page 1page 2page 3page 4page 5page 6page 7page 8page 9page 10page 11page 12page 13page 14page 15page 16page 17page 18page 19page 20page 21page 22page 23page 24page 25page 26page 27page 28REPORT TONATIONAL COUNCIL FOR SOVIET AND EAST EUROPEAN RESEARCHTITLE:THE IMPACT OF ALTERED RIVER FLOW ONTHE ECOSYSTEM OF THE CASPIAN SEAAUTHOR:Michael A. RozengurtJoel W. HedgpethCONTRACTOR:San Francisco State UniversityPRINCIPAL INVESTIGATOR:Michael A. RozengurtCOUNCIL CONTRACT NUMBER : 900-01DATE:December 1989The work leading to this report was supported by funds provided bythe National Council for Soviet and East European Research. Theanalysis and interpretations contained in the report are those ofthe author.This offprint is a revised and expanded version of an Interim Reportfrom the same contract distributed by the Council in July 1988 entitle d"Soviet Water Policy and its Implications for the Ecological- EconomicDestruction of the Caspian Sea".Aquatic SciencesThe Impact of Altered River Flow onthe Ecosystem of the Caspian SeaMichael A. Rozengurt and Joel W. HedgpethI.INTRODUCTIONA. Physical CharacterlsticsThe Caspian Sea lies in the world's largest inland basin,extending from 47° 43' to 54° 51' E (Figure 1). The shortestdistance between the Caspian Sea and the Black Sea basin, thenearest basin having an open connection with the Mediterraneanand through it with the Atlantic Ocean, is across the Caucasus.The northern and southern boundaries of the Caspian watershedare located between 62° N and 35° N (i.e., north of Leningradamd south of Teheran), and its area of 3.5 x 106 km' is equalto about 25% of the continental landmass of the U.S. Thisenormous basin extends from subarctic to subtropical regions.The climatological, morphometrical, and geophysical featuresof this area are responsible for the formation of the environmentof the Caspian Sea and surrounding lands extending hundredsof kilometers from its shoreline.FIGURE1.The CaspianSeawatershed (Modifiedafter Reference6.)The average surface area of the Caspian Sea (3.784 x 105km') constitutes 18% of the total area of all lakes of the world,'about five times the surface area of Lake Superior and about2.7 and 10 times the surface area of the Adriatic Sea and Seaof Azov, respectively. It is roughly equal to the size of GreatBritain (Figure 2). The volume of the Caspian Sea (78.lx10' km3) accounts for 44% of the total volume of inland lakesof the world and about 241 and 3.6 times the volume of theSea of Azov (U.S .S.R.) and the Baltic Sea, respectively. Over130 rivers and numerous streams discharge an average of almost300 km3/year into the Caspian Sea (or 6% of the total naturalrunoff in the U.S.S.R.), from which about 85% originates inthe Volga-Kama and Ural River basins and about 15% in thesouthern river drainages of the Caucasus region, the Terek,Sulak, Samur, and Kura rivers and Iranian rivers and streamsalong the southern part of the Caspian Sea (Table l).Despite the impressive morphometric characteristics of theCaspian Sea, its area constitutes only 10.8 and 27.4% of theCaspian basin and Volga watershed, respectively. Therefore,any significant changes (climatological and man induced) overthe draimage region have a strong impact on the ecologicalconditions of the Sea.The major water users im the river basins are agriculture(60%), hydroelectric power plants, industry, municipalgovernmemt, shipping, and commercialfisheries.2-10Theextensive water developments of the last decades in significantparts of six republics of the U.S .S.R. located in the Caspianwatershed (i.e., U.S.F.S.R., Azerbaijian, 38Armenia, Georgia,Kazakhstan, and Turkmenistan) and in the Iranian coastal zone(Figure 3), with an aggregate population of more than 7.5x10' people, have had deleterious effects on all aspects of theSea, its estuaries, and its fisheries.11-14B. Locatlon/GeographyThe Caspian Sea is located at the far southeastern marginof the European part of the U.S .S.R., along the boundary ofEurope and Asia. This relict sea occupies the largest continentaldepression, with a surface level about — 28 m below meanocean level.The Caspian Sea is a landlocked remnant of the TethyanSea, which was divided into several basins in the MioceneDr. Rozengurtreceived his M.S. from the Hydrometeorological In-stitute, Department of Oceanography, Moscow University, Odessa,U.S.S.R. and his Ph.D. from the Federal Oceanographic Institute,Moscow. U.S.S.R. He is currently a Senior Research Scientis1 at thePaul F. Romberg Tiburon Center for Environmental Studies, San Fran-cisco State University, Tiburon. California.Dr. Hedgpethearned hisB.A., M.A., and Ph.D. from the University of California at Berkeley.He is Professor of Oceanography Emeritus at Oregon State Universityand resides in Santa Rosa, California.1989337Reviews InFIGURE 2.The regions of the Caspian Sea. (Modified after Reference 6.)Epoch. One of these was the Ponto-Caspian basim . About1million years ago, this basin was partially divided into the twomajor water bodies named in the historic past as the Black andCaspian Sea. Recently, the Caspian Sea has undergone manygeological and geophysical transformations that gradually ledto its full isolation from the Black Sea and, therefore, the worldocean. For the last several thousand years, its climatological,hydrological, and biological characteristics have undergonesubstantial changes.The Caspian Sea is usually divided into three sections: north,middle (central), and south (Figure 2). This division is basedon morphological, physical, chemical, and biological peculiar-ities in the regions considered. 5-7In turn, the North Caspian isdivided into two parts — western and easternwhich differim terms of morphometric characteristics and natural regimes.The western part is deeper than the eastern, although theirsurface areas are almost equal. Their average and maximumdepths are: 5.6 and 25 m amd 3.3 and 9In,respectively.'Correspondingly, the western region comprises 63% of the totalvolume of the North Caspian; it is used for shipping (throughthe deep Volga-Caspian canal) and serves as a major historicalroute for migration of anadromous fish (Bakhtemir branch).The North and Middle Caspian are separated by a submergedpart of the Mangyschlak Peninsula, and the Middle and SouthCaspian are separated by the shoal of the Apsheron Penimsula(near the city of Baku).Of the 91,942 km2of the North Caspian, 90,129 km2 isdefined as shoal area. This is the most important and productivearea of