Dietary overlap between invasion ctenophora (M . leidyi ) and anchovy(C. engrauliformis) in the southern parts of Caspian Sea
Summer 2004, Volume 1 - Number2 (7 صفحه - از 89 تا 95)
Mnemiopsis leidyi, native to America, Invaded the Caspian Sea in 1999. By the end of 2000, the entire seawas accupied with them. In parallel, a sharp decline in pelagic fish such accurrred.This survey was studied therelationship between the M. leidyi and this decline. Dietary analysis was conducted on anchovy sprat(Clupeonnela engrauliformis) and M. leidyi from August 2001 to October 2002 in the coastal water in thesouthern parts of Caspian Sea, in Iran. M. leidyi was caught by plankton net, (the mesh size ~5 mm), at threedepth at 5, 10 and 15 m . Sprat was caught by fisheries boat at Babolasar fishery harbor. Samples were not fixedin M. leidyi common fixative, 96% Ethanol were used. The Schoener index analysis reflected a similar dietcomposition of both species, with an critical level of overlap (>89 in Babolsar samples and >84 in Noushaharsamples). This competition is one of the reasons for the decline of anchovy sprat. also, the results show M. leidyiis feeding on fish eggs, but effects of this factor on anchovy population is less than feeding competition.Controlling of M. leidyi population is reducing the pressure of its invasion and the effective approach isintroduces a predator to the Caspian Sea.
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