caa a22 4500 44589234X CHVBK 20180317145620.0 cr unu---uuuuu 170323e20110701xx s 000 0 eng 10.1007/s10750-011-0654-z doi (NATIONALLICENCE)springer-10.1007/s10750-011-0654-z Response of biofilm extracellular enzymes along a stream nutrient enrichment gradient in an agricultural region of north central Pennsylvania, USA [Elektronische Daten] [Steven Rier, Kevin Nawrocki, Julian Whitley] Anthropogenic nitrogen and phosphorus loading to streams has the potential to shift ecosystems from inorganic nutrient limitation toward increased carbon flux. We tested the hypothesis that relative patterns in the activities of carbon-, phosphorus- and nitrogen-acquiring extracellular enzymes associated with stream microbial communities could potentially indicate a transition from nutrient limitation to increased carbon flux. Biofilm extracellular enzyme activities (β-glucosidase, β-xylosidase, phosphatase, and leucine-aminopeptidase) were measured in 23 streams along an agricultural nutrient gradient in north central Pennsylvania. We also measured water column total nitrogen and total phosphorus along with biofilm chlorophyll a, ash free dry mass, and phosphorus concentrations. Although most absolute enzyme activities tended to be positively correlated with phosphorus concentrations, relative activities between carbon- and phosphorus-acquiring enzymes indicated a shift away from phosphorus limitation within a relatively narrow and low range of phosphorus concentrations. These results have potential implications for establishing nutrient guidelines for streams because they indicate that nutrients such as phosphorus might elicit a significant ecosystem-level response at relatively low concentrations of phosphorus before more apparent changes in community structure or biomass are observed. Springer Science+Business Media B.V., 2011 Functional indicator nationallicence Biofilm nationallicence Periphyton nationallicence Algae nationallicence Change-point analysis nationallicence Nutrients nationallicence Rier Steven Department of Biological and Allied Health Sciences, Bloomsburg University of Pennsylvania, 17815, Bloomsburg, PA, USA aut Nawrocki Kevin Department of Biological and Allied Health Sciences, Bloomsburg University of Pennsylvania, 17815, Bloomsburg, PA, USA aut Whitley Julian Department of Geography and Geosciences, Bloomsburg University of Pennsylvania, 17815, Bloomsburg, PA, USA aut Hydrobiologia Springer Netherlands 669/1(2011-07-01), 119-131 0018-8158 669:1<119 2011 669 10750 https://doi.org/10.1007/s10750-011-0654-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10750-011-0654-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Rier Steven Department of Biological and Allied Health Sciences, Bloomsburg University of Pennsylvania, 17815, Bloomsburg, PA, USA aut NATIONALLICENCE 700 1- Nawrocki Kevin Department of Biological and Allied Health Sciences, Bloomsburg University of Pennsylvania, 17815, Bloomsburg, PA, USA aut NATIONALLICENCE 700 1- Whitley Julian Department of Geography and Geosciences, Bloomsburg University of Pennsylvania, 17815, Bloomsburg, PA, USA aut NATIONALLICENCE 773 0- Hydrobiologia Springer Netherlands 669/1(2011-07-01), 119-131 0018-8158 669:1<119 2011 669 10750 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer