Ecosystem-level effects of re-oligotrophication and N:P imbalances in rivers and estuaries on a global scale
Ibáñez, Carles (University of Maryland)
Caiola, Nuno (Technological Centre of Catalonia. Department of Climate)
Barquín, José (Universidad de Cantabria)
Belmar, Oscar (Institut de Recerca i Tecnologia Agroalimentàries)
Benito-Granell, Xavier (Institut de Recerca i Tecnologia Agroalimentàries)
Casals, Frederic (CTFC-Forest Science and Technology Centre of Catalonia)
Fennessy, Siobhan (Kenyon College)
Hughes, Jocelyne (University of Oxford)
Palmer, Margaret (University of Maryland)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Romero, Estela (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Sardans i Galobart, Jordi (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Williams, Michael (University of Maryland Center for Environmental Science)

Date:	2023
Abstract:	Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two-three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides phytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc. , have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the other hand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e. g. , lower dominance of macrophytes) or estuaries (e. g. , limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries.
Note:	Altres ajuts: by the Catalan Government through the funding grant ACCIÓ-Eurecat (Project AquaSCI-2022).
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Cascading effects ; Chlorophyll ; Ecosystem shift ; Oligotrophication ; Phosphorus ; Primary producers ; Running waters ; Stoichiometry
Published in:	Global change biology, Vol. 29, Issue 5 (March 2023) , p. 1248-1266, ISSN 1365-2486

DOI: 10.1111/gcb.16520
PMID: 36366939

19 p, 9.3 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Articles > Research articles
Articles > Published articles