Urban streams across the USA: lessons learned from studies in 9 metropolitan areas Author(s): Larry R. Brown, Thomas F. Cuffney, James F. Coles, Faith Fitzpatrick, Gerard McMahon, Jeffrey Steuer, Amanda H. Bell, and Jason T. May Source: Journal of the North American Benthological Society, 28(4):1051-1069. 2009. Published By: The Society for Freshwater Science DOI: http://dx.doi.org/10.1899/08-153.1 URL: http://www.bioone.org/doi/full/10.1899/08-153.1 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. J. N. Am. Benthol. Soc., 2009, 28(4):1051–1069 ’ 2009 by The North American Benthological Society DOI: 10.1899/08-153.1 Published online: 27 October 2009 Urban streams across the USA: lessons learned from studies in 9 metropolitan areas Larry R. Brown1,5, Thomas F. Cuffney2,6, James F. Coles3,7, Faith Fitzpatrick4,8, Gerard McMahon2,9, Jeffrey Steuer4,10, 4,11 1,12 Amanda H. Bell , AND Jason T. May 1 US Geological Survey, Placer Hall, 6000 J Street, Sacramento, California 95819 USA 2 US Geological Survey, 3916 Sunset Ridge Road, Raleigh, North Carolina 27607 USA 3 US Geological Survey, 331 Commerce Way, Pembroke, New Hampshire 03275 USA 4 US Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 USA Abstract. Studies of the effects of urbanization on stream ecosystems have usually focused on single metropolitan areas. Synthesis of the results of such studies have been useful in developing general conceptual models of the effects of urbanization, but the strength of such generalizations is enhanced by applying consistent study designs and methods to multiple metropolitan areas across large geographic scales. We summarized the results from studies of the effects of urbanization on stream ecosystems in 9 metropolitan areas across the US (Boston, Massachusetts; Raleigh, North Carolina; Atlanta, Georgia; Birmingham, Alabama; Milwaukee-Green Bay, Wisconsin; Denver, Colorado; Dallas-Fort Worth, Texas; Salt Lake City, Utah; and Portland, Oregon). These studies were conducted as part of the US Geological Survey’s National Water-Quality Assessment Program and were based on a common study design and used standard sample-collection and processing methods to facilitate comparisons among study areas. All studies included evaluations of hydrology, physical habitat, water quality, and biota (algae, macroinver- tebrates, fish). Four major conclusions emerged from the studies. First, responses of hydrologic, physical- habitat, water-quality, and biotic variables to urbanization varied among metropolitan areas, except that insecticide inputs consistently increased with urbanization. Second, prior land use, primarily forest and agriculture, appeared to be the most important determinant of the response of biota to urbanization in the areas we studied. Third, little evidence was found for resistance to the effects of urbanization by macroinvertebrate assemblages, even at low levels of urbanization. Fourth, benthic macroinvertebrates have important advantages for assessing the effects of urbanization on stream ecosystems relative to algae and fishes. Overall, our results demonstrate regional differences in the effects of urbanization on stream biota and suggest additional studies to elucidate the causes of these underlying differences. Key words: urbanization, urban intensity, algae, diatoms, macroinvertebrates, fishes. Cities contain an increasing fraction of the global local scales, urbanization has been linked to changes population and have a disproportionate impact on in stream habitat (Chin 2006, Roy et al. 2003), water local, regional, and global human and environmental chemistry (Mahler et al. 2005, Gilliom et al. 2006), and systems (Grimm et al. 2008, Pickett et al. 2008). At hydrology (Poff et al. 2006, USEPA 1997). Altered physical and chemical characteristics of urban streams, in turn, can serve as stressors that affect 5 E-mail addresses: [email protected] 6 benthic algae (Coles et al. 2004, Walker and Pan 2006), [email protected] fish (Meador et al. 2005, Roy et al. 2007), and 7 [email protected] macroinvertebrates (Roy et al. 2003, Cuffney et al. 8 [email protected] 2005). 9 [email protected] Despite the large and growing body of scientific 10 [email protected] work documenting the effects of urbanization on 11 [email protected] stream ecosystems, most urban ecosystem studies 12 [email protected] have examined the relationship between urbanization 1051 1052 L. R. BROWN ET AL. [Volume 28 FIG. 1. US metropolitan areas studied. Shaded areas contain the watersheds surveyed in each study. and stream ecosystems in a single location. In their The USGS initiated a series of urban stream studies reviews, both Walsh et al. (2005b) and Wenger et al. as part of the NAWQA program (http://water.usgs. (2009) identified some consistent patterns across gov/nawqa/urban/). These studies were based on a studies from single locations. They also noted common study design, with standardized data-col- variability in the relative importance of individual lection and processing methods (Tate et al. 2005). The effects common to all locations and the importance of goal was to compare the effects of urbanization on additional effects not observed at all locations. Such stream ecosystems in 9 major US metropolitan areas variability probably is partially the result of real (MAs)—Boston, Massachusetts (BOS); Raleigh, North differences in stream processes among environmental Carolina (RAL); Atlanta, Georgia (ATL); Birmingham, settings. However, different study designs and meth- Alabama (BIR); Milwaukee-Green Bay, Wisconsin ods used by different researchers also can affect the (MGB); Denver, Colorado (DEN); Dallas-Fort Worth, results because different suites of environmental Texas (DFW); Salt Lake City, Utah (SLC); and Port- variables are measured and responses of different land, Oregon (POR) (Fig. 1, Table 1). The least groups of biota assessed. The need to better under- urbanized sites in each watershed were representative stand interactions of stressors across urban land- of the landscapes being developed in each MA. In scapes (Walsh et al. 2005b, Wenger et al. 2009) each MA, a sampling network was established along a requires measurement and analysis of similar suites gradient of urbanization intensity to characterize of environmental variables in different locations. differences in stream environmental conditions and Responses to environmental stressors differ among biota relative to urbanization. This design was a groups of biota (e.g., algae, macroinvertebrates, fish). space-for-time substitution intended to give insight Therefore, designers of large monitoring programs into the changes in streams as urbanization occurs in a have incorporated sampling of multiple taxa (e.g., US region. Environmental Protection Agency [EPA] Environmen- Our study was designed to address 3 questions: 1) tal Monitoring and Assessment Program [EMAP], How do responses of stream hydrology, geomorphol- USEPA 2002a; US Geological Survey [USGS] National ogy, and chemistry to urbanization vary based on Water-Quality Assessment [NAWQA] Program, Gurtz ecoregion, historic or present land use, or other 1993). environmental features of these MAs? 2) How do 2009] U TABLE 1. Minimum and maximum values for selected watershed characteristics, 2000 population density, mean annual precipitation (1980–1997), and level III ecoregion (Omernik 1987) for 9 metropolitan study areas in the US. Population Watershed Mean Range/ Developed Crops/ Mean annual density area watershed Forest grassland land pasture precipitation Metropolitan area Code (persons/km2) (km2) elevation (m) (%) (%) (%) (%) (cm) Level III ecoregion Boston, BOS 31–1068 46–125 31–236 16–80 0–1 1–76 2–12 123 Northeastern Coastal Massachusetts Zone Raleigh, North RAL 9–1293 5–82 89–284 1–76 0–8 3–98 0–37 119 Piedmont Carolina Atlanta, Georgia ATL 5–1198 43–146 178–350 11–71 1–11 2–85 1–33 133 Piedmont Birmingham, BIR 9–1545 5–66 162–324 3–74 0–8 3–96 1–23 147 Southwestern Alabama Appalachians Milwaukee-Green MGB 10–2174 11–100 202–273 1–23 0–2 3–99 0–87 85 Southeastern Bay, Wisconsin Wisconsin Till Plains Dallas-Fort Worth, DFW 3–1591 27–291 124–220 3–26 0–35 2–89 3–73 104 Texas Blackland Texas Prairies RBAN Denver, Colorado DEN 0–1860 4–559 1535–2024 0–9 2–92 1–90 0–63 43 High Plains Salt Lake City, SLC 14–2136 1–29 1370–2353 0–34 0–4 21–97 0–28 68 Central Basin and S Utah Range TREAMS ACROSS THE Portland, Oregon POR 1–1958 13–104 53–621 0–87 2–14 0–98 0–48 153 Willamette Valley factors, including hydrology,particular water stream quality, reach geomor- are mediated by aFalcone variety 2009). of existed in eachthe MA gradient (Tate2004). of et Study