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Interview: Deep-Sea Researcher Dr. Samantha Joye on Microbes in the Gulf

Posted On August 6, 2014 by

Dr. Samantha Joye aboard the research vessel Atlantis with the submersible Alvin in the background. Credit: Antonia Juhasz

This blog is part of a series of interviews with scientists who are championing marine research in the Gulf of Mexico.

Dr. Samantha Joye is a Professor of Marine Sciences in the University of Georgia in Athens, Georgia. She is an expert in biogeochemistry and microbial ecology and works in open-ocean, deep-sea and coastal ecosystems. Her work is interdisciplinary, bridging the fields of chemistry, microbiology and geology. Following the BP Deepwater Horizon oil disaster, Dr. Joye joined a team of scientists in the Gulf, investigating oil plumes from the disaster in the open ocean of the Gulf, which at the time BP claimed did not exist. Her team’s discoveries proved that there was more oil and gas in the water than BP and government agencies had predicted. She continues to study the impacts of the BP oil disaster, as well as the ecological processes at natural oil and gas seeps in the Gulf, Arctic Ocean and in the Guaymas Basin.

OC: How long have you been conducting research in the Gulf of Mexico, and what are your current research interests?

Dr. Joye: I embarked on my first Gulf of Mexico cruise in 1994, and I did my first submersible dive on that cruise. I was completely enthralled and totally hooked on deep-water exploration from that instant. I began working in the Gulf in earnest when I joined the faculty at Texas A&M University (College Station) in 1995. I have been working in the Gulf since that time. My research interests include understanding the environmental and physiological factors that regulate microbial hydrocarbon degradation in the Gulf’s waters and in both shallow (upper meter) and deep (>5 meters) sediments. We are interested in the cycling of a wide spectrum of hydrocarbons, ranging from methane to polycyclic aromatic hydrocarbons. We are also interested in the metabolic potential and capacity for hydrocarbon degradation (i.e., determining which microorganisms are there naturally, their abundance, and how fast and how well do they respond to large hydrocarbon infusions like that resulting from the Deepwater Horizon disaster).

OC: Here at the Ocean Conservancy offices, we have been following the deep-sea expeditions in the Gulf this summer, watching the live feeds, and listening to the scientists discuss what they are seeing. We would love to hear more about these cruises from you. What types of information have you been collecting? What have you learned on the cruises?

Dr. Joye: Our cruise in April 2014 was on board the R/V Atlantis. It was the first official research cruise using the newly renovated human occupied vehicle, Alvin, which was very exciting for us. The goal of this particular cruise was to visit and sample sites impacted by the Macondo blowout and to sample two types of very salty seafloor ecosystems called brines. Seawater is salty; it contains about 35 grams of salt per liter. However, in some places, super-salty brine fluids occur. Brines are defined as fluids containing more than 50 grams of salt per liter but some deep sea brines contain almost 10 times the amount of salt as seawater. Our saltiest site contained about 340 grams of salt per liter. We are studying two types of brines: those derived from ancient salt dissolution (which contain mainly sodium and chlorine and are sulfate-free) and those derived from gas hydrate formation (which are basically concentrated seawater and thus contain sulfate)

Our research cruises are intense; we conduct operations around the clock. Alvin operations occur between 8a.m. and 5p.m., and starting around 6p.m., we collect water and deeper sediment samples through the night. We also do geophysical surveys at night and during transits between sites to search for interesting seafloor geological features and gas and oil plumes. Being an oceanographer requires that you are able to thrive in this intense environment, where sleep is a luxury and where focused, hard work is required around the clock. It’s worth it because each dive presents an opportunity for discovery, and discovery is what it’s all about!

On our April cruise, we discovered some amazing things that we will be reporting in our science blog and in publications during the coming months. But first, a lot more hard work is required in the lab to process all of the sediment, water and brine fluid samples we collected on the ship. Cruises are intense, but it does not stop there. Post-cruise analyses and experiments keep us busy for often six to eight months. Then the phase of manuscript preparation and publication begins.

OC: Some people may not realize that as much as 16 million gallons of oil naturally seeps from the Gulf seafloor each year. How does that compare to the oil and gas that was released by the BP oil disaster?

Dr. Joye: Natural seeps are in no way similar to the Deepwater Horizon discharge, which released almost 210 million gallons of oil from a focused source (the wellhead) over the course of 84 days. Natural seepage releases about 0.04 million gallons a day over the entire Gulf of Mexico, while the Deepwater Horizon discharge released 2.5 million gallons a day in a localized area. If you compare the discharge per area released during the Deepwater Horizon disaster, the blown out well discharged orders of magnitude more oil than natural seepage. This was an unprecedented perturbation that led to a large number of unanticipated phenomena and impacts to the Gulf ecosystem even hundreds of kilometers from the discharging wellhead. The chronic impacts of this perturbation are only now coming to light.

OC: Considering that there are natural petroleum seeps in the Gulf, does this lessen the impacts of the BP oil disaster?

Dr. Joye: Absolutely not. Many people argue that since the Gulf is a site of extensive natural hydrocarbon seepage, a large discharge such as the Deepwater Horizon disaster would have little effect on the system. The implicit assumption here is that the system was primed and poised to respond to hydrocarbon inputs because the waters are exposed routinely to hydrocarbons. But this argument has several shortcomings. First, what this assumption neglects to consider is that the offshore Gulf is a blue water system, where the nutrients that fuel microbial growth are sparse and fiercely competed for. Oil and gas oxidizing bacteria require nutrients to build biomass and increase metabolic rates. Nutrient availability may well have limited the degradation of Deepwater Horizon oil and gas significantly. Second, natural seepage inputs are sparse and diffuse so the populations of microbes that eat oil and gas during normal conditions are, in fact, rare. They can respond rapidly, but as has recently been shown, they are often not able to sustain high rates of hydrocarbon consumption. So, how much of the Deepwater Horizon hydrocarbons were consumed by bacteria? I don’t think we know for sure, but I have done some simple back of the envelope calculations of nutrient demands by hydrocarbon degraders, and the results suggest it would be difficult to consume all of the discharged hydrocarbons given the nutrient pool available.

OC: Can you describe what a cold-seep community is and how the BP oil disaster might have affected those in the Gulf?

Dr. Joye: Natural hydrocarbon seeps are magical systems that evolve and change over time. The biological diversity of these environments – which is fueled by oil and gas degradation, driven by the activity of indigenous hydrocarbon-degrading bacteria – is astonishing. I remember vividly my first dive to the Gulf seafloor in a submersible in 1994. When the lights came on and I saw all the odd and amazing organisms living on oil and gas, I was simply shocked. My jaw was on the floor and I knew I wanted to study these incredible systems for the rest of my career, because they are fascinating and because we know so little about what makes them tick.

Natural seep habitats, especially deep-water coral communities which are the “old growth forest” analog of the seep evolution sequence, were impacted by the Deepwater Horizon oil plume and by weathered oil-containing marine snow, or tiny bits of organic matter that sink down from the surface to the seabed. Dispersants may well have also impacted the organisms at natural seeps, but many more experiments are needed to verify this hypothesis.

OC: A few of your recently published papers have focused on the fate of dispersants in the Gulf, and the impacts of the BP oil disaster on open-ocean ecosystems in the Gulf. Can you tell us more about your research on these topics?

Dr. Joye: Dispersants are complex chemical mixtures that act to break up oil and presumably make it small enough for microorganisms to eat. However, the literature on this is split: few studies show increased hydrocarbon biodegradation after dispersant application, and many show no effect or a negative effect on biodegradation. The Deepwater Horizon dispersant application was made after much scientific discussion and debate. The dispersants were applied to keep oil from reaching the coastline, and the potential impacts on open-water organisms, from microorganisms to fish to sharks, were not known. We still do not know conclusively how dispersants impact microorganisms, but what we do know is that it affects different microorganisms in substantially distinct ways. We need to know a lot more, and we are working diligently to obtain this information by doing detailed experiments in the laboratory. So the jury is out on whether dispersants increase hydrocarbon degradation and on how they impact the structure and function of the hydrocarbon-degrading bacterial communities that they are supposed to stimulate.

OC: During your deep-sea expeditions in the Gulf, have you found significant differences between oiled sites and non-oiled sites, or differences at the same site before and after oil exposure?

Dr. Joye: Both. We had been studying one site, Mississippi Canyon 118, for about five years prior to the oil spill, so we had a very good baseline there. The microbiology and geochemistry of the water column and sediments changed after the discharge. If you compare an oiled site to a non-oiled site, you also see striking differences, irrespective if you are at a ‘control site’ or a natural seep. The oiled sites are distinct in terms of microbiology and geochemistry. The differences are significant and prominent.

OC: How might these impacts affect the larger Gulf ecosystem and food web?

Dr. Joye: The Gulf’s food web starts at the top, and the key there is nutrients. A key question is how much of the nutrient inventory was taken up by oil-degrading bacteria and how much of that sunk to the bottom. It will take a very, very long time to return those nutrients from the seafloor up to the surface where phytoplankton can again incorporate them into the food web from zooplankton to small fish and ultimately big game fish and whales. Food web impacts often take 5-10 years to materialize (i.e., to be quantifiable) because it takes a while to start catching the fish from the 2010 year-class. Other considerations include the impact of oil and dispersant exposure on larval fish; that will also take a long time (5-10 years) to become quantifiable. Finally, there is the consideration of oil and dispersant exposure on adult fish and their health. A recent study by Dr. Steve Murawski at the University of South Florida showed that fish caught recently contained Deepwater Horizon polycyclic aromatic hydrocarbons in their livers. So the food web impacts from the Deepwater Horizon incident are poorly understood and will take years more of research to fully unravel and understand.

OC: Looking forward to the restoration process, it is clear we didn’t have a good baseline understanding of some of the habitats in the Gulf before the BP oil disaster. How will we know when they are recovered? What are realistic goals for restoration of some of these areas, such as deep-sea and open-ocean ecosystems?

Dr. Joye: Baselines are essential when it comes to evaluating environmental impacts. It is clear that not enough funds have been invested in developing baselines for microbial communities in the open water and seafloor of the Gulf. This is both surprising and disappointing, given the industrial presence in the Gulf. I believe it is in the best interest of the oil and gas industry to devote substantial resources into developing collaborations between industry and academic scientists to obtain such baseline data. What would this require: instrumentation, monitoring platforms, access to research vessels and interested scientists on both sides. I believe all of the required parts are there; the missing piece of the puzzle is funding. Given the amount of money generated by the oil and gas industry in the Gulf, the funding required to generate environmental baselines for the system would be small potatoes (relative to oil company profits), but the value of these baseline data would be immense.

Because we do not know the baseline, it is extremely difficult to judge when the system is recovered. We don’t even know if it will recover to the “baseline”. It could end up at a new steady state.

But there is satellite data that can be use that to evaluate how chlorophyll has changed since the oil disaster and those data can be used to describe pre- and post-spill carbon fixation scenarios. So, it is easier to evaluate the status of the open-ocean system compared to the seafloor system because deep-water corals, for example, grow very slowly. When a 500-year-old coral is damaged or killed by oiling, it will require a very long follow up study to evaluate recovery of that system.

Restoration of these systems is essentially impossible; what we can do is monitor recovery and attempt to understand what regulates its efficacy. That is the goal that many of us are working towards.

OC: It has been over four years since the BP oil disaster – what is the status of the ongoing research in your area of expertise? Are you as far along as you and your fellow researchers hoped to be by this point?

Dr. Joye: I am a microbial geochemist. Basically, that means I study the effects of microbial processes on elemental cycles. The Deepwater Horizon discharge served, in essence, as a tragic experiment. Tragic because eleven people lost their lives, and thousands more lost their livelihoods and an experiment because we have never had a marine oil disaster of this scale in U.S. waters. As far as microbial research goes, we have learned a great deal from it and we’ve had quite a few surprises and some interesting debates along the way. We’ve also realized how much we do not know.

Every research cruise we go on, every experiment we do, every time I simply sit in my office and ponder what I’ve seen and what my group and our collaborators have done, these things lead to additional questions that require further observation and experimentation. That’s how science works. Science is not static, and there is no end to it. There is always more work to do, more things to learn, more discovery and more excitement. I feel like we have made a tremendous amount of progress, but we have so much more to do and so much more to learn. In my opinion, we have only now begun to scratch the surface and dig into the details that drive many of the patterns observed during the discharge.

Honestly, I had no idea where we would be four years out because I did not know where the initial studies would lead us, but they have led us to very fruitful ground that will keep us busy for decades, funding permitting.

OC: What research remains to be done in the Gulf? What are the most important gaps we need to fill for research in the deep-sea, open-ocean or other ecosystems you study in the Gulf of Mexico? How can we fill those gaps?

Dr. Joye: The microorganisms that call the ocean home have enormous metabolic potential and, when exposed to perturbations, it is almost certain that some microorganisms are sentinels that could alert us to changes that are occurring in their environment. There are numerous data gaps – we know so little about the physiology of the billions of microorganisms that are present in a few drops of seawater. What are the dominant organisms and how do they respond to perturbation? What about the rare organisms? Who are they and how do they respond to perturbation? We have to understand the language of microorganisms – their language is spoken in terms of their diversity, physiological capacity and ability to tolerate or adapt to perturbation. We have to understand these three things to know what they are telling us when a perturbation occurs, whether that perturbation is a hurricane, ocean acidification or an oil discharge.

But this is my dream – to develop long-term microbial observatories in the Gulf and elsewhere. When I look at what one long-term ocean observatory site has taught us, Station ALOHA off of the island of Oahu in Hawaii, I know that this is a dream that I simply must make come true.

OC: Thanks for your time Dr. Joye! It has been a pleasure chatting with you and we look forward to hearing more about your future research.