Marine oligotrophication due to fine sediments and nutrient starvation caused by anthropogenic sediment and water retention in large rivers: the Nile damming case

Frontiers in Marine Science

Marine Science

Daniela Ransby¹  Ahuva Almogi-Labin²  Amir Sandler²  Helmut W. Fischer³  Barak Herut⁴  Tamar Guy-Haim⁴  Timor Katz⁴  Simona Avnaim-Katav⁴ 

[1] Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany;Geological Survey of Israel, Jerusalem, Israel;Institute of Environmental Physics, University of Bremen, Bremen, Germany;Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel;

关键词: nutrients;    sediments;    anthropogenic;    dams;    foraminifera;    Mediterranean Sea;    oligotrophic;    radionuclides;   

DOI  :  10.3389/fmars.2023.1226379

 received in 2023-05-21, accepted in 2023-09-18,  发布年份 2023

来源: Frontiers

【 摘 要 】

In the last two centuries, human activities have radically reduced the transport of suspended sediment and water to marine systems, mainly in the northern hemisphere, while complete sediment retention has been reported for the Nile River after the construction of the Aswan High Dam (AHD). Here, we focused on changes in the inner-shelf sediments most exposed to the pre-AHD flood plume in the distal part of its littoral cell as a predictor of the ecological response to large river fragmentation. Substantial reductions in fine (15-40%) and increases in coarse (~8 fold) sediment accumulation rates, increases in CaCO3 (~50%), decreases in autochthonous and total organic carbon (OC), and changes in the benthic foraminiferal assemblage toward more OC-sensitive species suggest an enhanced oligotrophication trend. The reduced nutrient fluxes and OC accumulation, and the coarsening of the shelf sediments inhibit the retention of “blue” carbon. Combined with fast climate warming and salinization, river fragmentation may have essential implications for the Eastern Mediterranean ecosystem via benthic oligotrophication processes.

【 授权许可】

Unknown   
Copyright © 2023 Herut, Guy-Haim, Almogi-Labin, Fischer, Ransby, Sandler, Katz and Avnaim-Katav