Surface waters are an attractive foraging ground for small fish in the open ocean. This study aims to determine the importance of vertically migrating species in the neuston of oceanic waters across the Atlantic, Indian and Pacific Oceans and to ascertain the influence of environmental variables on their distribution patterns. Neustonic fish assemblages were primarily controlled by light. They were dominated by late-larvae and juveniles of Exocoetidae, Hemiramphidae and Scomberesocidae during the day. At night, the vertical migration of mesopelagic species changed the dominance pattern in favour of Myctophidae and Scomberesocidae. The neustonic families' distribution was primarily related to sea surface temperatures, whereas environmental variables at deeper layers were related to mesopelagic migrating families. Canonical correspondence analysis showed a low but statistically significant contribution of several environmental variables to myctophid species composition (10%), with minimum oxygen concentrations ranking first in variance explanation followed by maximum fluorescence, sea surface temperature and 400-m temperature. Spatial autocorrelation also explained 17% of the variance, indicating the influence of other factors such as historical, demographic and dispersal constraints. The low number of myctophid species in the North Pacific Equatorial Countercurrent appears to be related to the low oxygen concentrations observed in this province.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We are very grateful to all the participants and crew of the Malaspina 2010 expedition for their assistance during the cruise. Mikhail Emelianov was available whenever we needed him to translate the Beeker identification book from Russian. We are really in debt with Dr J. Paxton and Dr A. Williams for allowing the first author to use their drafts of the 'Illustrated Keys to Australian Lanternfishes'. American Journal Experts edited the English version of the manuscript. This study was financed by the Spanish Ministry of Economy and Competitiveness (Consolider-Ingenio 2010, CSD2008-00077 and CTM2012-39587-C04-03).