Phosphorus and nitrogen are essential nutrients for living organisms. Their concentration in the water of an aquatic ecosystem is one of the factors responsible for the trophic status of the lake and is related to the soils of the region and to the human activities carried out in their basins. These nutrients are also found in the bottom sediments, where they can either be retained or re-enter the water column. Since the information about the concentrations of nutrients in the water of some lakes of La Pampa (Argentina) is fragmentary, the aim of this study is to describe the trophic status of some shallow lakes of the semiarid center of Argentina and analyze its relation with the human activities in their basins, the concentrations of nutrients and organic matter and particle size distribution of sediments. To this end, we studied ten shallow lakes subjected to different anthropogenic influences (agriculture, agriculture and livestock and impacted by cities). All were hypertrophic and the concentrations of total phosphorus and total nitrogen were among the highest reported globally. Since some lakes had no fish, cladoceran grazing (top-down effect) led them have reduced concentrations of phytoplankton chlorophyll-a and high water transparency. This relativizes the use of these parameters to determine the trophic status. The sediments of seven of the studied lakes were predominated by fine sands, whereas three were predominated by silts. Nutrient and organic matter content were high, with higher concentrations in lakes with prevalence of fine particles. The reduced adsorption capacity of sediments, the resuspension by wind, the anthropogenic input and the accumulation favored by the arheic character of the basins would explain the high concentrations of nutrients in the water of these Pampean environments.
 S. Carpenter, N. Caraco, D. Correll, R. Howarth, A. Sharpley and V. Smith, “Nonpoint Pollution of Surface Waters with Phosphorus and Nitrogen,” Ecological Applications, Vol. 8, No. 3, 1998, pp. 559-568.
 K. Arbuckle and J. Downing, “The Influence of Watershed Land Use on Lake N: P in a Predominantly Agricultural Landscape,” Limnology and Oceanography, Vol. 46, No. 4, 2001, pp. 970-975.
 K. Krogerus and P. Ekholm, “Phosphorus in Settling Matter and Bottom Sediments in Lakes Loaded by Agriculture,” Hydrobiologia, Vol. 429, 2003, pp. 15-28.
 M. Bremigan, P. Soranno, M. González, D. Bunnell, K. Arend, W. Renwick, R. Stein and M. Vanni, “Hydrogeomorphic Features Mediate the Effects of Land Use/Cover on Reservoir Productivity and Food Webs,” Limnology and Oceanography, Vol. 53, No. 4, 2008, pp. 1420-1433.
 C. Zhou, Y. Zhou, X. Chen, Y. Li, X. Cao and C. Song, “Linkage between Land Use Patterns and Sediment Phosphorus Sorption Behaviours along Shoreline of Chinese Large Shallow Lake (Lake Chaohu),” Knowledge and Management of Aquatic Ecosystems, No. 403, 2011, pp. 6-14. http://dx.doi.org/10.1051/kmae/2011067
 A. Hargeby, I. Blindow and L. Hansson, “Shifts between Clear and Turbid States in a Shallow Lake: Multi-Causal Stress from Climate, Nutrients and Biotic Interactions,” Archives fur Hydrobiologie, Vol. 161, No. 4, 2004, pp. 433-454. http://dx.doi.org/10.1127/0003-9136/2004/0161-0433
 M. Genkai-Kato, “Regime Shifts: Catastrophic Responses of Ecosystems to Human Impacts,” Ecological Research, Vol. 22, No. 2, 2007, pp. 214-219.
 W. K. Dodds, “Trophic State, Eutrophication and Nutrient Criteria in Streams,” Trends in Ecology and Evolution, Vol. 22, No. 12, 2007, pp. 669-676.
 M. Søndergaard, J. Jensen and E. Jeppesen, “Role of Sediment and Internal Loading of Phosphorus in Shallow Lakes,” Hydrobiologia, Vol. 506-509, No. 1-3, 2003, pp. 135-145. http://dx.doi.org/10.1023/B:HYDR.0000008611.12704.dd
 K. Lukawska-Matuszewska, R. Vogt and R. Xie, “Phosphorus Pools and Internal Loading in a Eutrophic Lake with Gradients in Sediment Geochemistry Created by Land Use in the Watershed,” Hydrobiologia, Vol. 713, No. 1, 2013, pp. 183-197.
 E. Liu, J. Shen, H. Yuan, E. Zhang and C. Du, “The Spatio-Temporal Variations of Sedimentary Phosphorus in Taihu Lake and the Implications for Internal Loading Change and Recent Eutrophication,” Hydrobiologia, Vol. 711, No. 1, 2013, pp. 87-98.
 I. de Vicente, V. Amores and L. Cruz-Pizarro, “Inestability of Shallow Lakes: A Matter of the Complexity of Factors Involved in Sediment and Water Interaction?” Limnética, Vol. 25, No. 1-2, 2006, pp. 253-270.
 M. Hupfer and J. Lewandowski, “Oxygen Controls the Phosphorus Release from Lake Sediments—A LongLasting Paradigm in Limnology,” International Review of Hydrobiology, Vol. 93, No. 4-5, 2008, pp. 415-432.
 Y. Kang, X. Song and Z. Liu, “Sediment Resuspension Dampens the Effect of Nutrient Inputs on the Phytoplankton Community: A Mesocosm Experiment Study,” Hydrobiologia, Vol. 710, No. 1, 2012, pp. 117-127.
 M. Boveri and R. Quirós, “Trophic Interactions in Pampean Shallow Lakes: Evaluation of Silverside Predatory Effects in Mesocosms Experiments,” Verhandlungen des Internationalen Verein Limnologie, No. 28, 2002, pp. 1-5.
 A. Torremorell, J. Bustingorry, R. Escaray and H. Zagarese, “Seasonal Dynamics of a Large, Shallow Lake, Laguna Chascomús: The Role of Light Limitation and Other Physical Variables,” Limnologica, Vol. 37, No. 1, 2007, pp. 100-108.
 M. Boveri and R. Quirós, “Cascading Trophic Effects in Pampean Shallow Lakes: Results of a Mesocosm Experiment Using Two Coexisting Fish Species with Different Feeding Strategies,” Hydrobiologia, Vol. 584, No. 1, 2007, pp. 215-222.
 S. Echaniz, A. Vignatti and P. Bunino, “El Zooplancton de un Lago Somero Hipereutrófico de la Región Central de Argentina. Cambios Después de una Década,” Biota Neotropica, Vol. 8, No. 4, 2008, pp. 63-71.
 S. Echaniz, A. Vignatti and C. Cabrera. “Características Limnológicas de una Laguna Turbia Orgánica de la Provincia de La Pampa y Variación Estacional del Zooplancton,” Biología Acuática, No. 26, 2009, pp. 71-82.
 S. Echaniz, A. Vignatti, S. B. José de Paggi and G. Cabrera, “El Modelo de Estados Alternativos de Lagos Someros en La Pampa: Comparación de Bajo de Giuliani y El Carancho,” Libro de Trabajos del 3° Congreso Pampeano del Agua, 2010, pp. 45-53.
 S. Echaniz, A. Vignatti, S. B. José de Paggi and J. C. Paggi, “Los Nutrientes en los Sedimentos de Lagunas de La Pampa. Relación con la Granulometría y uso de la Tierra,” Libro de Trabajos del 3° Congreso Pampeano del Agua, 2010, pp. 23-31.
 S. Echaniz, A. Vignatti, G. Cabrera and S. B. José de Paggi, “Zooplankton Richness, Abundance and Biomass of Two Hypertrophic Shallow Lakes with Different Salinity,” Biota Neotropica, Vol. 12, No. 2, 2012, pp. 37-44. http://dx.doi.org/10.1590/S1676-06032012000200005
 S. Echaniz, G. Cabrera, C. Rodríguez and A. Vignatti, “Do Temporary Lakes Vary from Year to Year? A Comparison of Limnological Parameters and Zooplankton from Two Consecutive Annual Cycles in an Argentine Temporary Saline Lake,” International Journal of Aquatic Science, Vol. 4, No. 1, 2013, pp. 44-61.
 S. Echaniz and A. Vignatti, “Seasonal Variation and Influence of Turbidity and Salinity on the Zooplankton of a Saline Lake in Central Argentina,” Latin American Journal of Aquatic Research, Vol. 39, No. 2, 2011, pp. 306-315. http://dx.doi.org/10.3856/vol39-issue2-fulltext-12
 A. Vignatti, G. Cabrera and S. Echaniz, “Changes in the Zooplankton and Limnological Variables of a Temporary Hypo-Mesosaline Wetland of the Central Region of Argentina during the Drying,” Pan American Journal of Aquatic Sciences, Vol. 7, No. 2, 2012, pp. 93-106.
 E. J. Arar, “In Vitro Determination of Chlorophylls a, b, c + c and Pheopigments in Marine and Freshwater Algae by Visible Spectrophotometry,” Method 446.0. US Environmental Protection Agency, 1997.
 M. Russell, D. Weller, T. Jordan, K. Sigwart and K. Sullivan, “Net Anthropogenic Phosphorus Inputs: Spatial and Temporal Variability in the Chesapeake Bay Region,” Biogeochemistry, Vol. 88, No. 3, 2008, pp. 285-304. http://dx.doi.org/10.1007/s10533-008-9212-9
 J. Brooks and S. Dodson, “Predation, Body Size and Composition of Plankton,” Science, Vol. 150, No. 3692, 1965, pp. 28-35.
 M. Scheffer and E. Jeppesen, “Regime Shifts in Shallow Lakes,” Ecosystems, Vol. 10, No. 1, 2007, pp. 1-3.
 E. Jeppesen, M. Søndergaard, M. Meerhoff, T. Lauridsen and J. P. Jensen, “Shallow Lake Restoration by Nutrient Loading Reduction—Some Recent Findings and Challenges Ahead,” Hydrobiologia, Vol. 584, No. 1, 2007, pp. 239-252. http://dx.doi.org/10.1007/s10750-007-0596-7
 E. Jeppesen, M. Meerhoff, B. Jacobsen, R. Hansen, M. Søndergaard, J. Jensen, T. Lauridsen, N. Mazzeo and C. Branco, “Restoration of Shallow Lakes by Nutrient Control and Biomanipulation—The Successful Strategy Varies with Lake Size and Climate,” Hydrobiologia, Vol. 581, No. 1, 2007, pp. 269-285.
 E. Bakker, J. Sarneel, R. Gulati, Z. Liu and E. van Donk, “Restoring Macrophyte Diversity in Shallow Temperate Lakes: Biotic versus Abiotic Constraints,” Hydrobiologia, Vol. 710, No. 1, 2013, pp. 23-37.
 E. Cano, “Inventario Integrado de los Recursos Naturales de la Provincia de La Pampa,” Instituto Nacional de Tecnología Agropecuaria (INTA), Provincia de La Pampa y Universidad Nacional de La Pampa, Buenos Aires, 1980.
 A. Pilati, M.Vanni, M. González and A. Gaulke, “Effects of Agricultural Subsidies of Nutrients and Detritus on Fish Andplankton of Shallow-Reservoir Ecosystems,” Ecological Applications, Vol. 19, No. 4, 2009, pp. 942-960. http://dx.doi.org/10.1890/08-0807.1
 S. Wang, X. Jin, H. Zhao and F. Wu, “Phosphorus Fractions and Its Release in the Sediments from the Shallow Lakes in the Middle and Lower Reaches of Yangtze River Area in China,” Colloids and Surfaces A Physicochemical Engineering Aspects, No. 273, 2006, pp. 109-116.
 G. Kapanen, “Phosphorus Fractionation in Lake Sediments,” Estonian Journal of Ecology, Vol. 57, No. 4, 2008, pp. 244-245.
 A. Smolders, L. Lamers, E. Lucassen, G. Van Der Velde and J. Roelofs, “Internal Eutrophication: How It Works and What to Do about It—A Review,” Chemistry and Ecology, Vol. 22, No. 2, 2006, pp. 93-111.
 S. Katsev, I. Tsandev, I. Heureux and D. Rancourt, “Factors Controlling Long-Term Phosphorus Effluxes from Lakes Sediments: Exploratory Reactive-Transport Modeling,” Chemical Geology, Vol. 324, No. 1-2, 2006, pp. 127-147.
 K. Havens, K-R. Jin, N. Iricanin and R. James, “Phosphorus Dynamics at Multiple Time Scales in the Pelagic Zone of a Large Shallow Lake In Florida, USA,” Hydrobiologia, Vol. 581, No. 1, 2007, pp. 25-42.
 E. Nagid, D. Canfield Jr. and M. Hoyer, “Wind-Induced Increases in Trophic State Characteristics of a Large (27 km2), Shallow (1.5 m Mean Depth) Florida Lake,” Hydrobiologia, Vol. 455, No. 1-3, 2001, pp. 97-110.
 H. Markensten and D. C. Pierson, “A Dynamic Model for Flow and Wind Driven Sediment Resuspension in a Shallow Basin,” Hydrobiologia, Vol. 494, No. 1-3, 2003, pp. 305-311. http://dx.doi.org/10.1023/A:1025459525880
 C. Borell Lovstedt and L. Bengtsson, “The Role of Non-Prevailing Wind Direction on Resuspension and Redistribution of Sediments in a Shallow Lake,” Aquatic Sciences, Vol. 70, No. 3, 2008, pp. 304-313.
 U. Selig and G. Schlungbaum, “Characterisation and Quantification of Phosphorus Release from Profundal Battom Sediments in Two Dimictic Lakes during Summer Stratification,” Journal of Limnology, Vol. 62, No. 2, 2003, pp. 151-162.