Seascape Projects

For History Geeks

2012-05-09T18:58:18Z

Two days ago, I used this image in a scientific talk: From Edmondson 1971, it depicts the "phylogenetic tree" of the famous ecologist G. E. Hutchinson. Branches on the tree represent Hutchinson's doctoral students, with subsequent generations represented by further branching. Many iconic names appear on this tree, such as the legendary Gordon Riley, who designed what is now the canonical theory for ocean ecosystems. I was not surprised to discover later that members of my audience belonged on the tree as well, if further branches were to be drawn. I was discussing this matter with Jeff Runge--who advised much of my Ph.D. work, and who is, himself, tangled in the many branches of this tree. Having difficulty reading the digital version, we decided to dig up the original paper from Jeff's old bound copies of Limnology and Oceanography, which he inherited from another zooplankton ecologist. Flipping through the dusty tomes, with pages marked by folded corners and scraps of toilet paper, the book suddenly sprung open to the very page we sought. There, marking the page, was a letter from Gordon Riley himself, discussing the Festschrift honoring Hutchinson. Jeff kindly allowed me to keep this priceless historical artifact. -Nick Record, signing off

Rebecca in Norway

2012-05-08T13:28:53Z

Rebecca Jones, from our partner lab, is spending the month of May doing some field work in Norway. Her blog is here:

Zooplankton Research in Norway

In Search of the Magic Climate Fairy

2012-05-01T14:49:31Z

The vast majority of climate scientists, including us lowly oceanographers, are convinced that increased atmospheric carbon dioxide in the atmosphere warms the planet. There is abundant evidence for recent warming and abundant evidence that CO2 is the trigger. As a scientist, I think it's important to consider alternative hypotheses, but at this point, there are a vanishingly small number of alternatives to the standard model of anthropogenic climate change: climate change is initiated by CO2, amplified by water vapor and other feedbacks, and yields a climate sensitivity of 3°C for every doubling of CO2.

As recently outlined in the New York Times, many of the most common arguments, at least those that have some shred of real science, involve clouds. The granddaddy of these hypotheses is Richard Lindzen's notion that warming will lead to a negative cloud feedback. The basic idea is that warming leads to an increase in evaporation in the tropics. The warm, moist air then condenses as low, puffy clouds or precipitates as rain, instead of rising higher into the atmosphere to form cirrus clouds. Because high clouds tend to retain heat, reducing their number reduces warming. My understanding is that this hypothesis has been evaluated in a variety of ways and that, if anything, the cloud feedback is slightly positive (warming-->more clouds-->more warming). Even if Lindzen is right and that the feedback is strongly negative, it would have to be incredibly strong to counteract the other positive feedbacks, yet it would essentially be so subtle that we can't observe it at the moment.

I can't help but see a bit of magical thinking at work here. Perhaps, if we just believe hard enough, a Magic Climate Cloud Fairy will appear and cause the earth to cool. As suggested by Nick, here are two potential magical climate creatures that could rescue is from our warming fate:

Magically Migrating Copepod: Loyal Seascape reader(s) are well aware of the many wonders of the copepod. One cool thing that we haven't talked about is the penchant of many copepods and other zooplankton to migrate up and down every day. While at depth, the magical copepods respire some of the carbon they acquired by feeding at the surface. This helps pump carbon down into the water, away from the atmosphere. As surface waters get warmer, this will force the copepods to migrate further down, increasing their potential to remove carbon. Few zooplankton vertical migration studies have been done in the open ocean, so we must be wildly underestimating this flux.

Ocean Garbage Troll: The presence of plastics in the ocean has been well documented. In the Troll hypothesis, the increase in small plastic particles leads to higher mortality of zooplankton and mesopelagic fish. When they die, they sink, carrying their carbon with them. Because the amount of garbage in the ocean is directly related to industrial activity and thus CO2 levels, and because the reproductive potential of zooplankton and small fish is very high, increased CO2 will lead to increased flux of carbon to the deep sea in the form of dead fish and plankton. Because of the time required to get plastic from the land to the ocean, the full effects of the Troll will only be apparent in the future.

Ph.D. Metadata

2012-03-29T18:34:48Z

Ahoy. Having defended my dissertation approximately 48 days ago, I've had some time to reflect on the process and experience of working on a Ph.D. Sadly, I've come to no revelations or even iotas of wisdom to confer. Instead, I've decided to spew a series of mildly interesting statistics, and to let you, dear reader, come to your own conclusions. To youngsters considering the prospect of a Ph.D. program, take note. You can safely expect all of these effects. Statistic #1: Coffee consumption. In the weeks leading up to my defense, my coffee consumption increased by about 50%. You can see the sharp increase in the attached plot, and some of the effects it had on my web-making abilities.

Statistic #2: MATLAB burnout. I counted in my logs 8,762,838 lines of MATLAB code (including the script that I wrote to count lines of code). Yes, that's almost 9 million lines. No wonder my keyboard looks like a scene from The Thing. I can only assume that a significant chunk of that is due to large matrices accidentally displayed to the screen. Statistic #3: Herding cats. It takes three months of rescheduling and postponing in order to get five (excellent) committee members in the same place at the same time for a defense. Without Skype, it may not have been possible at all. Statistic #4: Days at sea. Something to think about if you're planning a Ph.D. in oceanography. Not as relevant if you're studying gender roles during the Enlightenment.
Statistic #5: Reproductive output. Before starting my program, r = 0 per day. Since starting my program, r = 4.6e-4 per day. This represents a very significant increase. -Nick Record, signing off.

HMS AP Meeting Day 2

2012-03-15T02:27:47Z

Well, I will keep this short since our days have been long and jam packed with discussion. Today the focus was on amendments to the shark plan and swordfish amendments. I will not address each of these in the detail we discussed, but I will say that a common theme across all HMS species is the lack of certainty with the stock assessments for these species. In fact, for many species of large and coastal shark species there is so little data or the data is so poor the assessments scientist cannot even make a recommendation as to how the stock should be managed. Also, some species of coastal sharks are thought to be so low in numbers that their rebuilding plans are to set to achieve rebuilt stats by 2070-2099. That is not a typo.........the stocks for some of these species would take almost 100 years to rebuild. Now this is, in my opinion, a little ridiculous since we can barely assess stock within a couple of years. In any case I think it indicates there are some serious problems with some of these species. At the end of the day comments on bluefin were extended about another 30 minutes and then a small off the record discussion went on for another hour or so til about 7:30pm. Sorry to keep this short, but gotta run.

HMS AP Meeting

2012-03-14T02:55:50Z

Hello all. Well, I am quite behind in making my first blog entry as a member of the lab, but here goes. I was recently appointed to the Highly Migratory Species Advisory Panel which meets twice a year in DC to discuss the challenges of incorporating the international management of tuna, billfish, sharks, and swordfish at the domestic level. For those of you not familiar with the process you can kind of think of it like a regional management council meeting, but with an international component and covering the entire eastern seaboard including the Gulf of Mexico and waters beyond the exclusive economic zone (out past 200 miles). The members of the meeting are from a diverse group of organizations which include the NMFS, commercial and recreational fishermen, academic (my position), and environmental (PEW, OCEANA, Environmental Defense etc). The morning session included mostly updates on the ICCAT meeting and recommendations followed by the proposed fishing quotas for the different user groups within the U.S. domestic fleets. In case you do not know there are several groups which receive bluefin quota those include the haroon, purse seine, longline, recreational, and commercial rod and reel/handline. A large portion of the afternoon was dedicated to going over several possible amendments to current issues in the bluefin fishery. Most of this time was spent discussing the bycatch issue in the pelagic long line fleet. For those who do not know the quota from ICCAT is strict, and overage has to be accounted for and even fish that are not landed count against the quota. Over the past few seasons there have been increased interaction between the longline fleet and bluefin. Now, there is no directed fishery for bluefin by longlines so this is all incidental bycatch. Nonetheless the fish have to be counted and if one group goes over quota has to be pulled from the reserve or taken from another category and transferred to cover the overage. If you cannot cover this the US will incur a penalty the next year and be out of compliance with ICCAT. Not to go into too much detail, but the issue is complex and options span the range of simply putting observers on boats to shutting down the Gulf of Mexico (the entire thing!) to pelagic longline to protect bluefin on the spawning grounds. As you can imagine such topics brought up some lively discussion. All in all the day went well and while there are extreme differences in the views shared by the different groups the conversation remains civil and constructive. Things take a long time to move forward in this process which can be a good thing as the panel weighs lots of different options for addressing the current issues facing the fisheries. Well, I will leave it there, tomorrow we move onto sharks followed by swordfish the next day. I will keep you posted.

Ocean Sciences Meeting 2012

2012-02-23T05:20:13Z

Ocean Sciences Meeting 2012, here we are! This important meeting occurs every two years and it's a joint venue of the American Geophysical Union (AGU) and the Association for Sciences in Limnology and Oceanography (ASLO). This year it gathers about 4000 people in Salt Lake City.

That's a bit too much to be cozy, but that means a lot of opportunities for great meetings, new ideas and enlightening and sometimes entertaining talks. And it's almost guaranteed that you'll experience the great research, the one compelling you to continue searching further and deeper with passion. I think some common traits of those exceptionally successful researches are that they address overarching issues over long periods of time through a rigorous, systematic and essentially original approach, with a deep understanding of its broader context and implications for science and society.

Dr. Record

2012-02-11T17:00:03Z

Nick successfully defended his Ph.D. yesterday, and as the photo below shows, he is now Dr. Record*.

Not that kind of doctor.

The general assessment of Nick's committee was that his thesis was one of the best they've read. It covered a wide range of topics, from computational methods, to copepod life history, to biodiversity theory. The Kraken, though, seemed a bit skeptical, and had posed one of the harder questions:

I thought Nick handled the question well, but the Kraken seemed to have more he wanted to discuss. Still, Kraken did decide to give Nick a bottle of something to help him celebrate. Congrats Nick!

*assuming he turns in his thesis.

Sea Ice

2012-02-06T07:47:55Z

Editor's note: Since Titanic is the best (only) movie featuring large ships and ice bergs, I found some relevant movie quotes to go along with Karen's latest entry. Perhaps Fred can loan us one of his Celine Dion albums.

Working in sea ice is a unique experience. When the LMG first got into the ice, I heard and felt it before I saw it. The boat slowed and it felt like something was jostling the entire ship from below: a little jolt this way, then that way. And the sound of it- mostly slush against the metal hull with an occasional bang and grind- was attention-grabbing. Due to the white overcast, the sea and sky blended together into a white-wash of bright though diffuse light. Magical!

An ice and skyscape, tweeked blue.

Lookout: "Ice berg right ahead!"

Up close and personal with sea ice.

Ruth: "So this is the ship they say is unsinkable."

Cal Hockley: "It is unsinkable. God himself could not sink this ship."

Deploying scientific instruments and collecting water and plankton in sea ice is a real challenge. Large chunks of ice can damage and break cables; they can smash sensors, and they can rip nets. The people deploying the gear, whether CTD, net or towfish, must communicate with each other, a winch operator and the person steering the boat. The winch operator lets wire and cable in or out depending on whether the equipment is to be lowered or raised. The person steering the boat must watch for large ice bergs, hold a course, stay on station and provides wash behind the boat which clears the ice away. The people on deck must coordinate everything and physically guide the equipment into the water. It is common to have to replace nets that get snagged on ice.

The coordination of all people involved in deploying equipment takes extra communication when working in ice.

After this deployment, the net was ripped so badly that we had to replace it with a spare.

Jack: "I don't know about you, but I intend to write a strongly worded letter to the White Star Line about all of this. "

Another exciting aspect of working in ice is the different wildlife you can see. Ross seals are often observed floating around on chunks of ice. Killer whales are also found along the ice edge, hunting seals. We were lucky enough to find a pod of killer whales; the whale researcher onboard attempted to biopsy and photograph the group. Unfortunately for us, killer whales are fast and smart; no successful biopsy was collected. However, photos for individual identification were collected. Unique dorsal fin shapes and features, as well as the saddle patches (a lighter patch on the backs of killer whales), are used for categorizing individuals.

Three killer whales in a pod of around 10 individuals.

Here you can see how different the dorsal fins are; they males have the tallest fins (left).

Jack: "it hits you like a thousand knives stabbing you all over your body. You can't breathe. You can't think. At least, not about anything but the pain. Which is why I'm not looking forward to jumping in there after you."

This photo clearly shows this animals saddle patch, used for identification and cataloguing of individual animals.

I thoroughly enjoyed the opportunity to work and travel in and around the sea ice. Unfortunately, it kept us from reaching our southernmost station, but was beautiful and exciting all the same.

A sunrise with some distant icebergs.

One of our only sunny days!

Rose: "Look. It's so beautiful."

Jack: "Yeah."

Growing Copepods

2012-02-04T10:00:57Z

Editor's note: The LTER zooplankton team has generously allowed Karen some time and resources to do some of her own work.

While here in Antarctica, I am trying to grow copepods. Copepods are small crustaceans that are part of the zooplankton, a word for all animals whose movement in the sea is mainly due to the movement of their liquid surroundings. Their sizes range from less than one millimeter to several. They have complex life histories, involving both naupliar and copepodite stages, before reaching maturity. Copepod growth rates are thought to be primarily controlled by food availability, while their development rates are likely linked more to temperature. Therefore, under different temperature conditions, it is likely that copepods will mature at different sizes. I would like to find out what the relationship is between copepod egg development and temperature; eggs are interesting in this respect because they do not require food from the environment outside of the egg.

I began by collecting live copepods in a net, selecting out mature females, carefully placing them in glass petri dishes. I placed trays of petri dishes into two incubators at two different temperatures (0 and approximately 4 degrees Celsius). The first time I did this, the copepods lived for about four days and that was it; nothing happened. I was a little discouraged.

Many copepods together under a microscope; there are a few different species here. The red-colored bits are their antennae, which they use to sense their surroundings.

A tray of petri dishes sitting at the bottom of the 0 degree incubator. I had to keep them at the bottom of the incubator, or they would freeze: a lesson learned by mishap.

The second time I tried the experiment, I had better luck. The copepods I selected laid eggs within a couple days in the warmer incubator and within a couple more days in the colder one! The eggs have yet to hatch and may have stopped developing. The copepods that laid eggs were a Calanus species, the ones with the red antennae, which I have yet to identify to a species level.

Calanus sp. used in my experiment

Editor's note: Notice the shiny sack of oil filling out the copepod's carapace. This is why everyone wants to eat Calanus.

Copepod eggs

There is incredible copepod diversity here; it is both exciting and a little overwhelming trying to learn the different species.

A copepod of the genus Candacia, distinguishable by its frilly black legs. When Candacia are floating around in a tub with lots of other zooplankton, all you can see is their legs because their bodies are transparent.

Editor's note: I think Candacia would be an excellent candidate for the next stuffed copepod.

A mature female Paraeuchaeta antarctica, with a spermatophore attached to her uromsome (tail).

Editor's note: Paraeuchaeta is a voracious predator. Not quite in the same league as a honey badger, but close.

The setae on the posterial corners of a Paraeuchaeta antarctica: a feature that helps distinguish this copepod from other species.

I am still working on definitively identifying the Calanus species that I used in my experiment; they may be Calanus propinquus. You can tell the difference between Calanus spp. and Calanoides spp. by a serrated upper, inner edge of the most rear swimming legs. Try seeing that in a microscope on a moving ship! It's a great challenge.

A More Detailed Look at Zooplankton--Salps & Their Poop

2012-02-01T08:00:00Z

Editor's note: Some science from Karen. Zooplankton poop is the most globally significant fecal material.

One of the zooplanktonic critters that we catch in our nets from time to time is salps. The species seen most commonly here in large numbers is Salpa thompsoni. Salps have received a lot of attention in marine science lately due to the nature of their poop. Compared with the fecal pellets of other marine zooplankton, the poop produced by salps is denser and in a larger pellet-like form. Krill on the other hand produce a long strand of poop. Copepod fecal pellets are much smaller. The result of having such dense, large turds is that salp poop sinks faster and is not broken down as quickly as others as it sinks, making it a first-rate organic matter transporter from the surface waters where it is generated, to depth where it eventually settles. This process is one mechanism that naturally sequesters carbon (organic matter) in the ocean. Futher, salps are thought to thrive in relatively nutrient-poor waters, making them able to proliferate where other organisms, such as krill, may not.

Salp species are found in the ocean world-wide. They have two different adult life-cycle forms: aggregate and solitary. Aggregates can form long chains, up to several meters in length.

Salpa thompsoni in aggregate form- note its pointy ends, characteristic of aggregates. Also, note the lighter muscle bands and bright orange gut.

Solitary salps are more barrel-shaped than aggregates, and in our net tows are less common. Their poops are larger than aggregate poops, in fact, Kate, a scientist conducting fecal pellet production experiments on this cruise, nearly collapsed a large hard plastic carboy while trying to filter a solitary salp's poop, though she had filter plenty of aggregate salps' poop before with no problems. Solitary salps reproduce asexually by budding off chains of tens to hundreds of clones, whereas aggregate salps reproduce sexually. Younger chains of salps produce the female gametes, which are fertilized by male gametes from older chains. Eventually, embryos are released and grow in the solitary form. We sometimes catch salp embryos.

A salp embryo

When we collect net tows in an area rich with salps, it's a big mess and takes a long time to sort though to find other non-salp zooplankton. This tends to happen at our offshore stations, rather than inshore; we have only had this situation once thus far.

Miram holds graduated cylinders full of salps that we have picked through for other zooplankton; this took around 10 hours!

A handful of salps in a strainer.

The weather on this cruise has been (typical of Antarctica) highly variable. The majority of the time has been overcast. We have had a few snow storms, and just yesterday we had to cancel science for the day because it was blowing 50 knots with 15 foot seas. However, we have also had several beautiful days, with nice sun and moon rises and sets.

A lovely sunset

Editor's note: sunset pic inserted to counterbalance the poop.

An equally lovely and coinciding moon rise on the other horizon.

Is Winter Getting Shorter?

2012-01-28T10:30:30Z

The average temperature of the earth has been rising steadily, and climate scientists are ver confident in their prediction that the trend will continue for the foreseeable future. While global conditions can be forecast pretty well, relating global changes to local conditions is much harder. One of the simplest climate predictions is that rising temperatures will lead to fewer days of winter-like weather. Here is an animation of changes in the duration of winter across North America:

In the movie, red indicates a shorter winter at that location, relative to the average duration between 1871-2010. I used a very human-centric definition of winter. Winter was declared to start on the day where temperature falls below 5°C and stays below this level for five consecutive days. Winter ended when temperature exceeded 10°C for five days. More detail on the data is below.

Not surprisingly, there is a lot of blue (longer than average winters) in the beginning and lots of red (shorter winters) at the end. In between, you see red and blue blobs come and go. Even early in the time series, there are some areas with shorter winters, and even at the end there are some areas with longer winters. In any one location, winter duration fluctuates, but the general trend is towards shorter winters. For example, I plotted the winter durations for Maine (thin blue line) against the average duration for the whole region (thick black line).

Positive numbers indicate longer than average winters. So, winters are definitely getting shorter over North America, and the trend is very consistent since the late 1970s. The 30s and 40s tended to have shorter winters, while those in the late 60s and early 70s were longer. Maine is much noisier, but tends to follow this overall pattern. The period of shorter winters in the 1940s is more extreme in Maine, and only in the last couple of years have we exceeded those values. I would love to hear some recollections of the late 1990s: were winters really ~25 days longer than the last few years? If you're not a fan of cold weather, this looks like a pretty good trend: fewer days in the puffy jacket and fewer days running the old oil burner. However, it's not all sunshine and roses (which of course will bloom earlier). In Maine, mild winters allow the dreaded deer tick to flourish, making gardening an extreme sport.

Data Processing

The data for the animation and the figure were taken from the NOAA Earth System Research Lab's 20th C Reanalylsis (V2). I downloaded the daily maximum temperatures and extracted North America. Starting from midsummer in each year, I went through the next 365 days of data looking for a period where the temperature was 5°C or lower for 5 consecutive days. The first period I found was declared to be the start of the following winter. For example, if I started searching in June 1973, and found December 15 as the first winter day,my algorithm would say that the start of winter in 1974 was -15 days. I then searched until I found five days of temperatures above 10°C and declared that to be the end of winter. The duration was then the difference between the ending and starting dates. If a location never fell below 5°, there was no

winter at that location. Similarly, if the location was always colder than 5°, then the duration was 365 days.

I now have a map for each year with the winter durations. To reduce some of the local variability, I computed a five year running mean at each location (1973 is now the mean of 1973-1977). I then took the average duration at each location in the map and then subtracted the observed duration from the average, producing a map of anomalies. In the movie, I interpolated on to a finer grid, to make the images less blocky. Between each year, I inserted five images that were blendings of this year and the next. This allows the movie to change smoothly.

Elephant Seals

2012-01-25T15:10:50Z

Editor's note: No, Karen's ship didn't run aground. She is still safely on the water, we're just publishing this post out of order to save you from too many cute animal pictures in a row. Plankton fans: don't worry, your day will come soon...

This entry is really an excuse to wow you with pretty pictures of seals. Elephant seals are one of the species commonly seen around the Antarctic Peninsula and they were fairly abundant around Palmer Station. Other seal species that live here include: leopard seals, Weddell seals, crab-eater seals and fur seals. Elephant seals live in harems of females, for which male individuals fight. It is therefore common to see one large male with several females.

An elephant seal smiles for the camera

Trying to reach that itch- not easy when you're HUGE!

Inter-species interaction? Unlikely.

A group of elephant seals at the bottom of the glacier at Palmer Station- a great surprise in the middle of a lovely hike.

At the moment, little work is being done on seals in Antarctica. Researchers opportunistically survey their populations for numbers and distribution. Moms and pups are surveyed for their respective weights. A study that ended a few years ago sought to understand the lipid (fat) transfer from mother Weddell seals to their pups; this work was conducted out of McMurdo Research Station. I wonder what the trends are in different seal populations and whether each species is susceptible to different environmental factors, perhaps related to their respective food sources. I also wonder how much the animals' distributions change over time- do the seals use one habitat for an amount of time and then shift to another? Does this happen on the scale of one animal's lifetime? Multiple generations? Just some food for thought...so to speak.

1880-2011 Warming

2012-01-21T09:36:05Z

For those of you keeping score at home, NASA has concluded that 2011 was the ninth warmest year on record. (All together now: We're number 9! We're number 9!) Furthermore, nine of the 10 warmest years have occurred this century. They've put together a mesmerizing visualization of temperature patterns since 1880 (white=mid 20th C average, blue=colder than average, yellow-red=warmer).

It's worth taking a stop in some specific years (this is easier if you download the mp4 file from the NASA site):

1930s--notice the warming over the US. The warming in the 30s was associated with the Dust Bowl period and one of the largest displacements of people in the US (think Grapes of Wrath).
1916--one of the coldest years in the record. Only a few areas of above average temperatures.
1960--a pretty good representation of the "mid century average". The colors are muted and the splotches of orange and blue are scattered evenly around the globe.
1978--the start of the current warming trend. Start from here and watch the red appear!
1997--very strong El Nino year. Notice the cone of warm water centered over the Pacific.
2010--the warmest year on record. While most of the world is orange, notice how the warming is stronger in the Arctic, and to a certain extent, the Antarctic. While the global average temperature in 2010 is ~0.5°C higher than average, the temps in the Arctic are almost 2°C warmer.
2011--"cone shaped" pattern of cold water in the Pacific indicates La Nina conditions.

SCIENCE ABOARD THE LMG

2012-01-14T08:46:30Z

Another update from austral graduate student Karen:

This research cruise is part of a Long Term Ecological Research Program (LTER), an NSF-funded project to study long-term change in a diverse set of ecosystems. Palmer Station and the LTER cruise are the primary components of the Antarctic LTER. Long-term research is expensive to support and does not turn out a lot of results in the short-term. However, without it, people would have no way of knowing how the world is changing over time. It is therefore exceedingly important.

LTER science covers many aspects of the ecosystem. There are people studying gases and trace metals in the ocean, bacteria, phytoplankton (plant plankton), zooplankton (animal plankton), birds and whales. Carbon flux is a major focus that crosscuts many of the different project teams.

The group that I work with studies zooplankton and their role in the Antarctic carbon cycle. Dr. Deborah Steinberg, from the Virginia Institute of Marine Science (VIMS), runs the project. We conduct different kinds of net tows to sample the zooplankton at different locations and at different depths around the peninsula. In addition, some of us are conducting experiments to look at fecal pellet production, gut evacuation rates and development rates. Each of these aspects of zooplankton ecology directly relates to carbon cycling.

The rockin' zooplankton team working their magic aboard the LMG, LTER 2012.

Carbon cycling is important because carbon is one of three primary elements that simulate the growth of life in the sea; the other two are nitrogen and phosphorus. In addition, carbon in the ocean can exist as carbon dioxide (CO2), a major player in greenhouse gas warming. It is therefore of utmost importance to understand how carbon moves in the marine system, and under what conditions it remains in the sea versus exits into the atmosphere.

The way we catch zooplankton is with large nets that are towed behind the boat. We use nets made of different sized meshes to catch different sized organisms.

picture:

Our two meter "metro" net is deployed off the stern of the ship. We typically tow this net down to 120 meters. For every regular sampling station, we take a tow with this net, and another with a smaller (one meter) net down to 300 meters.

Once we have our zooplankton samples onboard, we sort, identify and count all of the animals that we have caught; this takes quite a long time! Some examples of animals that we typically catch include: krill, salps, amphipods, copepods and chaetognaths. We also occasionally catch larval and juvenile fish and squid.

Kate and Miram take a gander at what we have caught in our latest tow.

A mélange of zooplankton swim around in a large beaker after being brought inside the lab; here you can see different ages and species of krill, chaetognaths and more.

We are not the only ones out here trying to catch zooplankton; whales are a great indicator of large numbers of krill in the area. In fact, when we do a net tow in the presence of whales, we usually find big healthy-looking krill in the sample.

The head and dorsal fin of a humpback whale feeding near one of our sampling stations.

Humpback whale flukes- the patterns on the underside of humpback whale flukes are used to identify individual animals. The longest animal migration on record was recorded after a humpback known to frequent American Samoa was sighted in Antarctica.

The zooplankton community changes with the oceanographic conditions in different areas. Nearshore, the water contains more phytoplankton, while offshore, the waters are less phytoplankton-rich. We tend to find large schools of krill inshore, where phytoplankton is most abundant. Offshore, less krill are seen but we also catch more salps, a type of gelatinous zooplankton. Salps tend to be found in nutrient-poor waters, potentially indicating ecosystem niche-differentiation from krill.

While tiny, zooplankton are an incredibly important component of the Antarctic ecosystem. They are the link between the organisms converting sunlight into useable energy, and all higher trophic levels here. ¬ There is evidence that as the climate warms and ice conditions change, major changes in the zooplankton community will follow. LTER scientists are seeking to describe and understand these changes, as they occur.