Marine Diel Vertical Migration (DVM), perhaps the largest movement of animals on Earth, is composed of mesopelagic species migrating vertically every night to feed in epipelagic depths and return to deeper water during the day. The objective of this study infers potential taxonomic identity of organisms in the DVM via their association with bacterioplankton signatures. High throughput sequencing of the 16S rRNA V4 region and the use of bioinformatics and statistics provided evidence to which bacteria appeared associated with either upward or downward vertical migration during two cycles.
Seawater samples were collected during a DEEPEND (Deependconsortium.org) research cruise in May 2017 using a niskin bottle array from 0-326 meters depth. Real-time acoustic echosounder data was used to direct sample collection in order to capture seawater samples above, during, and below the DVM. DNA was extracted from the water samples and sequenced. Data analysis was performed using R Studio software.
Our results confirm the vertical movement of bacterial taxa throughout the pelagic depths. The most abundant bacteria present during the Vertical Migration were of Genera Marinobacter, Alteromonas, Prochlorococcus, and class Gammaproteobacteria. These taxa occurred at depth of 320 meters which is the mesopelagic zone. Proteobacteria was only found during the vertical migration at mesopelagic depths, whereas Cyanobacteria was only found during the vertical migration at epipelagic depths. This indicates that these two phyla of bacteria are distinct to their respective zones.