Phosphorus accumulates faster than nitrogen globally in freshwater ecosystems under anthropogenic impacts

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Underwater image of a lake. Photo by Pexels

Human activities have drastically accelerated Earth’s major biogeochemical cycles, altering the the nitrogen (N) and phosphorus (P) cycles.

Combined effects of cumulative nutrient inputs and biogeochemical processes that occur in freshwater under anthropogenic eutrophication could lead to myriad shifts in N:P stoichiometry in global freshwater ecosystems, but this was not yet well-assessed.

In a new study in the journal Ecology Letters researchers from Peking University and CREAF-CSIC evaluated the characteristics of N and P stoichiometries in bodies of freshwater and their herbaceous macrophytes across human-impact levels, regions and periods.

Freshwater and its macrophytes had higher N and P concentrations and lower N:P ratios in heavily than lightly human-impacted environments, further evidenced by spatiotemporal comparisons across eutrophication gradients. N and P concentrations in freshwater ecosystems were positively correlated and N:P ratio was negatively correlated with population density in China.

“Our findings indicate that anthropogenic eutrophication might thus shift aquatic ecosystems from a state of predominant P limitation to being potentially limited or co-limited by N, or by other factors such as light, especially in rapidly developing regions such as China” said Zhengbing Yan, researcher from Peking University.

“These results indicate a faster accumulation of P than N in human-impacted freshwater ecosystems, which could have large effects on the trophic webs and biogeochemical cycles of estuaries and coastal areas by freshwater loadings, and reinforces the importance of rehabilitating these ecosystems”, said Prof. Josep Penuelas from CREAF-CSIC Barcelona.

Citation: Yan, Z., Han, W., Penuelas, J., Sardans, J., Elser, J.J., Du, E., Fang, J. 2016. Phosphorus accumulates faster than nitrogen globally in freshwater ecosystems under anthropogenic impacts. Ecology Letters 19, (2016), 1237-1246. doi: 10.1111/ele.12658