Silicon Retention in River Basins: Far-reaching Effects on Biogeochemistry and Aquatic Food Webs in Coastal Marine Environments

  title={Silicon Retention in River Basins: Far-reaching Effects on Biogeochemistry and Aquatic Food Webs in Coastal Marine Environments},
  author={Christoph Humborg and Daniel J. Conley and Lars Rahm and Fredrik Wulff and Adriana Cociasu and V. Ittekkot},
Abstract Regulation of rivers by damming as well as eutrophication in river basins has substantially reduced dissolved silicon (DSi) loads to the Black Sea and the Baltic Sea. Whereas removal of N and P in lakes and reservoirs can be compensated for by anthropogenic inputs in the drainage basins, no such compensation occurs for DSi. The resulting changes in the nutrient composition (DSi:N:P ratio) of river discharges seem to be responsible for dramatic shifts in phytoplankton species… 
Riverine transport of biogenic elements to the Baltic Sea ? past and possible future perspectives
The paper reviews critical processes for the land-sea fluxes of biogenic elements (C, N, P, Si) in the Baltic Sea catchment and discusses possible future scenarios as a consequence of improved sewage
Decreased Silica Land–sea Fluxes through Damming in the Baltic Sea Catchment – Significance of Particle Trapping and Hydrological Alterations
We tested the hypothesis that reservoirs with low water residence time and autochthonous production influence river biogeochemistry in eutrophied river systems draining cultivated watersheds. The
The silica-carbon biogeochemical cycle in the Bohai Sea and its responses to the changing terrestrial loadings
Abstract. Silicon (Si) and carbon (C) play key roles in the river and marine biogeochemistry. The Si and C budgets for the Bohai Sea were established on the basis of measurements at a range of
Verification of the Silica Deficiency Hypothesis Based on Biogeochemical Trends in the Aquatic Continuum of Lake Biwa– Yodo River–Seto Inland Sea, Japan
Investigation of the aquatic continuum composed of Lake Biwa, the Yodo River, and the Seto Inland Sea, Japan, showed that the silica was retained both in the lake and nearby the estuary, suggesting the global significance of this hypothesis.
Verification of the silica deficiency hypothesis based on biogeochemical trends in the aquatic continuum of Lake Biwa-Yodo River-Seto Inland Sea, Japan.
The silica deficiency hypothesis holds that increases of still waters caused by hydraulic alterations and high nitrogen (N) and phosphorus (P) discharges enhance the growth of freshwater diatoms,
Global Dam‐Driven Changes to Riverine N:P:Si Ratios Delivered to the Coastal Ocean
River damming alters nutrient fluxes along the land‐ocean aquatic continuum as a result of biogeochemical processes in reservoirs. Both the changes in riverine nutrient fluxes and nutrient ratios
Impact of human disturbance on the biogeochemical silicon cycle in a coastal sea revealed by silicon isotopes
Biogeochemical silicon (Si) cycling in coastal systems is highly influenced by anthropogenic perturbations in recent decades. Here, we present a systematic study on the distribution of stable Si
Coupled biogeochemical cycles: eutrophication and hypoxia in temperate estuaries and coastal marine ecosystems
Nutrient fluxes to coastal areas have risen in recent decades, leading to widespread hypoxia and other ecological damage, particularly from nitrogen (N). Several factors make N more limiting in


Effect of Danube River dam on Black Sea biogeochemistry and ecosystem structure
Rivers contribute significantly to the pollution and eutrophication that have caused drastic changes to the ecosystem of the Black Sea1–3. Although damming is known to affect riverborne nutrient
Coastal eutrophication near the Mississippi river delta
CHANGES in delivery of river-borne nutrients such as dissolved phosphate, nitrate and silicate, owing to land-use changes and anthropogenic emissions, are known to result in eutrophication1— enhanced
Coastal eutrophication in relation to atmospheric nitrogen deposition: Current perspectives
Recent increases in toxic and non-toxic phytoplankton blooms in these waters may be linked to accellerating nutrient loading at the land-sea interface, which may play a central role in mediating “new” production in coastal oceans downwind of emissions.
Time series analysis of nutrient inputs to the Baltic Sea and changing DSi:DIN ratios
Decline in the DSi:DIN ratio in the Baltic Sea from 1970 to 1990 indicates that spring diatom growth may become DSi limited in the near future, as the optimal DS i:Din ratio for diatom Growth is approximately 1:l, while the Baltic proper is generally assumed to be N limited.
It is concluded that a reduction by at least half of external N and P inputs to the Baltic sea, and of N input to the Kattegat is needed to mitigate the negative effects of eutrophication.
Fluctuating silicate:nitrate ratios and coastal plankton food webs.
  • R. E. Turner, N. Qureshi, J. Cope
  • Environmental Science
    Proceedings of the National Academy of Sciences of the United States of America
  • 1998
This coastal ecosystem appears to be a pelagic food web dynamically poised to be either a food web composed of diatoms and copepods or one with potentially disruptive harmful algal blooms, directed between these two ecosystem states by Mississippi River water quality, which is determined by land-use practices far inland.
Changes in the hydrochemistry of the Black Sea inferred from water density profiles
DURING the past two decades, catastrophic changes have occurred in the Black Sea ecosystem: the influx of pollution from the major rivers has caused intense eutrophication at the northwest coastal
Long-term ecological changes in Romanian coastal Waters of the Black Sea
Environmental changes of the last three centuries indicated by siliceous microfossil records from the southwestern Baltic Sea
Four short sediment cores from the southwestern Baltic Sea were analysed with respect to their content of siliceous microfossils. The aim was to detect and date changes in the composition of the