Myctophids in the diet of Antarctic predators
The aim of the present study is to review published data on the diet of various top predators (birds, seals, whales, fish and squids) in order to help evaluate the importance of myctophids in their diets. This review covers publications for the period since 1984-85 to the present. In total, over 50 publications contained some information on the myctophid component of the diet of Antarctic predators. Myctophids were found in the diet of one species of squid, 18 species of fish (Nototheniidae - eight, Channichthyidae - seven, Bathydraconidae - two and Rajidae - one), 18 species of birds (penguins - seven, albatrosses - four, petrels - five, prions - one and cormorants - one) and two species of seals. Myctophids in the diet of predatory species are represented by 16 species of genera Krefftichthys (one species), Protomyctophum (four species), Electrona (five species), Metelectrona (one species) and Gymnoscopelus (four species). However, the total number of species may be underestimated because identification of myctophids in predator food samples is still difficult. Many species of fish, birds and seals take myctophids opportunistically in addition to their staple diet. Penguins have the largest proportion of myctophids in their diet. The king penguin in the Antarctic Polar Front area of the Indian Ocean is the only one specialist predator on myctophids. The Bathydraconidae fish, Gynmodraco acuticeps, from the Kosmonavtov Sea (Indian Ocean sector) may be the second most important predator of myctophids. The occurrence of myctophids in the diet of predatory species appears to be highly variable though there are insufficient data to evaluate this. It is obvious that myctophids are widespread in diets of many Antarctic predators. More quantitative studies on as many as possible species of predators are required in order to assess the role of myctophids in the Antarctic ecosystem. Information on the diet of myctophids themselves is also important. These studies should use standardised methods, be carried out in different seasons and have a wide geographical coverage.