Ecosystem‐level effects of re‐oligotrophication and N:P imbalances in rivers and estuaries on a global scale

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

Modelling the potential for local management practices to offset climate change impacts on freshwater macroinvertebrate communities

“…Furthermore, between Thames at Oxford and Thames at London the trends in macroinvertebrate responses are reversed by the P removal strategy, as absolute reductions in P and associated improvements in water quality build up along the catchment. This reinforces the idea that although climate change is predicted to have widespread impacts on water quality that will build up along catchments, local land-use practices and re-oligotrophication will still be extremely important in determining the realised ecological status of freshwater ecosystems (Ibáñez et al, 2023;Vaughan & Gotelli, 2019).…”

“…While agricultural intensification was not predicted to impact macroinvertebrate responses, the P removal strategy had a very large effect that was able to offset the impacts of even the more severe climate change scenario. These results add to the growing body of evidence that local land-use practices can either mask or counteract the direct impacts of climate change (Durance & Ormerod, 2009;Ibáñez et al, 2023;Kuemmerlen et al, 2015;Morris et al, 2022;Vaughan & Gotelli, 2019). Chlorophyll-a (resulting from algal growth following eutrophication).…”

Gestión socioambiental y estrategias para el control de especies macrófitas invasoras en embalses: perspectivas nacionales y regionales

“…(C. Ibáñez et al, 2023;I. Ibáñez et al, 2021) Esta tabla proporciona una visión general de las diversas formas en que las macrófitas acuáticas pueden ser aprovechadas de manera sostenible para beneficio humano y ambiental.…”

Implications of Anthropic Activities in the Catchment Area of a Temporary Mediterranean Wetland Complex in the South of Spain

“…Therefore, phosphate content in detergent was reduced by law at the EU level [29]. This measure enabled a worldwide reduction in anthropogenic phosphate spills in the last decade, especially in high-income countries [30]. Although relative limitation by phosphate occurs, the phosphate concentrations observed in the eutrophic and hypertrophic wetlands (TP > 177 mg L −1 ; DIP > 9.65 mg L −1 ) are far from being limiting for algal growth.…”