Trophic BATS: Post # 12 (Day 10 - Final)

Sunrise shortly before our return to Bermuda.

As we were spooling off the lines I got a rare sensation of dock rock. There are two kinds of dock rock, the first kind is what happens after a cruise in evening – it involves a BBQ and a Karaoke player (and its on a dock). The second kind is the sensation where you still feel like you’re swaying back and forth like you’re on the boat. The ground can interestingly look like seismic pulses, slowly lifting up the ground like periods of sea swell.

Jojo and June spooling off the sediment trap lines from the winch.

We arrived back to BIOS at 0930 this morning and shortly after lunch almost all of our cruise gear was off-loaded. The majority of it was hiked up into the laboratories for inventory before crates and boxes are stored until July. The spooling of the array lines was last on the to-do list and shortly after 1430, the cruise has almost officially wrapped up.

Science party watches the Atlantic Explorer navigating Ferry Reach, where the BIOS dock is located.

Now, some of the science party will take the weekend to relax in Bermuda before heading back to their respective institutions. In just about 4 months, the summer Trophic BATS cruise will commence. 2011 and 2012 were funded for field work, with 23 cruise days each year. In the summer, the cruise will be 13 days and likely, the majority of scientists will be returning for the fun. The scientific plan will be roughly the same: sample cyclonic or anticylonic eddies to determine their differences in food web processes, but ultimately focusing on how carbon transfers from the autotrophic community to export from the euphotic zone.

Once again, let’s revisit our research question.

How does plankton community composition and trophic interactions modify carbon export from the euphotic zone?

Now let’s recap the routes we took to measure each portion of the research question. Hopefully the food web from NASA’s Earth Observatory can put help put it into visual perspective.

http://earthobservatory.nasa.gov/Features/Phytoplankton/images/carbon_flux.jpg

First, phytoplankton, the base of the food web, need nutrients to grow. We measured these elemental stocks using CTD casts which gave us physical measurements of the water column (temperature, salinity, dissolved oxygen, and density) by using in-situ sensors. We collected water from the cast to process the chemical stocks such as carbon, nitrogen, phosphorous, and silica in both inorganic/organic and dissolved/particulate forms. Now we have a sense of the substrate in which the autotrophic community converts sunlight and inorganic nutrients into organic matter.

Samplers at the CTD.

To investigate the phytoplankton community structure, we took samples for chlorophyll, pigments (HPLC), and flow cytometry. We can get cell counts through flow cytometry that give us a good picture of the proportions of the dominate phytoplankton in the Sargasso Sea. We also made rate measurements using Carbon-14 to give us an estimate of primary production. One of the future challenges will be determining if these primary production measurements can be sorted using the cytometer to give us taxon-specifc measurements of production.

Primary Produciton/Grazing Array getting deployed.

Now, we have an idea (or will have an idea once all the samples are run) of who’s in the water, how fast they are growing, and what their source of nutrition looks like. From there we move up a trophic level to the grazers. Conducting net tows will give us a measure of zooplankton biomass. With the primary production experiments, micro-zooplankton experiments were carried out as well to measure the overall grazing rate. Separate grazing experiments were made to determine stable isotope fractions of the zooplankton’s food source and then the zooplankton’s organic matter. This will be used to answer the more specific question of who’s eating who. Additionally, DNA analysis of gut content and fecal pellets will be another indicator of zooplankton diet.

Naomi and Molly haul in the zoop net.

This simplified explanation (I didn’t focus on the cycling aspect, which will be absolutely part of the analysis) gives us a general idea of plankton community composition and a few of the trophic interactions. Our sediment traps will hopefully provide us with the answers to how much and what type of organic matter is being exported. The sediment traps will be measured for carbon, nitrogen, phosphorous, thorium, and silica. We also sampled for DNA and pigments in the trap material, giving us clues to the sources of the zooplankton diet, which was converted into fecal pellets and exported to depth.

Sediment traps making their way back on deck.

This research will hopefully provide a quantified model of how carbon flows through each of these relationships starting from the primary producers to the exported flux. Of course, there is much more work to be done. One more research cruise, much more sample analysis, and finally data synthesis and presentation.

This will be the last post, so to summarize – oceanography is awesome. And to generalize, science is awesome.

Thanks for reading.

Doug Bell

Research Technician, Phytoplankton Ecology Lab

I’m going to the beach.

Trophic BATS: Post # 11 (Day 9)

Naomi and Molly congratulating each other after a net tow with a hive-five. They should be happy, they just completed all their work.

“We are officially done!” Rob just announced next to me. Team Condon wrapped up the cruise with a few night net tows just about an hour ago and now we begin our steam back to Bermuda. We’re only 30 miles to the pilot station where we’ll get ushered in to dock at BIOS right around 0930.

It has been a great cruise. No injuries. Calm seas, sunny skies. Research objects completed. No lost or damaged gear. Everyone has been in agreement that the cruise was a success. The past few hours have been a bit busy for some of the labs; cleaning, drying, and packing away supplies for their storage at BIOS or their respective shipments back home.

Matt Baumann performing a regular check up on the in-situ pumps. Foreground includes PEL's sediment traps littering the CTD garage.

For our group, the off load is relatively a breeze. Crates come off and get shoved in the labs. Floating array gear gets craned off and shoved near the warehouse. The cytometer van gets craned off and shoved, well no, way to big to be shoved….it’s relocated on Biostation grounds. For other groups and in general other cruises, off loading and shipping can be a major headache. Scientists are worried about temperature sensitive samples (required storage in liquid nitrogen or –80C) that need to be delivered as fast as possible. Depending on the project they may also have to locate space for annual storage or if not, costly shipments back to their home institutions. Luckily, as this is a multi-year project, much of the entire team’s gear is able to be stored at BIOS.

This will be a short post and tomorrow will be a wrap up summary. Hope you’ve enjoyed the blog. We’d be happy to hear feedback from this little session, so if you thought it was good, let us know (doug.bell@bios.edu).

The Trophic BATS Team!

Doug Bell

Research Technician, Phytoplankton Ecology Lab

School of Hard Knocks

FINAL OBLIGATORY SUNSET PHOTO (I added it to take up space).

Trophic BATS: Post # 10 (Day 8)

The R/V Atlantic Explorer is a terrific research platform for the Bermuda Institute of Ocean Sciences and visiting oceanographic research teams, but it wouldn’t be the outstanding vessel and working environment it is without the great crew and masters of the A/E.

The Explorer arrived to Bermuda after undergoing some major changes over its 3-decade life span. Originally named the Sea Trojan, she was constructed in 1982 to serve as an offshore oil supply vessel in the Gulf of Mexico. After 6 years, she made her conversion to marine science research and was renamed to the R/V Edwin Link in honor to the naval architect of her design. The Link operated out of Harbor Branch Oceanographic Institute in Ft Pierce, Florida specializing in submersible/ROV support. After 15 years as the Edwin Link, she was furthered modified and underwent another name change to the Seward Johnson II. Finally in 2006, she was converted to the state the boat you see today and given the title R/V HSBC Atlantic Explorer.

Once she came to BIOS, her bridge turned into a teaching lab, where I am currently writing. Another deck was added above (the 03 deck – 3 decks up from the main) for the new bridge. Outside of those changes, her engineering specs have stayed the same. The Explorer sits at 168ft with a gross tonnage of 288 tons. She can travel to 11 knots and has an incredible range of 7000 nautical miles. The current captain, George Gunther, has made a voyage with her from Florida all the way to Northern Italy. The trip took 27 days, which is basically as far as she can go, while constantly steaming ahead. However, the ship is in fact capable of 42 days at sea.

She runs with 2 16V 149 Detroit Diesels 900 shp each. Additionally, the A/E also has a 360^o rotatable bow thruster with 465 hp and 10,000 lbs of thrust. The bow thruster allows the boat to pivot near its bow (it sits below the galley maybe 1/3 the length stern of her bow) which gives added control especially when docking and keeping lines and cables straight in the water.

R/V HSBC Atlantic Explorer, returning to St. George’s harbor. She is part of the University-National Oceanographic Laboratory System (UNOLS) fleet.

Where all the magic happens.

During the Trophic BATS trip, Captain George Gunther leads us. George is back with the Explorer after a few years away, but knows the ship well. He began working with it while she was the Edward Link at Harbor Branch. Captain Gunther splits his time with The Explorer and the Western Flier conducting research in the Sea of Cortez.

Captain George, part of the self-titled A-Team on the 8-12 am/pm watch with mate Eric Parcon. George jokingly admits his 4-hour shift mostly consists of fixing the previous watches mistakes.

Captain maintains a terrific working environment on the ship and cites the team attitude that the mates and crew share with each other. Much of this attitude has to do with health and safety of the ship and science crew, the single most important aspect of a successful cruise. While I don’t have a great deal of experience on different ships, I have sailed on both U.S Coast Guard and Canadian Coast Guard and also on another ship within UNOLS. Without a doubt, the crew onboard is some of the most helpful deckhands, cooks, and engineers I have worked with so far.

Jojo Paitone is the ship's bosun. The bosun is in charge of all the deck operations. Right now he is operating the winch that is connected with the zooplankton net tow.

Al Soliva is one of the ship's motormen. Al operates the stern A-frame during back deck operations. Below the main deck, Al maintains the engines making sure everything is operation for our cruising.

Able seaman Eric Parcon making sure everything is set before the production/grazing array is deployed. He standing in front of what we call a "spar". It sits vertical in the water and has an GPS tracking device (by his knee) then a strobe and orange flag for sighting and a radio frequency beacon for local positions.

Buddy Manalo enjoying a cup of tea after dinner. Dexter and Buddy are the chefs that are in charge feeding 30 people each meal. Exceptional cooks.

As mentioned, the major concern and responsibility of the captain is safety. Medical risks can always arise due to seasickness and from the general aspects of people working on a rolling, rocking, and pitching platform, which makes for a low, but consistent tally of injuries. Typically, the Explorer conducts research at BATS, only 60 statute miles SE of Bermuda, but other cruises may take the ship farther. Each year, the A/E heads to Puerto Rico for the annual BATS Validation cruise. Since the majority of research time is spent near Bermuda, a quick port call may only take 6 hours to drop off a passenger with a medical concern.

The other aspect of safety is the weather. The mates (each cruise has a captain, a first and a second mate, all keeping individual shifts at the helm of the ship) and keep an eye on the weather reports coming in. We have Internet on board (but I think you’re probably figured that out), so we’re able to get weather reports from Bermuda, NOAA, etc. If we lose Internet connection, we still have the ability to update weather status from single side band radio with reports from Norfolk.

When rough weather rolls around (except on this cruise) science may stop. When there is a break in science, the captain, along with the chief scientist determine a cruise schedule to optimize our sampling requirements, which may mean dropping some operations or switching their order. Again, we are lucky to be conducting research locally, which allows some flexibility shifting schedules or returning to port quickly when weather turns inhospitable for a scientific research vessel.

Today is our second to last day. For the majority of you, this is depressing because the blog will end. For the scientists on board, we will be keen to have our feet on firm ground, although the weather during this cruise has been absolutely perfect. Tomorrow, we still have the final recoveries and processing of the production/grazing in-situ experiments and also retrieving the drifting sediment trap array. It will be a busy day tomorrow. Once each group ends their sampling, we will begin to pack up for the offload early Friday morning.

Another obligatory sunset photo.

Doug Bell

Research Technician, Phytoplankton Ecology Lab

This is the blogger.

We found more gloves.

Trophic BATS: Post # 9 (Day 7)

Dr. Stephanie Wilson is one of our zooplankton experts on board with Trophic BATS. She is currently working at the University of Bangor as an Assistant Professor, but is working on this project with Susanne Neuer. Steph’s interests cover all aspects of zooplankton ecology, but she is currently working on projects investigating the link between pelagic zooplankton and the flux of particulate organic material (typically as fecal pellets) to the benthos.

Stephanie is conducting fecal pellet production experiments during the Trophic BATS cruises and is additionally analyzing gut content of zooplankton from the net tows and fecal pellets from the sediment traps. From the fecal pellets and guts she will analyze the DNA content which she will match with phytoplankton DNA. DNA analysis would be able to show the presence of particular phytoplankton taxa in zooplankton diet and in the excreted, sinking material. These analyses will hopefully provide a link between zooplankton diet and particle flux.

Stephanie has also graciously given us some awesome photos (and great info on the organisms) from net tows over the past few days. Enjoy!

These are some of the types of fecal pellets that Stephanie is measuring. These bundles of particulate organic matter are from salps (gelatinous zooplankton), which Stephanie coined the vacuum cleaners of the ocean. The pellets are capable of sinking 1000m per day, which provides food for the benthos and for any swimmers that come into contact on its downward flux. These pellets are 1mm in width and were excreted from a 3cm salp.

This is a nice collection of the zooplankton recovered from the net tow. The tow drags in all organisms larger than 200um. In the photo you can see copepods, ostracods, a pteropod, and a chateognath. See if you can spot the chaetognath!

A calanoid copepod with modified appendages. Copepods, which are crustaceans, are the single most abundant multicellular organism in the animal world, next to unicorns.

A eusphausid which is maybe more commonly known as krill. Euphausids are ubiquitous like copepods. Similar to most zooplankton, euphausids exhibit vertical migration during the nighttime for mostly because of predator avoidance. Spending their time at depth during daylight hours also keeps them out of the harms way of UVB rays and also the colder depths help conserve energy. Vertical migrators can travel between 2m and 500m(!!!) for their feeding time. When compared to human body size that’s like traveling 25 miles before breakfast…which a large portion of Americans do each morning. By car.

This is probably the coolest zooplankton I’ve seen to date; although Leptodora kindi is a close second. This amphipod (crustacean omnivore) was actually the design for Ridley Scott’s Alien. You can slightly tell from the body shape, but this amphipod also has a unique taste for eating out the inside of a salp where it then lays its eggs and departs. We found it sitting inside a salp. It then killed 2 scientists.

These are pyrosomes. It is not actually a single organism, but a colony of tunicates, which are gelatinous zooplankton, related to salps. Each individual tunicate can be seen on the pyrosome from the orange/brown dots of each separate gut. Also that comment about killing scientists was a joke.

I want this to be a stingray (or even a horse shoe crab) but its not. It’s a shelled pteropod (mollusc) with distinct markings and ironic spacing of its guts which gives it somewhat of a clown face. It did NOT however tell any jokes. Punishment for that is a formalin bath... forever. The pteropod organism that lives inside the shell uses wings as a form of locomotion and secretes a mucus net which collects particles before it hauls the net in for dinner.

This is the heteropod carinaria. It is an omnivore which predates on copepods. It’s actually a snail and you can see the slightest hint of a shell (brown bit) on the left hand side of the animal. Some on board believe it looks like an elephant. I’ve seen a few elephants on TV and in the zoo and that thing looks nothing like an elephant. It looks like a heteropod.

And last but not least a baby squid!

Doug Bell

Research Technician, Phytoplankton Ecology Lab

We're about to run out of gloves

Trophic BATS: Post # 8 (Day 6)

Chief Scientist Tammi Richardson looks on from the bridge deck during the sediment trap recovery.

Early this morning, we arrived at our third and final station. Our comparison site, which is outside of the cyclonic eddy, also happens to be the site of the Bermuda Atlantic Time-series Study (BATS). BATS is quite useful to have as a comparison site as the time-series provides researchers reference data for physical, chemical, and biological parameters. Long-term time series, like BATS (monthly sampling began in 1988) are incredibly important in understanding the process of ocean biogeochemical cycling on seasonal to decadal time-scales. Observations from time-series allow projects like Trophic BATS to fuel more in depth research on the complexity of the open ocean ecosystem.

As a whole, Trophic BATS is a single research project, however, there are many individual components that are projects of themselves, especially to the graduate students participating on this cruise.

Out of the University of Rhode Island, Matt Baumann and Brenden Mackinson are paired up with the BIOS squad. Matt’s project isn’t directly related to Trophic BATS, but he has previously worked with the group on the Bering Sea Ecosystem Study, and will be conducting thorium measurements from the water column and sediment traps.

Also, Matt and Brenden operate the in-situ pumps that have the ability to filter hundreds of liters of seawater from a specific depth. From the collected filter, re-suspended particulate will be analyzed for POC, pigments, and potentially DNA. The in-situ pumps also have the ability to size fractionate filtered water, which is an additional compliment for the team’s questions surrounding the importance of small cells in primary production and contribution to export. Brenden’s project will partially focus on Trophic BATS and investigating the role of small cells in carbon export.

Matt and Brenden anxiously await the return of their in-situ pump.

Bridget Bachman leads the primary productivity measurements. As a graduate student with Tammi Richardson at South Carolina, her project will investigate size-fractionated primary production and taxon specific production. To obtain taxon-specific production, the flow cytometer (and Stacey!) will sort Bridget’s samples into multiple groups: prochlorococchus, synechococchus, and pico-eukaryotes. Using this sorting technique, she will be able to determine production per group, per cell, and their growth rates. Ultimately, Bridget will be tying these measurements, along with the entirety of measurements made by each research team during Trophic BATS into an ecosystem model. The model will hope to be used as an estimate for quantifying the flow of carbon between specific trophic levels (using rates measured from our research cruises) and carbon export – all dependent on food web community structure.

Bridget and Francesca imitate hurling bottles at the Production/Grazing array at superhuman speeds. Both of them pursued oceanography from their true passion, filtering.

All for today!

Doug Bell

Research Technician, Bermuda Institute of Ocean Sciences

Trophic BATS: Post # 7 (Day 5)

At day 5, this is the half way point of Trophic BATS and at the minute we are steaming to our next and final station, outside of the eddy. While investigating the transfer of carbon through the complex food web processes, we are choosing our experimental sites based upon on certain physical features of the ocean current. These physical features are called eddies, which are rotating rings within large-scale ocean currents. Eddies are initially formed by instabilities in wind patterns and can range in size. In the North Atlantic, meso-scale eddies (rings of 100km diameter) generate in the east and progress along west until they meet the Gulf Stream. This transit usually takes between 6-8 months.

Now why is there such an interest in eddies? If an eddy circulates counter clockwise (anti-cyclonic) in the Northern Hemisphere, down welling events take place inside the core. If an eddy circulates clockwise (cyclonic) upwelling events occur. These upwelling events introduce deep, cold water enriched with nutrients that can help fuel phytoplankton blooms. Determining the variations of food web structure within and outside of these meso-scale eddies, both anti-cyclonic and cyclonic, may be very important in understanding the complexity of the biological carbon pump. On this cruise, we chose a local cyclonic eddy and have indeed seen relatively large amounts of biomass from collected water.

Phytoplankton collected from Matt Baumann and Brenden Mackinson (URI) in-situ pumps. Pumps will run for a predetermined programmable time. Matt sets the pumps to run between 2-4 hrs and set depths. Pumping for that duration can filter between 300-500L of water!

So far, we’ve talked about the majority of the research and experiments taking place on this cruise. However, I have still failed to introduce the 20ft container on the 01 deck (deck up from the main deck). Check back to Post #1 to see it being loaded onto the ship. Inside of the van contains an instrument called a flow cytometer and/or cell analyzer/sorter. The flow cytometer is a part of Dr. Mike Lomas’s Phytoplankton Ecology Lab on this cruise, along with myself, Stacey Goldberg (flow tech/superhero), and two POGOs (international graduate students), Priscilla Lange and Arvind Singh.

Hopefully I’ll do the instrument (and its owner and operator!) justice and correctly explain its functioning and applications. The first cell counters were originally designed in the 50’s-60’s to be used in hospitals for the enumeration of blood cells. In the 1970-80’s flow cytometers passed from strictly medical purpose to new fields, such as oceanography. In oceanography, its application was similar, but instead of blood cells, scientists were counting smaller phytoplankton cells. While years have passed, the instruments have evolved into incredibly powerful tools for oceanographic research.

Typically, these instruments stay in the lab. But as I mentioned previously, container vans (portable science labs) can be made for any designed purpose and Mike specifically had it in mind to design a van that could be equipped with cytometer to take out to sea. This is no easy endeavor as seen after watching the van being loaded onto the ship and then hearing that only a handful of ocean scientists have successfully brought their flow cytometers into the field. Its jump from lab to ship is beneficial for two reasons. First, samples can be processed at sea generating data in real-time. Second, with processing at sea, there is no use of fixatives (needed for long-term storage), which eliminates assumptions of chemical impact to sample integrity. Mike’s flow tech, Stacey Goldberg, is quite pleased and impressed with their found ability to successfully operate the instrument while working on a rocking and rolling platform. Weather has been incredibly cooperative which immensely alleviates the challenge of operating the cytometer.

Inside of the Cytometer van. Red light can be used allowing technicians to see while they work, while still making sure phytoplankton are not able to utilize any light source.

Mike explains that the challenges of operation are not dependent on vibrations of the ship, but the pitching and rolling of the ship. Thousands of water droplets are produced each second from the instrument and that droplet’s motion is dependent on gravity. For certain applications, each droplet needs to be collected, so when you consider a free-falling object with a moving target, the difficulties can be seen.

The Cytopeia flow cytometer. Note the straps.

Just like all the researchers on this cruise, the cytometer is incredibly hard working. It’s so hard working that it runs at a rate of 20,000 events per second. I can barely multi-task (limited to eating and shouting), so needless to say it is impressive. Each event starts out from the sample, where the sample stream meets a sheath fluid (perpendicular cross road). Based upon a specific hydrostatic pressure, the flow of sample now has individual cells aligned in single file. This pressure separates each cell for analysis, and a harmonic generator will disrupt the flow, eventually producing a free falling water droplet with an individual cell that can be collected.

Now before it’s water droplet period, each cell will meet a laser (as pictured below). The cell will absorb the light and emit the light at a longer wavelength and lower energy. The fluorescence produced along with the forward scatter of the light characterizes the cell into taxon specific groups and size, respectively. From this instant, the instrument generates population counts of several types of phytoplankton from the sample.

Blue - 488nm Laser equipped on the cytometer.

However, another application of the cytometer is its ability to sort, which is what Stacey has been doing for the majority of the cruise. Once the instrument identifies the cell type, it sends a message to produce an electric charge in the stream. This instrument is so clever that within 5 x 10^-5 of a second the charge is produced and given to each water droplet before the instant if forms. Once the droplets free-fall, they pass between charged plates that will direct the charged particles into a tube. Like and opposite charges of different strength are given to each specific taxa of phytoplankton, enabling all similar taxa, such as synechochus and prochlorococchus to be grouped together and kept for taxon-specfic analysis. Pretty nifty.

Analysis post sort include genomics, biogeochemistry, and cell physiology. The applications of sorting seem to be continuously evolving as well. The Phytoplankton Ecology Lab focuses on producing “sorts” for genomic analysis and biogeochemistry. On Trophic BATS, Bridget and Francesca are having their primary production and grazing samples analyzed by the cytometer to give them taxon specific rates. PEL filters water for taxon-specific carbon, nitrogen, and phosphorus quantities.

Well that's all for today. Unfortunately, I don't have any zooplankton pictures of the day, but I have organisms of the day and another sunset picture to make you all jealous.

Organisms of the Day: Half the crew awaiting the CTD recovery. Way more exciting than it looks.

Obligatory sunset photo

PEACE! (emphatically)

Doug Bell

Research Technician, Phytoplankton Ecology Lab

You all should comment

Trophic BATS: Post # 6 Day (4)

Mike settling the PITS traps back on deck.

The first deployment of our 3-day sediment traps were tracked down shortly after dinner. Over 3 days, they had traveled about 23 miles and from Rob Condon’s conversions, the array was traveling at 13.9 cm per second. Ocean surface current’s speed average 15 cm/s.

From this array, scientists are able to measure the flux of particulate material settling to deeper depths from the euphotic zone. The amount of exported material gives researchers the ability to determine two things: the strength of the biological carbon pump (amount of downward flux of organic matter) and efficiency (export flux compared to primary production).

Particle Intercept Traps (PITS)

33 traps total, formally named Particle Intercepter Traps (PITS), sit at 150m, 200m, and 300m. Each trap is dedicated to a particular measurement. On Trophic BATS, the team is measuring quite a large suite of analytes when considering sediment traps. We will measure for carbon, nitrogen, and phosphorous and biogenic silica. From these 4 elements we can compare the ratios of C:N:P:Si between material that is exported to depth and what elemental ratios exist in living biomass and their ambient chemical conditions. Other measurements are for thorium (which scavenges for decaying material in the ocean) and for DNA sequences of phytoplankton.

The story of DNA measurements in sediment traps is an interesting one and one familiar to the Sargasso Sea. Dr. Susanne Neuer (Arizona State University) previously had a project at BATS investigating the DNA signatures of picoplankton that had been collected by the sediment traps. Susanne, along with Mike Lomas, hypothesized that smaller cells contributed to a considerable portion of the annual flux of sinking material. Rather than large, heavier cells like diatoms that sink to depth, smaller cells had a chance to become export flux from repackaging by zooplankton and particle aggregation. At Trophic BATS, the Neuer team is continuing these measurements. Dr. Stephanie Wilson adds to this aspect of research by comparing the DNA gut content of collected zooplankton to the export flux. This will give us further evidence of zooplankton grazing on very small phytoplankton.

Dr. Neuer and Francesca model with the In-situ Production/Grazing Array. The array is clamped onto a weighted line, so the line is vertical and the array sits perpendicular to the line in the water. Bottles for grazing experiments and for primary production get loaded into the bungees on the outer edge.

Along with Dr. Neuer’s work with the sediment traps, her research is involved with almost all the pieces of the Trophic BATS puzzle. Her graduate student, Francesca de Martini helps lead the grazing in-situ incubations, which are paired with the primary production deployments. Francesca’s grazing experiments are designed on the “Dilution Method.” For this method, 200um filtered seawater is collected and used in the experiments as “whole” – 100% seawater and 25% seawater (75% filtered seawater). The comparisons of diluted vs. undiluted incubation bottles give insight into two very important aspects of the food web. The difference in chlorophyll shows the bulk phytoplankton growth rate and it’s inverse, the bulk microzooplankton (zooplankton between 20-200um) grazing rate. While, these are bulk rates, Neuer and team are able to determine plankton species composition by Epifluorescence microscopy and flow cytometry. Epifluorescence uses DAPI, a biological stain, to attach to DNA and if excited by UV light, the DNA excites and fluoresces which can be visibly seen by the microscope and described as a starry night sky by Francesca.

Francesca performing her favorite task on board: filtering liters and liters of water.

It is certainly a unique and interesting portion of the project. Tomorrow, we’ll focus on the two words I mentioned earlier with Susanne’s research – flow cytometry.

Told you it was good news the BBQ was heading out.

Doug Bell
Research Technician, Phytoplankton Ecology Lab
I ate all the steaks

Trophic BATS: Post # 5 (Day 3)

Foreground: (left) Stardboard A-frame - used for deploying the CTD. (right) Stern A-frame - used for array deployments, net tows, and in-situ pumping.

Background: (left) The Sun - used to provide life for the entire planet.

This is what we’ve had to deal with all day. Rough isn’t it. I checked the weather report for the next week (we return Friday 3/23) and laughed out loud at what I read. Over the next 7 days no winds are supposed to break 15 kts, while averaging below 10 and with a wave height of a whooping 2-4ft. This has made all the ship operations go as smoothly as possible, allowing us to stay on schedule even getting ahead of ourselves.

Right now (2300) Dr. Rob Condon and his research technicians are performing several net tows. Zooplankton net tows are done both during the day and at night. Zooplankton perform what is termed diel vertical migration. During the night, certain species of zooplankton will ascend to the surface for optimal foraging, thus differences in tow composition will likely be observed between day and night. From the tow collections, Rob will separate half the tow and dedicate it to species identification by microscopy. The other half is size fractionated and then measured for carbon. Other times, plankton collections from the tow will be hand picked and individual swimmers will be used in experiments for grazing and for fecal pellet/DOM production.

To fill us in on a little more detail on the research of zooplankton’s role in the food web, Dr. Rob Condon, Research Senior Marine Scientist from Alabama's Dauphin Island Sea Lab, has kindly agreed to answer of our few questions.

Q: How does one measure the flux of carbon transfer through zooplankton?

Rob: Our understanding of the open ocean food web is based on classical food web paradigm of a phytoplankton being eaten by copepods being eaten by a fish. As we develop new techniques and become more multidisciplinary in our approach, we are discovering that food webs are not simple but rather very complex, with interactions between many trophic levels. One way to determine the structure of the pelagic food web is to use stable isotopes (13C and 15N) as a way of interpreting energy source and what eats what based on these elemental signatures in organic matter, plankton and fish. Rate processes such as grazing, excretion, respiration and fecal pellet production are also important metrics in understanding of how food webs function. We are conducting experiments measuring the source-sink dynamics of carbon in zooplankton and how this feeds into the bioavailability of carbon to higher trophic levels vs the loss of carbon from surface waters through flux (e.g., fecal pellets).

Q: What are the major differences between zooplankton groups with respect to carbon transfer?

Rob: Zooplankton encompasses a wide range of organisms ranging from microzooplankton that consume very small particles and phytoplankton to crustacean zooplankton such as copepods that are important food for fish and gelatinous plankton. My research team is focusing on the crustacean and gelatinous zooplankton. Most studies to date have focused on copepods but the jellies are of particular interest as very little is known about them but are potentially important for carbon transfer in food webs. Some jellies, such as salps, produce very large fecal pellets that can sink rapidly to the deep ocean, which may be important means of transporting carbon via the biological pump (the process whereby oceans sequester carbon at depth). Other groups, such as medusae and ctenophores, can be voracious predators that produce and release a lot of organic carbon as mucus. This mucus is rapidly utilized by microbes for respiration, a process that converts energy back into a form (carbon dioxide) that can't be used by higher organisms, thus these gelatinous organisms may act as a shunt energy in food webs.

Q: What are the challenges that exist when performing your measurements and experiments?

Rob: There are inherent problems associated with dealing with animals that makes experiments a challenge. For example, we know that gelatinous plankton are abundant in open ocean environments but many kinds are extremely delicate, such as ctenophores (comb jellies) that will explode on touch. We have to use blue water diving techniques to examine these type of animals. Many of these organisms live in deep waters and migrate to the surface at night but are likely important components of the open ocean and mesopelagic food webs. To study these animals requires use of ROVs or submersibles which are expensive and hard to come by in oceanographic expeditions.

Q: From a zooplankton perspective what are the major implications of this research?

Rob: There are several significant implications from this research. The first centers on the implications of food web structure for fisheries production vs carbon flux. If primary production is linked to copepods then this represents potentially more energy for fisheries production, which in turn has consequences for fisheries management in the open ocean. By contrast, not very much is known about what predators consume gelatinous plankton, and what their overall role is in biogeochemical cycles. Do jellies reduce carbon flow to fish or make food webs more complex? And do they increase carbon export to depth? There is also a paradigm that jellyfish are increasing in the world's oceans as a response to a variety of human insults to the sea. Most studies have focused on coastal and estuarine systems with very little focus on the gelatinous species that exist in the open ocean that cover 70% of our planet. Understanding how energy is partitioned between crustacean and gelatinous plankton will help us better manage ecosystems and resources in this delicate marine environment.

Awesome! Thanks, so much Rob.

Emily, Molly, and Rob await the approaching net tow. Copepods dominate the zooplankton community composition at 50-70%, followed by euphausids, ostracods, and then gelatinous zooplankton. However, estimating the real contribution of gelatinous zooplankton is a major focus of Rob's. The organisms are very delicate and prone to disruption during recovery, thus proving difficult to accurately measure its abundance.

Rob and Molly hover over the recovered net tow, quickly eyeing their catch.

This is a single organism recovered from a a net tow. Nicknamed the spaghetti monster by Dr. Stephanie Wilson it is actually a siphonophore, a type of jelly. In the same tow, the zoop team discovered an amphipod that was the inspiration of design for the alien in the movie Alien. When someone informed me, I expected the lab to be littered with bodies and imagined a tail escaping through the ceiling covers, but alas the little creature was about the size of my fingernail and was simply hiding inside of an another gelatinuous zoop called a Salp.

Well, that is all for tonight. Catch everybody tomorrow!

Doug Bell

Research Technician, Phytoplankton Ecology Lab

Oceanographic Filterer: Level 17

Trophic BATS: Post # 4 (Day 2)

With our first full day out at sea, the Trophic BATS research team began our first full suite of experiments and measurements. Each day and with occasional edits, the “Science Schedule” is posted on the ship’s white board so that crew and colleagues can see the daily event order of science. Today, it looked something like this:

Time – Event Type – Measurements (Scientist in Charge)

0100 – CTD 500m – Pigments (Goldman)

0230 – CTD 200m – Production/Grazing Cast (Richardson/Neuer)

0500 – Deploy Production Array (Richardson/Neuer)

0600 – Deploy 24hr Sediment Trap Array (Bell)

0800 – CTD 500m – Dissolved Inorganic Carbon (Condon)

1000 – Net Tows x2 – Zooplankton (Condon)

1200 – CTD 1000m – Core Cast (Nutrient stocks, pigments, Thorium) (Bell/Lomas)

1400 – In-Situ Pumps – 4hr Large Volume Pumping (Baumann)

1830 – CTD 3000m – Bacteria Experiment (Lomas/Condon)

2200 – Net Tows x2 – Zooplankton (Condon)

Marine Technician Emily Dougan (BIOS) and Able Seaman June Muras (R/V AE) deploy the CTD.

Time at sea is certainly expensive, so scientists must make sure to fully utilize any possible chance for sampling and the collection of data. We may refer to part of this as wire time, which refers to operations such as a CTD deployment, zooplankton tow, or an in-situ pump as an active use of one of the ships hydraulic winches and lines. If we are not moving to and from station, the plan is to have these wires in operation. In between the timing of events, scientists prepare materials for sample collection, sample from the CTD while other events are in progress, and process the collected water/net tows.

Tomorrow, the sequence of events is generally similar, however, instead of beginning production and grazing incubations, we will recover the arrays and the Richardson and Neuer teams will start their long morning of processing all of their samples. Today and tomorrow’s schedule will repeat itself hopefully 4 times total - twice inside of the eddy and twice outside of the eddy, to compare the differences within the water structure.

Personally, days like today, where the workday is full and the ocean and sky are calm and bright are incomparable for a working environment. In the past 3 years, I have likely spent about 4.5 months aboard the R/V Atlantic Explorer so it has been somewhat like a second home while working in Bermuda. Getting a chance to work out at sea provides a reminder for much of the research group about their passion for science.

Work seems to not feel so much like “work” and somehow even the occasional leisure time turns into scientific inquiry. Jojo, the ship’s incredible bosun snagged and reeled in a beautiful bonito this afternoon. Shortly after its time on deck, a knife was in the back of the fish’s head. The Condon group, which is investigating the role of zooplankton within the food web, will take a small section of fish meat along with the bonito’s otolith (ear bone, used to determine age) for isotopic analysis to determine the fish’s food source and elucidate its role in the food web. We’ll be providing a Q & A with Dr. Condon on tomorrow’s post, so stay tuned!

Grad Student Eric Lachmeyer (USC) and Research Technician Molly Bogeberg (DISL)

Doug Bell

Research Technician, Phytoplankton Ecology Lab

In need of a fresh pair of socks