Updated: 6 mar. 2019

Knowledge on the biology, ecology and population dynamics of marine species is fundamental to understand ecosystem functioning. Southern Ocean food webs are extremely dynamic as a result of a strong variability in spatial and temporal structure, and are mainly supported by krill, a key element in feeding fish, penguins and whales. This variability is important to shape species interactions, mainly due to the predator migrations during the winter and, consequently, leading to reductions in energy demand at higher trophic levels.

Myctophids are among the most diverse and abundant fishes in all oceans. They carry out extensive daily vertical migrations and the presence of luminescent tissues, called photophores, makes myctophids a distinctive group of animals. Myctophid photophores play an important role in the vertical migrations, both in searching food and intraspecific communication.

Myctophids, also called lanternfishes, play an important role in trophic dynamics. They are second-order consumers, occupying the third level of the trophic systems. Due to their high biomass, myctophids

have a great impact on the consumption of zooplankton, as well as on the production (biomass increase) of top predators. This means, myctophids are important linking primary consumers and top predators, also contributing to the transport of organic matter between the surface and the deep ocean.

The effects of climate change are reflected in the interactions between the different species inhabiting the region. The ice melting around the Antarctic Peninsula affects zooplankton populations through changes in phytoplankton composition, which may have deep implications on the Antarctic trophic structure. Due to its ecological role, the study of mesopelagic species (e.g. myctophids) is essential to provide new perspectives towards the conservation of a region as vulnerable as the Antarctic Ocean.

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Sources:

Atkinson, A., Siegel, V., Pakhomov, E., Rothery, P. (2004). Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature 432, 100–103. doi: 10.1038/nature02996.

Catul, V., Gauns, M., Karuppasamy, P. K. (2010). A review on mesopelagic fishes belonging to family Myctophidae. Reviews in Fish Biology and Fisheries. doi: 10.1007/s11160-010-9176-4.

Cherel, Y., Fontaine, C., Richard, P., Labat, J. (2010). Isotopic niches and trophic levels of myctophid fishes and their predators in the Southern Ocean. Limnology and Oceanography Abstracts 55 (1), 324–332. doi: 10.4319/lo.2010.55.1.0324.

Clarke, A., Murphy, E. J., Meredith, M. P., King, J. C., Peck, L. S., Barnes, D. K. A., Smith, R. C. (2007). Climate change and the marine ecosystem of the western Antarctic Peninsula. Philosophical Transactions of the Royal Society B 362, 149-166. doi: 10.1098/rstb.2006.1958.

Hulley, P. A. (1990). Family Myctophidae. In Gon O., Heemstra, P. C. (Eds) Fishes of the Southern Ocean. J.L.B. Smith Institute of Ichthyology, Grahamstown, 462 pp.

Murphy, E. J., Watkins, J. L., Trathan, P. N., Reid, K., Meredith, M. P., Thorpe, S. E., Johnson, N. M., Clarke, A., et al. (2007). Spatial and temporal operation of the Scotia Sea ecosystem: a review of large-scale links in a krill centred food web. Philosophical Transactions of the Royal Society B 362, 113–148. doi: 10.1098/rstb.2006.1957.

Shreeve, R.S., Collins, M. A., Tarling, G.A., Main, C.E., Ward, P., Johnston, N. M. (2009). Feeding ecology of myctophid fish in the northern Scotia Sea. Marine Ecology Progress Series 386, 221-236. doi: 10.3354/meps08064.

Author: Rui Pedro Vieira