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Zooplankton transfer through the Gibraltar Strait and peculiarities of its taxonomic composition and distribution in adjacent areas

V. N. Greze, A. V. Kovalev, E. P. Baldina, O. K. Bileva and A. A. Shmeleva

Institute of Biology of the Southern Seas, 2 Nahimov Avenue, Sevastopol 99011, Ukraine

Summary

Zooplankton investigations made in August 1970 and September 1974 on R/V "Mikhail Lomonosov" and "Akademic Vernadsky" in the Gibraltar Strait and adjacent regions of the Atlantic and the Alboran Sea supplemented the list of species known from these areas by 104 new ones. The specific diversity of copepods was twice more on the Mediterranean side of Gibraltar than on the Atlantic side. In different layers in 0-300 m limits the indices of diversity after MARGALEF varied from 3.22 to 5.33 in the Alboran Sea and from 1.23 to 2.47 in the Atlantic.
The mechanism of zooplankton accumulation in the Alboran Sea due to existing in the Strait system of countercurrents and diurnal vertical migrations of organisms is discussed. A drastic elimination of zooplankton penetrating the Atlantic with undercurrent was shown on the western slope of the Gibraltar Strait threshold.
After hydrological data on water exchange through the Strait and according to observed quantities of zooplankton its transfer from the Atlantic Ocean to the Mediterranean Sea was estimated, in August-September as about 56 000-57 000 tons of biomass and opposite outflow Mediterranean Sea with undercurrent - about 17 000 tons monthly.

Investigetion Pesquera. - 1985. - Vol. 49, No 1. - pp. 3-13

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