Can you imagine the swaths of animal migrations taking place in the underwater depths of the oceans? New research published in the Journal of Animal Ecology documents the seasonal migrations of deep-sea fish from over seven years of deep-sea photographic data from West Africa.
The research was spearheaded by scientists at Nova Southeastern University (NSU) and the University of Glasgow who tracked linking seasonal patterns in surface-ocean productivity with observed behavioral patterns of deep-sea fishes. While the deep-sea refers to depths greater than 200 meters, for this study the scientists looked at fishes at depths of 1,500 meters.
"We are extremely excited about our findings, which demonstrate a previously unobserved level of dynamism in fishes living on the deep sea floor, potentially mirroring the great migrations which are so well characterized in animal systems on land," said Rosanna Milligan, Assistant Professor at Nova Southeastern University, who started the work at the University of Glasgow.
The researchers used data from Deep-ocean Environmental Long-term Observatory System (DELOS) to monitor deep-sea fish migrations. They observed high fish abundances in late November with a smaller peak in June and hypothesized that these seasonal changes had behavioral drivers.
"The work really adds to our understanding of movement patterns in deep-sea fishes and suggests reasons for their behaviors,” Milligan said. "Because we were able to link the abundances of fish observed at the seafloor to satellite-derived estimates of primary productivity, our results suggest that even top-level predators and scavengers in the deep oceans could be affected by changes filtering down from the surface of the ocean."
The deep sea is one of the greatest unexplored territories on our planet, despite advances in technology that have given us a peek into the mysteries of deep waters. This study offers insight to expand our understanding of mass animal migrations, a phenomenon that has been well-studied on land but lacks breadth in the marine world.
"Animal migrations are really important in nature because when animals move from place to place, they transport energy, carbon and nutrients,” explains Dr. David Bailey, Senior Lecturer in Marine Biology at the University of Glasgow's Institute of Biodiversity, Animal Health and Comparative Medicine. “These kinds of long-term projects and the datasets they generate are vital to understanding ongoing change in the oceans and how they may be impacted in the future."