Featured Scientist: Karen Selph

Karen in the lab-van whispering to the flow cytometer!

Hello blog, today Dr. Karen Selph from the University of Hawaii at Manoa shares some of her expert insight into the nutrient-limited world! Karen shared with the blog just a few of the multiple experiments she carried out while on board the NOAA Ship Nancy Foster during NF1704 as part of our NOAA RESTORE project. Karen’s main focus was collecting phytoplankton to analyze with a “flow cytometer” – a machine that tells us how many phytoplankton are out there and gives us a rough idea of their types.

In addition, she measured water column light levels used for photosynthesis by phytoplankton with a photosynthetically-active radiation (PAR) sensor that was attached to the CTD rosette. Karen shared with the blog: "The 6 casts that we performed will yield invaluable information on the light regime during the cruise." 

"The nutrient limiting phytoplankton growth in the Gulf of Mexico is nitrogen.  Nitrogen has many forms, and most phytoplankton can only use reduced inorganic forms (e.g., nitrate (NO₃), ammonium (NH₄)).  However, some phytoplankton can use nitrogen gas (N₂), which is in abundant supply.  This is quite a trick, as the chemistry involved is anaerobic (no or low oxygen) and phytoplankton produce oxygen! 

Karen and Lucy carry out one of the PAR casts

On this cruise, we collected many samples to figure out which of the larger nitrogen-fixing organisms that might be present – in particular, Trichodesmium (usually a bane to those who study zooplankton, as it can clog their nets!!).   Additionally, to assess the base line N-isotopic value for Trichodesmium, we collected samples for stable nitrogen isotope analyses.  We even analyzed a sample of Sargassum to figure out its isotopic signature with respect to the other nitrogen-fixing players in the GOM.  Once we get back to the lab, we will also examine our samples under the microscope looking for the presence of other nitrogen-fixers – some diatoms and other species harbor symbionts capable of this remarkable feat!"

The dynamic duo, Tom and Karen processed hundreds of samples during the survey

Shaun, Karen's travel companion, makes some new friends

Featured Scientist: Michael Landry

As we wrap up this year's survey, the first of two annual research surveys in the Gulf of Mexico for the NOAA RESTORE Act Science Program, we'd like you to get to know the PI from Scripps Institution of Oceanography, Professor Mike Landry! Read on as he describes his research and our cruise goals in his own words!

"I am a biological oceanographer. I have been on many ocean research expeditions over the years (since the 1970s), but never on a cruise in the Gulf of Mexico, never on a NOAA ship and never with fisheries scientists trying to understand a specific fisheries-related problem. So this particular cruise is special and a new learning experience in many respects. At the same time, it is also familiar. What we have investigated on past expeditions is how plankton food webs in different areas of the oceans function under different environmental conditions in order to understand the “rules” of why systems vary and how they respond to change. Our hope in this project is to apply the techniques that we have developed and the results from past experiences to characterize the unique aspects of the Gulf of Mexico habitat that lead to rapid growth and success of larval bluefin tuna (why do momma tunas migrate vast distances to spawn in only few small places in the ocean?) so that fisheries scientists might be better able to predict how they might be affected by future ocean changes.

Above: Groups of water bottles to
be sent to different depths
Below: Our filtration set up -
6 bottles at once!

"In this project, we are taking two approaches to studying food-web relationship and rates. One is experimental, involving direct measurements of community composition, productivity and nutrient uptake by phytoplankton, the microscopic plants of the sea. We also measure the consumption (grazing) of phytoplankton by zooplankton, the slightly larger but still pretty small protozoa and small animals that comprise the first 2-3 steps of the ocean food web. This is the “what is there,” "what are they doing,” and “how fast are they doing it” part of the study. Phytoplankton often go through one or two generations (cell divisions) per day, and they get eaten almost as fast as as they divide, so the tricky part of these experiments is separating the two rates (production growth and grazing loss) that are going on at the same time. We have a technique for this, which involves dilution of the grazing impact (using filtered water, changing the encounter frequency of predators and prey) in some of our experimental bottles. It is also important that we run our experiments under natural conditions of underwater light and temperature, so all of our experimental bottles that contain the plankton that we collected at different depths are put in net bags and attached at same depth to a line underneath a free-floating drifter float that we track by satellite for a day before picking up and exchanging bottles for a new batch of experiments. After a lot of filtering, preservation or freezing, and later analysis in our lab on shore, we should have a pretty good picture of how productivity and nutrients are moving through various routes in the food web to get to the specific zooplankton prey that bluefin tuna larvae like to eat.

Tom (L) and Mike (R) attach bottles to the sediment trap array

Mike (L) and Aki (R) hunt for BFT using microscopes onboard

"In the second approach to this study, we will use the tuna larvae themselves to tell us where they reside in the food web and what is the main source of nutrients (nitrogen) for primary production. This information resides in the nitrogen isotopic composition of the amino acids that make up the proteins of the tuna larva muscle tissue, which varies with the source of nitrogen (N2 gas for nitrogen fixation versus nitrate from deep water upwelling) and the number of predator-prey steps that the nitrogen has taken to get to the larvae, starting from phytoplankton. This sounds complicated, but the isotope analysis is easier to do than all of the experiments that are needed to assemble the food-web picture. One of our goals is to see if results from these two approaches agree, which has never been done before for any system because the isotope approach is so new. If this works out, it would validate using the isotopes in future studies, or also to look at changes in food-web structure and nitrogen sources that may have already occurred with climate change, using the muscle tissues of fish samples that have been taken in the past and preserved in museum collections."

Featured scientist: Loni Mnich

We are wrapping up this year's survey!... but we still have a few more posts from our scientists and will give you the numbers (eventually!)!

Rinsing down the bongo net

Meet our newest UMiami RSMAS marine science graduate, Alanna (Loni) Mnich! Loni has been a volunteer at the FORCES Lab and she shares some of her experiences on her first research survey aboard the NOAA Ship Nancy Foster.

Decked out with safety gear, ready for deployment

She shared with the blog: “My goal for this cruise is get my first at sea experience. I hope to gain a better understanding through practice of field research concepts and learn more about plankton and the early life stages of fish that I can then apply in the lab and in future studies. I am excited to see some cool organisms over the course of this cruise!

“I have been in the FORCES lab at NOAA for about a year and a half. My experience there began with sorting plankton that was collected on other oceanographic cruises, so I am excited to participate in the collection stage now. During the past months I have focused on cephalopod paralarvae as the subject of my undergraduate senior thesis, which I hope to expand into a publication.

Loni takes command of the Bongo and Ring net tows in the dry lab

"Over the course of this cruise I have gained significant hands on experience in plankton collection and processing, including deploying the bongo net, driving the bongo, fixing samples, as well as deploying the CTD. I will soon be able to apply these skills if I get an opportunity to participate in another cruise (hopefully in late July!). Through the rest of the summer, I will be back in the FORCES lab, likely sorting plankton from the cruise and continuing my previous work with cephalopods. In the future, I would like to gain more hands on lab and field experience and I also plan on attending graduate school to expand my studies."

Featured guest: Angie Fay Allman

Hi everyone! Today we get to have a unique perspective! One of the crew of the Nancy Foster wanted to stop by and say hello! Meet Angie Fay Ullmann. Angie was our survey technician on the night watch (midnight to noon shift) and helped us safely deploy and recover countless equipment during her watch! She is a NOAA wage mariner, her official position is an “Able-bodied Seaman” and is part of the ‘deck’ department. The science party works closely with the crew members from the survey and deck department as they facilitate multiple and often difficult tasks that include deployment, recovery, set up, break down, winch operations, small boat operations, among many others.

Angie on the bow of the Foster leaving Key West, FL

Angie shared with our blog from her angle:

“I have worked for NOAA for 2.5 years now and have worked on 10 of the 16 ships in our fleet. I am required to do many different tasks on each assignment, but this last cruise really stands out from the rest. I got to work more closely with the scientists and asked more questions about what they were looking for and why. I really enjoyed being more involved and the crew I worked with was a lot of fun and made the days pass by quickly. I hope the data we collected helps contribute to a better future- it gives so much more purpose and satisfaction to my work- even if I don't directly do any science, I'm helping it happen! Before this cruise, I didn't realize the scarcity of bluefin tuna nor that so many scientists try to analyze its behavior in efforts to revitalize its population.”

Angie shows Lucy the ropes, he he

We truly enjoyed working with Angie and hope she will join us again in one of our next adventures on Nancy or another NOAA ship!

Night shift crew!

Featured Scientist: Rachel Thomas

Today on the blog, we have a guest post from Rachel Thomas, learn about her research objectives during this survey in the Gulf of Mexico!

Rachel takes the CTD down to 2500m in the Gulf of Mexico!

My name is Rachel Thomas and I’m a PhD student at Florida State University studying the marine nitrogen cycle with the Knapp Lab.

Filtering sea water

On this cruise, I am looking at the concentrations of nitrate, a nutrient required by primary producers, found in the upper 300 meters of the water column. Water samples are prepared using a colorimetric technique that will turn the water varying degrees of pink, depending on concentration, and analyzed at a certain wavelength. I am also collecting water samples from various depths ranging from a depth of 2500 meters and 3 meters below the surface. These samples will be taken back to FSU where we will look at the different nitrogen isotope signatures found in the water parcel.

Rachel examines nitrate concentrations

Think of an isotope signature as a fingerprint, where each source of nitrogen has its own unique fingerprint. By comparing the known signatures of each source to our water parcel, we will be able to determine where the nitrogen is coming from.

Collecting water from the CTD rosette 

It is important to understand where these nutrients are coming from to fuel primary producers in order to better understand how changes in nutrient sources will affect the GOM productivity.

Featured Scientist: Lucy Fitzgerald

Hi everyone, I'm Lucy Fitzgerald, a rising senior and a marine science/biology major at Eckerd College in St. Petersburg, FL. Though I've logged plenty of lab time, this is my first experience on a research vessel. This trip is the beginning of my NOAA Hollings internship at the SEFSC FORCES Lab in Miami. I've been on the night shift and am learning the ropes with tasks such as deploying nets and the CTD, logging data, and tracking the SVP drifter buoy. I have also gotten to see a lightning storm at night, fabulous sunrises, and tons of plankton!

My goal is to learn about the upstream process of collecting specimens before working with them in the lab this summer, looking at the age and growth of billfish. As an undergrad, I'm trying to figure out what field of research I want to go into before applying to graduate school.

Karen and Lucy send the CTD to 300m in the GOM

Lucy learns about the array recovery from Tom and Becca

I don't have a specific research focus yet but my research experience has been primarily with paralarval squid, Doryteuthis pealeii, and looking at the effects of hypoxia on the boundary layer of the egg capsules as well as hatching rates/cues last summer and winter at the Woods Hole Oceanographic Institution. I have also looked at the population genetics of the brown Sargassum snail and bandtooth conger eel in the western Atlantic.

Being out in the open water where these species live brings a whole new perspective to my work in the lab!

Featured Scientist: Meet Jason!

Today's featured scientist is Jason Mostowy - read on for more about his cruise and future goals!

My name is Jason, I graduated from the University of  Miami in 2015 with a B.S. in Biology/Marine Science, and I've been working as a research tech in the FORCES Lab since 2013.

Larval lionfish (Pterois volitans/miles)
Image credit: FORCES

My main work for the lab involves processing the zooplankton samples we collect on cruises like this one - meticulously removing fish larvae and other target organisms, fitting the results into our considerable database, and dissecting larval fish for otoliths (earstones, used for ageing studies), gut contents, or genetic analysis projects. I'm also currently working on a project to characterize the larval distribution of the highly invasive Indo-Pacific lionfish (Pterois volitans/miles) in the tropical western Atlantic. Gaining a better understanding of the early life ecology of this harmful species will help scientists better predict levels of lionfish population replenishment, which in turn can be used to determine where and how often lionfish removal efforts should be performed.

Jason sorts through plankton search for tunas

Jason rinses down the Bongo-90 with
Sarah and Lulu during night shift

This is my third year sailing aboard the Foster. I love working in the field, especially the many perks that come with going to sea - the chances to practice and expand my scientific skill set, the opportunities to get to know other scientists from a variety of disciplines, the stewards rescuing me from my unfortunate cooking for a few weeks, etc. It's been a long cruise for me; I first embarked way back on April 13th, and by the time we reach port on June 2nd I'll have spend 35 of the last 48 days at sea!

This fall - after what I hope will be a commensurately long and relaxing stint on solid ground over the summer - I plan to start graduate school where I will continue to study the factors that mediate the distribution and survival of larval fish in the GOM and Caribbean.