Teachers’ Posts from Sea


Seeing with Sound
     If you were a dolphin (or other toothed whale) and you lived in the deep ocean, your eyes wouldn’t help you catch a fish or krill.  Your eyes would be useless to you.  So how are you going to find food and hang out with your friends?  No problem, you have skills:  echolocation takes over where your eyes leave off.
As a dolphin you can emit sounds like high pitched clicks.   When these clicks hit an object, some of the sound will echo back.   By listening to the echo,  interpreting the time it takes to return and it’s strength, you can tell if it is a fish, big or little.
     Similarly, we are also looking for fish and krill here on the R/V Melville.   Our equipment sends out pings, and then captures the sound wave when it returns, with special technological tools such as  “the Pod”. ( This apparatus looks to me like a big foot attached to a big fat metal light pole stuck to the port side of the vessel.)  It uses echo sounding to convey information about the fish and krill.    A little about sound waves:  the lower the frequency of the wave the deeper it can go.  The lower frequency has a longer wavelength.  We use four different frequencies (measured in kilohertz) 38, 70, 120 and 200 to find krill and fish.  At 120- 200 khz you can “see krill”.  At 38-70 khz you can “see fish”.
     Scientists look at visual displays produced by echo sounding and make interpretations about fish type, size and number of fish.  Even more fantastic, we can see right down to the bottom of the ocean and all of the minute distributions as we go. There are some really fascinating facts to be extrapolated from the data.  For example, some fish and plankton go on migrations!  We usually think of a migration as a horizontal movement, the journey across the sea of an animal like a sea turtle, for example.  But some sea creatures go on vertical migrations.  To explain, many organisms will stay down below the euphotic zone (where light penetrates) because they don’t want to get eaten. At night, they rise up toward the surface to dine on chlorophyll-rich phytoplankton and the small zooplankton.  When the sun comes up they travel back down to hide in the dark.  This vertical migration is information “the pod” sends to the computers on board our ship.  The scientists can see the biomass and the line of descent on the monitors.

The Pod "captures" plankton on migration, their images that is!

The Pod

The image to the right is a screen shot taken on October 8, 2008 that shows this vertical migration.
Seeing these echos and interpreting them is not enough.  We use the trawl method to catch specimens so that we can identify and classify the various species.  The trawl nets catch a fraction of the fish   (approximately 15%) that is moving along when we cross their paths.  But fish can be sneaky.  They avoid the nets.  So by using both acoustics and a trawl we can get a pretty good picture of what is out here.  Each sampling method is like a little window.   With each window we have a different perspective.  Working as a team, all of the scientists collaborate and share the data they gather.  When you put all of the windows together we have a really big view.  Last but not least, the Scripps scientists and R/V Melville crew REALLY know how to work like a team, collaborating and sharing their scientific discoveries about the California Current Ecosystem.  What an inspiration you all are to me.
Thank you Tony Koslow, SIO, CalCOFI Director for explaining your scientific contributions on board, for editing this report and for sharing  with me all the unique creatures of the deep!
Signing off,  Laurie Guest,  Your Teacher at Sea

Ryan on Bongos

Ryan on Bongos

Jessie Powell, SIO Grad Student:  Great Team Player

Monday October 27th, 2008: Jessie Powell, SIO Grad Student Great Team Player; Mark Ohman, PI, MVP Dream Team (Photo by: Lauire Guest)

THE FRONT STORY

The California Current Ecosystem (CCE)  Long Term Ecological Research (LTER) site is comprised of scientists, students and educators that are working to understand and communicate  the connections between large-scale natural processes such as warm water/cold fronts and the feeding success, and reproduction of marine life.  The upwelling of cold water is a variable area that extends out from the coast toward the open ocean.  We have been studying the cooler water that hugs the land masses. Further offshore the water is warmer.  What happens at the boundary between cool and warm water?  This “front” is an area of intense interest.  When we hit the cold front, which is a wall of water,  the crew worked around the clock.  Day shifts flowed into night shifts and cycled back around.  We were able to compare and contrast the specimens from the first four cycles with the warm water specimens.  Scientists ask questions about the front including whether the food web is the same or different on either side of the wall and what is life like inside of it?
   What we do know is that water with lower temperatures is more nutrient rich.  Some of the lesson plans I am writing focus on those concepts, but for now we are hypothesizing that the cold water will have more plankton and more krill.
So that’s why I am writing this report outside.  My concurrent hypothesis is THERE ARE WHALES OUT HERE TODAY!  Yes, I am excited, watching and waiting with camera, binoculars, lab notebook, pencil, and most important a good attitude.  There is a low gray mist that obscures the view.  Baby, it’s cold outside. The sky is gray, the sea is gray, the deck is painted gray and probably my roots will be gray by the time I finish writing this for the blog.

The Jars Tell the Story

The Jars Tell the Story: The jars in the middle are from the cold front. You can see how dense they are: a microscopic stew of life. Water with lower temperature is more nutrient rich; and supports high productivity in plankton.

Let’s talk about the physical characteristics of the water.  The higher density is because the temperature is lower and the water is more saline.  Lower density water is warmer and less salty.  What happens when they meet?  The higher temperature within an organism, the more quickly the energy-releasing processes happen.  Since many marine organisms are the same temperature as the surrounding water, their internal temperatures match that of the water around them.  Their metabolic rate speeds up.  Phytoplankton, for example, take in more nutrients and grow faster. Zooplankton metabolize their food

Preserved jar of Euphausia pacifica caught in the mockness trawl off of the RV Melville

Preserved jar of Euphausia pacifica caught in the mockness trawl off of the RV Melville (Photo by: Christy Millsap)

very quickly.  Incidentally,  they deplete the nutrients in the warmer water as a direct result.   So, the result after a while in warm water, is that there are less nutrients in the water, less phytoplankton, and less zooplankton for the fish and whales.  The systems “run down” at higher ocean temperatures.
    A key concept is that the primary production of plankton shapes the ecosystem. Since there is a relationship between organisms in the food chain, scientists are interested in just how much productivity is evident in the cold front.
    My blog report is almost done and no whales are in sight so I am going;  besides my extremities are almost frozen to the deck chair.  Hey, what’s that?  Nah, a dorsal fin?   GETOUTTAHERE!  I am seeing a dolphin leaping along starboard. No, make that two.  Oh my goodness, in the distance I can see about 30 or 40 Common dolphins.  Hey, they’re gray too, with white underneath.  I am shooting pictures like crazy, because I know you are not going to believe this.  They are very close to me now, but every time one comes up, I point, click and floop the dolphin dives under.  Well, take my word for it. Wow, this cold front is so cool.     Final note: Thank you Mark Ohman, Scripps Institute of Oceanography,  Principle Investigator. Your veracity is much appreciated and your verbosity always enjoyable. Signing off, Teacher at Sea, Miss Guest

This is another sampling method: the trawl.  That's Jim the RES/TECH.

This is another sampling method: the trawl.

Vampire Squid

Vampire Squid

I hope you will find  information on the blog useful and fun to read. I look forward to having an audience learn about the marine science that is taking place on the cruise.  I am hoping my little MIT students are reading and asking questions.  This blog will answer the questions I have been getting, which are less scientific and more personal. 

Things are really great: I am learning to use cameras, shoot still frames and video and fixing them so they are “blogified”.  It is amusing to see the shots of me.  When I’m outdoors I am all happiness. Inside the lab I look kind of unpleasant and very serious.  I call them “ugshots”.

This morning, I should have looked elated because I successfully assisted in retrieving the CTD! Talk about a deep sea Dragon Fish being under pressure! I grrabbed a pole, a  rrope, and tightened up my arrrms. No prrroblem.  But oooh my muscles ache today.  My mother, from Scotland, would tell me “Don’t be so dramatic”.  I think I miss my mother.  She is so great.  I get sentimental like any other sailor.

Later I  took a hot tub on an upper deck.  (Well deserved after my chemistry lab work on the samples from the CTD were done, about 4:00 am. ) There were shooting stars and falling stars and a waning sliver of a crescent moon.   The hot tub is big, rectangular and filled with salt water sent through the engine where you can float like a plankton and splash like an otter.
Little things make people happy at Sea.
* good lookin’ color printouts of krill in a jar.
* breakfast with fresh fruit all cut up for you
* shopping in the ship store
* knowledge that our ship is coming in (five more days) makes a lot of the hard working grad students very thrilled.
For me I am happy and grateful because everyone here is so nice to me.  They spend lots of time getting me up to speed with the science, and technology as well other important things like how to live aboard the ship. Getting to see the stars so bright, and my favorite kind of moon in the Channel Islands is icing on the cake.  (The cook makes those REALLY GOOD, too.)

Signing off: Your Teacher at Sea,  Laurie Guest

We pulled blue bioluminescing dinoflagellates in a BONGO net pull.  Here I am in the lab.

Laurie, along with Jean Baptiste, deploying the Mochness

Laurie, along with Jean-Baptiste, deploying the Mocness

Wow, more than halfway done with the cruise.  It is a powerful upward curve that I am going through and I am working at every opportunity to learn more about science.  As you know, I work the night shift with the equipment deployment, so I slept from 2pm-5pm.  Awaking, I was in the twilight zone not knowing what to do with myself before my shift began.  For the past two days I had been working with cameras, writing a sea surface temperature lesson, a salinity lesson, and a fishy story about a plankton but  I was saturated with technology and reading; not even feeling like doing artwork.  I guess my lost look was evident.  One of the scientists from France , had a good suggestion that I should “Go to bed” but “mais non”.  I found myself whining silently ” I don’t wanna.” Inwardly I rolled my eyes at myself because I sounded just like you kids.

October 23rd, 2008: Laurie Guest Teacher at Sea

I was glad I pushed myself out of the doldrums because we soon saw wonderful things from the catch in the bongo nets:  blue bioluminescing dinoflagellates, a heteropod (very rare drifting snail), ctenophores, a dragon fish and something called a bleh, clod or fhlerg: I missed what the scientist called it.  At the time he said it, I gave one of those wise head nods but I really had no idea, and he rapidly moved on.  In the wet lab, using a camera and a binocular microscope, we tried to make a plankton spark in a petri dish but its “foof had fizzled”.  Still, we then added a small part of acetic acid (vinegar) to the plankton which sometimes makes them spark, but not now.  Usually dinoflagellates release light when agitated, so I went out to look for them.  Alone, I went up on an upper deck on the forward bow to look at the sea.  Ah ha! There they were far below.  They were blue sparks spread out in the giant black waves.

Dinoflagellate

Dinoflagellate

 It was pitch dark out, tons of stars, and the moon had not yet risen.  Seeing them in their natural state was gratifying.  I was feeling a little sad that I had made the plankton slightly moribund in the dish.  I like working in the night as everything seems intense: both the people and the equipment.    The enormous, slippery  BONGO nets gleam and drip with masses of plankton.  The MOCNESS  always looks intimidating by its sheer size and greatness; indeed it is a hairy experience putting it in.  Conducting hydrowire, pulleys, winches, motors, ropes, whew!  When it’s cruising alongside the ship peacefully it is a big relief to me.

Signing off,
Miss Guest, Teacher at Sea

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