The Big Picture: Why and How We Study Deep-Sea Shipwrecks

This slideshow requires JavaScript.

It’s critical to remember the objective, no matter the task. When working on an ongoing study like GOM-SCHEMA, the main objective could fade into the background when focusing on details. Our goals and objectives are the drivers behind everything we do out here, so why not have them fresh in our minds? Therefore, it’s a good time to step back and look at the big picture to ties all of the moving pieces of a research cruise to the whole study. It does make executing the small (but equally as important) tasks fulfilling.

The goal of GOM-SCHEMA is to better understand and profile the microbial communities associated with historic shipwrecks in the northern Gulf of Mexico. The interactions between these communities and the shipwrecks are ripe for discovery of microbial habitats and unique ecological niches. The  characteristics of the wrecks, specifically the materials they are made of play a role in establishing microbial habitats. To address questions regarding hull materials, we are visiting four 19th or pre-19th century wooden-hull shipwrecks and four WW2 era steel-hulled shipwrecks during the SCHEMA May 2016 cruise.

On top of characterizing microbial communities naturally associated with shipwrecks, we also are investigating the effects of the Deepwater Horizon spill on shipwreck microbial communities.  Through this work, and annual cruises in 2014, 2015 and 2016, we can ask,  if the introduction of hydrocarbons (related to the spill) or chemicals dispersants effect microbial communities on and around the wrecks, and how this may impact the preservation of the wrecks over time.

With these questions in mind, we selected our study sites based on their proximity to spill, the existence of a pre-spill archaeological investigation, water depth, and hull type.

Now that we have touched base with our goals, we can connect new participants in the study to both the big picture, and the intricate details that make up a scientific research cruise.

On this cruise aboard the R/V Pelican, our sample collection utilizes two instrument, a MC800 deep-water multicorer, and a CTD (conductivity, temperature, and depth). The MC800 collects eight (when it works perfectly) replicate sediment cores from depths up to 2000m.  The multicorer has a frame which engages the seafloor, and once that occurs, a weight stand is free to lower the core tubes into the seabed.  When this happens, a lid closes on top of the core tube, creating a vacuum, and an arm swings down to catch the mud from falling out the bottom. As soon as the MC800 is on deck, our team swarms the device and begins logging them, describing them, and preparing them for chemical and biological analyses.
The CTD (conductivity, temperature, and depth) profiles the hydrodynamics of the water column and collects water from any depth of interest using a Niskin bottle.  These, and the hundreds of mud samples from the MC800 are used to profile microbial communities with both molecular biological and biogeochemical analyses.

We are fortunate to collect samples once or twice a year at these sites to help further understanding of the effect of the spill on shipwreck ecosystems, but also to explore a unique microbial habitat in the deep sea.  The time we spend out here is small compared to that in the lab, and the work is hard, but it’s worth it to for the information we create, and to obtain the one of a kind samples we collect.

Only two more days left on the cruise. Stay tuned!

Zeima K