The impact of accelerating land-use change on the N-Cycle of tropical aquatic ecosystems: Current conditions and projected changes |
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Authors: | JA Downing M McClain R Twilley JM Melack J Elser NN Rabalais WM Lewis Jr RE Turner J Corredor D Soto A Yanez-Arancibia JA Kopaska RW Howarth |
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Institution: | (1) Department of Animal Ecology, Iowa State University, Ames, IA, U.S.A;(2) RSMAS-MGG, University of Miami, Miami, FL, U.S.A;(3) Department of Biology, University of Southwestern Louisiana, Lafayette, LA, U.S.A;(4) Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, U.S.A;(5) Department of Zoology, Arizona State University, Tempe, AZ, U.S.A;(6) Louisiana Universities Marine Consortium, Chauvin, LA, U.S.A;(7) Center for Limnology, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, U.S.A;(8) Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, U.S.A;(9) Department of Marine Science, University of Puerto Rico, Mayaguez, PR;(10) Facultad de Pesquierías y Oceanografía, Instituto de Ciencias Naturales y Exactas, Universidad Austral de Chile, Puerto Montt, Chile;(11) Department of Coastal Resources, Institute of Ecology A.C., Xalapa, Veracruz, Mexico;(12) Section of Ecology and Systematics, Cornell University, Ithaca, NY, U.S.A |
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Abstract: | Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will lead to greatly increased primary production in freshwaters and large changes in tropical freshwater communities. Increased freshwater nutrient flux will also lead to an expansion of the high production, N- and light-limited zones around river deltas, a switch from P- to N-limitation in calcareous marine systems, with large changes in the community composition of fragile mangrove and reef systems. Key information gaps are highlighted, including data on mechanisms of nutrient transport and atmospheric deposition in the tropics, nutrient and material retention capacities of tropical impoundments, and N/P coupling and stoichiometric impacts of nutrient supplies on tropical aquatic communities. The current base of biogeochemical data suggests that alterations in the N-cycle will have greater impacts on tropical aquatic ecosystems than those already observed in the temperate zone. |
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Keywords: | estuaries lakes marine nitrogen phosphorus rivers streams temperate tropics |
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