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Effects of urbanization on stream physicochemistry andmacroinvertebrate assemblages in a tropical urban watershed in

Puerto Rico

Rebeca de Jesus-Crespo1 AND Alonso Ramrez2

Institute for Tropical Ecosystem Studies, University of Puerto Rico, P.O. Box 70377,San Juan, Puerto Rico 00936 USA

Abstract. Urbanization is degrading stream ecosystems worldwide. Tropical island streams may respondto urbanization differently than temperate streams because of their overall climate differences, and theymay respond differently than continental tropical urban streams because of their reduced biologicaldiversity and short drainages. We characterized the physicochemistry, physical habitat, and macroinver-tebrate assemblages of 16 stream tributaries in the Rio Piedras Watershed (San Juan, Puerto Rico). We alsodescribed landuse patterns upstream from each sampling site for the entire subwatershed and for riparian

buffers of 5- and 100-m width. Urbanization had a negative effect on the physicochemical and biologicalcondition of the Rio Piedras. Streams were distributed in ordination space along a strong physicochemicalgradient that was related to concentrations of K+, Mg2+, dissolved O2 (DO), and PO4

32. Along this gradient,DO and Mg2+ decreased and PO4

32 and K+ increased with higher % urban cover in the subwatershed.Macroinvertebrate assemblages also were related to urbanization, and more macroinvertebrate familiesand pollution-sensitive taxa were found at sites where physicochemistry reflected less urban cover. Familyrichness and pollution-sensitive taxa were positively associated with greater % forest cover in the 5-mriparian buffer zone, a result that supports the use of riparian buffers to ameliorate the effects ofurbanization on stream biointegrity in the Rio Piedras. Our results are similar to findings in urban streamsin temperate zones and in tropical continental streams. Therefore, despite island characteristics, tropicalisland stream physicochemistry and macroinvertebrate assemblages responded to urbanization in waysthat are in general agreement with the predictions of the Urban Stream Syndrome.

Key words: urban stream ecology, tropical, macroinvertebrates, riparian buffers, land use, water

physicochemistry.

Streams are tightly connected with the terrestrialenvironment, and most activities in the watershedhave associated responses in their stream ecosystems(Roth et al. 1996, Allan et al. 1997, Meador andGoldstein 2003, Allan 2004). The River ContinuumConcept is a classic example of how interactions

between streams and watersheds are essential indetermining water physicochemistry and the struc-ture and composition of biotic communities in

streams (Vannote et al. 1980, Allan et al. 1997).Therefore, changes in landuse patterns can causedirect, and frequently negative, effects on streamecosystems (Roth et al. 1996, Allan et al. 1997, Boothet al. 2002, Roy et al. 2003, Walsh et al. 2005b).

Landuse effects can alter both downstream andupstream reaches, ultimately leading to broad-scalechanges in stream ecosystem function and services(Pringle 1997, Walsh et al. 2005b).

Urbanization is one of the most extreme types oflanduse change resulting from anthropogenic activi-ties. Urban streams undergo a series of alterations thatare relatively similar across geographic regions. Thesecommonalities led to the description of an Urban

Stream Syndrome

to characterize stream responsesto urbanization (Meyer et al. 2005, Walsh et al. 2005b).High percentages of impervious surfaces increasesurface runoff and decrease water travel time tostreams, which, in turn, increase the frequency offlash flood events and bank erosion rates. Impervioussurfaces also decrease water infiltration, lower watertables, and reduce base flow in urban streams (Walshet al. 2005b). Moreover, surface runoff in urban areascarries anthropogenic contaminants, most of which

1 Present address: Odum School of Ecology, University ofGeorgia, Athens, Georgia 30602 USA. E-mail: [email protected]

2 E-mail address: [email protected]

J. N. Am. Benthol. Soc., 2011, 30(3):739750 2011 by The North American Benthological SocietyDOI: 10.1899/10-081.1Published online: 21 June 2011

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have been implicated in stream ecosystem degrada-tion (DAdamo et al. 1997, Schueler and Holland 2000,USEPA 2003, Walsh et al. 2005b, Wenger et al. 2009).

Studies of the effects of urbanization on streamecosystems have been done mostly in temperateregions (Walsh 2000, Pompeu et al. 2005, Ramrez

et al. 2009). Exceptions include studies of rivers inBrazil (Pompeu et al. 2005, Couceiro et al. 2006,Moreno et al. 2009), Hong Kong (Dudgeon 1992,1996), Hawaii (Brasher et al. 2004), and CentralAmerica (Sanchez-Arguello et al. 2010). The informa-tion gained in these studies provides insight into theconsequences of urban impact on tropical biomes.However, generalizations from one tropical site to thenext are difficult because a great range of biologicaland climatic variability exists within the tropics(Boyero et al. 2009). Puerto Rico is an example of atropical island that has experienced rapid rates ofurbanization. Land use changed dramatically on the

island during the transition from an agriculture-basedeconomy in the early 1900s to an industry-basedeconomy around the 1940s and 1950s (Grau et al.2003). Industrialization led to rapid populationgrowth and expansion of metropolitan areas, espe-cially San Juan (Pares-Ramos et al. 2008).

Streams in Puerto Rico, like those in other Carib-bean islands, differ from temperate and continentaltropical streams in many ways. For instance, theytend to have small and steep drainages that result innaturally flashy hydrographs, and they supportrelatively reduced biodiversity (Ramrez et al. 2009).They lack the seasonal temperatures characteristic

of temperate biomes but are exposed to frequenthydrologic disturbances from storms and hurricanes.Island streams tend to have lower diversity anddensity of benthic macroinvertebrates than do conti-nental streams (Bass 2003, Brasher et al. 2004, Covich2006).

Our project is part of ongoing efforts to understandhow urbanization affects tropical streams in PuertoRico (Ramrez et al. 2009). Urbanization on PuertoRico does not result in some of the expectedalterations to stream ecosystems, at least with respectto flashiness and the loss of native fish assemblages(Ramrez et al. 2009). We focused on assessing therelationship between water physicochemistry andmacroinvertebrate assemblages and land use in thesubwatershed and riparian buffer zones. We hypoth-esized that both physicochemistry and macroinverte-

brates would be negatively affected by watershedurbanization and would respond as expected basedon results of studies from both temperate and tropicalsites (Walsh et al. 2005b, Moreno et al. 2009, Sanchez-Arguello et al. 2010). In addition, we expected streams

with more forest cover in their riparian buffers tohave greater overall stream integrity in this urbanwatershed because riparian vegetation provides avariety of ecosystem services and may buffer theimpacts of human activities on aquatic ecosystems(Lammert and Allan 1999, Groffman and Crawford

2003, USEPA 2003, Sweeney et al. 2004, Moore andPalmer 2005, Newham et al. 2010).

Methods

Study sites

We conducted our study in the Rio Piedraswatershed, which drains metropolitan San Juan, themost highly urbanized area in Puerto Rico. Averagedaily air temperatures in San Juan range from 24 to30uC (NCDC 2009). Human population on the islandhas increased 86% since 1940, and most of thepopulation is concentrated in the urban area of San

Juan and surrounding cities (Osterkamp 2001). In2000, the population of San Juan reached 434,374inhabitants, with a density of 14,600 inhabitants/km2

(US Census Bureau 2000). The 67-km2 Rio Piedraswatershed is mostly flat and coastal, but its headwa-ters are in mountainous terrain with highest eleva-tions at ,200 m asl. The large amount of urbandevelopment in the watershed results in high runoffrates, and ,72% of the rainfall becomes stream flow(Osterkamp 2001). Limited information exists onurban impacts to the Rio Piedras ecosystem, butknown sources of pollution include urban runoffand sporadic discharges of untreated wastewater, in

particular in the upper parts of the watershed(Osterkamp 2001, Ramrez et al. 2009).

Riparian zones in the Rio Piedras watershed weredescribed by Lugo et al. (2001) as diverse ecosystemsdominated by plant species tolerant to urban distur-

bances and exotic species. Vegetation consists ofgrasses near the channel margins and small trees 10to 20 m from the water. Grasses are dominated byPaspalum paniculatum and trees by introduced species,such as Albizia procera, Cecropia peltata, and Spathodeacampanulata (Lugo et al. 2001).

We used US Geological Survey (USGS) topographic

maps for San Juan and Aguas Buenas municipalities(scale 1:20,000), which cover the entire Rio Piedraswatershed, to select 16 tributaries to the Rio Piedras(Fig. 1). We identified potential sampling sites frommaps and visited each site to select accessible reaches.Final field selections were geolocated with a globalpositioning system device. At each site, we delimiteda 20-m reach of channel upstream from a roadcrossing access point. This length could be consideredshort relative to lengths used in other studies, but,

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except at channelized sites, each reach generallycontained one rifflepool sequence. Smaller reachesallowed quicker sampling and reduced safety con-cerns related to the high potential for flash floods andvandalism. We characterized reaches in terms ofwater chemistry, physical habitat, and macroinverte-

brate assemblage density and composition. We also

assessed land use in the subwatershed and riparianbuffer upstream of the study reach (see below).

Data collection

Landuse analysis.We characterized land use withinthe Rio Piedras watershed by digitizing 2004 aerialphotographs of the San Juan coastal area (4-mresolution, digital orthophotograph quadrangles) ata scale of 1:10,000. We used ArcGIS (version 9.2; ESRI,

Redlands, California) to delimit polygons and assignthem to 1 of 6 landuse categories: urban, suburban,forest, highways, pasture, and empty lots plus others(Table 1). The last category included empty lots andthe stream channel. For each sampling site, theupstream subwatershed area was determined fromDigital Elevation Models obtained from the USGSwebsite (at 30-m resolution) and the watershed tool inArcGIS software.

We determined% land use within the subwatershedand within 2 riparian buffer widths (5 m and 100 m)that extended 1000 m upstream of the sampling reach.Puerto Rican law requires a minimum buffer width of5 m between any development and a stream of anyorder (PR Law 49, 4 January 2003). However, 100-m

buffers have been suggested as optimal to maintainenvironmental services provided by riparian buffers

FIG. 1. Map of the Rio Piedras watershed and Puerto Rico (insert) showing land uses. The Rio Piedras as shown in the mapincludes the main tributaries in the basin.

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(Wenger and Fowler 2000). We selected a buffer lengthof 1000 m upstream from the sampling site based onprevious studies of effects of riparian buffers on streamcondition (Roth et al. 1996, Sponseller et al. 2001). Forexample, Sponseller et al. (2001) found that thepresence of buffers extending from 200 to 2000 mupstream affected macroinvertebrate assemblages,water temperature, and substrate size.

Water physicochemistry.We collected water sam-ples once at each site during baseflow conditions

between May and August 2006. Average dischargeduring this period in the Rio Piedras was 0.65 m3/s(USGS 2010b), which is comparable to the averagemonthly discharge recorded for the watershed overthe last 2 decades (USGS 2010a). Therefore, watersamples were representative of the water quality ofthis watershed although they were limited in scope.

We filtered samples through WhatmanH glassmicrofiber filters (GF/F, 47 mm) and stored themfrozen in new plastic bottles (250 mL) until analyzed.We determined major ion concentrations (Na+, Ca2+,NH4

+, K+, Mg2+) with an ICS-1000 Ion Chromatogra-phy System (Dionex Corporation, Sunnyvale, Califor-nia). NO32-N and PO4

32-P concentrations were

analyzed using the cadmium reduction and ascorbicacid methods, respectively (APHA 1998). All wateranalyses were conducted at the Water QualityAnalysis Laboratory, University of New Hampshire(Durham, New Hampshire). We measured dissolvedO2 (DO), pH, conductivity, and temperature in situusing a QuantaH multi-parameter instrument (Hydro-lab Corporation, Loveland, Colorado) at 3 randomly

selected locations within the 20-m reach. We estimat-ed water turbidity with a Secchi tube and canopycover with a concave densitometer by taking 3measurements of both variables at different pointsin the reach. We averaged values to characterize thestudy site.

We applied Hawaiis Visual Assessment Protocol(HSVAP; USDA 2001) to the 20-m sampling reachto assess physical habitat. The HSVAP is a rapidassessment protocol that scores stream physical

condition based on variables, such as presence oftrash, riparian vegetation, and flow alterations. Weselected this protocol because it was developed foruse on an island and it provided a rapid evaluation ofphysical alteration of the stream. Further details onhow we applied this protocol to the Rio Piedras areprovided by de Jesus-Crespo and Ramrez (2011).

Macroinvertebrate assemblages.We characterizedmacroinvertebrate assemblages by collecting semi-quantitative samples from the 4 dominant habitats:runs, margin vegetation, pools, and riffles in each20-m reach. We standardized sampling effort bylimiting it to 15 min/habitat (Maue and Springer2008). During those 15 min, 3 collectors handpickedall macroinvertebrates found in the habitat with handnets. At the end of the 15-min period, collectorsswitched to a new habitat and repeated the procedureuntil each collector had surveyed all habitats once.The proportion of each habitat within the 20-m reachwas estimated visually by the same collectors andaveraged among observers. This value was multiplied

by the number of individuals from a particular taxon

TABLE 1. Percent cover for each landuse category and the riparian buffer on the Rio Piedras watershed. The category Emptylots and others includes empty areas and open stream channel.

Stream

Landuse categories Riparian buffer

Urban Suburban Forest Highway PastureEmpty lotsand other 5 m 100 m

1 0 14 75 3 7 1 37 292 0 17 64 0 12 6 67 523 0 18 72 0 8 2 73 684 0 23 33 0 9 35 73 775 27 0 67 6 0 0 83 616 3 31 40 0 0 27 59 377 14 22 44 0 14 8 68 428 22 17 47 2 7 5 39 399 21 25 40 0 2 11 67 33

10 35 13 39 2 6 6 88 5811 38 13 37 2 6 3 60 2912 40 13 33 3 6 4 50 2213 56 11 13 11 7 1 33 1014 59 10 24 0 5 2 70 4215 62 8 12 11 6 1 47 15

16 67 6 20 0 5 2 92 64



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collected within that habitat to calculate the habitat-weighted abundance. We summed the weightedabundances of each taxon from all habitats to obtainan overall habitat-weighted value per taxon per site.This approach enabled us to use balanced compari-sons among sites that had different proportions ofstream habitats (Grubaugh et al. 1996). Macroinverte-

brate samples were preserved in 80% ethanol andidentified to family with keys in McCafferty (1998),Merritt and Cummins (1996), and our laboratoryreference collection. We characterized assemblages ateach site by determining the number of families,Simpsons diversity index, and Hilsenhoffs ModifiedFamily Biotic Index (FBI) (Hilsenhoff 1987, Barbouret al. 1999).

Statistical analyses.We used principal componentsanalysis (PCA) to explore physicochemical similaritiesamong our sampling sites. We used stepwise multipleregressions to identify which land uses were relatedto physicochemical gradients formed by major PCAaxes. We used nonmetric multidimensional scaling(NMDS) to assess similarities among streams basedon their macroinvertebrate assemblage composition.

We used linear regression to evaluate the relationbetween NMDS axes and macroinvertebrate metrics(e.g., number of families, Simpsons diversity, andFBI). In addition, multiple regressions were applied toassess relationships between NMDS axes and envi-ronmental variables (e.g., PCA axes and land uses).We ran PCA and NMDS with PC-ORD Software(McCune and Mefford 1999) and multiple regressionswith JMP (version 4.04; SAS Institute, Cary, NorthCarolina).

Results

Land use in the Rio Piedras watershed

Landuse composition of the Rio Piedras water-shed was 49% urban, 25% forest, 11% suburban, 7%empty lots and others, 4% pasture, and 3% roadsand highways. Land use within individual sub-watersheds ranged from 0 to 67% urban and from12 to 75% forest cover (Table 1). Five-meterriparian buffers had 33 to 92% forest cover and

100-m buffers had 10 to 77%

forest cover (Table 1,Fig. 1).

Water physicochemistry vs watershed land use

Two streams had HSVAP scores (,1) that indicatedhighly degraded physical conditions, whereas theremaining sites had scores indicating medium- (1.11.4) or high-quality (1.5) habitat (Table 2). Waterphysicochemistry was highly variable among streams.Some variables reached values that indicated strongdegradation. For example, DO reached 3.4 mg O2/L,PO4

32 reached 556 mg PO432-P/L, and NO3

2 reached1487 mg NO3

2-N/L (Table 2).Streams were distributed along a strong physico-

chemical gradient in ordination space (Fig. 2). PCAaxis 1 explained 36% of the variance and was relatedto concentrations of solutes (mainly K+, Mg2+, DO,and PO4

32). PCA axis 2 explained an additional 18%of the variance and was related to water tempera-ture and NO3

2 concentration. Based on the broken-stick eigenvalue method, only axes 1 and 2 wereinterpretable.

TABLE 2. Stream physicochemical characteristics, Hawaiis Visual Assessment Protocol (HSVAP), and nutrient and ionconcentrations at each study site. Physicochemical values are means of 3 measurements taken at different locations along thestudy reach. Nutrient and ion concentrations are the result of a single water sample per site.

Stream HSVAPTemperature

(uC)Conductivity

(mS/cm2) pHDO

(mg/L)% canopy

coverRiparian

width (m)Turbidity

(NTU)

1 1.4 25.4 56.3 7.4 7.7 87 5 1202 1.3 26.9 22.3 7.6 5.5 92 8 243 1.5 25.5 42.3 7.2 7.1 89 3 1004 1.6 31.8 52.7 7.0 8.2 67 20 1025 1.7 27.1 34.0 8.3 4.9 88 20 1106 1.6 25.6 42.6 7.4 6.5 83 20 777 1.7 27.6 41.0 7.8 4.5 32 20 728 1.4 26.3 35.2 8.0 5.8 51 20 359 1.7 26.9 32.6 6.3 4.7 68 17 120

10 1.3 28.8 32.1 6.7 6.5 62 10 3211 1.5 30.2 42.0 7.6 4.8 74 20 4012 1.1 26.9 45.0 7.5 4.2 75 20 5513 0.5 45.3 7.7 44 0 3214 1.3 27.4 41.1 7.7 3.4 58 20 9615 0.8 28.8 40.5 8.3 5.6 71 9 4116 1.7 27.0 44.3 7.6 5.5 88 16 120



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PCA axis 1 was negatively related to% urban cover(stepwise multiple regression, partial r2 = 0.46, p ,0.01), indicating that sites with limited urban coverhad high DO and Mg2+ and low K+ and PO4

32. Axis 2was not related to landuse variables. HSVAP scoreswere negatively related to % road cover (stepwisemultiple regression, partial r2 = 0.50, p , 0.001),indicating that sites with a high % road cover had lowscores (i.e., degraded physical conditions).

Macroinvertebrate response to land use

We found 18 families and collected 2565 individualmacroinvertebrates. The most commonly observedinsect families were Chironomidae (Diptera), Caeni-dae and Leptophlebiidae (Ephemeroptera), and Coe-nagrionidae (Odonata) (Table 3). Snails (Gastropoda)

dominated the noninsect group (Table 3). We ob-served freshwater shrimps and crabs in several of thesampling sites, but our sampling method was notappropriate to assess their densities. Simpsonsdiversity values ranged from 0 to 0.89, whereas thenumber of families ranged from 1 to 12/stream. FBIvalues ranged from 3.64 (low tolerance) to 7.99 (hightolerance). Sites with low FBI scores (indicating goodstream quality) were dominated by baetid andleptophlebid mayflies and hydroptilid caddisflies(e.g., sites 13 in Table 3). In contrast, sites with highscores (indicating poor stream quality) had few or nomayflies and high densities of larval chironomids (i.e.,sites 1416 in Table 3).

NMDS ordination of macroinvertebrate assem-blages yielded 3 major axes, and Axes 2 and 3explained most of the variation. Axis 2 formed astrong gradient, whereas differentiation along axis 3was mostly the result of 2 sites with low values(Fig. 3). NMDS axis 2 was strongly related to thenumber of macroinvertebrate families and FBIscores. Streams with positive values on NMDS axis2 had high macroinvertebrate family richness andlow FBI scores, results indicating good waterquality (Fig. 4A, B). Stepwise multiple regressions

indicated that NMDS axis 2 was related to PCA axis1 and the amount of forest cover in 5-m buffers(model R2 = 0.82; Axis 1: p = 0.03, 5-m buffer: p =0.04). Streams with positive values on NMDS axis 2had low PO4

32 and high Mg2+, DO, and % forestcover in 5-m riparian buffers. Streams with positivescores on NMDS axis 3 tended to have low FBIscores, but this relationship was not significant.Stepwise multiple regressions indicated that NMDSaxis 3 was strongly related to HSVAP scores.Streams with positive values on NMDS axis 3 hadhigh HSVAP scores, indicating good physicalhabitat in those subwatersheds.

Discussion

Our study in the Rio Piedras watershed advancesour understanding of how urbanization affects trop-ical island streams. Overall, urbanization negativelyaffected streams, resulting in clear signs of degrada-tion (e.g., high PO4

32 and K+ concentrations coupledwith low DO). Sites with low levels of urbanizationhad the highest macroinvertebrate richness and the

Na+

(mg/L)K+

(mg/L)Mg2+

(mg/L)Ca2+

(mg/L)PO4

32

(mg P/L)NO3

2

(mg N/L)

14.1 0.8 13.7 24.4 8.0 829.027.3 2.2 9.9 8.1 16.0 333.016.8 1.4 10.3 18.8 16.0 711.017.5 1.3 14.7 14.9 2.0 41.018.2 2.2 9.6 20.5 9.0 837.018.0 1.6 7.6 18.7 10.0 1114.022.9 2.4 12.4 23.2 12.0 949.016.3 2.5 7.6 16.3 6.0 840.023.1 3.6 7.2 15.4 9.0 888.019.4 2.6 9.0 18.3 31.0 708.021.6 2.7 9.0 21.3 13.0 926.022.6 2.9 8.9 25.6 52.0 628.024.6 5.0 4.6 13.6 556.0 81.024.9 2.5 9.7 21.4 102.0 1352.022.4 4.6 1.4 8.5 157.0 1125.026.7 2.1 10.3 28.2 16.0 1487.0

TABLE 2. Extended.

FIG. 2. Principal Component Analysis (PCA) of streamphysicochemistry. Axis 1 explained 36% of the variance,whereas axis 2 explained an additional 18% of the variance.Numbers refer to sites.



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most pollution-sensitive taxa. Our results also suggestthat macroinvertebrate assemblage composition wassensitive to the lack of riparian vegetation, indicatingthat the presence of vegetated buffers might mitigateurbanization impacts on stream ecosystems.

In spite of the limited scope of our water-qualityassessment, the effect of urbanization on streamphysicochemistry in the Rio Piedras agrees witheffects reported for urban streams in general. Forinstance, P concentrations increase as urbanization

increases (Carpenter et al. 1998, Johnson and Treece1998, Paul and Meyer 2001, Roy et al. 2003, Walsh

FIG. 3. Nonmetric Multidimensional Scaling (NMDS)ordination of stream macroinvertebrate assemblages. Axes2 and 3 explained most of the variation. Numbers referto sites.

FIG. 4. Regression analysis between Nonmetric Multidi-mensional Scaling (NMDS) axis 2 and the family richness(r2= 0.45, p , 0.01) (A) and Family Biotic Index (FBI) scores(r2 = 0.56, p , 0.001) (B). Numbers refer to sites.

TABLE 3. Macroinvertebrate habitat-weighted density (no./m2) in each study stream. Only taxa that were present in numbers.1% of the total abundance of macroinvertebrates are presented.

Stream

Ephemeroptera Odonata Hemiptera Trichoptera

Leptophlebiidae Baetidae Caenidae Libellulidae Coenagrionidae Veliidae Hydroptilidae Philopotamidae

1 1.12 0.19 0.19 0.00 0.00 0.00 1.30 0.00

2 7.40 1.54 1.30 0.83 1.01 0.06 0.00 0.003 4.80 4.00 0.80 0.20 0.00 6.40 66.80 0.004 0.00 13.76 5.56 1.44 0.76 0.36 0.84 4.085 5.42 3.84 1.86 0.48 0.14 2.52 0.00 0.666 0.00 0.00 30.74 0.04 3.07 6.45 0.00 0.007 3.88 3.18 5.28 0.32 2.88 1.06 0.00 0.008 0.87 2.63 2.02 0.02 0.14 0.04 0.00 0.009 0.00 0.00 0.00 0.20 0.80 0.00 0.00 0.00

10 0.54 1.75 2.74 0.06 0.81 0.39 0.00 0.0011 0.56 0.10 0.10 1.12 10.64 0.00 0.00 0.0012 0.00 0.05 0.10 0.05 0.70 0.05 0.00 0.0013 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0014 0.06 0.06 5.88 0.36 2.52 0.00 0.00 0.0015 0.00 0.00 0.00 0.15 0.15 0.00 0.00 0.0016 0.00 0.00 0.15 0.25 23.05 4.50 0.00 0.00



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et al. 2005b). Sources of P in urban areas includewastewater and fertilizers, and in some cases, suchinputs exceed those from intensely agricultural areas(Omernik 1976, Osborne and Wiley 1988, Paul andMeyer 2001). In the Rio Piedras, we have observedevidence of sewage pollution, potentially from

broken pipes or overflows after heavy rains, whichcould account for the high P. High P concentrationswere accompanied by low DO. Our measurementswere made during the day, so the low DO valuesprobably were caused by high microbial respiration

in our urban streams. K+ patterns were also inagreement with those reported for urban siteselsewhere (Paul and Meyer 2001, Schoonover et al.2005). High K+ levels in urbanized areas commonlyare linked to sources, such as lawn fertilizers, engineexhaust, and leakage from sewage pipes (Cheng et al.2008). Mg2+ increased as % urban cover decreased, apattern opposite of what was expected from previousstudies (Paul and Meyer 2001). This pattern probablyarose from watershed soil and geological character-istics (Webster and Valett 2007) and might notnecessarily reflect anthropogenic influence. HighMg2+ in less urbanized areas of the Rio Piedras could

be caused by the low cation-retention capacity of theultisols that dominate the southern and less devel-oped portion of the watershed (Lugo-Lopez et al.1973, Lathwell and Grove 1986, Davidson et al. 2004).Soil properties and characteristics, in particularriparian soils, can play an important role determin-ing nutrient dynamics in urban stream ecosystems(Pickett et al. 2001), but this role remains to beexplored in tropical urban areas.

The absence of a positive relationship between NO32

concentrations and % urban cover was unexpected.However, NO3

2 concentrations already were high inmost streams within the Rio Piedras relative to instreams in forested watersheds. The highest NO3

2

concentrations were 1 order of magnitude higher than

those reported for forested watersheds in Puerto Rico(McDowell and Asbury 1994). Authors of a recentstudy in the Rio Piedras reported low rates of NO3

2

uptake and variable rates of denitrification relative toin small streams in temperate and other tropicalregions (Potter et al. 2010). Therefore, these urbanstreams might be exporting N to coastal ecosystems,including the San Juan Bay Estuary, part of the USEnvironmental Protection Agencys National EstuaryProgram (USEPA 2009).

Macroinvertebrate assemblages in the Rio Piedraswere similar to those reported for natural streams inPuerto Rico. Forested streams within El Yunque

National Forest are dominated by leptophlebidmayflies, caddisflies from the families Hydropsychi-dae and Hydroptilidae and dipterans, mostly Chir-onomidae (Ramrez and Hernandez-Cruz 2004).Those groups also were present in variable densitiesin the Rio Piedras. Macroinvertebrate assemblages inthe Rio Piedras had a lower diversity of sensitivetaxa, in particular Trichoptera and Diptera, thanassemblages in forested streams. For example, wefound only 2 of the 10 Trichoptera families reportedfor Puerto Rico (Flint 1992). The Rio Piedras also hada larger component of noninsect taxa, in particularsnails, which are more abundant at low elevations in

Puerto Rico (AR, unpublished data).Macroinvertebrates in the Rio Piedras appear to

be resistant to urban effects. In general, macroin-vertebrate assemblages in urban streams show signsof degradation at a critical point ,,20% urbancover (Wang et al. 1997, Roy et al. 2003, Cuffney etal. 2010). However, the Rio Piedras, supports highdiversity and family richness and sensitive families(e.g., Elmidae and Baetidae) at levels of develop-ment as high as 40% urban + suburban cover. Ourresults suggest that the stream biota in this systemcan withstand higher levels of disturbance, but weargue that this pattern is partly the result of ourlevel of identification (i.e., family) and partly

because of the presence of riparian vegetation andhigh benthic habitat diversity (i.e., most sites hadrifflepool sequences). Even so, macroinvertebratemetrics indicated a decrease in stream conditionwith increasing urbanization. The FBI performedwell in this tropical watershed, even though it wasdesigned for assessment of temperate regionstreams (Hilsenhoff 1987). FBI scores consistently

Coleoptera Diptera Gastropoda

Elmidae Chironomidae Simuliidae Snails

0.39 1.41 3.90 0.19

0.23 0.71 0.00 3.773.00 0.00 3.40 0.000.00 1.80 0.72 0.000.20 2.98 0.00 4.700.00 0.04 0.00 0.390.58 3.36 0.00 1.462.55 1.70 0.00 3.530.00 0.00 0.00 87.160.00 1.97 0.00 15.200.00 0.00 0.00 14.480.00 6.81 0.00 1.410.00 36.00 0.00 0.000.00 5.88 0.00 23.900.00 225.15 0.00 0.450.25 4.50 0.00 6.75

TABLE 3. Extended.



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indicated poor stream conditions in highly urban-ized reaches and better conditions in streams withhigh HSVAP scores (i.e., sites with good physical-habitat conditions). In addition to biotic indices, wefound that taxa considered tolerant (e.g., Chirono-midae) or sensitive (e.g., Ephemeroptera) were good

indicators of environmental conditions in the RioPiedras. This result is consistent with those ofprevious studies (Morse et al. 2003, Roy et al. 2003,Walsh et al. 2005a, b, Baptista et al. 2007) andsupports our expectation that macroinvertebratesrespond to urban effects in tropical island streams inthe same manner observed in temperate andcontinental tropical streams. Our results providefurther support for the use of macroinvertebrates inthe assessment of stream condition in tropicalwatersheds (Fenoglio et al. 2002, Prat et al. 2009).In addition, our study highlights the importance ofhabitat management for maintaining good stream

conditions, especially at sites exposed to high levelsof urban impact.

The ability of riparian vegetation to buffer land-use effects on stream ecosystems is well established(Wenger and Fowler 2000). In the Rio Piedras,riparian vegetation appears to ameliorate someof the negative effects of urbanization on streamintegrity, a result that supports our hypothesis andagrees with results of studies from temperateregions (Lammert and Allan 1999, Groffman andCrawford 2003, USEPA 2003, Sweeney et al. 2004,Moore and Palmer 2005) and other tropical streamswhere water pollution was lower in urban sites with

high riparian vegetation cover (Newham et al.2010). However, riparian buffers in urban areasare commonly bypassed by structures that reducetheir ability to buffer urban impacts. For example,Snyder et al. (2003) and Roy et al. (2006) found norelationship between the presence of riparian

buffers and stream condition in the Opequon Creekwatershed, West Virginia, and north-central Geor-gia, respectively. Riparian vegetation alone cannotprovide adequate protection in urban watersheds,especially when discharge structures deliver stormrunoff directly to streams. Some streams in the RioPiedras have degraded riparian areas that have

been landscaped for visual appeal or have drainagepipes that bypass the riparian area and dischargecontaminants directly into streams. Our studyhighlights the potential of these practices to de-grade stream ecosystems because riparian coverhelps to maintain biointegrity in the Rio Piedras.Our results also show the importance of effectivepolicy implementation with regard to riparian-zonemanagement in Puerto Rico. The currently estab-

lished regulations in the island (i.e., PR Law 49, 4January 2003) appear to provide minimal protec-tion. Our analysis of 100-m buffers did not indicatethat they affected stream variables, but these larger

buffers probably have less continuity and morebypass structures than the smaller buffers required

by law. Overall, urban streams would be betterprotected by a combination of more riparian buffersand fewer runoff structures that discharge directlyto streams.

In general, patterns observed in the Rio Piedras arein agreement with symptoms of the Urban StreamSyndrome in other tropical and temperate urbanstreams. Our results highlight the importance ofimplementing riparian protection laws and betterplanning and watershed management techniques forthe conservation of aquatic ecosystems on the island.The similarities observed between the Rio Piedrasand temperate streams suggest that comprehensive

watershed management schemes developed in tem-perate regions could be implemented effectively indeveloping cities in Puerto Rico and other islandcountries in the Caribbean region.

Acknowledgements

Our study design and the resulting manuscriptwere greatly improved by comments from N. Brokaw,C. Colon-Gaud, J. Kominoski, T. Moulton, J. R. Ortiz-Zayas, G. Small, J. Thomlinson, and an anonymousreferee. We thank W. H. McDowell for analyzingwater samples and for providing input on their

interpretation. Aurelio Castro and Coralys Ortizprovided great help with our landuse analysis.Support for this research was obtained from theLuquillo Long-Term Ecological Research program,the Center for Applied Tropical Ecology and Conser-vation (CATEC) at the University of Puerto Rico, andUS Forest Service International Institute of TropicalForestry.

Literature Cited

ALLAN, J. D. 2004. Landscapes and riverscapes: the influenceof land use on stream ecosystems. Annual Review ofEcology, Evolution, and Systematics 35:257284.

ALLAN, J. D., D. L. ERICKSON, AND J. FAY. 1997. The influence ofcatchment land use on stream integrity across multiplespatial scales. Freshwater Biology 37:149161.

APHA (AMERICAN PUBLIC HEALTH ASSOCIATION). 1998. Stan-dard methods for the examination of water andwastewater. 20th edition. American Public HealthAssociation, Washington, DC.

BAPTISTA, D., D. BUSS, M. EGLER, A. GIOVANELLI, M. SILVEIRA,AND J. NESSIMIAN. 2007. A multimetric index based onbenthic macroinvertebrates for evaluation of Atlantic



10/13

Forest streams at Rio de Janeiro State, Brazil. Hydro-biologia 575:8394.

BARBOUR, M. T., J. GERRITSEN, B. D. SNYDER, AND J. B. STRIBLING.1999. Rapid bioassessment protocols for use in streamsand wadeable rivers: periphyton, benthic macroinver-tebrates and fish. 2nd edition. EPA 841-B-99-002. Officeof Water, US Environmental Protection Agency, Wash-

ington, DC.BASS, D. 2003. A comparison of freshwater macroinverte-

brate communities on small Caribbean islands. BioSci-ence 53:10941100.

BOOTH, D. B., D. HARTLEY, AND R. JACKSON. 2002. Forest cover,impervious surface area and the mitigation of storm-water impacts. Journal of American Resources Associ-ation 38:835845.

BOYERO, L., A. RAMIREZ, D. DUDGEON, AND R. G. PEARSON. 2009.Are tropical streams really different? Journal of theNorth American Benthological Society 28:397403.

BRASHER, A. M. D., R. H. WOLFF, AND C. D. LUTON. 2004.Associations among land use, habitat characteristics,and invertebrate community structure in nine streams

on the Island of Oahu, Hawaii, 19992001. Water-Resources Investigations Report 03-4256. US GeologicalSurvey, Reston, Virginia.

CARPENTER, S. R., N. F. CARACO, D . L . CORRELL, R. W.HOWARTH, A . N . SHARPLEY, AND V. H. SMITH. 1998.Nonpoint pollution of surface waters with phosphorusand nitrogen. Ecological Applications 8:559568.

CHENG, Z., D. RICHMOND, S. O. SALMINEN, AND P. GREWAL. 2008.Ecology of urban lawns under three common manage-ment programs. Urban Ecosystems 11:177195.

COUCEIRO, S. R. M., B. R. FORSBERG, N. HAMADA, AND R. L. M.FERREIRA. 2006. Effects of an oil spill and discharge ofdomestic sewage on the insect fauna of Cururu stream,Manaus, AM, Brazil. Brazilian Journal of Biology 66:3544.

COVICH, A. P. 2006. Dispersal limited biodiversity of tropicalinsular streams. Polish Journal of Ecology 54:523547.

CUFFNEY, T. F., R. A. BRIGHTBILL, J. T. MAY, AND I. R. WAITE.2010. Responses of benthic macroinvertebrates toenvironmental changes associated with urbanization innine metropolitan areas. Ecological Applications 20:13841401.

DADAMO, R., S. PELOSI, P. TROTTA, AND G. SANSONE. 1997.Bioaccumulation and biomagnification of polycyclicaromatic hydrocarbons in aquatic organisms. MarineChemistry 56:4549.

DAVIDSON, E. A., C. NEILL, A. V. KRUSCHE, V. V. R. BALLESTER,D. MARKEWITZ, AND R. D. O. FIGUEIREDO. 2004. Loss ofnutrients from terrestrial ecosystems to streams and the

atmosphere following land use change in Amazonia.Ecosystem and Land Use Change, Geophysical Mono-graph Series 153:147158.

DE JESUS-CRESPO R., AND A. RAMIREZ. 2011. The use of a streamvisual assessment protocol to determine ecosystemintegrity in an urban watershed in Puerto Rico. Physicsand Chemistry of the Earth (in press).

DUDGEON, D. 1992. Endangered ecosystems: a review of theconservation status of tropical Asian rivers. Hydrobio-logia 248:167191.

DUDGEON, D. 1996. Anthropogenic influences on Hong Kongstreams. GeoJournal 40:5361.

FENOGLIO, S., B. BADINO, AND F. BONA. 2002. Benthic macro-invertebrate communities as indicators of river envi-ronment quality: an experience in Nicaragua. Revista deBiologia Tropical 50:11251131.

FLINT, O. S. 1992. New species of caddisflies from Puerto

Rico (Trichoptera). Proceedings of the EntomologicalSociety of Washington 94:379389.

GRAU, H. R., T. M. AIDE, J. K. ZIMMERMAN, J. R. THOMLINSON, E.H. HELMER, AND X. ZOU. 2003. The ecological conse-quences of socioeconomic and land-use changes inpostagriculture Puerto Rico. BioScience 53:11591168.

GROFFMAN, P. M., AND M. K. CRAWFORD. 2003. Denitrificationpotential in urban riparian zones. Journal of Environ-mental Quality 32:11441149.

GRUBAUGH, J. W., J. B. WALLACE, AND E. S. HOUSTON. 1996.Longitudinal changes of macroinvertebrate communi-ties along an Appalachian stream continuum. CanadianJournal of Fisheries and Aquatic Sciences 53:896909.

HILSENHOFF, W. L. 1987. An improved biotic index of organic

stream pollution. Great Lakes Entomologist 20:3139.JOHNSON, G. C., AND M. W. TREECE. 1998. Phosphorus in

streams of the Upper Tennessee River Basin, 197093.Open-File Report 98-532. US Geological Survey, Reston,Virginia.

LAMMERT, M., AND J. D. ALLAN. 1999. Assessing bioticintegrity of streams: effects of scale in measuring theinfluence of land use/cover and habitat structure onfish and macroinvertebrates. Environmental Manage-ment 23:257270.

LATHWELL, D. J., AND T. L. GROVE. 1986. Soil plant relation-ships in the tropics. Annual Review of EcologicalSystems 17:116.

LUGO, S., B. BRYAN, L. REYES, AND A. LUGO. 2001. Riparian

vegetation of a subtropical urban river. Acta Cientifica15:5972.

LUGO-LOPEZ, M. A., L. J. BARTELLI, AND F. ABRUNA. 1973. Anoverview of the soils of Puerto Rico: classification andphysical, chemical and mineralogical properties. Publi-cation no. 79. College of Agricultural Sciences, Univer-sity of Puerto Rico, Mayaguez Campus, Rio Piedras,Puerto Rico. (Available from: http://136.145.83.33:8000/jspui/)

MAUE, T., AND M. SPRINGER. 2008. Effect of methodology andsampling time on the taxa richness of aquatic macroin-vertebrates and subsequent changes in the water qualityindex from three tropical rivers, Costa Rica. Revista deBiologia Tropical 56:257271.

MCCAFFERTY, W. P. 1998. Aquatic entomology. Jones andBartlett Publishers, Sudbury, Massachusetts.

MCCUNE, B., AND M. J. MEFFORD. 1999. PC-ORD multivariateanalysis of ecological data. Version 4. MjM SoftwareDesign, Gleneden Beach, Oregon.

MCDOWELL, W. H., AND C. E. ASBURY. 1994. Export of carbon,nitrogen, and major ions from 3 tropical montanewatersheds. Limnology and Oceanography 39:111125.

MEADOR, M. R., AND R. M. GOLDSTEIN. 2003. Assessing waterquality at large geographic scales: relations among land



11/13

use, water physicochemistry, riparian condition, andfish community structure. Environmental Management31:504517.

MERRITT, R. W., AND K. W . CUMMINS (EDITORS). 1996. Anintroduction to the aquatic insects of North America. 3rd

edition. Kendall/Hunt, Dubuque, Iowa.

MEYER, J. L., M. J. PAUL, AND W. K. TAULBEE. 2005. Stream

ecosystem function in urbanizing landscapes. Journal ofthe North American Benthological Society 24:602612.

MOORE, A. A., AND M. A. PALMER. 2005. Invertebratebiodiversity in agricultural and urban headwaterstreams: implications for conservation and manage-ment. Ecological Applications 15:11691177.

MORENO, P., J. S. FRANCA, W. R. FERREIRA, A. D. PAZ, I. M.MONTEIRO, AND M. CALLISTO. 2009. Use of the BEASTmodel for biomonitoring water quality in a neotropicalbasin. Hydrobiologia 630:231242.

MORSE, C. C., A. D. HURYN, AND C. CRONAN. 2003. Impervioussurface area as a predictor of the effects of urbanizationon stream insect communities in Maine USA. Environ-mental Monitoring and Assessment 89:95127.

NCDC (NATIONAL CLIMATIC DATA CENTER). 2009. Normal dailymean temperatures. National Oceanographic and Atmo-spheric Administration, Washington, DC. (Available athttp://lwf.ncdc.noaa.gov/oa/climate/online/ccd/meantemp.html)

NEWHAM, M. J., C. S. FELLOWS, AND F. SHELDON. 2010.Functions of riparian forest in urban catchments: a casestudy from sub-tropical Brisbane, Australia. UrbanEcosystems. doi: 10.1007/s11252-010-0151-6

OMERNIK, J. M. 1976. The influence of land use on streamnutrient levels. EPA-600/276-014. US EnvironmentalProtection Agency, Washington, DC.

OSBORNE, L. L., AND M. J. WILEY. 1988. Empirical relationships

between land use/cover and stream water quality in anagricultural watershed. Journal of Environmental Man-agement 26:927.

OSTERKAMP, W. R. 2001. Earth surface processes, materials use,and urban development: A case study of the San Juanmetropolitan area, northeastern Puerto Rico. Water Re-sources Division, US Geological Survey, Tucson, Arizona.

PARES-RAMOS, I . K. , W. A. GOULD, AND T. M. AIDE. 2008.Agricultural abandonment, suburban growth, andforest expansion in Puerto Rico between 1991 and2000. Ecology and Society 13:1.

PAUL, M., AND J . L. MEYER. 2001. Streams in the urbanlandscape. Annual Review of Ecology and Systematics32:333365.

PICKETT, S. T. A., M. L. CADENASSO, J. M. GROVE, C. H. NILON,R. V. POUYAT, W. C. ZIPPERER, AND R. COSTANZA. 2001.Urban ecological systems: linking terrestrial ecological,physical, and socioeconomic components of metropol-itan areas. Annual Review of Ecology and Systematics32:127157.

POMPEU, P. S., C. BERNARDO, M. ALVES, AND M. CALLISTO. 2005.The effects of urbanization on biodiversity and waterquality in the Rio das Velhas Basin, Brazil. AmericanFisheries Society Symposium 47:1122.

POTTER, J. D., W. H. MCDOWELL, J. L. MERRIAM, B. J. PETERSON,AND S. M. THOMAS. 2010. Denitrification and total nitrateuptake in streams of a tropical landscape. EcologicalApplications 2:21042115.

PRAT, N., B. RIOS, R. ACOSTA, AND M. RIERADEVALL. 2009. Losmacroinvertebrados como indicadores de calidad de lasaguas. Pages 631654 in E. Domnguez and H. R.

Fernandez (editors). Macroinvertebrados bentonicossudamericanos. Sistematica y biologa. Fundacion Mi-guel Lillo, Tucuman, Argentina.

PRINGLE, C. M. 1997. Exploring how disturbance is transmit-ted upstream: going against the flow. Journal of theNorth American Benthological Society 16:425438.

RAMIREZ, A., R. DE JESUS-CRESPO, D. M. MARTINO-CARDONA, N.MARTINEZ-RIVERA, AND S. BURGOS-CARABALLO. 2009. Urbanstreams in Puerto Rico: what can we learn from thetropics? Journal of the North American BenthologicalSociety 28:10701079.

RAMIREZ, A., AND L. R. HERNANDEZ-CRUZ. 2004. Aquatic insectassemblages in shrimp-dominated tropical streams,Puerto Rico. Biotropica 36:259266.

ROTH, N. E., J. D. ALLAN, AND D. L. ERICKSON. 1996. Landscapeinfluences on stream biotic integrity assessed at multi-ple spatial scales. Landscape Ecology 11:141156.

ROY, A. H., M. C. FREEMAN, B. J. FREEMAN, S. J. WENGER, J. L.MEYER, AND W. E. ENSIGN. 2006. Importance of riparianforests in urban catchments contingent on sediment andhydrologic regimes. Environmental Management 37:523539.

ROY, A. H., A. D. ROSEMOND, M. J. PAUL, D. S. LEIGH, AND J. B.WALLACE. 2003. Stream macroinvertebrate response tocatchment urbanization (Georgia, U.S.A.). FreshwaterBiology 48:329346.

SANCHEZ-ARGUELLO, R., A. CORNEJO, R. G. PEARSON, AND L.BOYERO. 2010. Spatial and temporal variation of stream

communities in a human-affected tropical watershed.Annales de LimnologieInternational Journal of Lim-nology 46:149156.

SCHOONOVER, J. E., B. G. LOCKABY, AND S. PAN. 2005. Changesin chemical and physical properties of stream wateracross an urbanrural gradient in western Georgia.Urban Ecosystems 8:107124.

SCHUELER, T. R., AND H. K. HOLLAND. 2000. The practice ofwatershed protection. Center for Watershed Protection,Ellicott City, Maryland.

SNYDER, C. D., J. A. YOUNG, R. VILLELLA, AND D. P. LEMARIE.2003. Influences of upland and riparian land usepatterns on stream biotic integrity. Landscape Ecology18:647664.

SPONSELLER, R. A., E. F. BENFIELD, AND H. M. VALETT. 2001.Relationships between land use spatial scale and streammacroinvertebrate communities. Freshwater Biology 46:14091424.

SWEENEY, B. W., T. L. BOTT, J. K. JACKSON, L. A. KAPLAN, J. D.NEWBOLD, L . J . STANDLEY, W . C . HESSION, AND R. J.HORWITZ. 2004. Riparian deforestation, stream narrow-ing, and loss of stream ecosystem services. Proceedingsof the National Academy of Sciences of the UnitedStates of America 101:1413214137.



12/13

US CENSUS BUREAU. 2000. Census data for Puerto Rico 2000.US Census Bureau, Department of the Interior, Wash-ington, DC. (Available from: http://www.census.gov/census2000/states/pr.html)

USDA (US DEPARTMENT OF AGRICULTURE). 2001. Hawaii streamvisual assessment protocol. Version 1.0. Natural ResourceConservation Service, US Department of Agriculture,

Washington, DC.USEPA (US ENVIRONMENTAL PROTECTION AGENCY). 2003.

Watershed protection research monograph. No. 1: Impactsof impervious surfaces on aquatic systems. Center forWatershed Protection, Office of Wastewater Management,US Environmental Protection Agency, Washington, DC.

USEPA (US ENVIRONMENTAL PROTECTION AGENCY). 2009.National estuary program: San Juan Bay. US Environ-mental Protection Agency, Washington, DC. (Availablefrom: http://www.epa.gov/nep/programs/sjb.html)

USGS (US GEOLOGICAL SURVEY). 2010a. Surface-water month-ly statistics for Puerto Rico: calculation period: 1990-10-01 2008-09-27. US Geological Survey, Reston, Virginia.(Available from: http://waterdata.usgs.gov/pr/nwis/

monthly/)USGS (US GEOLOGICAL SURVEY). 2010b. Surface-water month-

ly statistics for Puerto Rico: calculation period: 2006-05-01 to 2006-07-27. US Geological Survey, Reston, Virgin-ia. (Available from: http://waterdata.usgs.gov/pr/nwis/monthly/)

VANNOTE, R. L., G. W. MINSHALL, K. W. CUMMINS, J. R. SEDELL,AND C. E. CUSHING. 1980. The river continuum concept.Canadian Journal of Fisheries and Aquatic Sciences 37:130137.

WALSH, C. J. 2000. Urban impacts on the ecology of receivingwaters: a framework for assessment, conservation andrestoration. Hydrobiologia 431:107114.

WALSH, C. J., T. D. FLETCHER, AND A. R. LADSON. 2005a. Streamrestoration in urban catchments through redesigningstormwater systems: looking to the catchment to savethe stream. Journal of the North American BenthologicalSociety 24:690705.

WALSH, C. J., A. H. ROY, J. W. FEMINELLA, P. D. COTTINGHAM, P.M. GROFFMAN, AND R. P. MORGAN. 2005b. The urban

stream syndrome: current knowledge and the search fora cure. Journal of the North American BenthologicalSociety 24:706723.

WANG, L., J. LYONS, P. KANEHL, AND R. GATTI. 1997. Influ-ences of watershed land use on habitat quality andbiotic integri ty in Wisconsin streams. Fisheri es 22(6):612.

WEBSTER, J. R., AND H. M. VALETT. 2007. Solute dynamics.Pages 169187 in F. R. Hauer and G. A. Lamberti(editors). Methods in stream ecology. 2nd edition.Elsevier Academic Press, Burlington, Massachusetts.

WENGER, S. J., AND L. FOWLER. 2000. Protecting stream andriver corridors: creating effective local riparian bufferordinances. Carl Vinson Institute of Government, The

University of Georgia, Athens, Georgia. (Availablefrom: http://www.rivercenter.uga.edu/publications/pdf/riparian_buffer_guidebook.pdf)

WENGER, S. J., A. H. ROY, C. R. JACKSON, E. S. BERNHARDT, T. L.CARTER, S . FILOSO, C. A. GIBSON, W. C. HESSION, S. S.KAUSHAL, E. MARTI, J. L. MEYER, M. A. PALMER, M. J. PAUL,A . H . PURCELL, A . RAMIREZ, A . D . ROSEMOND, K. A .SCHOFIELD, E. B. SUDDUTH, AND C. J. WALSH. 2009. Twenty-six key research questions in urban stream ecology: anassessment of the state of the science. Journal of theNorth American Benthological Society 28:10801098.

Received: 7 June 2010Accepted: 7 April 2011



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