Back to the Seafloor

AT 42-05 | 17 November 2018

Exploring the Guaymas Basin, Gulf of California

The Gulf of California is an active young ocean undergoing early phases of rifting, seafloor spreading, and hydrothermal imprinting. The hot, thick organic rich sediments, hydrothermal spires, and other geological oddities found at the seabed in the Gulf of California offer ideal locales to study extremophiles and search for novel microorganisms and metabolisms. On this expedition, our work will focus on the Guaymas Basin, located in the central area of the Gulf of California. The next two weeks are sure to be filled with beautiful, mesmerizing, and stunning seafloor scenes.

The UGA group – me along with Post Doc Guang-Chao Zhuang, PhD students Andy Montgomery, Hannah Choi, and Rachael Karns – left Athens before the crack of dawn. We met up with artist-extraordinaire Rebecca Rutstein at the Atlanta airport and boarded our flight to Hermosillo, Mexico. It was a long (18 hour) travel day. The next morning we met another UGA PhD student, Tito Peña-Montenegro, who arrived before us and together, we traveled to the port of Guaymas where we boarded the R/V Atlantis.

The R/V Atlantis, operated by Woods Hole Oceanographic Institution, is one of the most sophisticated sea-going research vessels in the world. The Atlantis is also home to the world’s most famous research submersible, the ALVIN. We loaded our gear onto the ship and spent much of the next 24 hours setting up the labs and preparing for our work. On this expedition we will be deploying in situ instrumentation at the seabed, collecting bottom water, sediments and rock samples using ALVIN, and sampling the water column – searching for hydrothermal plumes – using the CTD/Niskin rosette. Over the coming weeks, I will share stories about these aspects of our work.

Today (Saturday November 17th) will be the first dive of this expedition. We will be visiting Cathedral Hill, an area of extensive microbial mats and mounds that we have visited and sampled before. Why go back?? Well, in hydrothermal areas, the forces of nature interact dramatically and dynamically: geological fluxes drive chemistry and biology, biology creates it’s own geology and physics also plays a role. This means that things change, often in surprising ways. It is unlikely that things will be the same as before; instead it is very likely that things will be different. Changing flux regimes and pulsed perturbation are common in hydrothermal areas. While some organisms thrive in hydrothermal areas by being able to tolerate extreme conditions, others thrive by being able tolerate changing conditions and perturbation. Today, we will have a look and see how Cathedral Hill and a site nearby – Rebecca’s Roost – look now, compared to the last time we were here in 2016. 

Joining me in the ALVIN today is Andy Montgomery, a PhD student in my research group; this will be Andy’s first ALVIN dive. Andy studies chemoautotrophic microorganisms. Yes, chemoautotrophic is a mouth full but this term refers to microorganisms that use chemical processes (“chemo”, for example, microbes that oxidize ammonium, hydrogen, or carbon monoxide) to generate energy for growth. These microbes obtain their structural carbon from carbon dioxide (they convert carbon dioxide into biomass). In other words, Andy studies primary producers that live in the dark at the bottom of the ocean using nifty metabolisms that take advantage of the high fluxes of ammonium, hydrogen, carbon monoxide and methane. It is sure to be an incredible dive day followed about 24 hours of non-stop sample processing.

By the end of the expedition, we are sure to be a bit sleep-deprived. But, all the hard work and long hours are worth it. I’m excited about seeing new things, developing new ideas, and am sure that, by the end, I will be even more fired up to return for more sampling in February.

 

2018 DEEPSEARCH Atlantis Expedition: Pea Island Seep

21 August 2018

This has been is a week of firsts. Tuesday morning, I wrote an email to my oldest daughter (she was too young to exchange email with before) saying: ‘I’m going in the ALVIN today to visit the animals at the bottom of the ocean. I’m excited”. Little did I know how perfectly those words – visiting animals at the bottom of the ocean – would fit the dive.

It is exceedingly rare to have the opportunity to do something that no human being has ever done before. For me, Tuesday was one of those days: I was one of three scientists in the research submersible ALVIN traveling to a depth of some 500m along the continental slope off the southeast US coast to visit a recently discovered seep field, the Pea Island Seeps. This site was mapped using an AUV but before our dive, it had never had “eyes on the bottom”, via either a remotely operated vehicle or a human occupied vehicle. Tuesday, we visited the area with the ALVIN and oh what a dive it was.

The Pea Island area is characterized by widespread gas seepage. We know this because we mapped the area using the multibeam echo sounder (MBES) and observed diffuse areas of gas seepage as well as gas flares. Some of these flares were strong enough to generate vertical plumes that reached 300m above bottom. Such strong flares link seabed and water column processes, at times, even connecting the seafloor with the surface ocean.

The dive was packed with unexpected events. We landed close to the target –  waypoint 1 – and observed soft, brown sediment inhabited by a diverse suite of animals: anemones, worms, shrimps, crabs, small and large fish, eels, squid, and more. There were many, many squid and they were curious and intrusive times. The squid managed to interfere with everything from visibility, by obscuring the windows, to coring, by dancing around the manipulator as we attempted to core and disturbing the sediment by blowing away patches – literally – in the mats as we tried to sample them.

Our goals on this dive were to characterize the area and to collect sediment samples from areas of seepage, microbial mats dominated by Beggiatoa, and from any areas that lacked seepage, the latter serving as comparative controls. Fairly quickly, we found areas covered by thick Beggiatoa mats and we saw methane bubbles emanating from various small vents all across the mat area. Beggiatoa are gammaproteobacteria that can oxidize hydrogen sulfide to sulfate using either oxygen or nitrate as the electron acceptor. These “giant” filamentous bacteria are visible to the naked eye. They form thick markers, acting as a bulls-eye at the seabed marking areas of active seepage. We sat ALVIN down and commenced coring. After collecting nine sediment cores from the Beggiatoa mat, we flew over it to obtain video describing the site.

We then embarked on a run to try and locate the large gas vent that we observed with the MBES. Unfortunately, we did not find the vent but we saw a number of interesting features. We observed carbonate outcrops – probably authigenic (which means ‘formed in situ’) carbonates. The carbonates were home to a lot of sessile (anemones, …) and mobile animals. We collected carbonate rocks for characterization back in the lab and for use in microbiology experiments.

From there, we moved on towards a northern line. About ½ way there, we stopped and sampled non-seep sediment. These sediments were brown and occupied by worms. Other animals (squid were still with us) were also present. We sat down and collected samples and then moved further north. Along the second line, we found more microbial mats and sampled them.

When we finished sampling, about 8 hours after boarding ALVIN, we signaled that we had completed our mission and were ready to return to the surface.

I’ve been lucky enough in my career to do a lot of submersible dives and roughly 1/3 of my dives have been in the ALVIN. There is something surreal about diving to the bottom of the ocean in this amazing and famous vehicle. The first few minutes on the bottom are amazing – just taking it all in and appreciating the beauty and diversity of the deep sea. It never gets old and each dive is a new, incredible experience. Every dive, I see something I have not seen before. Every dive teaches me something I did not know about the deep sea. And, every dive leaves me with a number of questions I need – and want – to answer, serving as fodder for new experiments and possibly, new projects.

For more about our expedition, please see NOAA’s Ocean Explorer web site, https://oceanexplorer.noaa.gov/explorations/18deepsearch/welcome.html, or follow us on Twitter @OceanDeepSearch, @DeepseaECOGIG, @BOEM_DOI, @oceanexplorer, @thenopp, @USGS, @CordesLab, @ademopoulos, @SeepExplorer, @c_m_dangelo or by searching for the hashtag #DeepSearch.

2018 DEEPSEARCH Atlantis Expedition: Underway

AT 41 – 20 August 2018

Continental margins across the globe are home to diverse seafloor habitats. The Deep Search research consortium explores three key margin habitats – Canyons, Cold Seeps, and Corals. The Deep Search study area encompasses sites located along the shallow and deep slope from the Florida-Georgia border and north to the canyons offshore Virginia. These seafloor habitats are home to diverse biological communities that are inextricably linked with the overlying water column. Margin habitats provide many ecosystem services that many people are not aware of.

Yesterday, August 19th, marked the start of the first of three Deep Search expeditions which will take place in the coming 8 months. Conducting research at sea is not easy: months are spent picking the research sites and discussing the details of the sampling scheme. Plans for developed, re-hashed, and re-written. Finally, there is an expedition plan and an exhaustive list of collections and analyses that will be performed on each sample collected.

On Thursday and Friday, August 16th and 17th, a diverse team of scientists from across the US, gathered in Woods Hole, Massachusetts to load their research gear onto the R/V Atlantis for a 2-week “Deep Search” expedition. The R/V Atlantis is a global class research vessel; it is also the mother ship to the human occupied vehicle (HOV), ALVIN. The HOV ALVIN is one of the most widely recognized vehicles for science in the world. We have 12 ALVIN dives planned for this expedition. The vast majority of these study sites have not been visited by humans in a manned submersible and the Deep Search team is excited see what is there!

This morning at 0530, the Atlantis set sail for our first dive site: Wilmington Canyon. I will be sharing news of our dives and shipboard adventures over the coming days. As we made our way from Woods Hole, we passed Martha’s Vineward on a stormy morning.

Follow our expedition here, on this blog, on NOAA’s Ocean Explorer web site, https://oceanexplorer.noaa.gov/explorations/18deepsearch/welcome.html, or on Twitter: @OceanDeepSearch, @DeepseaECOGIG, @BOEM_DOI, @oceanexplorer, @thenopp, @USGS, @CordesLab, @ademopoulos, @SeepExplorer, @c_m_dangelo or by searching for the hashtag #DeepSearch.

Extreme eruptions

Extreme eruptions

As you can probably tell, the Brine Microbial Observatory Project is all about extreme environments and the microorganisms that thrive there. Today, the story is about extreme eruptions. Back in about 2005, we found an interesting site in Garden Banks Lease Block 697 (GB697). We observed massive discharges of fluidized mud and Ian MacDonald, my good colleague from Florida State University, coined the name “The Hot Site”; because, usually these types of eruptive mud discharges are a little hot (~40 ºC). We visited the area with Alvin back in 2010 and discovered that the erupting fluids were in fact cold (about 5 ºC), which was perplexing. Still, the terrain was astonishing and extremely interesting, so to us it’s still a hot site.

Treasured moments

Treasured moments

To have a brine-filled basin like Orca, the super-salty fluid has to flow in from somewhere. But where? The published literature on Orca geology suggests that the salt diapirs that donate salt to the deep basin are located on the eastern flank of the central basin. We wanted to find it and better yet, SEE it, and, even better, SAMPLE it!