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Researchers analyze the factors that enable fish to reproduce in the Gulf of Cadiz

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Credit: CC0 Public Domain Researchers from the Marine Biology Laboratory of the University of Seville, led by Professor José Carlos García Gómez, have studied the factors involved in fish reproduction and breeding in the Gulf of Cadiz. Their analysis focused on estuaries which, due to their specific conditions, created by the mixing of river and sea water, are especially favorable for the reproductive function of the species in the area.

The Guadalquivir estuary showed the highest density of early stages fish and also of macro-zooplankton (fish prey). A higher concentration of organic matter (preferential food of the macrozooplanton in the Guadalquivir), provided by a greater flow of fresh water and correlated with total suspended solids, inorganic matter and turbidity, were the most typical characteristics of the Guadalquivir. This, along with the salinity gradient, may explain its high densities of macro-zooplankton and early stages fish. In contrast, the recurrent booms of jellyfish (Blackfordia virginata) and ctenophores (Bolinopsis sp.) observed in the Guadiana and Bay of Cadiz estuaries affected their breeding capacities. The most abundant fish species in the Gulf of Cadiz, particularly in the interior of the Guadalquivir estuary, was the anchovy Engraulis encrasicolus.

The results show that the estuaries of the […]

read more here —> phys.org

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