State of Mnemiopsis leidyi (Ctenophora: Lobata) and mesozooplankton in Iranian waters of the Caspian Sea during ۲۰۰۸ in comparison with previous surveys
Publish place: Iranian Journal of Fisheries Sciences، Vol: 11، Issue: 4
Publish Year: 1391
نوع سند: مقاله ژورنالی
زبان: English
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شناسه ملی سند علمی:
JR_JIFRO-11-4_003
تاریخ نمایه سازی: 22 اسفند 1400
Abstract:
Mnemiopsis leidyi which was accidentally
introduced into the Caspian Sea in ۱۹۹۹ and
since then has colonized extensively. The horizontal distribution of M. leidyi and dominant mesozooplankton
species was investigated in the south western Caspian Sea during February, May,
July and November ۲۰۰۸. The average number and biomass of M. leidyi were in the same range (ca ۲۰۰ individuals.m-۳
(۲۰۰۰ ind.m-۲) and ۱۶ g wet weight.m-۳
(۱۸۰ g.m-۲) in comparison with previous surveys. As in previous
years the population consisted mainly of individuals <۱ cm. The decline in
mesozooplankton species observed since ۱۹۹۶ continued in ۲۰۰۸. Only two species
of the previously recorded ۲۴ Cladocera
species were found in ۲۰۰۸. Of five Copepoda species recorded in ۱۹۹۶, only one,
Acartia tonsa, was found in ۲۰۰۸ and
even here adult individuals have reduced ۳-fold since ۱۹۹۶. Bivalve larvae have declined by one
order of magnitude since ۱۹۹۶. Among the dominant species, only the numbers of
Cirripedia larvae and in part the numbers of Pleopis polyphemoides
(Cladocera) were in the same range as in ۱۹۹۶.
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