Publication Date:
2021-05-19
Description:
Mnemiopsis leidyi is one the species of comb-jelly. It belongs to the Ctenophore phylum and Lobate order. It is a purely marine, free-swimming animal with a transparent jelly-like walnut-shaped body, which was transported from the Black Sea into Caspian possibly at the end of 1990s. This species is food rival of pelagic fish. It has been reported that the ctenophore caused the dramatic decrease of zooplankton and pelagic fish stock in the Black Sea. In this study, sampling on Mnemiopsis leidyi, zooplankton, phytoplankton was conducted from December 2003 to March 2005, from a total of 11 stations located along four transects (Anzali , Khazarabad, Tourkman and Gorgan Bay) by METU net in the Iranian coasts of the Caspian Sea. Clupeonella catch was done by light fishing with fishing vessel in Anzali region. The results showed that the biomass of M.leidyi had some fluctuation in different seasons and its maximum biomass was recorded in summer with a figure of 524.4±156.2 g.m2 Tourkman region and the minimum biomass was observed in winter with a figure of 5.15±1.81 g.m2 in Anzali region. Study of stomach of Mnemiopsis showed, that Acartia (belonged of Copepoda with 66 %), lamlibranchia (13 %) has the highest frequency and the lowest were Balanus nauplii, Rotatoria, Tintinnopsis and Podon polyphemoides. The maximum mean abundance of zooplankton was 29368±24318 n.m3 in winter (Anzali region) and the minimum was recorded 4170±5014 n.m3 in summer (Tourkman region). Copepoda was dominant zooplankton in the Iranian coasts of the Caspian Sea. Chrysophyta with 150000000±440000000 n.m3 and Euglenophyta with 260000±521000 n.m3 had the highest and the lowest frequency respectively in the Caspian Sea. The main foods of Clupeonella were Acartia with 80 %. The survey of stomach of Clupeonella showed that the feeding of these species was not good and the highest fullness index was recorded 220.95±314.67. These results showed, the main food item of Ctenophora and Clupeonella were Copepoda (Acartia). It seems, the impact of Mnemiopsis leidyi feeding has been the important factor in declining zooplankton populations, Clupeonella stocks, and also increasing of phytoplankton abundance.
Description:
Iranian Fisheries Science Research Institute
Description:
Published
Keywords:
Ctenophora
;
Mnemiopsis leidyi
;
Diet
;
Species
;
Phylum
;
Pelagic fishes
;
Sampling
;
Zooplankton
;
Phytoplankton
;
Acartia
;
Ctenophora
;
Population
;
Abundance
Repository Name:
AquaDocs
Type:
Report
,
Refereed
Format:
53pp.
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