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GLIN==> SEMINAR - Ann Arbor



NOAA-University of Michigan Great Lakes Seminar Series

SEMINAR

Monday, June 4, 2007

10:30 am, Main Conference Rm

Great Lakes Environmental Research Lab
2205 Commonwealth Blvd
Ann Arbor, MI

For directions:
http://www.glerl.noaa.gov/facil/triptik.html


Title: 
"Biodiversity of the Aral Sea and possible ways to rehabilitate and
conserve its remnant water bodies"

Speaker: 
Dr. Nick Aladin
Zoological Institute of the Russian Academy of Science
St. Petersburg, Russia

Abstract:
 
The Aral Sea was the 4th largest lake in the world by water surface area
in 1960. At that time its area was 67,499 km2 (Large Aral 61,381 km2,
Small Aral 6,118 km2) and its volume was 1,089 km3 (Large Aral 1,007
km3, Small Aral 82 km3). The Aral Sea was +53.4 m above ocean level with
maximum depth 69 m. It was a slightly saline lake with average salinity
about 10 g/l. The Aral Sea was inhabited by about 12 species of fishes
and about 150 species of free-living invertebrates excluding Protozoa
and small-size Metazoa. Since 1960 the Aral Sea has steadily become
shallower, owing overwhelmingly to water withdrawals upstream for
irrigation. In January 2006 the Aral was around 17000 km2 (25% of 1960),
with a volume of 108 km3 (10% of 1960). The Large Aral was 14,325 km2
(23% of 1960) and had a volume around 81 km3 (8% of 1960). Salinity of
the Large Aral ranged from 70+ to more than 100 g/l. The values for the
Small Aral were 3000+ km2 (~50% of 1960), 21 km3 (~26% of 1960), and
average salinity about 13 g/l.

Prior to the 1920s, the following aboriginal free-living animals were
present: Fishes – 12, Coelenterata – 1, Turbellaria – 12, Rotatoria –
58, Oligohaeta – 10, Cladocera – 14, Copepoda – 7, Harpacticoida – 15,
Ostracoda – 11, Malacostraca – 1, Hydracarina – 7, Bivalvia – 9,
Gastropoda – 3. Total – 160. Protozoa and some other small Metazoa are
not included. Due to intended and accidental introductions that started
in the 1920s, the number of free-living animals grew. In the Aral Sea
the following new fishes and invertebrates introduced by man appeared:
fishes – 21, Mysidacea – 5, Decapoda – 3, Copepoda – 3, Polychaeta – 1,
Bivalvia – 4. Total – 37. 
Until 1961 the shape and salinity of the Aral Sea hadn’t changed
significantly since the middle of the 19th century. 

Since the end of 1980’s, when the level dropped by about 13 m and
reached about +40 m, the Aral Sea divided into the Large and Small Aral
with area 40,000 km2 (60% of 1960); volume 333 km3 (33% of 1960);
salinity 30 g/l (3 times higher than in 1960). In both new lakes
salinity increased and under these new conditions the following
free-living animals survived: Fishes – 10; Rotatoria – 3; Cladocera – 2;
Copepoda – 2; Ostracoda – 1; Decapoda – 2; Bivalvia – 2; Gastropoda –
>2; Polychaeta – 1. Total: >25.

Since the Aral Sea division its volume has decreased from 1000 km3 to
400 km3 by year 2001 and to 108 km3 by year 2005 with the Large Aral Sea
volume (2005) at 85 km3 and the Small Aral Sea volume (2005) at 23 km3.
After the Aral Sea division salinity in the Large Aral continued to rise
and reached 90 g/l (western part) and 160 g/l (eastern part) in 2005,
while in the Small Aral it decreased and reached 17 g/l in 2005.

Four main approaches for conservation and rehabilitation of Aral Sea and
its ecosystems were discussed in Geneva in September 1992 (UNEP meeting)
and have since been initiated:
1. Conservation and rehabilitation of Small Aral;
2. Conservation and rehabilitation of Large Aral;
3. Conservation and rehabilitation of delta and deltaic water bodies of
Syr Darya;
4. Conservation and rehabilitation of delta and deltaic water bodies of
Amu Darya.

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