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A large-scale field experiment across six rivers illustrates how the effects of resource enrichment are context dependent.
Bovill, William D; Downes, Barbara J; Bond, Nick R; Reich, Paul; Coleman, Rhys; Lake, P S.
Afiliação
  • Bovill WD; School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, VIC, Australia. wbovill@unimelb.edu.au.
  • Downes BJ; Department of Infrastructure Engineering, University of Melbourne, Parkville, VIC, Australia. wbovill@unimelb.edu.au.
  • Bond NR; School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, VIC, Australia.
  • Reich P; Centre for Freshwater Ecosystems, La Trobe University, Wodonga, VIC, Australia.
  • Coleman R; Victorian Department of Energy, Environment and Climate Action, Melbourne, VIC, Australia.
  • Lake PS; Melbourne Water, Docklands, VIC, Australia.
Oecologia ; 202(1): 41-54, 2023 May.
Article em En | MEDLINE | ID: mdl-37138043
ABSTRACT
Resource supplementation can increase species richness and change the faunal composition of communities, but experiments have produced variable outcomes. An often overlooked element is that species richness can only increase if new taxa can disperse to resource-rich locations and invade established, local communities. We experimentally increased a basal resource (detritus) in six rivers in south-eastern Australia by driving wooden stakes into the riverbed to increase retention of detritus. Control sites were left untreated. Sites were located in agricultural sections with mostly cleared vegetation, but with intact (uncleared) reference sites upstream to provide sources of prospective colonists. We measured channel retentiveness and sampled benthic detritus and invertebrates before and after manipulation. We tested whether greater retentiveness increased detritus densities, species richness and abundances and altered faunal composition; manipulation sites reached bio-equivalence with reference sites; new species arose from upstream reference areas; and whether outcomes were consistent across rivers. Only three rivers gained increases in detritus densities. All had low pre-existing amounts of in-stream wood compared with rivers that did not respond to treatment. Two rivers (Hughes Creek, Seven Creeks) gained higher species richness and invertebrate densities within 12 months and reached bio-equivalence with reference sites. In contrast, Turtons Creek showed species turnover through replacement of individuals. Only in Hughes Creek was there evidence of successful dispersal from the upstream reference area. The outcomes show that the effects of resource supplementation vary between rivers and suggest that pre-existing conditions (e.g. channel retentiveness) may cause these differences, providing clear evidence of context dependence.
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Texto completo: 1 Base de dados: MEDLINE Assunto principal: Rios / Invertebrados Idioma: En Ano de publicação: 2023 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Rios / Invertebrados Idioma: En Ano de publicação: 2023 Tipo de documento: Article