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    On the status of mesopelagic fish (myctophidae) in the Southern Ocean ecosystem

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    A.N. Kozlov (Russia)
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    Analysis and synthesis of results of Russian and foreign research into the trophic relationships of myctophids demonstrate that this group of mesopelagic fish plays a significant role in the community of marine organisms of the Southern Ocean. The trophic status of myctophids has been determined - they are zooplankton-eaters who consume a considerable amount of meso and macroplankton which determines their high abundance and biomass. Thus, according to a preliminary estimate the yearly consumption of zooplankton by Electrona carlsbergi, the most numerous species of myctophid, ranges from 196 to 364 million tonnes. According to its position in the trophic system of the Southern Ocean, myctophids occupy the third trophic level and are consumers of the second order. Myctophids play a major role as producers, in turn guaranteeing the production of organisms at higher trophic levels (certain species of squid, notothenoids, sea birds and mammals). The large deepwater squid Mesonychoteuthis hamiltoni each year consumes approximately 48 to 57 million tonnes of myctophids. A summary table of the trophic relationships of myctophids is presented, based on general patterns of energy transformation from one trophic level to the next.