The ecology of acidification and recovery: changes in herbivore-algal food web linkages across a stream pH gradient

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We examined the effects of acidification on herbivore-algal food web linkages in headwater streams. We determined the structure and abundance of consumer and benthic algal assemblages, and gauged herbivory, in 10 streams along a pH gradient (mean annual pH 4.6-6.4). Biofilm taxonomic composition changed with pH but total abundance did not vary systematically across the gradient. Mayflies and chironomids dominated under circumneutral conditions but declined with increasing acidity and their consumption of algae was strongly reduced. Contrary to expectations, several putative shredder species consumed algae, maintaining the herbivorealgal linkage where specialist grazers could not persist. These shifts in functioning could render the communities of acidified streams resistant to reinvasion when acidity ameliorates and water chemistry is restored to a pre-acidification condition. This hypothesis is discussed in the light of recent trends in the chemistry and biology of the UK Acid Waters Monitoring Network sites. (c) 2005 Elsevier Ltd. All rights reserved.


Original languageEnglish
Pages (from-to)103-108
Number of pages6
JournalEnvironmental Pollution
Publication statusPublished - 1 Sep 2005


  • herbivory, community, food web, acidification, functional group