شناسه هاي افزوده :
مكرمي، علي ، همكارطرح , خداپرست، نوربخش ، همكارطرح , كيهانثاني، عليرضا ، همكارطرح , نصرالهتبار، عبداله ، همكارطرح
چكيده انگليسي :
In order to determine the impact of the new invasive ctenophore (Mnemiopsis leidyi) of the Caspian Sea, it is needed to monitor the temporal and spatial distribution as well as seasonal biomass fluctuation of this animal. At the present study, sampling was conducted in 8 transects such as Astara, Anzali, sephidroud, Tonekabon Nowshar, Babulsar, Amirabad and Bandar Torkaman. Each transect had four stations located at the points off the shore where the bottom depth was 5, 10, 20 , 50 and 100m, respectively. Ctenophore samples were collected with planktonic net and simultaneously some morphometric characteristics such as weight, length, abundance and biomass were measured. Statistical analysis was done based on the averages of year, season, location, depth and size of the M. leidyi. In 2008, mean abundance and biomass of M. leidyi were recorded 63 7 ind.m3 and 7.70 2.34 g.m3, respectively. M. leidyi abundance and biomass were ranged of 0-639 ind.m3 and 0-158 g.m3, respectively. The maximum seasonal average of abundance was 150 17 ind.m3 while the maximum biomass was 26.59 4.61.m3 in summer. There is a significant different between abundance and biomass in summer and autumn, respectively (p<0.05). Comb jelly length in autumn was smaller than in summer. Minimum M. leidyi abundance was observed in spring (4.0 0.7ind.m3) and winter (6 2ind.m3). The lowest average of seasonal biomass was observed in winter (0.50 0.07 g.m3). The maximum of M. leidyi biomass was recorded at the depth 5m of Anzali in summer 2008 with 639 ind.m3 and 158 g.m3, respectively. There was not significant different between abundance and biomass in various transects (p>0.05). The results showed that the highest abundance and biomass coincide to photic zone ( 20 m in depth) in which there is a significant different between photic zone and various layer (p<0.05). The maximum ctenophore size was recorded 55 mm in 2006 and 60 mm in 2007, in which it was 50 mm in 2008. The data of M. leidyi from 2001 to 2008 indicated that abundance and biomass of comb jelly decrease in trend. Therefore, the results showed that the M. leidyi is a superficial and littoral species in the southern Caspian Sea. Keywords:, Abundance, biomass, Mnemiopsis leidyi, Caspian Sea
كليدواژه :
Mnemiopsis leidyi , زيتوده , درياي خزر , تراكم
