and Species Group
  • Chairs the Scottish Biodiversity Information Forum.
  • Represents Buglife on the English National Pollinator Strategy Stakeholder group.
  • Committee member of Biological Recording in Scotland (BRISC).
  • Summary

  • This study has analysed the results of invertebrate sampling at six sites on the main stem of the River Spey. The data was sourced from the Scottish Environment Protection Agency (SEPA) and covers a 39-year period between 1981 and 2019. It is not complete however, with only one site, at Fochabers having samples for each of the 39 years.
  • Overall, the Invertebrate populations of the Spey appear to be in good health. The total number of riverfly species is stable or increasing slightly and most families show increases in abundance in recent years. The total number of families and species richness both also show slight increases over time. The species diversity is also generally stable, however slight declines are evident at Grantown and Fochabers.
  • There is evidence of a decline in abundance of a number of families during the 1990s however in most cases numbers have subsequently recovered. The populations of Isoperla grammatica, Brachycentridae and Glossosomatidae show variation in their abundance, particularly in the middle river. At Garva, the caddisfly Sericostomatidae appears to have colonised the site in recent years suggesting that it could be expanding its range upstream.
  • A number of biotic indices were calculated from the data which reveal that water quality in the Spey remains very good. There is some evidence of lower flows influencing the composition of the invertebrate population, which may also be leading to a slight increase in sedimentation, however the river is still minimally impacted by sediment.
  • You can find the file here.

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