Microbial Mysteries: Linking Microbial Communities and Environmental Drivers

Dr. Samantha Joye and her multi-national team will compare the biology, geology, chemistry, and microbiology of sites along the southern to the northern Gulf. The northern area is largely unexplored and the geological characteristics, microbiology, and seafloor fauna are unknown, making a portion of the expedition exploratory in nature. We will explore known and new sites in the Guaymas and Pescadero Basins, building on previous work and diving on new sites. The team aims to identify and quantify habitat-specific microbial populations and assess how those microorganisms interact with the geologic structures and megafauna of vents, seeps, and hydrates. The scientists will visit eight areas in the Gulf, seeking to reveal previously unknown areas with shipboard mapping that is followed by collection of sediment, fluid, and microbiology samples collected with ROV SuBastian. In-situ tools including the ABISS autonomous lander and jumbo osmotic fluid samplers will be used to obtain geochemical data under in situ conditions. Together, these data will help us unravel the microbial mysteries of the Gulf of California.

The science team aims to identify and quantify habitat-specific microbial populations and assess how those microorganisms interact with the geologic structures and megafauna of vents and seeps. During the expedition, the team will try a few new things to characterize microbial populations. Genetic sequencing will begin on board the Falkor using an Oxford Nanopore MinION sequencing system. The MinION system allows for genetic sampling using a device the size of a thumb drive. With minimal prep, this amazing sequencer will provide a real-time assessment of microbial-omics data. In addition to -omics data, the science team will assess rates of microbial activity using sensitive isotopic tracer techniques and shipboard incubations, and carry out comprehensive geochemical characterization of each habitat.

Back on land, state-of-the-art sequencing tools will yield additional data of metagenomes (DNA), transcriptomes (RNA), and metabolomes (organic carbon metabolites) of the different habitats. These “-omic” methods will provide thorough and robust characterization of microbial activities, and may reveal new microorganisms, new metabolisms, and new microbe-macrofaunal interactions.

Beyond Microbes
The scientists will visit eight sites in the Gulf, looking for hydrothermal plumes above active vents. These plumes will be sampled using the CTD with transect mapping used to better characterize the vent signatures. ROV SuBastian will be deployed to collect sediment, fluid, microbial mats, and benthic fauna samples. Finally, using the ABISS Lander, a novel biogeochemical seafloor observatory, developed in part by the Girguis lab at Harvard, will be used for in-situ sampling.

Special ROV-mounted Jumbo Rapid OSMO samplers, designed by Dr. Joye and colleague Laura Lapham at Maryland, will allow researchers to recover fluids from the deep ocean to determine in situ concentrations of dissolved constituents. The team will also use microscopy to visualize collected microbes and animals.

This expedition will not only advance our understanding of seafloor spreading dynamics, but inform responsible use and protection of valuable marine resources from these rare and underexplored regions.