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Effect of Danube River dam on Black Sea biogeochemistry and ecosystem structure

Abstract

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 loads, and thus riverine ecosystems, evidence for significant effects in open coastal waters is sparse4–6. Here we present long-term data sets of water and nutrient discharge from the River Danube to the Black Sea. These data reveal a reduction in the dissolved silicate load of the river by about two-thirds since dam constructions in the early 1970s. A concomitant decrease in wintertime dissolved silicate concentrations by more than 60% was observed in central Black Sea surface waters. The consequent changes in silicon to nitrogen ratio of the Black Sea nutrient load appear to be larger than those caused by eutrophication alone, and seem to be responsible for dramatic shifts in phytoplankton species composition from diatoms (siliceous) to coccolithophores and flagellates (non-siliceous). Our results strongly suggest that the damming of the Danube has been instrumental in causing the observed changes in Black Sea surface waters3,7–9, and that the large number of dams in operation around the world today could similarly affect the food web structure and biogeochemical cycling in coastal seas.

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References

  1. Cociasu, A., Dorogan, L., Humborg, C. & Popa, L. Long-term ecological changes in the Romanian coastal waters of the Black Sea. Mar. Pollut. Bull. 32, 32–38 (1996).

    Article  CAS  Google Scholar 

  2. Mee, L. D. The Black Sea in a crisis: a need for concerted international action. Ambio 21, 278–285 (1992).

    Google Scholar 

  3. Murray, J. W. et al. Unexpected changes in the oxic/anoxic interface in the Black Sea. Nature 338, 411–413 (1989).

    Article  ADS  CAS  Google Scholar 

  4. Admiraal, W., Breugem, P., Jacobs, D. M. L. H. A. & De Ruyter van Steveninck, E. D. Fixation of dissolved silicate and sedimentation of biogenic silicate in the lower river Rhine during diatom blooms. Biogeochemistry 9, 175–185 (1990).

    Article  CAS  Google Scholar 

  5. Bennekom van, A. J. & Salomons, W. in River Inputs to Ocean Systems (eds Martin, J.-M., Burton, J. D. & Eisma, D.) 33–51 (UNEP, IOC, SCOR, United Nations, New York, 1981).

    Google Scholar 

  6. Conley, J. D., Schelske, C. L. & Stroemer, E. F. Modification of the biogeochemical cycle of silica with eutrophication. Mar. Ecol. Prog. Ser. 101, 179–193 (1993).

    Article  ADS  CAS  Google Scholar 

  7. Codispoti, L. A., Friederich, G. E., Murray, J. W. & Sakamoto, C. M. Chemical variabiity in the Black Sea: Implications of continuous vertical profiles that penetrated the oxic/anoxic interface. Deep-Sea Res. 38, 691–710 (1991).

    Article  ADS  Google Scholar 

  8. Falkner, K. K., O'Neill, D. J., Todd, J. F., Moore, W. S. & Edmond, J. M. Depletion of barium and radium-226 in Black Sea waters over the past thirty years. Nature 350, 491–494 (1991).

    Article  ADS  CAS  Google Scholar 

  9. Tugrul, S., Basturk, O., Saydam, C. & Yilmaz, A. Changes in the hydrochemistry of the Black Sea inferred from density profiles. Nature 359, 137–139 (1992).

    Article  ADS  CAS  Google Scholar 

  10. Martin, J.-M., Burton, J. D. & Eisma, D. (eds) River Inputs to Ocean Systems (UNEP, IOC, SCOR, United Nations, New York, 1981).

  11. Nixon, S. W. Coastal eutrophication: a definition, social causes and future concerns. Ophelia 41, 199–219 (1995).

    Article  Google Scholar 

  12. Smayda, T. J. in Toxic Marine Phytoplankton (eds Graneli, E., Sundström, B., Edler, L. & Anderson, D. M.) 29–41 (Elsevier Science, New York, 1990).

    Google Scholar 

  13. Officer, C. B. & Ryther, J. H. The possible importance of silicon in the marine eutrophication. Mar. Ecol. Prog. Ser. 3, 83–91 (1980).

    Article  ADS  CAS  Google Scholar 

  14. Turner, R. E. & Rabalais, N. N. Coastal eutrophication near the Mississippi river delta. Nature 368, 619–621 (1994).

    Article  ADS  Google Scholar 

  15. Popa, A. Liquid and sediment inputs of the Danube River into the north-western Black Sea. Mitt. Geol.-Paläontol. Inst. Univ. Hamburg 74, 137–149 (1993).

    Google Scholar 

  16. Liss, P. S. in Estuarine Chemistry (eds Burton, J. D. & Liss, P.S.) 118–127 (Academic, New York, 1976).

    Google Scholar 

  17. Edwards, A. M. C. & Liss, P. S. Evidence for buffering of dissolved silicon in fresh waters. Nature 243, 341–342 (1973).

    Article  ADS  CAS  Google Scholar 

  18. Almazov, N. M. Stok rastverennykh solej i biogennykh veschestv kotorye vynoseatsya rekami USSR. v. Chernoe More. Naukovi Zapiski Odes. Biol. St., Kiev 3, 99–107 (1961).

    Google Scholar 

  19. Bodeanu, N. Structure et dynamique de l'algoflore unicellulaire dans les eaux du littoral roumaine de la Mer Noire. Cercetari Marine 20/21, 19–250 (1987–88).

    Google Scholar 

  20. Humborg, C. Untersuchungen zum Verbleib der Nährstoffrachten der Donau. Ber. Inst. Meereskunde, Kiel 264, (1995).

  21. Hay, B. J. Particle flux in the western Black Sea in the present and ove the last 500 years: Temporal variatibility, sources, transport mechanisms. Thesis, Woods Hole Oceanographic Inst. (1987).

  22. Brzezinski, M. A. The Si:C:N ratio of marine diatoms: interspecific variability and effects of some environmental variables. J. Phycol. 21, 347–357 (1985).

    Article  CAS  Google Scholar 

  23. Oguz, T. et al. Circulation in the surface and intermediate layers of the Black Sea. Deep-Sea Res. 40, 1597–1612 (1993).

    Article  Google Scholar 

  24. Brewer, P. G. Hydrographic and Chemical Data from the Black Sea 75–66 (Tech. Note, Woods Hole Oceanogr. Inst., Woods Hole, 1971).

    Google Scholar 

  25. Tolmazin, D. Changing coastal oceanography of the Black Sea. I: The northwestern shelf. Prog. Oceanogr. 15, 217–276 (1985).

    Article  ADS  Google Scholar 

  26. Goudi, A. The Human Impact on the Natural Environment 177–234 (MIT Press, Cambridge, MA, 1994).

    Google Scholar 

  27. Hays, J. D., Imbrie, J. & Shackleton, N. J. Variations in the earth's orbit: pace maker of the ice ages. Science 194, 1121–1132 (1976).

    Article  ADS  CAS  Google Scholar 

  28. Mesko, A. Digital Filtering Applications in Geophysical Exploration for Oil (Wiley, New York, 1984).

    Google Scholar 

  29. Koroleff, F. in Methods of Seawater Analysis (eds Grasshoff, K., Erhardt, M. & Kremling, K.) 125–187 (Verlag Chemie, Weinheim, 1983).

    Google Scholar 

  30. Chirila, V. in Ecologie Marina Vol. 1 (ed. Bacescu, M.) 139–185 (Academiei Rebulicii Socialiste Romania, Bucuresti, 1965).

    Google Scholar 

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Humborg, C., Ittekkot, V., Cociasu, A. et al. Effect of Danube River dam on Black Sea biogeochemistry and ecosystem structure. Nature 386, 385–388 (1997). https://doi.org/10.1038/386385a0

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