The Impact of Trophic Status and Climate Change on the Benthic Community in Lake Sevan, Armenia

Yıl 2019, Cilt: 7 Sayı: 2, 43 - 62, 27.12.2019

Karen Jenderedjian Susanna Hakobyan M. Scott Demyan

Öz

Artificial
water level drop and eutrophication radically changed the ecosystem of Lake
Sevan. During 1928-2018 the Values of Primary Production of the Lake (VPPL =
phytoplankton production + phytobenthos production) and varied energy
equivalent of biomass (B_Z) and gross production (P_Z) of
zoobenthos varied by a factor of 10 or more. Strong positive dependencies of
both B_Z and P_Z on VPPL were found. Similar dependencies
were also revealed separately for Chironomidae, Oligochaeta and detritivores. Regression
equations of dependencies were then used to estimate the development of
zoobenthos under different trophic conditions: oligotrophic, mesotrophic and
eutrophic. Significant climate change was observed over the past 80 years. From
1935–2012, the annual mean temperature in Armenia increased by 1.03°C. The
climate change projections for Lake Sevan are an
increase of mean annual water temperature of 0.5°C by
2030, 2°C by 2070 and
4°C by 2100 against the baseline of 9.1°C. Observations showed that in Lake Sevan an order
of magnitude increase of VPPL results in an increase of
the gross production of macrozoobenthos by factor of 7. Meanwhile, a 4°C temperature increase is
estimated to increase the rate of zoobenthos production (P_Z/B_Z)
only by a factor of 2. Therefore, the most effective measure required for the
mitigation of climate change effects on the Lake Sevan ecosystem is keeping the
trophic status of the lake as low as possible, and should include:

- runoff
prevention of of organic materials from agricultural, industrial and domestic
origins into Lake Sevan;

-
prohibition of any activity that involves the use of organic phosphorus and
organic nitrogen directly in the lake.

Destekleyen Kurum

Caucasus Mountain Forum 2019, 30 October - 1 November, 2019 in Ankara, Turkey

Proje Numarası

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Teşekkür

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The Impact of Trophic Status and Climate Change on the Benthic Community in Lake Sevan, Armenia

Öz

Artificial
water level drop and eutrophication radically changed the ecosystem of Lake
Sevan. During 1928-2018 the Values of Primary Production of the Lake (VPPL =
phytoplankton production + phytobenthos production) and varied energy
equivalent of biomass (B_Z) and gross production (P_Z) of
zoobenthos varied by a factor of 10 or more. Strong positive dependencies of
both B_Z and P_Z on VPPL were found. Similar dependencies
were also revealed separately for Chironomidae, Oligochaeta and detritivores. Regression
equations of dependencies were then used to estimate the development of
zoobenthos under different trophic conditions: oligotrophic, mesotrophic and
eutrophic. Significant climate change was observed over the past 80 years. From
1935–2012, the annual mean temperature in Armenia increased by 1.03°C. The
climate change projections for Lake Sevan are an
increase of mean annual water temperature of 0.5°C by
2030, 2°C by 2070 and
4°C by 2100 against the baseline of 9.1°C. Observations showed that in Lake Sevan an order
of magnitude increase of VPPL results in an increase of
the gross production of macrozoobenthos by factor of 7. Meanwhile, a 4°C temperature increase is
estimated to increase the rate of zoobenthos production (P_Z/B_Z)
only by a factor of 2. Therefore, the most effective measure required for the
mitigation of climate change effects on the Lake Sevan ecosystem is keeping the
trophic status of the lake as low as possible, and should include:

- runoff
prevention of of organic materials from agricultural, industrial and domestic
origins into Lake Sevan;

-
prohibition of any activity that involves the use of organic phosphorus and
organic nitrogen directly in the lake.

Anahtar Kelimeler

trophic status, zoobenthos, climate change, temperature increase

Proje Numarası

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Kaynakça

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