Milligan, R.J. et al. (2020) Evidence for seasonal cycles in deep-sea fish abundances: A great migration in the deep SE Atlantic? Journal of Animal Ecology, 89(7), pp. 1593-1603. (doi: 10.1111/1365-2656.13215) (PMID:32198925)
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Abstract
1. Animal migrations are of global ecological significance, providing mechanisms for the transport of nutrients and energy between distant locations. In much of the deep sea (>200 m water depth), the export of nutrients from the surface ocean provides a crucial but seasonally variable energy source to seafloor ecosystems. Seasonal faunal migrations have been hypothesized to occur on the deep seafloor as a result, but have not been documented. 2. Here, we analyse a 7.5‐year record of photographic data from the Deep‐ocean Environmental Long‐term Observatory Systems seafloor observatories to determine whether there was evidence of seasonal (intra‐annual) migratory behaviours in a deep‐sea fish assemblage on the West African margin and, if so, identify potential cues for the behaviour. 3. Our findings demonstrate a correlation between intra‐annual changes in demersal fish abundance at 1,400 m depth and satellite‐derived estimates of primary production off the coast of Angola. Highest fish abundances were observed in late November with a smaller peak in June, occurring approximately 4 months after corresponding peaks in primary production. 4. Observed changes in fish abundance occurred too rapidly to be explained by recruitment or mortality, and must therefore have a behavioural driver. Given the recurrent patterns observed, and the established importance of bottom‐up trophic structuring in deep‐sea ecosystems, we hypothesize that a large fraction of the fish assemblage may conduct seasonal migrations in this region, and propose seasonal variability in surface ocean primary production as a plausible cause. Such trophic control could lead to changes in the abundance of fishes across the seafloor by affecting secondary production of prey species and/or carrion availability for example. 5. In summary, we present the first evidence for seasonally recurring patterns in deep‐sea demersal fish abundances over a 7‐year period, and demonstrate a previously unobserved level of dynamism in the deep sea, potentially mirroring the great migrations so well characterized in terrestrial systems.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Scott, Professor Marian and Bailey, Dr David |
| Authors: | Milligan, R.J., Scott, E.M., Jones, D.O.B., Bett, B.J., Jamieson, A.J., O'Brien, R., Pereira Costa, S., Rowe, G.T., Ruhl, H.A., Smith Jr., K.L., de Susanne, P., Vardaro, M.F., and Bailey, D.M. |
| College/School: | College of Science and Engineering > School of Mathematics and Statistics > Statistics College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine |
| Journal Name: | Journal of Animal Ecology |
| Publisher: | Wiley |
| ISSN: | 0021-8790 |
| ISSN (Online): | 1365-2656 |
| Published Online: | 21 March 2020 |
| Copyright Holders: | Copyright © 2020 The Authors |
| First Published: | First published in Journal of Animal Ecology 89(7):1593-1603 |
| Publisher Policy: | Reproduced under a Creative Commons License |
| Data DOI: | 10.1594/PANGAEA.909448 |
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