Quantifying Pelagic Habitat Use By Lanternfishes in the Northern Gulf of Mexico

In 2010, the Deepwater Horizon oil spill occurred at 1500 m in the northern Gulf of Mexico (GoM), and demonstrated a clear and urgent need for a better understanding of deep-pelagic ecosystems and the processes that shape deep-water assemblages. One of the most globally-important pelagic taxa is the Myctophidae (lanternfishes), which are a ubiquitous component of the deep-pelagic micronekton and important prey for several commercially-valuable species. In the present study, quantitative, depth-stratified trawl data were analysed to assess the assemblage composition and diversity of the dominant myctophid species in relation to meso-scale physical and chemical variables in the GOM during summer 2011. The data were collected through the NOAA-supported Offshore Nekton Sampling and Analysis Program. Significant correlations to meso-scale features associated with the Loop Current were observed at depths to 1000 m, but the effects were weak and only explained 6 – 11% of the observed variance in assemblage composition. These results indicate that myctophid assemblages were well-mixed in 2011 and suggest high dispersal rates across the study region (>500 km). These findings have implications for understanding the sensitivity of myctophid populations following different forms of disturbance.