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Effect of Mnemiopsis leydei on biomass of five commercial fish species in the southern part of the Caspian Sea
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Hasan Fazli   , Hasan Nasrolahzadae , Nima Porrang , Abolghasem Rohi , Fereshteh Eslami |
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Abstract: (5232 Views) |
| In recent decades, due to fluctuations in Seae water levels, environmental
pollutions, and invader species invasion, the ecosystem of the
Caspian Sea has been changed. In this study, assessing impact on ecosystem
functions was conducted according to the new invader species
(Mnemiopsis leidyi) using biomass of commercial fish species during
three periods: 1996-2000, 2001-2006 and 2007-2011 in three phases
of the invasion: establishment, expansion and adjustment, respectively.
The results showed that the total biomass of anchovy Kilka
(Clupeonella engrauliformis) declined from 185000 tons in 1996 to
158000 tons in 1999 and collapsed to 200 tons in 2011. Also the biomass
of big eye kilka (C. grimmi) decreased from 50000 tons in 1996
to less than 6000 tons in 2001. But the biomass of common kilka (C.
cultriventris) had an increasing trend from 20000 tons in 1996 to more
than 110000 tons in 2009. The biomass of two benthic feeder species
(Rutilus frisii kutum and Liza aurata) had the same trend changes as
first the biomasses had an increasing and then decreasing trend. During
three periods, ecosystem functions had changes. The ecosystem
functions were shifted E0 (No impact) in first period to E2 (moderate
impact) and E3 (strong impact) in the second and third periods. Loss
functions of two keystone species (anchovy and big eye Kilka) could
causes the sharp decline in upper layer of food web chain, i.e. sturgeons
and Caspian seal in the Caspian Sea. |
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| Keywords: Mnemiopsis leydi, Ecosystem function, Fish biomasses, Caspian Sea |
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Full-Text [PDF 735 kb]
(3023 Downloads)
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Type of Study: Research |
Subject:
Fisheries
Received: 2015/10/10 | Accepted: 2015/10/10 | Published: 2015/10/10
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