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Forecasting the combined effects of urbanization and climate change on stream ecosystems: from impacts to management options
Author(s) -
Nelson Kären C.,
Palmer Margaret A.,
Pizzuto James E.,
Moglen Glenn E.,
Angermeier Paul L.,
Hilderbrand Robert H.,
Dettinger Michael,
Hayhoe Katharine
Publication year - 2009
Publication title -
journal of applied ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.503
H-Index - 181
eISSN - 1365-2664
pISSN - 0021-8901
DOI - 10.1111/j.1365-2664.2008.01599.x
Subject(s) - urbanization , environmental science , climate change , impervious surface , ecosystem , watershed , surface runoff , ecology , habitat , streams , effects of global warming , baseline (sea) , hydrology (agriculture) , global warming , fishery , biology , computer network , geotechnical engineering , machine learning , computer science , engineering
Summary1 Streams collect runoff, heat, and sediment from their watersheds, making them highly vulnerable to anthropogenic disturbances such as urbanization and climate change. Forecasting the effects of these disturbances using process‐based models is critical to identifying the form and magnitude of likely impacts. Here, we integrate a new biotic model with four previously developed physical models (downscaled climate projections, stream hydrology, geomorphology, and water temperature) to predict how stream fish growth and reproduction will most probably respond to shifts in climate and urbanization over the next several decades. 2 The biotic submodel couples dynamics in fish populations and habitat suitability to predict fish assemblage composition, based on readily available biotic information (preferences for habitat, temperature, and food, and characteristics of spawning) and day‐to‐day variability in stream conditions. 3 We illustrate the model using Piedmont headwater streams in the Chesapeake Bay watershed of the USA, projecting ten scenarios: Baseline (low urbanization; no on‐going construction; and present‐day climate); one Urbanization scenario (higher impervious surface, lower forest cover, significant construction activity); four future climate change scenarios [Hadley CM3 and Parallel Climate Models under medium‐high (A2) and medium‐low (B2) emissions scenarios]; and the same four climate change scenarios plus Urbanization. 4 Urbanization alone depressed growth or reproduction of 8 of 39 species, while climate change alone depressed 22 to 29 species. Almost every recreationally important species (i.e. trouts, basses, sunfishes) and six of the ten currently most common species were predicted to be significantly stressed. The combined effect of climate change and urbanization on adult growth was sometimes large compared to the effect of either stressor alone. Thus, the model predicts considerable change in fish assemblage composition, including loss of diversity. 5 Synthesis and applications . The interaction of climate change and urban growth may entail significant reconfiguring of headwater streams, including a loss of ecosystem structure and services, which will be more costly than climate change alone. On local scales, stakeholders cannot control climate drivers but they can mitigate stream impacts via careful land use. Therefore, to conserve stream ecosystems, we recommend that proactive measures be taken to insure against species loss or severe population declines. Delays will inevitably exacerbate the impacts of both climate change and urbanization on headwater systems.