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Time lapse

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How can it be that a month has passed since the last entry?  Indeed, a poor showing by the seascapers.

Speaking of lapsing time...

Somehow, lost in my slurry of scientific ideas, I forgot to post this video last summer after our cruise.  Here it is: an afternoon's worth of sampling, collapsed into a minute of time-lapse imagery.

-Nick Record, signing off

Time lapse sampling near Mount Desert Island

Fishermen's Forum

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Greetings!  If you've visited this site before, you're probably aware that our lab has spent the past three July/Augusts cruising up and down the scenic coast of Maine, visiting coastal towns, gawking at amazing sealife, and gathering information on the zooplankton community under the speckled starlight of the summer sky.  Truly the good life.

It's one thing to spend your summers enjoying the Gulf of Maine, bobbing up and down, ogling skeleton shrimp under a microscope.  At the end of the day, however, we need to have something to show for our work.  There are many reasons to improve our understanding of the zooplankton community.  One such reason is so that we have better information on the migration patterns of planktivorous whales.  One of our main objectives has been to describe the feeding habitat of right whales, whose diet consists primary of the copepod Calanus finmarchicus.

This past weekend our lab and the biological oceanography lab presented some of the results of our cruises from 2008, 2009, and 2010 at the Maine Fishermen's Forum.  The forum is teeming with energy and activity, from seafood sampling to trade shows.  Thus I wondered to myself, as I found my way down a long, lonely hallway and up a grated stairway that led to our remote presentation room, How many people here will be interested in a talk with "Calanus finmarchicus" in the title?

After all, our time slot was competing with scallop farming, shrimp fishing, and "The Food Guys".

Not only was our talk well attended by an assortment of fishermen, managers, scientists, reporters, and others, but the array of questions that we received showed an impressive amount of interest, knowledge, and understanding of copepods and their ecological importance.  I doubt that there are many venues where a group of geeky scientists could talk about Calanus finmarchicus to such an eclectic audience, and receive such an enthusiastic response.

Nick Record, signing off.
Week 3 since the cruise, and the pieces of the puzzle are beginning to come into focus.  Cameron's incubation experiments indicate a presence we've not sensed since last year--the presence of diapausing copepods deep in the abyss.  As I typed earlier, I'm getting a similar signal in the laser data: an anomalously large aggregation of particles at just the size and depth we would expect to find C. finmarchicus.  Here is another view:


While it is possible that this deep aggregation of particles is some mysterious, and as yet undiscovered presence in the gulf, the evidence points to one plausibility: if it quacks like a copepod, it's probably a copepod.

I returned to my personal microcomputer to plot up quasi-silhouettes from the lasers, showing these particles.  Here are the preliminary results:

A glance at this image is far from conclusive, and it remains to demonstrate that the blobules we see are actually diapausing copepods.  I conjecture that they are indeed that, and I am presently taking steps to convince myself that I'm correct.

Nick Record, signing off.

With the thrill of the lobster molt wearing off, the time has come to crunch some numbers.  A few weeks ago--the 22nd of July, 2010 to be more precise--we spent a full day on our deep station in Wilkinson Basin.  For six relentless hours, we sampled profile after profile at the same station.  What began as a routine and sunny carefree day slowly morphed into grueling repetition, and as twilight descended upon us, so did the madness of tedium.  (I won't speak here of what that madness led to.)


The driving motivation behind this long series of profiles was to capture the twilight transition in Wilkinson Basin.  Every night, an unfathomable host of plankton emerges from the depths of the world's ocean to feed at the surface under the cloak of darkness.  This transition occurs, for the most part, during the twilight hours--hence the name of this sampling series.  Our objective is to sort out some of the major players in this massive migration, and to pinpoint as well as we can their preferred depths.

Naturally, we are in the early stages of unraveling this depth-stratified tapestry of plankton, but some curious signals are already appearing.  The plot shown below is taken from a night sample, well after the sun has set.  On the left is a plot from our laser optical plankton counter.  It shows the depth concentration of each size class of plankton--divided by equivalent spherical diameter (ESD).  You can see that most of the critters we observed are near the surface, with the concentration tapering off around a depth of 20-40 meters.  What stands out is the strong signal at the size range 1000-2000 microns (1-2 mm) at depths below 120 meters.  I have labeled this "Diapausing finmarks"-- what I believe to be the copepod Calanus finmarchicus, gathered in large numbers in its deep hibernation.  This is something that we hope to confirm with the net tows.

It is interesting to note that, while we think of this species as a cold-water animal at the southern edge of its range here in the Gulf of Maine, it appears to be actively avoiding the coldest depths at this station.  The right-hand plot shows a temperature profile, with a classic Maine-intermediate-water signal. I've labeled that.  It's a cold layer that forms between two warmer layers in the ocean, due to a combination of processes.

The other curiosity to this temperature plot is the blip of warmer water around 50 meters depth.  This I've labeled with a question mark.  It appears in nearly all of our profiles, at the same depth, and I've since noticed it in other temperature profiles from the Gulf of Maine.  I have yet to find an explanation.  Thus, another mystery has bubbled up to the surface.


PS in response to Pete's comment, I've posted some of the LOPC shapes on the LOPC blog:
I think these videos speak for themselves.

the presentation:

fancy snack from peter stetson on Vimeo.

the naming:

copepod sur la petite four from peter stetson on Vimeo.

just how good is it?

One for me, one for the birds from peter stetson on Vimeo.

mola mola mola mola mola

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Described as "stray visitors to the gulf" by Bigelow and Schroeder, the Mola mola, or ocean sunfish, is a large fish readily noticed by it's floppy dorsal fin when at the surface. They generally move pretty slowly, although I'm told (Bigelow and Schroeder, and personal communication with others) that they can really move when they want to. We came across one on day 5 of the cruise, in the vicinity of Jordan's basin. They like to eat Ctenophores and other jellies.

Top view of the mola as it approached the boat:

You can see in the pictures below, how it moves it's dorsal and anal fins to swim:

(in photo above: dorsal fin extended, anal fin pointing towards the camera)

(in this picture, the dorsal fin is at the surface bent toward us, and the anal fin is extended downward)

basking with a basking shark

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On day 3 of the cruise, between stations 5 and 6 (between the offshore most x's on the second transect from the right in Nick's map - see post below) we spotted a basking shark. Basking sharks can be quite large and scary looking, but, like whale sharks, they eat plankton. Which means you don't have to worry about one eating you. I had an underwater housing onboard, and the day was calm, so I asked the captain if I could jump in and try to get an underwater shot. I was in luck, the captain gave a green light to "operation swim with a shark" and I rushed to set-up the gear and don my wetsuit.
 I jumped in the water off the diving platform on the transom, fired off a test shot (the greater shearwater from below - also included is a greater shearwater shot from above. shots taken on separate days) and started swimming as fast as I could toward the shark.

     You can see from the shearwater "from below" shot, the water is beautiful. It's was ~400 feet deep, too. When you're looking down or in any direction other than up, it's all blue... unless you're within 20 or so feet of something.  This meant as I swam toward the ~25' shark, I was surrounded by immense blue and I wouldn't see anything in the water until I was right there next to it. My heartrate was flying.
     I was pretty far from the shark when I got in the water and was working hard to catch up. My thoughts were split between, "I hope I can get a shot" and "I hope I don't stumble upon this massive creature in the middle of the Gulf of Maine... to realize I mis-identified the species..."
     The folks on deck were kind enough to sing the JAWS theme when the basking shark went below the surface for a bit. Thanks guys.

     After a serious effort in the water, everyone on deck informed me that after I reached a certain point, the shark was swimming away from me just as quickly as I was approaching, and we had stations to finish. So, no underwater shot of a basking shark, this time. But Cameron got a nice shot from the deck of me swimming toward the shark, camera in tow, with a nice sized fin in the background.

Too add some size perspective, I've also included two shots of the shark shot from the deck before I jumped in. It was too big to fit in the frame of just one shot. In the first, you can make out the pectoral fin: the white markings below the surface. The nose and body of the shark are detectable by the subtle change in color from the water.
The second shot is easier to make out: The dorsal fin on the left, and the caudal fin just below the surface, stirring  the water on the right.


Swimming with the basking shark (above).

Dorsal and caudal fins seen from the boat (below).

Enjoy. I'll put up more pictures of other cruise adventures over the next week.

Hasty update

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Each night, as we dock further and further downeast, wireless resources dwindle.  One might find oneself quailed down against a warehouse, between a flickering coke machine and a trash bin, dodging raccoons, just to get a link to the grid.

So, I'll be brief. 

We continue to pound out our transects, as the attached cartography indicates.  We have only a handful of stations left.  Depending on how we prioritize our remaining time, we may or may not hit all of them.  In either case, we've had our most successful cruise of this project, covering a much broader area than in previous years.  Wildlife has been modest, though we have had cameos from fin, sei, and humpback whales, basking sharks and mola molas, and our old chum, the Atlantic puffin.  Expect Pete to follow up with photos, when we reach ample wireless.

Nick Record, signing off.


Dockside monstrosities

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We arrived in Stonington on Monday evening, after four straight days of good weather.  We'd knocked off four of our six transects already, and were feeling refreshed after a five-minute shower at the marina and some ice cream in town.  Not ready to call it a night, still with the thirst for scientific endeavor unsated, Pete and I poked our heads over the side of the dock to explore the ecosystem there.

A dockside ecosystem is a fascinating universe.  Small crabs were picking barnacles off the pilings, slinking away as we peered into the foggy black pool.  A headlamp illuminated a column of water that reached only a few inches in, before running into a wall of dense suspended sediment.  At first, we saw only specks.  We quickly noticed that some of the specks were moving--copepods.  Soon our patch of light was teeming and skittering with the little bugs, too numerous to count.

As Pete snapped photos, larger figures began to emerge from the shadowy border around our copepod city.  Mysid shrimp, zipping through the cloud of copepods, and disappearing into the dark.  Then other, larger crustaceans, eyes glowing in our light, each one dwarfing the last, until they were the size of fish.  Pete tried to catch one in a sieve, but it leapt from the water, and skipped ten feet along the surface to its escape.  And below those, just beyond the reach of the lamp's beam, still larger, ominous outlines glided silently by in a hazy blur.

Before the larger, man-eating crustaceans could creep in to catch us unawares, we were able to collect some interesting specimens to view on board in the lab.  Shown below are a couple of images of a caprellid amphipod--the skeleton shrimp.    This otherworldly creature latches on to other organisms with its rear legs, and snatches at passing prey with its (relatively speaking) massive claws.  We captured some eerie video of our skeleton shrimp squirming around the dish, gobbling up copepods one by one.  I'll post that later.  Meanwhile, here are a couple of stills.  

After a thrilling night of exploring the dockside ecosystem, we released all of the creatures back into the ocean.  To their freedom.  Except of course for the hoards of copepods that were mercilessly slaughtered by the skeleton shrimp.

Nick Record, signing off.


Day 1: well-oiled machine

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This is the third year for Ecosystem Modeling and Biological Oceanography labs' zooplankton sampling cruise, and this is the first time that I've managed to get on the boat.  I was there to practice whale surveys and to test the hydrophone.  Since there were no whales (well, one whale) the most interesting part of the trip was watching the team do its thing.  After three years, Becky, Nick, Pete, and Cameron have developed into an oceanographic sampling force.

As Nick documented, the cruises is divided into a series of transects that run perpendicular to shore.  Along each transect, we've specified several stations where the actual samples are taken.  The first step at any station is to lower the CTD instrument to near the bottom.  The instrument has three sensors.  The "C" stands for conductivity and this sensor measures how easily an electrical current can travel through the water. The more dissolved in the water, the easier the current can flow, so the conductivity sensor measures the salinity of the water. The "T" stands for temperature, and you all know what that measures.  Together, salinity and temperature determine the density of the water.  "D" stands for depth, and by measuring all three together, we can learn how the temperature and salinity change from the surface to the bottom.  This year, the Bio-Oce lab has added a PAR sensor to the CTD.  This sensor measures that amount of Photosynthetically-Active Radiation at each depth--basically, how far light reaches into the ocean.  In addition to being important for photosynthesis, visual predators like fish need light to see their prey,

After the CTD comes the main event, the ring net tows.  The ring net is actually two nets bolted together.  These are also lowered to the bottom and then pulled back up.  Water and plankton enter the mouth of the net.  The water goes out, but the plankton are collected.  We (meaning Becky and Cameron) will then identify and count the plankton. In order to determine the density of plankton (number per cubic meter of water), we need to know how much water passes through the net. Each net is equipped with a flow meter.  The tow begins with two people--usually Pete and Cameron, calling out the numbers on each flow meter.  
The net is then lowered into the water.  The crew member running the winch monitors the depth of the net by the amount of wire payed out.  When the net comes up, two people guide the nets on to the deck.  They read out the numbers on the flow meters and then hose them down to make sure all the plankton are washed down to the cod-end.  Then, the cod ends are unclipped and the contents are dumped onto a sieve.  
The cod ends are rinsed and dumped a few more times.  Then the stuff on each sieve is dumped into a jar containing formalin (a preservative).  

The last activity at the station is the Laser Optical Plankton Counter (LOPC) that Nick's been writing about.  This uses lasers to detect plankton and estimate their size and shape.  The LOPC allows us to get an idea of whether the plankton collected in the nets were packed into a few dense layers or spread out over a large range of depths.

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This page is an archive of recent entries in the Cruise July 2010 category.

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