Data Keeps Drifting In

Author: Laura Bracken, CARTHE Outreach Manager

After a month at sea conducting a variety of experiments, the Ronald H. Brown has returned home but data continues to pour in. As the ship circled the Gulf of Mexico (GoM), conducting cross-shelf transects, scientists onboard released 25 custom-made, GPS-equipped, biodegradable CARTHE drifters, described in the post “New biodegradable surface drifters to survey the ocean currents of the Gulf.” The drifters can transmit their location every 5 minutes for 1-3 months, providing scientists at the Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE) with accurate tracks of the ocean currents.

This experiment is unprecedented and will provide a much needed picture of how currents behave near the shelf.  CARTHE has conducted 3 large scale experiments in the northern GoM but by adding the full range of this vast body of water they will gain a better understanding of Gulf-wide dynamics.

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Figure 1. Cumulative map of ship track, drifter tracks, and hurricane tracks

The above map shows the ship track in green. The individual drifter tracks in black, with red dots indicating their last known position. The purple line that crosses Mexico represents Hurricane Franklin, while the purple line that stretches from the Bay of Campeche to Texas represents Hurricane Harvey. Luckily the ship was already home before Harvey developed, but was required to alter its course to avoid Franklin. Hopefully analysis of the drifter tracks near these storms will provide some information about how storms impact ocean currents.

As expected, there are several areas where drifters were retained over the shelves, mainly moving slowly across the shelf, rather than moving into the body of the Gulf. Of particular interest is the Yucatan Shelf.

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Figure 2. Yucatan shelf

The historical drifter database of the GoM shows a gap on the Yucatan Shelf/Campeche Bank (cf. Miron et al 2017).  These deployments will contribute to filling that particular gap. On the Bay of Campeche (west of the Campeche Bank) there are observations of a quasi-permanent cyclonic gyre (called the Campeche Gyre) that models have trouble to represent in the mean.  The drifters deployed in the region are expected to sample this cyclonic circulation, though this has not been seen yet.

CARTHE scientists will continue to track the progress of the drifters, to compare to previous drifter data, and to work towards better understanding how material in the Gulf of Mexico is transported by the ever changing surface currents.

Thank you to the crew of the Ronald H. Brown and the scientists and students who facilitated the release of the CARTHE drifters.

Reflections: Life on Board

Author: Courtney Tierney

Over the last 30 days of sampling and troubleshooting, sunset and moon-rise watching, ping-pong and card game playing, hacky-sacking and hammock laying, Spanish speaking, oil rig discussing, and stargazing, I have had the time to get to know some truly amazing people aboard this ship. I am so grateful to have been able to join them—working together to raise awareness about ocean acidification and collecting data that can make a difference.

Never would I have imagined myself here when I am only half-way done with my undergraduate studies. I had just turned 20 before boarding the Ron Brown (which coincidentally also turned 20 in the same month) and had a small I’m-an-adult-now life crisis. I’m passionate about what I study but have only an extremely broad idea about where I want my life to go. All I know is I love coral and want to explore the world. So, I have been investigating how each of these people—of all ages and backgrounds—ended up aboard one of NOAA’s global research vessels. I know that I can learn from their decisions, guiding my search for my own dream job (whatever that may be).

One scientist has just finished her undergraduate schooling (where I will be in two short years) and doesn’t have a solid plan either. I’m not alone! A crew member around our age who spent 5 years in the Navy right after high school is trying to figure out his next step as well. We have young engineers from the same military college, young NOAA Corps members who quickly moved up the ranks, and a large portion of the scientists are graduate students about to begin their careers. Some other crew members started out in the army and plan to further their education. Some of our scientists are currently completing their post-doctorate research, while this cruise is just a regular part of the job for others. There are crew members who are 30 and ready to settle down, some who have just started their families, and others whose youngest children are older than me!

From New Jersey, Mexico, Virginia, Cuba, Ohio, China, California, Spain, Pennsylvania, France, North Carolina, the Philippines, Georgia, the list goes on… each person I have met has taken a different path to get here. Everyone has been so open and willing to share their advice and experiences along with their personal lives. I have heard stories of tragedies and miracles; friends, families, and hometowns; past loves and future aspirations. I have learned that it certainly takes the right mentality to spend so much time at sea away from a traditional lifestyle.

I love being able to learn something new from someone new each day. Everyone has also given me insight on their past, present, and some hopefully future careers; some I never would have pictured myself doing don’t seem so out of reach anymore. From the knowledge I have coalesced from about 50 people, I have realized how many career options, traditional or not, are available and how many ways there are to get to them. Although I still don’t know exactly where I want to end up, I’d like to thank everyone for helping me figure out where I’d like to go along the way.

As our trip comes to a close after over a month of being suspended between the deep blue of the Gulf below and the stretch of Milky Way above us, I am still mesmerized by each. Unfortunately, I will have to say goodbye to these sights and these friends for now. Hopefully our paths will cross again when we all will certainly have more adventures to tell.

“Scientific Frenzy” Aboard the Ronald H. Brown

Author: Katelyn Schockman

Imagine packing up your entire workspace and relocating … to a boat. This will be your “office” for the next 36 days; talk about some remarkable views.

Essentially, this is what we scientists on board the R/V Ronald H. Brown have done.  While the lab procedures we run on the Brown are similar to our home labs, collecting quality data on a ship requires extensive preparation and a few adjustments to normal lab routines. Months before we set sail, my lab mates and I began assembling our packing lists. Lists upon lists. The impending month at sea meant we couldn’t forget anything. There’s no Home Depot in the middle of the Gulf, so if we forgot a part, we’d be out of luck. Additionally, we had to consider all the issues that could arise at sea and bring extra supplies just in case. 28 boxes of Kimwipes, 15 boxes of gloves, 80 spectrophotometric cells, extra power cords, computers, water baths, and the list goes on. Even with all the planning, there’s bound to be something forgotten. That’s when you get creative.

There are many simple tasks performed on land that cannot be done onboard. Everything must be pre-weighed because scales do not function correctly at sea, due to the constant movement. There’s also no tap for purified water; it must be made onboard with a machine. And most importantly, everything must be tied down. I mean everything. Each piece of lab equipment is either tied to a table or stored in a drawer. The ship is constantly rocking from the waves and swells, and the last thing we want is our precious equipment falling and breaking.

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Spectrophotometers, computers, and water baths all tied down at the pH and carbonate lab station.

Lots of time and energy is put into preparations, but once at sea the real science can begin. Sampling is done around the clock, as CTD and net tows are cast 24/7, from 100+ stations. There is no such thing as a “typical” 9-5 day here on the Ronald Brown. Everyday activities revolve around variable sampling times. We plan all of our meals, sleep, and exercise based on when the CTD will be ready to be sampled. Each lab station is manned at all hours, and shifts are typically noon to midnight and midnight to noon.  I’m on the night shift and it undoubtedly took me a few days to adjust to working such unorthodox hours.

The lab spaces are very open on the ship, with several groups in each lab area. This gives the lab a community feeling. Everyone is running samples simultaneously, so we can compare our results in real time and get a comprehensive picture of the chemistry through the water column at each station. In the main lab, for example, we have groups running ocean optic parameters, pH and carbonate ion concentrations, dissolved oxygen, and nutrient concentrations. The ship has a unique sense of camaraderie, as the crew and scientists are working and living in such close quarters. Each individual is a piece of the puzzle, and we need everyone to make the cruise a success.

 

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Scientists in the main lab running samples during the night shift. Leah Chomiak, far left, dissolved oxygen concentrations. Ian Smith, middle left, nutrient concentrations Ellie Hudson-Heck, middle right, pH. Katelyn Schockman, far right, carbonate ion concentrations.

While all of this science may sound exhausting, I can promise you that working on a ship is especially enjoyable as well. We partake in bingo and game nights, there are endless movies to watch, a library full of books, an exercise room, and the option of watching waves and searching for sea life right outside. Not to mention the plethora of shooting stars every night and spectacular sunrises and sunsets. Living on a ship is something not everyone gets to experience, and I’m thankful to be one of the lucky few aboard the Ronald H. Brown that does.

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One of the many beautiful sunset views from the ship. Photo Credit: Leah Chomiak.

What do the optical people do on Ronald H. Brown?

Author: Shuangling Chen

Finally, it is time for the optical guys to talk about something! Yes, it is us (Shuangling Chen & Yingjun Zhang, Fig. 1), Ph. D students from Dr. Chuanmin Hu’s Optical Oceanography Lab in College of Marine Science, University of South Florida (http://optics.marine.usf.edu/).

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Fig. 1. The optical guys from College of Marine Science, University of South Florida (left: Shuangling Chen, right: Yingjun Zhang).

Simply speaking, we measure ocean color. When sunlight gets into the ocean, it is attenuated with depth due to absorption and scattering by the constituents in water. Different constituents (such as Colored Dissolved Organic Matter (CDOM), phytoplankton, inorganic suspended matter) have different absorption and scattering characteristics, and that is basically why we see different ocean colors.

Since we got on board the first day, the most frequent question we were asked about was: “What is a HyperPro?” After it got clear, the question becomes, “Hey, HyperPro today?” I am so glad that people on the ship care so much about what we do, and I believe you, who is reading this blog, must be also curious about it!

The “Giant” HyperPro we brought is a Satlantic free-falling HyperPro II (left in Fig. 2), ~1 m long and 25 pounds heavy. It is a hyperspectral radiometer with a wavelength range of 350-800 nm. An independent surface reference system (right in Fig. 2) is also included to provide downwelling irradiance (Es) during casts. It is mounted high on the vessel to avoid any potential shading.

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Fig. 2. HyperPro profiler and the surface reference system.

The profiler, surface reference system, and a GPS device, are connected to a laptop via a deck unit for synchronous data transfer. Once all the pieces are connected, before the deployment, we need to do a pressure tare to record the reference pressure and a dark measurement to record the offset values of the sensors.  Then it is ready to go!

Since we measure light in the water, we do not want the solar light to be changed much by an unpleasant cloud. Therefore, usually we would deploy when the sky is clear and sunny. Also considering the satellite overpass time during a day, we would prefer to deploy during local 10 am – 4 pm. Besides, to avoid the ship’s shadow, and depending on the strength of the current, the ship may need to move slowly (~0.1 knots) to keep away from the profiler.

Usually, Yingjun is responsible for the deployment, and I’m in the lab to control the laptop for data logging and checking the depth and tilt of the profiler and communicating that back to Yingjun (Fig. 3). It sounds quite simple and easy, right? Well you’d be surprised at how much labor and coordination it needs, especially when you take into account the water pressure and currents. And that’s mainly why I say the HyperPro is a “Giant”. For stations over 200 m deep and if time allows, we need to cast to 50-70 m twice and then cast to 15 m 5 times, deploying and recovering by hand and often working against currents and water pressure at depth. It takes lots of labor (Thanks, Yingjun, you did a great job!)! One more thing to consider is the communication cable and preventing it from getting tangled. The survey tech on deck, with whom I communicate via radio during casts always helps to unravel it (Daniel and Josh, thanks! We really appreciate that!! See, we are doing science together!).

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Fig. 3. HyperPro deployments on deck and operations in the lab.

It is very hard work, but we really enjoy it! Look at the fancy data we collected (Fig. 4) and see how the light is attenuated at different wavelengths and depths, isn’t that cool?

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Fig. 4. An example of data collected at station 002 on July, 20th, 2017.

In addition to the HyperPro, we also carried 4 other optical instruments (Fig. 5): 1) a handheld spectrometer, to measure remote sensing reflectance; 2) a handheld sunphotometer, to measure light absorption in the ozone column; 3) an ALFA underway system, to measure chlorophyll fluorescence; and 4) a water filtration system, to filter water samples from the CTD or underway seawater line for measurements of particulate absorption, CDOM, and chlorophyll pigments.

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Fig. 5. Other instruments that we worked on.

I just realized that the cruise is going to end in 4 days. How time flies! Flipping over days past, it is the outstanding leadership of our conscientious and considerate chief and co-chief scientists Leticia and Denis and the awesome teamwork of our lovely and responsible crew members on Ronald Brown that makes all the science go smoothly. I believe all the scientists are collecting very interesting data, and science will never stop!

Dissolved Inorganic Carbon

Author: Joletta Silva

Hello, my name is Joletta Silva, and I am a master’s student at the University of Miami RSMAS studying Marine Conservation. On the GOMECC-3 cruise I have been working alongside Patrick Mears completing dissolved inorganic carbon (DIC) analyses.

DIC is comprised of CO2, and all the nonliving carbonate species (primarily carbonate and bicarbonate) that are dissolved in the seawater. Generally areas which have high concentrations of carbon dioxide will have correspondingly high levels of DIC. When our data is coupled with data from other carbon parameters (alkalinity, pH, etc) it can be used to determine the rates of ocean acidification in the Gulf of Mexico.

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The DICE lab on board Ron Brown. Image credit: Joletta Silva

The dissolved inorganic carbon lab is separate from the main lab on the ship and is built into a modified shipping container which is usually stored at the Atlantic Oceanographic and Meteorological Laboratory on Virginia Key, Florida. This makes transport and setup relatively simple and also allowed for me to become familiar with the machine setup before I got to the RV Ronald Brown.

Life on the ship:

I am working the night shift (11:30 pm to 11:30 am), and generally sleep or  nap during the day, and wake up at around 11 to start my shift. When we are on transect lines, the CTD (whom we have affectionately named Barbara) will descend at each station to various depths, and will return to the surface filled with seawater for sampling. We receive a daily schedule so that we know exactly when to be outside prepared to extract water. I generally take one full bottle from each of Barbara’s niskin containers (up to 24 total, each one containing seawater from a different depth). As soon as I fill the bottle and ensure that there are no bubbles in the sample, I poison it with a mercuric chloride solution to kill any living organisms and ensure that they do not breath, thus changing the CO2 concentration in the sample before it is run through the machine. After getting all my samples from Barbara, I return to the lab and begin to analyze them.

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CTD going down at a station. Image credit: Joletta Silva

This can be a long process, as each one of our samples takes about 15 minutes to run. The machines also take about 1.5 hours to calibrate and set up, so a lot of time is spent doing this. Sample analysis is completed using a coulometer and a Dissolved Inorganic Carbon Extractor (DICE).  The coulometer is used to help determine the amount of carbon in the cell. The carbon in the sample is converted to carbon dioxide gas, which then reacts with a proprietary reagent causing the formation of OH- and H+ ions which are detected by the machine which uses photogrammetry, or light streams, to detect and quantify the ions. Basically, the DIC in the sample is converted to carbon dioxide, which is then measured through a titration that gives us a total carbon count.

During a normal shift (when we are not in transit between station lines) I will sample between 2-4 CTDs at varying depths, and have to calibrate the machine twice. There are several other scientists who work night shifts measuring other parameters such as dissolved oxygen and nutrients, and we have become fast friends (something about sampling at 3 am while listening to some great music creates an instant bond). We have been fortunate to have some incredible experiences including outrunning tropical storm Franklin in the previous week. In addition to this, we just witnessed a meteor shower on August 12th that lasted the majority of the night!

We have a mere few days left of our 35 day cruise, and it has gone by far too quickly. It has been interesting to view the profiles of DIC along the varying transect lines and observe trends and changes in different areas and depths. This last week is going to be one of the busiest, since the transect lines and CTD stations are so close together. I am excited to continue to learn about inorganic carbon profiles in the Gulf, and see how the remainder of our results turn out. Here’s to the last week at sea, and the adventures that it will bring!

Unwilling hitch hikers of the oceans

Authors: Leticia Barbero and Kevin Sullivan

It’s the little things that make the hard and long hours on these cruises worth while. Little breaks from the monotony of station after station and sample analysis after sample analysis for 12 hours each day.

Sometimes those breaks come in the form of a group of dolphins playing alongside our ship for a while, a whale or two in the distance (or sometimes close to us!) or simply a little time enjoying a gorgeous sunset or a series of shooting stars at night. These are the sort of big awesome moments on the ship.

But sometimes there’s little things that make your day too. A couple of days ago we had one of those moments when we found an unexpected hitch hiker that had boarded our ship using the seawater line. It is relatively common to see smaller organisms captured along with water (samples), but this one is a fighter, for sure. As part of Kevin Sullivan’s supervision of our underway equipment, he noticed a small crab in the filter enclosure of the UW pCO2 analytical system.  It was swimming around feeding on the materials trapped by the filter.

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The underway pCO2 system. The arrow points at the filter where the crab was found. Photo credit Leticia Barbero

Try to imagine the ride this little crab went through: from the ocean, sucked through the seawater intake at the bow of the ship, on to the instrument chest, up through a sizable seawater pump, pushed along ~200 ft of piping into the hydro lab, then on through 3/8″ tygon tubing to the pCO2 wet box, an Evsco valve, and finally the filter enclosure. And he was still swimming up and down and around the filter enclosure! Talk about a spirit of survival!

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Close up of the crab in the filter. Photo credit Leticia Barbero

Kevin stopped the system while we were on station and put him in a beaker along with some of his buffet. Our on board biologists have confirmed that it’s a “he”. His water is re-oxygenated frequently. Given his ordeal, Kevin has named him Jean Valjean after the character in Les Misérables. Discussions are happening now about whether it’s better to release him far from his original dwelling or have him moved to a seawater tank back in Miami.

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The crab in its temporary new home. Photo credit Leticia Barbero

 

Linkages between Ocean Acidification and Marine Organisms

Author: Jesus C. Compaire

We have all have heard about how ocean acidification has an important impact on marine ecosystems (if you don’t know what ocean acidification is, our colleague Jon Sharp tells you in his entry about pH onboard GOMECC-3). One of the most known effects is coral bleaching in tropical areas, but this phenomenon does not only affect the sessile organisms (who cannot run looking for better areas for their growth). At different scales, the rest of plants and animals in the ocean can also be affected by ocean acidification since this reduces the calcification in many organisms (Orr et al., 2005). Species affected include planktonic calcifiers (coccolithophores, foraminifera, pteropods), and also other animals like echinoderms, bryozoans, molluscs, crustaceans, fish, and a long etcetera.

coral infographic

But, what exactly does “reduce the calcification” mean, you might ask yourselves, and why is this a negative impact? To try to understand this phenomenon let’s see a few cases in different animals. For example it has been documented that elevated pressure of CO2 (i.e. high concentration of carbon dioxide) reduces the growth of molluscs and sea urchins, which means that compared to normal levels of CO2, the animals that grew in high CO2 conditions had smaller sizes and body weights (Shirayama & Thornton, 2005). In other experiments with crabs, the combination of increased temperature and lower pH reduced the energy for reproduction (Paganini et al., 2014). Now let’s talk about fish, and in particular about the ichthyoplankton (the eggs and larvae of fish found mainly in the upper 200 meters of the water column) of the marine coastal species. The survival of their larvae depends on them being able to find a suitable adult habitat at the end of an offshore dispersive stage that can last weeks or months. The way that they may return to adult habitats is with their ability to detect olfactory cues from these adult places. However, under experimental ocean acidification conditions it has been noted that this ability was disrupted. So if acidification continues unabated, the impairment of the sensory ability may reduce the population sustainability of many marine species, with potentially profound consequences for marine diversity (Munday et al., 2009) and impacts to wide sections of the population whose economies depend on these species.

It is for all these reasons that we are taking zooplankton samples throughout the Gulf of Mexico in this cruise (if you are not sure about what the zooplankton is, please check out this blog entry from July 29th where our colleague Lucio Loman explains this in detail). We aim to study the species composition and their abundances, and their relationships with the physical and chemical characteristics of the water column. The long-term study of the communities composition in the Gulf of Mexico will allow for the monitoring of changes and impacts due to increased sea surface temperature and ocean acidification, which in turn, will help managers to reduce this impact.

References:

– Munday, P. L., Dixson, D. L., Donelson, J. M., Jones, G. P., Pratchett, M. S., Devitsina, G. V., & Døving, K. B. (2009). Ocean acidification impairs olfactory discrimination and homing ability of a marine fish. Proceedings of the National Academy of Sciences, 106(6), 1848-1852.

– Orr, J. C., Fabry, V. J., Aumont, O., Bopp, L., Doney, S. C., Feely, R. A., Gnanadesikan, A., Gruber, N., Ishida, A., Joos, F., et al. (2005). Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437, 681-686.

– Paganini, A. W., Miller, N. A., & Stillman, J. H. (2014). Temperature and acidification variability reduce physiological performance in the intertidal zone porcelain crab Petrolisthes cinctipes. Journal of Experimental Biology, 217(22), 3974-3980.

– Shirayama, Y., & H. Thornton (2005) Effect of increased atmospheric CO2 on shallow water marine benthos. Journal of Geophysical Research, 110, C09S08, doi: 10.1029/2004JC002618.

What is pCO2, and why do we measure it?

An Interview with Denis Pierrot

Interview by: Emma Pontes

I’m pleased to introduce Physical Chemist and Co-Chief Scientist of GOMECC-3, Denis Pierrot. On a normal day, he can be found in the computer lab overseeing CTD operations, but today, he’s kind enough to escort me to the Hydro Lab where the pCO2 Underway System lives. pCO2 is slightly different than regular CO2 concentration; it is the partial pressure of CO2 in a liquid or gas. On the Ron Brown, we have a pCO2 Underway System which Denis proudly tells me is state of the art, and the result of collaboration between several esteemed scientists around the world.

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Image 1. Image credit: Emma Pontes.

In Image 1, you can see the conglomerate of wires, equilibrators, and pumps that make up the system. A water line is connected to the system which pumps surface water from outside our ship in a constant flow into the system. The equilibrator (red circle) sprays the incoming water in a thin sheet which allows the air inside to become equilibrated with the water. This means that the pCO2 of the water will equal the pCO2 of the air inside the equilibrator. This equilibrated air is then sent to a gas analyzer (yellow circle) that measures the pCO2. In this manner, the pCO2 of the water is measured indirectly (by measuring equilibrated air pCO2) and graphed neatly on the laptop attached.

Additionally, the pCO2 Underway System has a gas line (green circle) that draws in air from the bow of the ship, ensuring the cleanest air possible with no contamination from ship emissions. This line is connected to the gas analyzer and the incoming air is measured for its pCO2 directly. The goal of this system is to measure the pCO2 of the water AND the atmosphere. The interaction and difference between ocean and air pCO2 is the basis of Denis’ work.

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Image 2. Image credit: Emma Pontes.

Image 2 shows a graph of the output from the pCO2 Underway System. The blue and brown dots represent pCO2 of the water, while the purple and green crosses represent pCO2 of the atmosphere (purple line). The goal here is to determine where and when the ocean acts as a source and sink of CO2. The ocean is a source of CO2 when the water pCO2 is higher than that of the atmosphere (above the purple line). Conversely, the ocean is a sink of CO2 when atmospheric pCO2 is higher than that of the water (below the purple line). Since gases always move from high to low concentration in an endless quest for equilibrium, Denis and his colleagues can tell if the ocean is releasing (source) or absorbing (sink) CO2 and at what rate. The rate of this CO2 exchange between ocean and atmosphere is called flux. Denis hopes to create an up to date flux map of the Gulf of Mexico complete with spatial and temporal attributes. Flux is constantly changing both seasonally and temporally, and is dependent on wind, ocean current, temperature, and other atmospheric factors.

One quarter of anthropogenic CO2 is dissolved into the ocean. This has important and unfavorable implications for calcifying organisms such as certain plankton, corals, sea urchins, and any other creature that relies on carbonate to build its shell or skeleton. CO2 is an acidic gas that lowers the pH of water which it is dissolved in. A lower pH means more acidic water, which also means less available carbonate for calcifying critters to utilize in their shell building. A more acidic ocean is one with fewer ecologically important corals (and other carbonate-reliant species) and fewer commercially important seafood items like shellfish. Denis is very passionate about his work, which has ecological and commercial implications under ocean acidification conditions.

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Co-Chief Scientist Denis Pierrot, hard at work in the Hydro Lab. Image credit: Emma Pontes.

Tropical Storm Franklin Reconfigures GOMECC-3 Cruise Track

Author: Leticia Barbero 

Ahoy land dwellers!

Another week gone and a fair number of stations is now under our belt. We completed the US section of our cruise and entered Mexican waters on Wednesday, August 2nd, after taking samples just outside of the Padre Islands National Park as part of our collaboration with the National Parks Service. We are now covering all new land (or rather, ocean) as far as the GOMECC cruises go. We completed the first line in Mexican waters and were halfway through the next one when the first weather reports started coming in talking about a potential cyclone. While we were at first hopeful that the system would dissipate, by Sunday it became clear that the system was not going anywhere and that Tropical Storm Franklin was determined to pay us a visit as we sailed through the Bay of Campeche.

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Probability of tropical-storm-force winds as Tropical Storm Franklin goes through the Bay of Campeche. Image credit: National Hurricane Center

We are a welcoming bunch here on the GOMECC-3 cruise, but we draw the line at hurricane-force winds, so we decided to hightail it out of there and head straight for the Yucatan peninsula, initially forfeiting our Campeche line. Franklin is in for a surprise when he finally arrives at the Bay of Campeche only to find that we are not there!

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GOMECC-3 Cruise Track, Post Franklin

After playing with scenarios A, B, C, D, and who’s counting anyway, we came up with a plan that will allow us to get enough coverage of the Bay of Campeche, despite having had to give up our plan to take surface samples all along the coast. See attached map below for our new sampling strategy, which includes a shortened Yucatan line (line 7 on the map) and a new, short line 8. The ship will have to crisscross along the Yucatan platform, but we think we can get it done with no overall loss of time.

Filtering the Gulf of Mexico

Author: Gabrielle Corradino

“Why would you spend 35 days on a boat just to filter seawater?”

This was the most common question (second most common was: “Don’t you get seasick?”) that I received as I explained what I would be doing during the GOMECC trip to my friends and family. The biology component of the GOMECC trip does include lots of filtering of water onto specialty glass fiber filters, but the research does not stop there!

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Preserved copepods from CTD 47. The copepods were isolated and placed into filtered seawater and formalin. This will allow observations to be made about the individual organisms in each sample.

Team Plankton (Mrun and myself) will have filtered over 236,000ml of seawater onto 550 filters to help answer questions on microbial species diversity using both molecular and pigment profiling. While invisible to the naked eye, each of the filters will have tens of thousands of tiny organisms (phytoplankton and protozoa) retained on their surface that represent the base of the food web within the GOM. The filters, which may turn a greenish color, if phytoplankton are present (Fig 1), are frozen on ship and will be brought back to North Carolina State University or University of Louisiana for further analyses.

Each filter will be used to collect a snapshot look at microbial assemblages, the presence/absence of certain taxa (DNA signal) and their activities (RNA signal). In unison, we also use several preservation methods to obtain intact plankton for microscopy analyses (Fig 2) from the CTD, a bucket (Fig 3) or with a plankton net.

This trip is intensive, but with the guidance from our rockstar chief scientists (Leticia and Denis), we will be able to gain unique insight into the microbial biogeography, biodiversity and functionality. We believe this data will serve as an important baseline as we study the impact of ocean acidification on the Gulf of Mexico.

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Whole water surface samples being filtered through a 200µm mesh and into a carboy. This water will be used for filtering and for the on-deck grazing experiments.
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Example DNA filter from a surface water sample. The filter will be frozen and brought back to North Carolina State University to have the DNA extracted for processing.