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1. Global patterns and controls of nutrient immobilization on decomposing cellulose in riverine ecosystems

Author

Costello, D. M. (David M.), Tiegs, S. D. (Scott D.), Boyero, L. (Luz), Canhoto, C. (Cristina), Capps, K. A. (Krista A.), Danger, M. (Michael), Frost, P. C. (Paul C.), Gessner, M. O. (Mark O.), Griffiths, N. A. (Natalie A.), Halvorson, H. M. (Halvor M.), Kuehn, K. A. (Kevin A.), Marcarelli, A. M. (Amy M.), Royer, T. V. (Todd, V), Mathie, D. M. (Devan M.), Albarino, R. J. (Ricardo J.), Arango, C. P. (Clay P.), Aroviita, J. (Jukka), Baxter, C. V. (Colden, V), Bellinger, B. J. (Brent J.), Bruder, A. (Andreas), Burdon, F. J. (Francis J.), Callisto, M. (Marcos), Camacho, A. (Antonio), Colas, F. (Fanny), Cornut, J. (Julien), Crespo-Perez, V. (Veronica), Cross, W. F. (Wyatt F.), Derry, A. M. (Alison M.), Douglas, M. M. (Michael M.), Elosegi, A. (Arturo), Eyto, E. (Elvira), Ferreira, V. (Veronica), Ferriol, C. (Carmen), Fleituch, T. (Tadeusz), Shah, J. J. (Jennifer J. Follstad), Frainer, A. (Andre), Garcia, E. A. (Erica A.), Garcia, L. (Liliana), Garcia, P. E. (Pavel E.), Giling, D. P. (Darren P.), Gonzales-Pomar, R. K. (R. Karina), Graca, M. A. (Manuel A. S.), Grossart, H.-P. (Hans-Peter), Guerold, F. (Francois), Hepp, L. U. (Luiz U.), Higgins, S. N. (Scott N.), Hishi, T. (Takuo), Iniguez-Armijos, C. (Carlos), Iwata, T. (Tomoya), Kirkwood, A. E. (Andrea E.), Koning, A. A. (Aaron A.), Kosten, S. (Sarian), Laudon, H. (Hjalmar), Leavitt, P. R. (Peter R.), Lemes da Silva, A. L. (Aurea L.), Leroux, S. J. (Shawn J.), LeRoy, C. J. (Carri J.), Lisi, P. J. (Peter J.), Masese, F. O. (Frank O.), McIntyre, P. B. (Peter B.), McKie, B. G. (Brendan G.), Medeiros, A. O. (Adriana O.), Milisa, M. (Marko), Miyake, Y. (Yo), Mooney, R. J. (Robert J.), Muotka, T. (Timo), Nimptsch, J. (Jorge), Paavola, R. (Riku), Pardo, I. (Isabel), Parnikoza, I. Y. (Ivan Y.), Patrick, C. J. (Christopher J.), Peeters, E. T. (Edwin T. H. M.), Pozo, J. (Jesus), Reid, B. (Brian), Richardson, J. S. (John S.), Rincon, J. (Jose), Risnoveanu, G. (Geta), Robinson, C. T. (Christopher T.), Santamans, A. C. (Anna C.), Simiyu, G. M. (Gelas M.), Skuja, A. (Agnija), Smykla, J. (Jerzy), Sponseller, R. A. (Ryan A.), Teixeira-de Mello, F. (Franco), Vilbaste, S. (Sirje), Villanueva, V. D. (Veronica D.), Webster, J. R. (Jackson R.), Woelfl, S. (Stefan), Xenopoulos, M. A. (Marguerite A.), Yates, A. G. (Adam G.), Yule, C. M. (Catherine M.), Zhang, Y. (Yixin), Zwart, J. A. (Jacob A.), Costello, D. M. (David M.), Tiegs, S. D. (Scott D.), Boyero, L. (Luz), Canhoto, C. (Cristina), Capps, K. A. (Krista A.), Danger, M. (Michael), Frost, P. C. (Paul C.), Gessner, M. O. (Mark O.), Griffiths, N. A. (Natalie A.), Halvorson, H. M. (Halvor M.), Kuehn, K. A. (Kevin A.), Marcarelli, A. M. (Amy M.), Royer, T. V. (Todd, V), Mathie, D. M. (Devan M.), Albarino, R. J. (Ricardo J.), Arango, C. P. (Clay P.), Aroviita, J. (Jukka), Baxter, C. V. (Colden, V), Bellinger, B. J. (Brent J.), Bruder, A. (Andreas), Burdon, F. J. (Francis J.), Callisto, M. (Marcos), Camacho, A. (Antonio), Colas, F. (Fanny), Cornut, J. (Julien), Crespo-Perez, V. (Veronica), Cross, W. F. (Wyatt F.), Derry, A. M. (Alison M.), Douglas, M. M. (Michael M.), Elosegi, A. (Arturo), Eyto, E. (Elvira), Ferreira, V. (Veronica), Ferriol, C. (Carmen), Fleituch, T. (Tadeusz), Shah, J. J. (Jennifer J. Follstad), Frainer, A. (Andre), Garcia, E. A. (Erica A.), Garcia, L. (Liliana), Garcia, P. E. (Pavel E.), Giling, D. P. (Darren P.), Gonzales-Pomar, R. K. (R. Karina), Graca, M. A. (Manuel A. S.), Grossart, H.-P. (Hans-Peter), Guerold, F. (Francois), Hepp, L. U. (Luiz U.), Higgins, S. N. (Scott N.), Hishi, T. (Takuo), Iniguez-Armijos, C. (Carlos), Iwata, T. (Tomoya), Kirkwood, A. E. (Andrea E.), Koning, A. A. (Aaron A.), Kosten, S. (Sarian), Laudon, H. (Hjalmar), Leavitt, P. R. (Peter R.), Lemes da Silva, A. L. (Aurea L.), Leroux, S. J. (Shawn J.), LeRoy, C. J. (Carri J.), Lisi, P. J. (Peter J.), Masese, F. O. (Frank O.), McIntyre, P. B. (Peter B.), McKie, B. G. (Brendan G.), Medeiros, A. O. (Adriana O.), Milisa, M. (Marko), Miyake, Y. (Yo), Mooney, R. J. (Robert J.), Muotka, T. (Timo), Nimptsch, J. (Jorge), Paavola, R. (Riku), Pardo, I. (Isabel), Parnikoza, I. Y. (Ivan Y.), Patrick, C. J. (Christopher J.), Peeters, E. T. (Edwin T. H. M.), Pozo, J. (Jesus), Reid, B. (Brian), Richardson, J. S. (John S.), Rincon, J. (Jose), Risnoveanu, G. (Geta), Robinson, C. T. (Christopher T.), Santamans, A. C. (Anna C.), Simiyu, G. M. (Gelas M.), Skuja, A. (Agnija), Smykla, J. (Jerzy), Sponseller, R. A. (Ryan A.), Teixeira-de Mello, F. (Franco), Vilbaste, S. (Sirje), Villanueva, V. D. (Veronica D.), Webster, J. R. (Jackson R.), Woelfl, S. (Stefan), Xenopoulos, M. A. (Marguerite A.), Yates, A. G. (Adam G.), Yule, C. M. (Catherine M.), Zhang, Y. (Yixin), and Zwart, J. A. (Jacob A.)

Abstract

Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter.

Published
2022

2. Global patterns and drivers of ecosystem functioning in rivers and riparian zones

Author

Tiegs, SD, Costello, DM, Isken, MW, Woodward, G, McIntyre, PB, Gessner, MO, Chauvet, E, Griffiths, NA, Flecker, AS, Acuna, V, Albarino, R, Allen, DC, Alonso, C, Andino, P, Arango, C, Aroviita, J, Barbosa, MVM, Barmuta, LA, Baxter, CV, Bell, TDC, Bellinger, B, Boyero, L, Brown, LE, Bruder, A, Bruesewitz, DA, Burdon, FJ, Callisto, M, Canhoto, C, Capps, KA, Castillo, MM, Clapcott, J, Colas, F, Colon-Gaud, C, Cornut, J, Crespo-Perez, V, Cross, WF, Culp, JM, Danger, M, Dangles, O, de Eyto, E, Derry, AM, Diaz Villanueva, V, Douglas, MM, Elosegi, A, Encalada, AC, Entrekin, S, Espinosa, R, Ethaiya, D, Ferreira, V, Ferriol, C, Flanagan, KM, Fleituch, T, Shah, JJF, Frainer, A, Friberg, N, Frost, PC, Garcia, EA, Lago, LG, Garcia Soto, PE, Ghate, S, Giling, DP, Gilmer, A, Goncalves, JF, Gonzales, RK, Graca, MAS, Grace, M, Grossart, H-P, Guerold, F, Gulis, V, Hepp, LU, Higgins, S, Hishi, T, Huddart, J, Hudson, J, Imberger, S, Iniguez-Armijos, C, Iwata, T, Janetski, DJ, Jennings, E, Kirkwood, AE, Koning, AA, Kosten, S, Kuehn, KA, Laudon, H, Leavitt, PR, Lemes da Silva, AL, Leroux, SJ, Leroy, CJ, Lisi, PJ, MacKenzie, R, Marcarelli, AM, Masese, FO, Mckie, BG, Oliveira Medeiros, A, Meissner, K, Milisa, M, Mishra, S, Miyake, Y, Moerke, A, Mombrikotb, S, Mooney, R, Moulton, T, Muotka, T, Negishi, JN, Neres-Lima, V, Nieminen, ML, Nimptsch, J, Ondruch, J, Paavola, R, Pardo, I, Patrick, CJ, Peeters, ETHM, Pozo, J, Pringle, C, Prussian, A, Quenta, E, Quesada, A, Reid, B, Richardson, JS, Rigosi, A, Rincon, J, Risnoveanu, G, Robinson, CT, Rodriguez-Gallego, L, Royer, TV, Rusak, JA, Santamans, AC, Selmeczy, GB, Simiyu, G, Skuja, A, Smykla, J, Sridhar, KR, Sponseller, R, Stoler, A, Swan, CM, Szlag, D, Teixeira-de Mello, F, Tonkin, JD, Uusheimo, S, Veach, AM, Vilbaste, S, Vought, LBM, Wang, C-P, Webster, JR, Wilson, PB, Woelfl, S, Xenopoulos, MA, Yates, AG, Yoshimura, C, Yule, CM, Zhang, YX, Zwart, JA, Tiegs, SD, Costello, DM, Isken, MW, Woodward, G, McIntyre, PB, Gessner, MO, Chauvet, E, Griffiths, NA, Flecker, AS, Acuna, V, Albarino, R, Allen, DC, Alonso, C, Andino, P, Arango, C, Aroviita, J, Barbosa, MVM, Barmuta, LA, Baxter, CV, Bell, TDC, Bellinger, B, Boyero, L, Brown, LE, Bruder, A, Bruesewitz, DA, Burdon, FJ, Callisto, M, Canhoto, C, Capps, KA, Castillo, MM, Clapcott, J, Colas, F, Colon-Gaud, C, Cornut, J, Crespo-Perez, V, Cross, WF, Culp, JM, Danger, M, Dangles, O, de Eyto, E, Derry, AM, Diaz Villanueva, V, Douglas, MM, Elosegi, A, Encalada, AC, Entrekin, S, Espinosa, R, Ethaiya, D, Ferreira, V, Ferriol, C, Flanagan, KM, Fleituch, T, Shah, JJF, Frainer, A, Friberg, N, Frost, PC, Garcia, EA, Lago, LG, Garcia Soto, PE, Ghate, S, Giling, DP, Gilmer, A, Goncalves, JF, Gonzales, RK, Graca, MAS, Grace, M, Grossart, H-P, Guerold, F, Gulis, V, Hepp, LU, Higgins, S, Hishi, T, Huddart, J, Hudson, J, Imberger, S, Iniguez-Armijos, C, Iwata, T, Janetski, DJ, Jennings, E, Kirkwood, AE, Koning, AA, Kosten, S, Kuehn, KA, Laudon, H, Leavitt, PR, Lemes da Silva, AL, Leroux, SJ, Leroy, CJ, Lisi, PJ, MacKenzie, R, Marcarelli, AM, Masese, FO, Mckie, BG, Oliveira Medeiros, A, Meissner, K, Milisa, M, Mishra, S, Miyake, Y, Moerke, A, Mombrikotb, S, Mooney, R, Moulton, T, Muotka, T, Negishi, JN, Neres-Lima, V, Nieminen, ML, Nimptsch, J, Ondruch, J, Paavola, R, Pardo, I, Patrick, CJ, Peeters, ETHM, Pozo, J, Pringle, C, Prussian, A, Quenta, E, Quesada, A, Reid, B, Richardson, JS, Rigosi, A, Rincon, J, Risnoveanu, G, Robinson, CT, Rodriguez-Gallego, L, Royer, TV, Rusak, JA, Santamans, AC, Selmeczy, GB, Simiyu, G, Skuja, A, Smykla, J, Sridhar, KR, Sponseller, R, Stoler, A, Swan, CM, Szlag, D, Teixeira-de Mello, F, Tonkin, JD, Uusheimo, S, Veach, AM, Vilbaste, S, Vought, LBM, Wang, C-P, Webster, JR, Wilson, PB, Woelfl, S, Xenopoulos, MA, Yates, AG, Yoshimura, C, Yule, CM, Zhang, YX, and Zwart, JA

Abstract

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented “next-generation biomonitoring” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.

Published
2019

3. Global patterns and drivers of ecosystem functioning in rivers and riparian zones

Author

Tiegs, S. D. (Scott D.), Costello, D. M. (David M.), Isken, M. W. (Mark W.), Woodward, G. (Guy), McIntyre, P. B. (Peter B.), Gessner, M. O. (Mark O.), Chauvet, E. (Eric), Griffiths, N. A. (Natalie A.), Flecker, A. S. (Alex S.), Acuna, V. (Vicenc), Albarino, R. (Ricardo), Allen, D. C. (Daniel C.), Alonso, C. (Cecilia), Andino, P. (Patricio), Arango, C. (Clay), Aroviita, J. (Jukka), Barbosa, M. V. (Marcus V. M.), Barmuta, L. A. (Leon A.), Baxter, C. V. (Colden V.), Bell, T. D. (Thomas D. C.), Bellinger, B. (Brent), Boyero, L. (Luz), Brown, L. E. (Lee E.), Bruder, A. (Andreas), Bruesewitz, D. A. (Denise A.), Burdon, F. J. (Francis J.), Callisto, M. (Marcos), Canhoto, C. (Cristina), Capps, K. A. (Krista A.), Castillo, M. M. (Maria M.), Clapcott, J. (Joanne), Colas, F. (Fanny), Colon-Gaud, C. (Checo), Cornut, J. (Julien), Crespo-Perez, V. (Veronica), Cross, W. F. (Wyatt F.), Culp, J. M. (Joseph M.), Danger, M. (Michael), Dangles, O. (Olivier), de Eyto, E. (Elvira), Derry, A. M. (Alison M.), Diaz Villanueva, V. (Veronica), Douglas, M. M. (Michael M.), Elosegi, A. (Arturo), Encalada, A. C. (Andrea C.), Entrekin, S. (Sally), Espinosa, R. (Rodrigo), Ethaiya, D. (Diana), Ferreira, V. (Veronica), Ferriol, C. (Carmen), Flanagan, K. M. (Kyla M.), Fleituch, T. (Tadeusz), Shah, J. J. (Jennifer J. Follstad), Frainer, A. (Andre), Friberg, N. (Nikolai), Frost, P. C. (Paul C.), Garcia, E. A. (Erica A.), Lago, L. G. (Liliana Garcia), Garcia Soto, P. E. (Pavel Ernesto), Ghate, S. (Sudeep), Giling, D. P. (Darren P.), Gilmer, A. (Alan), Goncalves, J. F. (Jose Francisco, Jr.), Gonzales, R. K. (Rosario Karina), Graca, M. A. (Manuel A. S.), Grace, M. (Mike), Grossart, H.-P. (Hans-Peter), Guerold, F. (Francois), Gulis, V. (Vlad), Hepp, L. U. (Luiz U.), Higgins, S. (Scott), Hishi, T. (Takuo), Huddart, J. (Joseph), Hudson, J. (John), Imberger, S. (Samantha), Iniguez-Armijos, C. (Carlos), Iwata, T. (Tomoya), Janetski, D. J. (David J.), Jennings, E. (Eleanor), Kirkwood, A. E. (Andrea E.), Koning, A. A. (Aaron A.), Kosten, S. (Sarian), Kuehn, K. A. (Kevin A.), Laudon, H. (Hjalmar), Leavitt, P. R. (Peter R.), Lemes da Silva, A. L. (Aurea L.), Leroux, S. J. (Shawn J.), Leroy, C. J. (Carri J.), Lisi, P. J. (Peter J.), MacKenzie, R. (Richard), Marcarelli, A. M. (Amy M.), Masese, F. O. (Frank O.), Mckie, B. G. (Brendan G.), Oliveira Medeiros, A. (Adriana), Meissner, K. (Kristian), Milisa, M. (Marko), Mishra, S. (Shailendra), Miyake, Y. (Yo), Moerke, A. (Ashley), Mombrikotb, S. (Shorok), Mooney, R. (Rob), Moulton, T. (Tim), Muotka, T. (Timo), Negishi, J. N. (Junjiro N.), Neres-Lima, V. (Vinicius), Nieminen, M. L. (Mika L.), Nimptsch, J. (Jorge), Ondruch, J. (Jakub), Paavola, R. (Riku), Pardo, I. (Isabel), Patrick, C. J. (Christopher J.), Peeters, E. T. (Edwin T. H. M.), Pozo, J. (Jesus), Pringle, C. (Catherine), Prussian, A. (Aaron), Quenta, E. (Estefania), Quesada, A. (Antonio), Reid, B. (Brian), Richardson, J. S. (John S.), Rigosi, A. (Anna), Rincon, J. (Jose), Risnoveanu, G. (Geta), Robinson, C. T. (Christopher T.), Rodriguez-Gallego, L. (Lorena), Royer, T. V. (Todd V.), Rusak, J. A. (James A.), Santamans, A. C. (Anna C.), Selmeczy, G. B. (Geza B.), Simiyu, G. (Gelas), Skuja, A. (Agnija), Smykla, J. (Jerzy), Sridhar, K. R. (Kandikere R.), Sponseller, R. (Ryan), Stoler, A. (Aaron), Swan, C. M. (Christopher M.), Szlag, D. (David), Teixeira-de Mello, F. (Franco), Tonkin, J. D. (Jonathan D.), Uusheimo, S. (Sari), Veach, A. M. (Allison M.), Vilbaste, S. (Sirje), Vought, L. B. (Lena B. M.), Wang, C.-P. (Chiao-Ping), Webster, J. R. (Jackson R.), Wilson, P. B. (Paul B.), Woelfl, S. (Stefan), Xenopoulos, M. A. (Marguerite A.), Yates, A. G. (Adam G.), Yoshimura, C. (Chihiro), Yule, C. M. (Catherine M.), Zhang, Y. X. (Yixin X.), Zwart, J. A. (Jacob A.), Tiegs, S. D. (Scott D.), Costello, D. M. (David M.), Isken, M. W. (Mark W.), Woodward, G. (Guy), McIntyre, P. B. (Peter B.), Gessner, M. O. (Mark O.), Chauvet, E. (Eric), Griffiths, N. A. (Natalie A.), Flecker, A. S. (Alex S.), Acuna, V. (Vicenc), Albarino, R. (Ricardo), Allen, D. C. (Daniel C.), Alonso, C. (Cecilia), Andino, P. (Patricio), Arango, C. (Clay), Aroviita, J. (Jukka), Barbosa, M. V. (Marcus V. M.), Barmuta, L. A. (Leon A.), Baxter, C. V. (Colden V.), Bell, T. D. (Thomas D. C.), Bellinger, B. (Brent), Boyero, L. (Luz), Brown, L. E. (Lee E.), Bruder, A. (Andreas), Bruesewitz, D. A. (Denise A.), Burdon, F. J. (Francis J.), Callisto, M. (Marcos), Canhoto, C. (Cristina), Capps, K. A. (Krista A.), Castillo, M. M. (Maria M.), Clapcott, J. (Joanne), Colas, F. (Fanny), Colon-Gaud, C. (Checo), Cornut, J. (Julien), Crespo-Perez, V. (Veronica), Cross, W. F. (Wyatt F.), Culp, J. M. (Joseph M.), Danger, M. (Michael), Dangles, O. (Olivier), de Eyto, E. (Elvira), Derry, A. M. (Alison M.), Diaz Villanueva, V. (Veronica), Douglas, M. M. (Michael M.), Elosegi, A. (Arturo), Encalada, A. C. (Andrea C.), Entrekin, S. (Sally), Espinosa, R. (Rodrigo), Ethaiya, D. (Diana), Ferreira, V. (Veronica), Ferriol, C. (Carmen), Flanagan, K. M. (Kyla M.), Fleituch, T. (Tadeusz), Shah, J. J. (Jennifer J. Follstad), Frainer, A. (Andre), Friberg, N. (Nikolai), Frost, P. C. (Paul C.), Garcia, E. A. (Erica A.), Lago, L. G. (Liliana Garcia), Garcia Soto, P. E. (Pavel Ernesto), Ghate, S. (Sudeep), Giling, D. P. (Darren P.), Gilmer, A. (Alan), Goncalves, J. F. (Jose Francisco, Jr.), Gonzales, R. K. (Rosario Karina), Graca, M. A. (Manuel A. S.), Grace, M. (Mike), Grossart, H.-P. (Hans-Peter), Guerold, F. (Francois), Gulis, V. (Vlad), Hepp, L. U. (Luiz U.), Higgins, S. (Scott), Hishi, T. (Takuo), Huddart, J. (Joseph), Hudson, J. (John), Imberger, S. (Samantha), Iniguez-Armijos, C. (Carlos), Iwata, T. (Tomoya), Janetski, D. J. (David J.), Jennings, E. (Eleanor), Kirkwood, A. E. (Andrea E.), Koning, A. A. (Aaron A.), Kosten, S. (Sarian), Kuehn, K. A. (Kevin A.), Laudon, H. (Hjalmar), Leavitt, P. R. (Peter R.), Lemes da Silva, A. L. (Aurea L.), Leroux, S. J. (Shawn J.), Leroy, C. J. (Carri J.), Lisi, P. J. (Peter J.), MacKenzie, R. (Richard), Marcarelli, A. M. (Amy M.), Masese, F. O. (Frank O.), Mckie, B. G. (Brendan G.), Oliveira Medeiros, A. (Adriana), Meissner, K. (Kristian), Milisa, M. (Marko), Mishra, S. (Shailendra), Miyake, Y. (Yo), Moerke, A. (Ashley), Mombrikotb, S. (Shorok), Mooney, R. (Rob), Moulton, T. (Tim), Muotka, T. (Timo), Negishi, J. N. (Junjiro N.), Neres-Lima, V. (Vinicius), Nieminen, M. L. (Mika L.), Nimptsch, J. (Jorge), Ondruch, J. (Jakub), Paavola, R. (Riku), Pardo, I. (Isabel), Patrick, C. J. (Christopher J.), Peeters, E. T. (Edwin T. H. M.), Pozo, J. (Jesus), Pringle, C. (Catherine), Prussian, A. (Aaron), Quenta, E. (Estefania), Quesada, A. (Antonio), Reid, B. (Brian), Richardson, J. S. (John S.), Rigosi, A. (Anna), Rincon, J. (Jose), Risnoveanu, G. (Geta), Robinson, C. T. (Christopher T.), Rodriguez-Gallego, L. (Lorena), Royer, T. V. (Todd V.), Rusak, J. A. (James A.), Santamans, A. C. (Anna C.), Selmeczy, G. B. (Geza B.), Simiyu, G. (Gelas), Skuja, A. (Agnija), Smykla, J. (Jerzy), Sridhar, K. R. (Kandikere R.), Sponseller, R. (Ryan), Stoler, A. (Aaron), Swan, C. M. (Christopher M.), Szlag, D. (David), Teixeira-de Mello, F. (Franco), Tonkin, J. D. (Jonathan D.), Uusheimo, S. (Sari), Veach, A. M. (Allison M.), Vilbaste, S. (Sirje), Vought, L. B. (Lena B. M.), Wang, C.-P. (Chiao-Ping), Webster, J. R. (Jackson R.), Wilson, P. B. (Paul B.), Woelfl, S. (Stefan), Xenopoulos, M. A. (Marguerite A.), Yates, A. G. (Adam G.), Yoshimura, C. (Chihiro), Yule, C. M. (Catherine M.), Zhang, Y. X. (Yixin X.), and Zwart, J. A. (Jacob A.)

Abstract

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented “next-generation biomonitoring” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.

Published
2019

5. Extraction and reconstitution of membrane proteins into lipid nanodiscs encased by zwitterionic styrene-maleic amide copolymers.

Author

Fiori MC, Zheng W, Kamilar E, Simiyu G, Altenberg GA, and Liang H

Subjects
Humans, Lipid Bilayers, Amides chemistry, Maleates chemistry, Membrane Proteins chemistry, Membrane Proteins isolation & purification, Nanostructures chemistry, Polymers chemistry, Styrene chemistry
Abstract

Membrane proteins can be reconstituted in polymer-encased nanodiscs for studies under near-physiological conditions and in the absence of detergents, but traditional styrene-maleic acid copolymers used for this purpose suffer severely from buffer incompatibilities. We have recently introduced zwitterionic styrene-maleic amide copolymers (zSMAs) to overcome this limitation. Here, we compared the extraction and reconstitution of membrane proteins into lipid nanodiscs by a series of zSMAs with different styrene:maleic amide molar ratios, chain sizes, and molecular weight distributions. These copolymers solubilize, stabilize, and support membrane proteins in nanodiscs with different efficiencies depending on both the structure of the copolymers and the membrane proteins.

Published
2020
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6. Global patterns and drivers of ecosystem functioning in rivers and riparian zones.

Author

Tiegs SD, Costello DM, Isken MW, Woodward G, McIntyre PB, Gessner MO, Chauvet E, Griffiths NA, Flecker AS, Acuña V, Albariño R, Allen DC, Alonso C, Andino P, Arango C, Aroviita J, Barbosa MVM, Barmuta LA, Baxter CV, Bell TDC, Bellinger B, Boyero L, Brown LE, Bruder A, Bruesewitz DA, Burdon FJ, Callisto M, Canhoto C, Capps KA, Castillo MM, Clapcott J, Colas F, Colón-Gaud C, Cornut J, Crespo-Pérez V, Cross WF, Culp JM, Danger M, Dangles O, de Eyto E, Derry AM, Villanueva VD, Douglas MM, Elosegi A, Encalada AC, Entrekin S, Espinosa R, Ethaiya D, Ferreira V, Ferriol C, Flanagan KM, Fleituch T, Follstad Shah JJ, Frainer Barbosa A, Friberg N, Frost PC, Garcia EA, García Lago L, García Soto PE, Ghate S, Giling DP, Gilmer A, Gonçalves JF Jr, Gonzales RK, Graça MAS, Grace M, Grossart HP, Guérold F, Gulis V, Hepp LU, Higgins S, Hishi T, Huddart J, Hudson J, Imberger S, Iñiguez-Armijos C, Iwata T, Janetski DJ, Jennings E, Kirkwood AE, Koning AA, Kosten S, Kuehn KA, Laudon H, Leavitt PR, Lemes da Silva AL, Leroux SJ, LeRoy CJ, Lisi PJ, MacKenzie R, Marcarelli AM, Masese FO, McKie BG, Oliveira Medeiros A, Meissner K, Miliša M, Mishra S, Miyake Y, Moerke A, Mombrikotb S, Mooney R, Moulton T, Muotka T, Negishi JN, Neres-Lima V, Nieminen ML, Nimptsch J, Ondruch J, Paavola R, Pardo I, Patrick CJ, Peeters ETHM, Pozo J, Pringle C, Prussian A, Quenta E, Quesada A, Reid B, Richardson JS, Rigosi A, Rincón J, Rîşnoveanu G, Robinson CT, Rodríguez-Gallego L, Royer TV, Rusak JA, Santamans AC, Selmeczy GB, Simiyu G, Skuja A, Smykla J, Sridhar KR, Sponseller R, Stoler A, Swan CM, Szlag D, Teixeira-de Mello F, Tonkin JD, Uusheimo S, Veach AM, Vilbaste S, Vought LBM, Wang CP, Webster JR, Wilson PB, Woelfl S, Xenopoulos MA, Yates AG, Yoshimura C, Yule CM, Zhang YX, and Zwart JA

Subjects
Human Activities, Humans, Carbon Cycle physiology, Ecosystem, Environmental Monitoring methods, Rivers microbiology, Temperature
Abstract

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.

Published
2019
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7. Factors Associated with Late Engagement to HIV Care in Western Kenya: A Cross-Sectional Study.

Author

Kwobah CM, Braitstein P, Koech JK, Simiyu G, Mwangi AW, Wools-Kaloustian K, and Siika AM

Subjects
Adult, CD4 Lymphocyte Count, Cross-Sectional Studies, Female, HIV Infections drug therapy, HIV Infections immunology, Humans, Kenya epidemiology, Male, Middle Aged, Young Adult, HIV Infections epidemiology, Time-to-Treatment statistics & numerical data
Abstract

Background: Late presentation of patients contributes significantly to the high mortality reported in HIV -care and treatment programs in sub-Saharan Africa., Methods: A cross-sectional study was conducted to assess factors associated with late engagement to HIV care at the Academic Model Providing Access to Healthcare in western Kenya. Late engagement was defined as baseline CD4 ≤100 cells/mm 3 ., Results: Of the 10 533 participants included in the analysis, 67% were female and mean age was 36.7 years. Overall, 23% of the participants presented late. Factors associated with late engagement included male gender (adjusted odds ratio [AOR]: 1.54, 95% confidence interval [CI]: 1.35-1.75), older age (AOR: 1.62, 95% CI: 1.02-2.56), and longer travel time to clinic (AOR: 1.18, 95% CI: 1.04-1.34)., Conclusion: Nearly one-quarter of HIV-infected patients in our setting present with advanced immune suppression at initial encounter. Being male, older age, and living further away from clinic are associated with late engagement to care., (© The Author(s) 2015.)

Published
2016
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8. PCBs in fish and their cestode parasites in Lake Victoria.

Author

Oluoch-Otiego J, Oyoo-Okoth E, Kiptoo KK, Chemoiwa EJ, Ngugi CC, Simiyu G, Omutange ES, Ngure V, and Opiyo MA

Subjects
Animals, Cestoda growth & development, Cestoda metabolism, Cyprinidae metabolism, Kenya, Cestoda chemistry, Cyprinidae parasitology, Environmental Monitoring methods, Lakes chemistry, Polychlorinated Biphenyls analysis
Abstract

Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs) regulated by the Stockholm Convention (2001). Although their production and use was stopped almost three decades ago, PCBs are environmental persistent, toxic, and bioaccumulate in biota. We assessed the levels of 7 PCB congeners (IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) in sediment and fish (Oreochromis niloticus, Lates niloticus, and Rastrineobola argentea) and evaluated the potential of cestode fish endoparasite (Monobothrioides sp., Proteocephalaus sp., and Ligula intestinalis) as biomonitors of PCBs in Lake Victoria, Kenya. The median concentration of Σ7PCBs in sediments and fish were 2.2-96.3 μg/kg dw and 300-3,000 μg/kg lw, respectively. At all the sampling sites, CB138, CB153, and CB180 were the dominant PCB congeners in sediment and fish samples. Compared to the muscle of the piscine host, Proteocephalaus sp. (infecting L. niloticus) biomagnified PCBs ×6-14 while Monobothrioides sp. (infecting O. niloticus) biomagnified PCBs ×4-8. Meanwhile, L. intestinalis (infecting R. argentea) biomagnified PCBs ×8-16 compared to the muscle of unparasitized fish. We demonstrate the occurrence of moderate to high levels of PCB in sediments and fish in Lake Victoria. We also provide evidence that fish parasites bioaccumulate higher levels of PCBs than their piscine hosts and therefore provide a promising biomonitor of PCBs. We urge further a long-term study to validate the use of the above cestode fish parasites as biomonitoring tools for PCBs.

Published
2016
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9. Short-Term Rationing of Combination Antiretroviral Therapy: Impact on Morbidity, Mortality, and Loss to Follow-Up in a Large HIV Treatment Program in Western Kenya.

Author

Bell AJ, Wools-Kaloustian K, Kimaiyo S, Liu H, Katschke A, Shen C, Simiyu G, Musick BS, Sidle JE, Siika A, and Braitstein P

Abstract

Background. There was a 6-month shortage of antiretrovirals (cART) in Kenya. Methods. We assessed morbidity, mortality, and loss to follow-up (LTFU) in this retrospective analysis of adults who were enrolled during the six-month period with restricted cART (cap) or the six months prior (pre-cap) and eligible for cART at enrollment by the pre-cap standard. Cox models were used to adjust for potential confounders. Results. 9009 adults were eligible for analysis: 4,714 pre-cap and 4,295 during the cap. Median number of days from enrollment to cART initiation was 42 pre-cap and 56 for the cap (P < 0.001). After adjustment, individuals in the cap were at higher risk of mortality (HR = 1.21; 95% CI : 1.06-1.39) and LTFU (HR = 1.12; 95% CI : 1.04-1.22). There was no difference between the groups in their risk of developing a new AIDS-defining illness (HR = 0.92 95% CI 0.82-1.03). Conclusions. Rationing of cART, even for a relatively short period of six months, led to clinically adverse outcomes.

Published
2012
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