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Urbanisation affects ecosystem functioning more than structure in tropical streams

Wiederkehr, Fabienne and Wilkinson, Clare L and Zeng, Yiwen and Yeo, Darren CJ and Ewers, Robert M and O'Gorman, Eoin J (2020) 'Urbanisation affects ecosystem functioning more than structure in tropical streams.' Biological Conservation, 249. ISSN 0006-3207

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Abstract

Urbanisation poses a clear threat to tropical freshwater streams, yet fundamental knowledge gaps hinder our ability to effectively conserve stream biodiversity and preserve ecosystem functioning. Here, we studied the impact of urbanisation on structural and functional ecosystem responses in low-order streams in Singapore, a tropical city with a mosaic landscape of protected natural forests, managed buffer zones (between forest and open-country habitats), and built-up urban areas. We quantified an urbanisation gradient based on landscape, in-stream, and riparian conditions, and found an association between urbanisation and pollution-tolerant macroinvertebrates (e.g. freshwater snail and worm species) in litter bags. We also found greater macroinvertebrate abundance (mean individuals bag−1; forest: 30.3, buffer: 70.1, urban: 109.0) and richness (mean taxa bag−1; forest: 4.53, buffer: 4.75, urban: 7.50) in urban streams, but similar diversity across habitats. Higher levels of primary productivity (measured from algal accrual on ceramic tiles) and microbial decomposition (measured from litter-mass loss in mesh bags) at urban sites indicate rapid microbial activity at higher light, temperature, and nutrient levels. We found that urbanisation affected function 32% more than structure in the studied tropical streams, likely driven by greater algal growth in urban streams. These changes in ecological processes (i.e. ecosystem functioning) possibly lead to a loss of ecosystem services, which would negatively affect ecology, society, and economy. Our results point to possible management strategies (e.g. increasing vegetation density through buffer park creation) to reduce the impacts of urbanisation, restore vital ecosystem functions in tropical streams, and create habitat niches for native species.

Item Type: Article
Uncontrolled Keywords: Anthropogenic stressors, Bacteriochlorophyll, Chlorophyll, Riparian, Stream health, Urban stream syndrome
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Elements
Date Deposited: 20 Aug 2020 08:47
Last Modified: 20 Aug 2020 08:47
URI: http://repository.essex.ac.uk/id/eprint/28528

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