What are we pumping from the deep sea?

The Plankton Pump is currently our most efficient means of collecting demersal [near-bottom] plankton from the deep sea. 

This includes both holoplankton (organisms that live as plankton their whole life) and meroplankton (organisms that live in the plankton only during one part of their life, such as larvae of benthic organisms).

Generally, the holoplankton is dominated by copepods (>50%), but other substantial groups include chaetognaths, ostracods, and polychaetes. Meroplankton, on the other hand, is very small and present at very low densities, which means that a very fine filter (mesh) size and a large sampling effort is needed to catch these organisms. However, the meroplanktonic component is of special interest because larvae of benthic organisms or other dispersal stages are very important for the supply and dispersal of benthic populations. Therefore, data about meroplankton is useful for estimating recovery abilities of benthic populations after a disturbance event, such as a mining operation. 

Oliver Kersten, the proud papa of the Plankton Pump free vehicle, flashes a look of satisfaction after a successful recovery.

After the acoustic release is contacted from the ship, the lander floats to the surface with the aide of 8 hard-hat glass floats.


When it is due to surface, everyone gathers on deck to watch for the flash of the strobe in the darkness.

After it is spotted, the captain maneuvers the ship alongside the lander, which is referred to as the "package" so that it can be snagged with a  grappling hook.

It is then walked around to the a-frame, where the winch is used to bring it back on board the ship.

 Recovery of the plankton pump free vehicle through the R/V Thompson's A-frame, made possible by the helpful hands of the ship's exceptional crew. They make even the trickiest of recoveries look effortless.

In order to sample the bentho-pelagic zooplankton community, a free-vehicle was outfitted with two plankton pumps that filter seawater 3 m above the abyssal plain (seafloor) for about 23 hours on each deployment.

Oliver really "dives in" to his work!

After recovery, the samples of each pump are split into two subsamples to allow for both a morphological analysis and DNA analysis. Based on the analysis type, these subsamples are then fixed and preserved in either formaldehyde or ethanol, and further analyzed (sorting, identifying organisms, DNA extraction etc.) back in the lab on land.

Written By: Oliver Kersten, Hawaii Pacific University

A few simple numbers: The tale of the respiration lander

The moonlight shone on the water in a bright streak, like a yellow brick road to the horizon. Various crew members chatted amongst themselves as they loitered on the deck. Just a few yards away, two scientists crouched beneath a ring of bright orange floats, making some last-minute adjustment that nobody dared to interrupt.

With one signal to the crew and a few frantic triple-checks, the lander was ready to go. The massive metal frame with her crown of floats was lifted over the side of the ship, released with a tug, and sent on her way to the deep.

The respiration lander is now in her fourth deployment of the cruise, and she is bringing back valuable data. The lander houses three benthic chambers – white plastic boxes that are pushed into the seafloor. By penetrating the sediment, the chambers effectively seal off an area of the seafloor, and we can measure the decrease in oxygen concentration over time in this isolated area. Oxygen concentration shows us the respiration rate, and the respiration rate shows us how active the organisms are.

Deep-sea sediments are filled with all sorts of organisms that cannot be seen with the naked eye. Prokaryotes, foraminiferans, nematodes, harpacticoids, polychaetes – the list of multisyllabic names goes on. Our job is to figure out how much carbon these animals consume and how much oxygen they respire, then compare our numbers to similar measurements from other areas of the ocean.

Andrew Sweetman, my adviser, has been developing his respiration lander for years. It’s been specifically designed to not only measure respiration but also run in situ experiments at the deep seafloor. Let’s say you want to figure out what path carbon takes as it gets worked through the benthic food web. Where does the energy go? Who eats whom? There’s a simple way to find out – well, as simple as engineering a 3-ton, quarter-million dollar lander and deploying it to the abyssal plain.

While the lander is sitting on the sediment and the optodes are measuring away, we artificially add some carbon to the benthic chambers. The added carbon is chemically labeled with heavy isotopes – carbon atoms that have 13 neutrons instead of 12 – so we can find it later and tell whose bodies it ends up in. You are what you eat, right?

Kirstin Meyer beams after a successful recovery of the respiration lander.

The lander is a complicated piece of equipment, and the data it collects are both rare and valuable. Standing on the edge of the deck, watching the lander sink away in the moonlight, we can only hope she will return to the surface again. Just a handful of samples and a few simple numbers allow us to push back the frontiers of science, one step at a time.

Written by: Kirstin Meyer, University of Oregon/International Research Institute of Stavanger

Exploring The Microbial Deep

Miles below the ocean’s surface, living within perpetual, icy darkness, microscopic powerhouses are at work, thriving off of inorganic and organic matter.

Brie Maillot, Hailey Farah (the Microbe team) bring in the CTD after its 4,000 m descent to the sea floor.

These are the prokaryotes of the deep sea and they can be found almost everywhere, whether it be miles below the seafloor, the water-sediment interface, or in the relatively ephemeral water column. The majority of these communities are composed of bacteria and their very distant cousins, Archaea. Unlike their relatives on land, which cause disease in a variety of organisms, these little guys are focused on using organic and inorganic matter to fuel their metabolisms and play key roles in biogeochemical cycles. Their distributions and roles in abyssal benthic communities are relatively unknown, even for deep sea standards, and the data set from this cruise (along with data from last cruise) will be one of the largest, if not the largest, data sets on these communities.

In order to analyze microbial communities, we are collecting from three main habitats: water column, sediments and nodules using a variety of tools (CTD, megacore, boxcore, respiration lander). People joke that we are the sample hogs of the cruise because we collect from almost every piece of equipment that is deployed. At this point, half-way through the cruise, we have over 500 samples to be analyzed in a shore-based lab (for nutrients, dissolved silica, DNA, RNA and flow cytometry/cell counting) and are quickly taking over the ship’s freezers.

The -80°C stockpile (mainly comprised of bags within bags of sediment)

Most of the equipment that we collect from is shared with other groups, but the CTD is all ours. CTD stands for Conductivity Temperature Depth and, as explained by the name, it’s a device that measures water column characteristics (salinity, temperature, oxygen concentration, fluorescence, pressure). The CTD itself is attached to a rosette of Niskin bottles which fire at certain depths to collect water. We collect water from these bottles, which is used to fill lots of little and big carboys. It can be wet work but when you’re in the tropics during the day, the 1.5°C bottom water is incredibly refreshing and does a terrific job of washing all the mud off your boots. Once we’ve collected all of our water, it takes a few hours of filtering the water to isolate the microorganisms for future DNA/RNA extraction and sequencing.

Our carboy stockpile (the larger ones)

The ship’s CTD and rosette. It looks pretty rough but has worked wonderfully thus far. The actual CTD in the middle below the bottles.

Our second sampling staple is the megacore, which we use to collect the microorganisms from the different sedimentary layers. Once collected, everything gets frozen using liquid nitrogen and placed in the nice, frosty -80°C freezer.

The megacore rising from the water with 12 full cores

Upon return to a shore-based laboratory, the DNA will be extracted from our samples and sequenced for prokaryotic and eukaryotic microorganisms. This data can then be compared to previous cruises and tell us more about the microbial assemblages in these habitats and surrounding polymetallic/manganese nodules.

 Written by: Brie Maillot, University of Hawaii at Manoa

We're having a Mega-good time!

As far as deep sea sediment collection goes, it doesn’t get much better than the Mega-corer! 





Multiple corers are known for collecting the most pristine, undisturbed samples from the depths, and our Mega-corer is no exception. With its complicated mechanics, this lady can be very temperamental, but with the proper love and attention it has proven very reliable for bringing back high quality samples on each dive.

The clear "top water" visible above the mud in the tubes, is an indicator that the samples are pristine because the sediment would have muddied the water had the surface sediments been disturbed upon collection.

Cassie Turner typically maintains the mega-corer between dives, and checks every nut, bolt, spring, and moving part each time it comes back on board. It is cleaned, tuned, and lubricated each time it comes on deck to ensure that it brings back 12 cores each time it is sent into the abyss.

Amanda Ziegler carries the heavy pinger out on deck.

A Pinger is placed on the winch wire 50 meters above the Megacorer to track it's descent to the bottom.

<Thomas Dahlgren holds the pinger while it is secured to the winch wire. He has a perfect record of not dropping a single one!! {knock on wood}

Each tube is photographed before it is removed for processing. Here Colin Seifer holds the label plate>

Upon recovery, special hooks are used to attach tag lines to the corer that will stabilize it while it is brought onto deck. Here Thomas Dahlgren prepares to attach a tagline while Helena Wiklund waits to remove the pole from the loading area. The ship's experienced crew, also pictured, are always very helpful in ensuring seamless deployments and recoveries.

  Amanda Ziegler is ready with wood planks, which are placed under the Mega-corer upon recovery. Having it set on the planks makes it easier to remove the sample tubes without losing top water or risking disturbing the sample.

The samples that we get from the mega-corer are divided among four teams of scientists and analyzed for macrofauna, meiofauna, genetics, and bioturbation among other analyses. 

When the megacorer comes on deck, all the scientists gather around to examine the cores and make their picks. It feels like a football draft as each team of scientists takes turns picking their preferred cores.

During some of the deployments, we have had some trouble with the shackle that attaches the Mega-corer to the winch wire allowing the wire to loop and fowl on the top of the corer. This causes some tense moments upon recovery because it usually ends in the Mega-corer slipping loose and dropping a few feet, risking the loss of

 samples or even the whole Mega-corer!    

To solve this problem, Craig Smith, the Chief Scientist, devised a rubber boot that covers the shackle and prevents it from fowling on the Mega-corer. The maiden voyage of the boot was last night, and it appeared to work perfectly! We were pleased to see the Mega-corer return to deck un-tangled and with 12 cores in toe.

Written by: Cassandra Turner, University of Hawaii at Manoa

That's one giant sled! The Brenke Sledge

Hello, we are the EBS (epibenthic sledge) team, also known as the “sledge dancers” onboard of the R/V Thomas G. Thompson. 

The EBS is a sampling device with two cone nets (an epi- and a supranet) designed to collect small animals in the upper centimeters of soft bottom sediments and of the sediment surface itself.

        Valeska Borges is rinsing the nets of 

         our epibenthic sledge, named “ANNA”.

During the last six EBS deployments a large amount of animals, such as crustaceans and bristle worms, and plenty of manganese nodules have been collected. That’s why some scientists here believe that we perform a dance ritual before every deployment to communicate with Neptune to grant us good biological samples.

 This is an amphipod crustacean caught with the EBS last night.

Aside from ritual dances, a well-conceived station planning, maintenance of the sledge, and controlling each stage of its deployment from going down, landing, and “maneuvering” it over the sea floor are crucial for successful sampling. Since the EBS is trawled like a sledge, the seafloor should be a plain without topographic highs. According to the seafloor topography obtained with multibeam sonar, we decide where to trawl the EBS.

A multibeam system, pictured above, is used to roughly map the seafloor. Station planning can be quite exciting when there suddenly appears a seamount on the map as we experienced before our second EBS deployment.

Valeska Borges, Inga Mohrbeck and Adrian Glover recovering the sledge. As shown here, behind every team is a great ship’s crew supporting the scientists.

At a water depth of 4100 m, it takes our sledge about 7 hours to return on board. Once the sledge is on board the content of the cod end samplers has to be fixed quickly.

Here Inga Mohrbeck and Lena Albers are sieving and fixing the main samples in the cod ends with chilled ethanol for molecular analysis of small crustaceans. We are looking forward to finding interesting and new deep sea species from the Clarion Clipperton Zone.

Written by: Inga, Valeska, and Lena; Senckenberg, German Center for Marine Biodiversity Research

Capturing the Deep: The Baited Trap

Do you ever wonder what strange creatures are lurking in the deep sea? 
We've all seen the footage on the Discovery Channel or in National Geographic specials, but Jeff Drazen's baited trap gives scientists on board a chance to see, touch, and sample fish and invertebrates from the deep sea with their own hands.







      Astrid Leitner and Clif Nunnally make up the shipboard team responsible for all things baited-trap. They handle the deployments, maintenance, and processing of creatures pulled up in the trap.

      The baited trap is a free-vehicle, so it is released off the side and later called to acoustically from the ship. The acoustic release on the lander then releases the weights that hold it to the bottom and begins the journey to the surface. At the sample depth of 4 km, which we have been experiencing on this cruise, it takes the lander nearly two hours to reach the surface!

The trap usually brings back amphipods, rattail fish, and their parasites. Here Astrid is shown displaying a rattail for Craig Smith, the chief scientist, and Oliver Kersten, a graduate student from HPU.

Diva Amon removes the amphipods from the smaller trap that was placed inside the baited trap lander.

A Eurythenes gryllus clings to the mesh of the bait bag from the trap.

Clif displays several amphipods from the baited trap that will be preserved for later analysis.

 Astrid inspects the fish from the trap. She takes tissue samples and removes any parasites before preserving the whole fish.

Andrew Sweetman manned the net to retrieve any fish that came loose during the baited trap recovery, and managed to save a rattail from floating away.

Written By: Cassandra Turner with information provided by Astrid Leitner, University of Hawaii at Manoa