Effect of intermittency on N spatial variability in an arid Mediterranean stream

Gómez, Rosa; García, V. García; Vidal-Abarca, Rosario; Suárez, Luisa Paz Rodríguez

doi:10.1899/09-016.1

Cited by 30 publications

(16 citation statements)

References 53 publications

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“…Although NH 4 was the nutrient showing the highest spatial heterogeneity, the spatial heterogeneity of all dissolved organic and inorganic forms of N and P increased with stream fragmentation. Our results support findings from previous studies showing increased spatial heterogeneity of N availability during stream fragmentation in arid streams in Arizona (Dent and Grimm 1999) and SE Spain (Gómez et al 2009), but contradict findings by Baldwin et al (2005) who showed low spatial heterogeneity of N concentrations in isolated pools from an Australian stream.…”

Section: Spatial Heterogeneity In N and P Concentrationssupporting

confidence: 85%

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Contraction, fragmentation and expansion dynamics determine nutrient availability in a Mediterranean forest stream

Schiller

Acuña

Graeber³

et al. 2011

Aquat Sci

100

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Temporary streams are a dominant surface water type in the Mediterranean region. As a consequence of their hydrologic regime, these ecosystems contract and fragment as they dry, and expand after rewetting. Global change leads to a rapid increase in the extent of temporary streams, and more and more permanent streams are turning temporary. Consequently, there is an urgent need to better understand the effects of flow intermittency on the biogeochemistry and ecology of stream ecosystems. Our aim was to investigate how stream nutrient availability varied in relation to ecosystem contraction, fragmentation and expansion due to hydrologic drying and rewetting. We quantified the temporal and spatial changes in dissolved nitrogen (N) and phosphorus (P) concentrations along a reach of a temporary Mediterranean forest stream during an entire contraction-fragmentation-expansion hydrologic cycle. We observed marked temporal changes in N and P concentrations, in the proportion of organic and inorganic forms as well as in stoichiometric ratios, reflecting shifts in the relative importance of in-stream nutrient processing and external nutrient sources. In addition, the spatial heterogeneity of N and P concentrations and their ratios increased substantially with ecosystem fragmentation, reflecting the high relevance of in-stream processes when advective transport was lost. Overall, changes were more pronounced for N than for P. This study emphasizes the significance of flow intermittency in regulating stream nutrient availability and its implications for temporary stream management. Moreover, our results point to potential biogeochemical responses of these ecosystems in more temperate regions under future water scarcity scenarios.

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Section: Spatial Heterogeneity In N and P Concentrationssupporting

confidence: 85%

“…Moreover, results from existing studies on this subject are controversial. Some studies uncovered marked increases in the spatial heterogeneity of nutrient concentrations during stream fragmentation (Dent and Grimm 1999;Gómez et al 2009), whereas others have found no significant effects (Baldwin et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Contraction, fragmentation and expansion dynamics determine nutrient availability in a Mediterranean forest stream

Schiller

Acuña

Graeber³

et al. 2011

Aquat Sci

100

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“…Several studies have used synoptic approaches in streams in desert (Dent et al 2001), prairie (Dodds and Oakes 2008), alpine (Gardner and McGlynn 2009), and boreal (Scrimgeour and Chambers 2000;Temnerud and Bishop 2005) biomes, and the number of synoptic data sets from urban or suburban sites is growing (Claessens et al 2010;Gómez et al 2009; Sivirichi et al 2010). Although it is challenging to analyze across studies due to interregional differences in controls on water chemistry and sampling regimes (Clark et al 2000), we compared longitudinal variation in our data to studies from temperate forested watersheds that represent climatic conditions similar to the Bronx River (Asano et al 2009;Claessens et al 2010;Likens and Buso 2006;Fig.…”

Section: Longitudinal Variation Of N and P In The Bronx River Relativmentioning

confidence: 99%

Spatial variability in nutrient concentration and biofilm nutrient limitation in an urban watershed

2011

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Nutrient enrichment threatens river ecosystem health in urban watersheds, but the influence of urbanization on spatial variation in nutrient concentrations and nutrient limitation of biofilm activity are infrequently measured simultaneously. In summer 2009, we used synoptic sampling to measure spatial patterns of nitrate (NO 3 -), ammonium (NH 4 ? ), and soluble reactive phosphorus (SRP) concentration, flux, and instantaneous yield throughout the Bronx River watershed within New York City and adjacent suburbs. We also quantified biofilm response to addition of NO 3 -, phosphate (PO 4 3-), and NO 3 -? PO 4 3-on organic and inorganic surfaces in the river mainstem and tributaries. Longitudinal variation in NO 3 -was low and related to impervious surface cover across sub-watersheds, but spatial variation in NH 4 ? and SRP was higher and unrelated to sub-watershed land-use. Biofilm respiration on organic surfaces was frequently limited by PO 4 3-or NO 3 -? PO 4 3-, while primary production on organic and inorganic surfaces was nutrientlimited at just one site. Infrequent NO 3 -limitation and low spatial variability of NO 3 -throughout the watershed suggested saturation of biological N demand. For P, both higher biological demand and point-sources contributed to greater spatial variability. Finally, a comparison of our data to synoptic studies of forested, temperate watersheds showed lower spatial variation of N and P in urban watersheds. Reduced spatial variation in nutrients as a result of biological saturation may represent an overlooked effect of urbanization on watershed ecology, and may influence urban stream biota and downstream environments.

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“…Dispersion, as a measurement of temporal variability, was lower at the forest catchments than at the rest of the sites (Table VI), which probably is related to flow intermittency, and greater variation in solute inputs from disturbed landscapes (Poor and Mc Donnell, 2007;Gómez et al, 2009;Bernal et al, 2012). Differences in pH, alkalinity and conductance values can be related, in part, to human disturbance but also geology can be affecting these variables.…”

Section: Figure 4 Principal Component Analyses (Pca) Based On Stream mentioning

confidence: 96%

The effects of human land use on flow regime and water chemistry of headwater streams in the highlands of Chiapas

Castillo

Morales

Valencia

et al. 2012

Knowl. Managt. Aquatic Ecosyst.

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Key-words: stream, catchment, land use, nutrient enrichment, abstractionWe studied the effects of land use changes on flow regime and water chemistry of headwater streams in the highlands of Chiapas, a region in southern Mexico that has experienced high rates of deforestation in the last decades. Samples for water chemistry were collected and discharge was measured between September 2007 and August 2008 at eight streams that differed in the land uses of their riparian and catchment areas, including streams draining protected forested areas. Streams with high forest cover (>70%) in their catchments maintained flow through the year. Streams draining more disturbed catchments exhibited reduced or no flow for 4−6 months during the dry season. Nitrate concentrations were lower at streams draining forested catchments while highest concentrations were measured where conventional agriculture covered a high proportion of the catchment and riparian zone. Highest phosphorus concentrations occurred at the catchment where poultry manure was applied as fertilizer. Differences between forest streams and those draining disturbed areas were correlated with the proportion of forest and agriculture in the riparian zone. Variation in stream variables among sampling dates was lower at the forest sites than at the more disturbed study streams. Conversion of forest into agriculture and urban areas is affecting flow regime and increasing nutrient concentrations, although the magnitude of the impacts are influenced by the type of agricultural practices and the alteration of the riparian zone. RÉSUMÉLes effets de l'utilisation des terres sur le régime d'écoulement et la composition chimique de l'eau des ruisseaux de tête de bassin des plateaux du Chiapas Mots-clés :ruisseau, bassin versant, aménagement du territoire, Nous avons étudié l'influence des changements d'aménagement du territoire sur le régime hydrographique et la composition hydrochimique de ruisseaux des plateaux du Chiapas, une région au sud du Mexique qui a subi une déforestation de grande ampleur ces dernières décennies.

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Effect of intermittency on N spatial variability in an arid Mediterranean stream

Cited by 30 publications

References 53 publications

Contraction, fragmentation and expansion dynamics determine nutrient availability in a Mediterranean forest stream

Contraction, fragmentation and expansion dynamics determine nutrient availability in a Mediterranean forest stream

Spatial variability in nutrient concentration and biofilm nutrient limitation in an urban watershed

The effects of human land use on flow regime and water chemistry of headwater streams in the highlands of Chiapas

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