February 2012 Archives

Ocean Sciences Meeting 2012

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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

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

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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

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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.
1_Assorted copepods.jpg
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.
2_Candacia spp.jpg
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.
3_Paraeuchaeta antarctica.jpg
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.
Paraeuchaeta antarctica seta on Pr5_comp.JPG
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

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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.
4_Salp aggregate.jpg
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.
5_Salp embryo.jpg
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.

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