Start at zero: succession of benthic invertebrate assemblages in restored former sewage channels
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We analysed the development of benthic invertebrate assemblages in restored urban streams in Germany. Prior to restoration these streams were open sewers and not inhabited by benthic invertebrates except Oligochaeta. Therefore, almost all taxa recolonised the streams after restoration. Restoration included the improvement of the water quality and the hydro-morphology. Following stream restoration, benthic invertebrate assemblages are supposed to undergo a distinct succession, as new habitats have been generated. These processes are poorly understood in streams. Our study revealed succession patterns and processes of benthic invertebrate assemblages in restored streams formerly transporting sewage, with pioneer taxa being dominant in the first years and a gradual assemblage maturation. We sampled 13 sites in seven restored streams in the springs of 2012 and 2013. Seven of these sites are connected to near-natural sections, whereas six sites lack this connection. The 13 sites differ in time since restoration and were sampled between one and 20 years after restoration. Additionally, we sampled 21 near-natural sites within the catchment and 11 near-natural sites in neighbouring catchments as potential recolonisation sources. Within 1 year, the restored sites underwent succession, which led to a higher resemblance of their assemblages to those of source sites. Derived from change values and non-metric multidimensional scaling, assemblages of young restored sites changed more than assemblages of old ones. In the first years after restoration we found assemblages with high abundances of pioneer taxa, while 5 years after restoration assemblages were increasingly similar to those of the source sites and mature assemblages were observed a decade after restoration. The succession towards near-natural assemblages is influenced by the instream habitats, catchment conditions and the recolonisation sources in the surroundings. Our findings reveal that monitoring results obtained fewer than 10 years after restoration will still be influenced by ongoing succession.
KeywordsConnectivity Emscher catchment Recolonisation Urban land use Urban streams
We thank Martin Sondermann for helping with calculating the land use patterns. The Emschergenossenschaft/Lippeverband (Essen) we thank for help with logistics and for providing data on the study streams. This study was financed by the project KuLaRuhr as part of the German Federal Ministry of Education and Research programme ‘Sustainable land use’ (BMBF, project number: 033L020A, http://www.kularuhr.de).
- ADV (Arbeitsgemeinschaft der Vermessungsverwaltungen der Länder der Bundesrepublik Deutschland) (2008) ATKIS-Objektartenkatalog Basis-DLM. NRW-Erfassung. Dokumentation zur Modellierung der Geoinformationen des amtlichen Vermessungswesens. ATKIS-Katalogwerke. Version 6.0. State: 11.04.2008Google Scholar
- Benjamini Y, Hochberg Y (1995) Controlling the false discovery rate: a practical and powerful approach to multiple testing. J R Stat Soc 57:289–300Google Scholar
- EGLV (Emschergenossenschaft/Lippeverband) (2014) Generationenprojekt für eine Region mit Zukunft. Available at: http://www.eglv.de/wasserportal/emscher-umbau.html. Accessed 27 Feb 2014
- Haase P, Sundermann A, Schindehütte K (2011) Operationelle Taxaliste als Mindestanforderung an die Bestimmung von Makrozoobenthosproben aus Fließgewässern zur Umsetzung der EU-Wasserrahmenrichtlinie in Deutschland. Available at: http://www.fliessgewaesserbewertung.de/downloads/Operationelle_Taxaliste_Mai2011.zip. Accessed 12 Dec 2013
- Narf RP (1985) Aquatic insect colonization and substrate changes in a relocated stream segment. Gt Lakes Entomol 18:83–92Google Scholar
- Nijboer RC, Schmidt-Kloiber A (2004) The effect of excluding taxa with low abundances or taxa with small distribution ranges on ecological assessment. Hydrobiologia 516:349–366Google Scholar