Ocean Acidification buoy validation measurements

An example of NOAA’s synergistic efforts to monitor coastal ocean acidification using a variety of platforms

Author: Leticia Barbero 

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OA buoy with the Ron Brown in the background. Image credit: Jay Hooper

We have just finished the third set of stations in our cruise, the Louisiana Line. This line is interesting for many reasons. The outflow of the Mississippi river into the Gulf changes the characteristics of the water we are sampling, sometimes dramatically. In the stations closest to the coast, which are more influenced by the riverine outflow, surface salinities are so low that they test the limits of the method we use for measuring pH with high precision and accuracy.  High nutrients from the outflow promote high primary production in the surface waters, which in turn ends up causing hypoxia (low oxygen concentrations) in the bottom waters. While regular oxygen values might be in the range of 120-250 umol/kg,  a sample from one of these bottom waters had an oxygen concentration of less than 20 umol/kg. Imagine having ten times less breathing oxygen than you are used to!

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One of many oil rigs we sailed close to during the sampling of the Louisiana Line. Image credit: Leticia Barbero

Besides the very interesting data we get from these stations, the Louisiana Line also affords us the chance to sail close to the dozens of oil rigs peppered along our route, which makes for good pictures for our personal albums.

And unexpectedly, two days ago the opportunity arose for an unplanned collaboration. We were notified that a buoy partially funded by NOAA’s Ocean Acidification Program, which also sponsors our GOMECC-3 cruise, has just been moved to a location close to our route. This buoy has pH, pCO2 and oxygen sensors. Our measurements on board can be used to validate the data from the buoy, so we decided to bring the ship as close to the buoy’s position as we could and take samples on site over a period of three hours. The scientists maintaining the buoy back on land will be able to use our data to calibrate their sensor data.

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Chief Bosun Mike Lastinger drives the Ron Brown’s small boat from the ship to the buoy. Image credit: Jay Hooper

Additionally, the ship was willing to accommodate a very last-minute request to use the ship’s small boat to get a water sample from right next to the buoy, for best quality comparisons. I am very grateful for our science team’s willingness to add extra samples to their already loaded stack of backed-up samples after a succession of stations that were very close together,  for Jay Hooper’s hard work handling the buoy sampling logistics on short notice and I am especially appreciative of  the efforts of the ship’s officers and deck crew to get us to the buoy in time to sync our sample with the buoy’s hourly measurements. We really have amazing science and ship teams working together on this cruise to collect the data we need to monitor ocean acidification conditions in the Gulf of Mexico.



Zooplankton, Pteropods, and their importance in a changing ocean

Author: Lucio Loman Ramos

Finally, we get into the biology of the macro zooplankton in this blog. My colleague Jesús Cano Compairé and I are involved in research of these tiny creatures that live in the oceans all over the world called Zooplankton. We are each interested in some specific group within this categorization.

Zooplankton (from the Greek: Zoon, animal; and planktos, wandering) are myriads of diverse floating and drifting animals with limited power of locomotion. The majority of them are microscopic, unicellular or multicellular forms with sizes ranging from a few microns to a millimeter or more.

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A brief view of the enigmatic Zooplankton

Talking about their role in the oceans, zooplankton are very important when studying the faunal bio-diversity of aquatic ecosystems, their ecology and also, they give us clues about their surrounding environment. They include representatives of almost every taxon of the animal kingdom and occur in the aquatic environment either as adults (holoplankton, which live all their life in the water column) or as larvae (meroplankton, which live part of their life at the bottom, attached to something and the other part in the water column). By sheer abundance of both types and their presence at varying depths, the zooplankton are utilized to assess energy transfer at secondary trophic levels. They feed on phytoplankton (microscopic plants) and facilitate the conversion of plant material into animal tissue and in turn constitute the basic food for higher animals including fishes, particularly their larvae.

One of the reasons why we are interested in collecting zooplankton here on GOMECC-3 is because certain planktonic organisms are capable of building hard structures of calcium carbonate, concentrating it as shells and thus can act as indicators of the chemistry of the water, they can tell us how they can be affected by environmental changes such as CO2 increase.

We are employing tow nets for zooplankton collection. The plankton nets we use are the Bongo type, called like this because they look like those big musical instruments. We are towing these nets with a steel cable attached to the NOAA ship Ronald H. Brown in a hauling type technique denominated oblique hauls, which allow us to collect zooplankton from a certain depth through all the water column to the surface. These plankton nets are conical in shape and consist of a ring (rigid and round), the filtering cone and the collecting bucket for collection of organisms. After the catch, we need to fixate them with some chemicals and then add preservatives to make them last many years. If we do this step carefully, years from now organisms will look almost the same as if they were caught the previous day, allowing us to make further qualitative and quantitative studies on them.

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Preparing and waiting for the deployment of the net
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Deploying and towing the nets. Image credit: Lucio Loman Ramos
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Left: Fresh samples just after washing the net. Right: Zooplankton just treated with a fixative. Image credit: Lucio Loman Ramos

Our group from ECOSUR Campeche, Mexico, is interested in Pteropods from the Gulf of Mexico. We are looking to have an extended database of pteropod communities and to use it as indicator of the extension of acidification in the Gulf of Mexico. Pteropods are a group of holoplanktonic heterobranch gastropod mollusks (related to seashells), in other words, tiny mollusks that have a shell and live in the water column, they are widespread and abundant in the marine zooplankton. They have been proposed as bioindicators to monitor the effects of ocean acidification because their calcium carbonate shells are exceptionally vulnerable to rising levels of CO2 in the global ocean. It is expected that anthropogenic carbon input into the ocean may affect marine life more severely than in the past, because it is happening much faster than, for instance, at the Paleocene-Eocene thermal maximum (PETM) ~56 million years ago. During the PETM, massive amounts of carbon were released into the atmosphere and ocean, leading to ocean acidification and warming, a situation that persisted for tens of thousands of years (Zachos et al., 2005). This resulted in major shifts in marine planktonic communities. So, we know what happens to some members of the plankton community when CO2 rises and we are interested to know if the anthropogenic activities are involved today in the alteration of plankton organisms with calcareous shells like pteropods in the Gulf of Mexico.

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Group: Pteropods, Suborder: Thecosomes. Commonly known as Sea butterflies.


Zachos JC, RoÈhl U, Schellenberg SA, Sluijs A, Hodell DA, Kelly DC, et al. Rapid acidification of the ocean during the Paleocene-Eocene Thermal Maximum. Science 2005; 308: 1611-1615.

Ian Smith, our on-board nutrient analyst

Interview by Courtney Tierney 

Ian Smith is a NOAA affiliate who is usually based in Miami doing small boat field work with sea grass and sport fish. On the Ron Brown, he is a nutrient analyst working from midnight to noon, 7 days a week. Nutrients can tell us about the quality of the water available for the organisms living here in the Gulf. Ian takes a sample either from our continuous flow of surface water (every three hours) or from a bottle collected at a specific depth from one of our stations (anywhere from 2 meters to 3000 meters). Once the sample is taken, Ian places it into a machine which automatically adds pre-made reagents (chemicals which perform a specific task, or reaction, to test for the presence of another substance) to each one. The system then computes the amounts of phosphates, nitrates, and silicates in the sample.

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Nutrients analyst Ian Smith enjoying a little brake in the fantail of the ship. Image credit: Courtney Tierney

These nutrients are usually most abundant in areas of deep water and where coastal sediment input is prominent. We are currently passing the mouth of the Mississippi River, which is a hotspot for coastal sediment, so Ian has been seeing higher amounts of nutrients than usual, as expected. Too many nutrients, on the other hand, can be bad for organisms because this causes extreme rates of photosynthesis. Algal blooms can then occur creating a shortage of oxygen in the water below. So, Ian’s data has the potential to show the extent to which the coast influences the waters in the Gulf.

So far, Ian says his favorite part of the cruise is being able to see the vast amounts of land-based effort being translated into sea-time success. We are all excited for the next 25 days.

New biodegradable surface drifters to survey the ocean currents of the Gulf

A collaborative effort with the Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE)

Author: Laura Bracken, CARTHE Outreach Manager

Over the next few weeks, researchers on the Ronald H. Brown will release CARTHE drifters throughout the Gulf in areas that we have not had the opportunity to study until now. We are excited about this collaborative project and can’t wait to see where the drifters go!

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A schematic of the planned drifter deployment. Available for the deployment are 25 CARTHE drifters. The drifters will be deployed (blue dots) during each of the planned CTD cruise stations (red dots).


During the Deep Water Horizon (DWH) oil spill, BP committed to fund $500 million in broad, independent scientific research in the Gulf, through the Gulf of Mexico Research Initiative (GoMRI). The Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE) was funded by GoMRI for the purpose of studying the oil spill and its impact on the Gulf’s delicate ecosystems. CARTHE’s scientific work focuses on the physical distribution, dispersion and dilution of petroleum, its constituents and associated contaminants under the action of physical oceanographic processes, air-sea interactions and tropical storms.  Simply put, CARTHE studies ocean currents to be able to predict where oil or other toxins may go in the event of a future spill.

In order to do this, we use GPS trackers on specially designed buoys called drifters.  The drifters move with the ocean surface currents and transmit their precise location via satellite to the scientists on land. By knowing where the drifters go and how fast they move, we can estimate how the currents are moving and where oil might go in the event of a future spill.


CARTHE has used many different types of drifters over the years but none of them were quite right for the large scale experiments (1000+ drifters released over a small area within a few weeks) that we had planned, so the team decided to develop our own. Over 2 years, Guillaume Novelli and Cedric Guigand at the University of Miami created 20+ prototypes, did extensive testing in both the ocean and the SUSTAIN wind-wave tank, and eventually met their criteria:

  1. Accurately follow the surface currents
  2. Hold GPS unit and batteries for accurate reporting of position over several months
  3. Compact and easy to assemble on a ship
  4. Biodegrade – a key requirement when conducting such a large release.

Considering the worldwide marine debris and ocean plastics problem, we felt it was imperative that such large experiments be conducted using biodegradable materials so that we were not contributing to the problem, only the solution. CARTHE drifters are made of PHA, a bioplastic that will degrade over time in the marine environment.  The finished drifters consist of two interlocking panels that can be assembled quickly onboard a research vessel, a donut-shaped float that houses the GPS and batteries in the center, and a chain that links the two sections together.

In January-February 2016, CARTHE released 1100 custom-made, biodegradable, GPS-equipped drifters into the northern Gulf of Mexico, near the site of the DWH oil spill, in the largest oceanographic experiment of its kind ever conducted. Then in April 2017, we returned to the Gulf, this time just west of the Mississippi delta near Grand Isle, LA, with 500 drifters to study how oil gets from offshore, across the shelf, and onto shore.  Additionally, other researchers have used the CARTHE drifters to study the currents in the Arctic Ocean, and to study how animals like mahi mahi and sea turtles use ocean currents. The possibilities are endless.

For a glimpse into the adventure of designing the CARTHE drifters, please watch Drifting into the Gulf by Waterlust.

To learn more about CARTHE drifters, please visit Pacific Gyre.

CARTHE drifters after deployment on GOMECC-3. Photo by Leticia Barbero

Plankton communities and incubation experiments on GOMECC-3

Author: Mrunmayee Pathare

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The microscopic phytoplankton that we study.

Our lab comprises some of the biological sampling being conducted aboard the Ronald Brown on the GOMECC-3 cruise. We study tiny ocean organisms called plankton which range in size from microscopic phytoplankton that use photosynthesis to produce energy, to millimeter sized copepods that can be seen by the naked eye “jumping” to catch their prey.

Phytoplankton form the base of ocean food webs, they are the tiny plants of the ocean, floating in the water column turning carbon dioxide into energy. Phytoplankton fix organic carbon found in the atmosphere and dissolved in the water into energy that is transferred through the food web by bigger organisms eating the smaller organisms. Most of these tiny organisms are eaten, but those that are not eaten fall to the ocean floor, drifting thousands of meters down the water column to be decomposed by bacteria. Phytoplankton fix 45 gigatons of inorganic carbon per year, and are an integral part of the mechanism removing CO2 from the ocean (fixing it), and turning it into food that gets passed up through the food chain, or falls to the sea floor as marine snow.

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A copepod predator that eats prey plankton.

On this cruise, we will be looking at the plankton communities in the top 5 meters of the Gulf of Mexico and who is eating whom. We are conducting a 24-hour incubation on a series of light and dark bottles containing seawater sampled by the CTD. Some of these bottles will contain only phytoplankton and small grazers, and some of them will contain phytoplankton and copepods. This set up will give us a snapshot of predator-prey dynamics at the base of the food chain (who is eating whom), how carbon moves through the base of the food chain in different conditions within the Gulf of Mexico (how much is being eaten and how it changes in different parts of the Gulf of Mexico). We also have some oxygen optodes fixed inside these bottles that will let us measure the amount of respiration taking place in the bottles during their incubation.

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Gluing the optodes (tiny orange circle on the forceps) inside the bottles took a surprising amount of contortion and skill!

To simulate the environment that we are taking these little critters from, we rigged up an incubation tank on the back deck of the ship. We had to get creative with the materials and the location, and then strap it down securely so it won’t move when the Gulf decides to throw bad weather at us.

The tank simulates the natural environment of the ocean and there is sea water constantly trickling through a hose to keep up the circulation and make sure the water inside the bottles doesn’t turn into plankton soup or get the photosynthesizing plankton fried by the sun.

We are conducting a total of 8 of these incubations over the course of the cruise, and although the results will be analyzed after we return from the cruise we are very excited to study the plankton communities of the Gulf of Mexico and contribute to the better understanding of carbon fate and transport.

Breathing in Science: Oxygen Measurements At Sea

Author: Emma Pontes

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Scientist Emma Pontes performing Winkler Titration on a water sample collected from the first station of the cruise. Photo taken by Leah Chomiak.

Take a deep breath. The air you just inhaled contains about 20% oxygen, 78% nitrogen, and 2% of a few other minor gases. Some might assume that oxygen is only available to terrestrial air-breathers, however, this assumption couldn’t be further from the truth.

Oxygen (O2) generally exists in a gaseous state, but also exists in the world’s oceans as a dissolved gas. Fish and other ocean biology utilize the available dissolved oxygen just like humans do; taking up O2 and discharging carbon dioxide (CO2). Just like on land, the ocean is home to millions of photosynthetic organisms such as plankton, algae, and other underwater plants that take up CO2 and release O2 during a process called photosynthesis. Therefore, there is a constant ebb and flow of CO2 and O2 being ‘inhaled’ and released into ocean waters.

So what does this mean for ocean chemistry, and why do we care? Dissolved oxygen in the ocean is a sensitive indicator of climate-related changes. The dissolved oxygen concentration can be used to determine how much anthropogenic CO2 (carbon dioxide released by humans resulting from the burning of fossil fuels) is being taken up by the ocean. Just like oxygen, CO2 can dissolve in ocean waters, and most of human-created CO2 has been sequestered by our oceans. The uptake of anthropogenic CO2 by the world’s oceans is a leading cause of ocean acidification. Therefore, it is of high importance to determine the O2 concentration of various locations around the world’s oceans, not only to learn more about the how ocean biology is functioning, but also to examine the effects of ocean acidification.

Enter GOMECC-3, Ocean Acidification Research Cruise. In the past, research vessels have travelled our current route collecting the same data we are gathering now at the same locations. We can get an idea of how ocean chemistry is changing over time by comparing the data we get on this cruise, to the historic data sets collected on the same path we are on now.

Work days on the ship consist of lowering the CTD rosette (stands for conductivity, temperature, and depth) into the ocean at a predetermined location called a Station. The CTD is a large cylindrical ring of bottles, called Niskins, that are triggered to close and collect water samples at predetermined depths. The CTD is a useful tool for scientists onboard to get insight as to how ocean chemistry changes with depth.

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CTD being lowered into the water at the first station of the cruise. Photo taken by Leah Chomiak.

My job is to collect water samples from the Niskins and analyze each sample for its dissolved oxygen concentration using a technique called Winkler Titration. This procedure requires the addition of chemicals to the water sample that act as a fixative; the chemicals bind to the oxygen in the water and create a solid precipitate that eventually sinks to the bottom of the water sample. You can think of it as ‘pickling’ the oxygen to preserve it, so that the sample can be analyzed anywhere from 1hr to 4 weeks after being collected. To learn more about the titration procedure, check out the peer-reviewed paper entitled ‘Determination of Dissolved Oxygen in Seawater by Winkler Titration Using the Amperometric Technique’ written by Dr. Chris Langdon in 2010, which basically serves as my lab manual on the ship. I am looking forward to collecting some meaningful data that will contribute to OA research as we continue our trip around the Gulf of Mexico!

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Water sample collected by Scientist Emma Pontes to be analyzed for dissolved oxygen. The white milky-looking substance at the bottom of the sample is the bonded oxygen precipitate. Photo taken by Emma Pontes.


Langdon, Chris. “Determination of dissolved oxygen in seawater by Winkler titration using the amperometric technique.” The GOSHIP Repeat Hydrography Manual: a Collection of Expert Reports and Guidelines, edited by: Hood, EM, Sabine, CL, and Sloyen, BM (2010).

Life Aboard

Author: Leah Chomiak

It’s day 2 here on the Ron Brown, and all souls on board have been busy adjusting to new sleep schedules, new office views, and a constant influx of incoming samples. Our first day out was nonetheless perfect; flat glassy seas, clear skies, a slight breeze, with sightings of whales, dolphins, and tuna schools in the distance! As this is my first time sailing on the Brown, I spent most, if not all my time, wandering around the ship, taking in the views, getting to know the crew and fellow scientists, and figuring out the endless maze that is the Ronald H. Brown… I can definitely say that the engine room is a great place for hide and seek, maybe we can get that game going later on in the transit! With our melting pot of individuals onboard, it’s been really fun to get to know everyone and hear how they ended up working on the Brown. Our crew diversity spans individuals of Navy, Army, Merchant Marine, Coast Guard, and NOAA Corps backgrounds, each with awesome stories of time spent at sea and working with NOAA. Our scientists hail from all over the western hemisphere – with undergraduates, graduate students, senior scientists, and our techs each bringing their own zest, humor, and wealth of knowledge to the mission.

Leah Chomiak and Joletta Silva snap a quick pic before boarding the Ron Brown in Key West. Credit: Leah Chomiak
Leah Chomiak and Joletta Silva snap a quick pic before boarding the Ron Brown in Key West. Credit: Leah Chomiak
Glass-like sea state on day 1 transiting to station 1. Credit: Leah Chomiak

Life on board has been pretty great so far! Mealtime is a conglomeration of most bodies on board, where the engineers and other crew crawl out of their caves, bunks, hatches, labs, and the bridge to feast; you’re guaranteed to see someone you’ve never seen before each time you eat! There is a library and movie room onboard, both with hundreds of selections of titles that are sure to please anyone.  My favorite spot onboard is definitely the bow, perfect for staring down at that “no-land-in-sight” ocean blue color, my favorite color that one cannot describe unless they’ve been out to sea. Working the night shift (midnight to noon), I am fortunate to work through a sky filled with billions of stars, and watch the sunrise each morning. Ah, rough life right? Someone’s gotta do it!

Our first station came at 2000 (8:00PM) off the coast of Dry Tortuga National Park, and the entire science crew crowded the deck to watch our massive, pink-framed, 24-niskin bottle CTD rosette be lowered for our first crack at sampling. It was a frenzy as soon as it was back onboard! Sampling teams crowded the rosette with their empty bottles, ready to be filled with water samples from the surface, mid-depth, and bottom. After a successful collection, teams returned back to their labs to process the samples sequentially, and prepared for the next station. In addition to CTD cast stations, underway sampling is collected every 3 hours from a spigot within the lab that is constantly pumping seawater from the surface. Sampling teams collect these samples to observe changes in the surface parameters during our sampling track, such as looking at changes in temperature, salinity, oxygen, pH, and nutrient parameters.

We are currently in a 24-hour plus transit until Station 2 is reached, therefore things are a little quiet on board – the calm before the storm (of samples), should I say. Once the first transect is reached, we will be coming up on stations one after another, and all scientists will be working throughout the day and night to ensure all samples get processed in a timely fashion. I am so thrilled to be on board, it’s been a blast already!! Let’s science!