Recently in Sea Life Category

Beluga rescue

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On a recent trip to Svalbard, I happened to spot a beluga calf become entangled in a net. We called the police, and they executed a very efficient rescue. The video isn't great, but here are some clips. Sorry for the short post. Here is the local news write-up:

Salp watch 2014

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Welcome to Salp Watch 2014. Lots of salp sightings this fall near the coast. Here's one we pulled up in a bucket during a GNATS cruise across the Gulf of Maine in September.

Thalia.jpg

It looks like Thalia democratica. The bloom was so dense you could see it off the bow for miles and miles.

In October, a group from the New England Aquarium reported huge salp blooms in the Bay of Fundy:


And around the same time I got this email:

"Yesterday out lobstering there was an incredible abundance of what I think were salps in the water near the surface. They were ladder like creatures about 4-6 inches long. In some areas there were dozens in a square meter (rough estimate). This picture doesn't do it justice but if you look at the lower right hand corner you can see a couple of them. The VHF chatter was all about how guys were having to clean their raw water intakes because they were getting clogged with jellies."

salps2.JPG

We have a salp model up and running at Bigelow now, and I hope to set this in forecasting mode for the bloom next fall (which is when our Maine salps bloom).

Nick Record, signing off

Invasion of the jellyfish!

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It seems like I'm the only one along the coast of Maine not to have seen a jellyfish this year.  That's probably more a comment on my lack of contact with the ocean because, by all reports, there are tons of jellyfish along the coast of Maine this year.

Everyone on the coast is talking about jellies, and it seems that Nick and I are what pass for jellyfish experts.  Perhaps someday we'll get a massive Calanus outbreak, but until then, it's really fun to have people talking about the ocean.  Although we don't know a whole lot of what a normal jellyfish year looks like, it's pretty clear that this year is unusual.  I think it's noteworthy that this summer is warm and that the reports started coming in when we had a big jump in temperature in early June.  The other year with lots of jellyfish chatter was 2012.  Still, lots of work is needed to really put this story together.

If you need your Nick and Andy fix, check us out in the Portland Press Herland and on the radio at MPBN.  Until I get to the ocean to get some real underwater jellyfish pics, here's one of me dressed as a jellyfish:

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photo by Petri Touhimaa, GMRI

Are chaetognaths gelatinous? You be the judge

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(Apologies in advance for the perhaps obscure and esoteric content of this entry.)

The "Jelly Ocean Hypothesis" suggests that due to human-driven changes in the environment, we are headed toward an ocean dominated by jellyfish. Before determining whether this scientifically intriguing dystopian nightmare comes to pass, we need to agree on what classifies as a "gelatinous zooplankton"

Some people assert that chaetognaths fit into this category; others do not. Since we are debating this in the lab now, here is some information for context. What we need is a measure of how gelatinous something is. Ideally we would like to have a measure of carbon-to-volume ratio for each taxon--basically a measure of organic density--but for now, dry weight as a percentage of wet weight (DW as %WW) will have to do. --Basically the amount of the organism that is not water.

Ctenophore01.jpg Calanus_CV.jpg 170px-MEB_back.png
ctenophore    copepod            chaetognath
gelatinous    not gelatinous       ??


Here are the numbers:

Euphausiid DW as %WW: range 20-24% (depending on stage) +/- ~3
(Iguchi & Ikeda 1998 table 1)

Copepod DW as %WW: average ~19% +/- 10
(computed from Mauchline 1998 fig 50)

Chaetognath DW as % WW: 8
(Sameoto 1972 reported in Feigenbaum 1982)

Thaliacea DW as %WW: average 5.5% +/- 2.47
Ctenophora DW as %WW: average 3.53% +/- 0.92
Cnidaria DW as % WW: average 4.07% +/- 1.23
(Lucas et al. 2011)

And in graphical format:

chaetognath1.jpg
<--------- more gelatinous                                       less gelatinous --------->


I think this crude and cursory analysis settles the debate. Now we can get back to talking about copepods.

Nick Record, signing off

References

Lucas CH, Pitt KA, Purcell JE, Lebrato M, Condon RH (2011) What's in a jellyfish? Proximate and elemental composition and biometric relationships for use in biogeochemical studies. Ecology 92:1704.

Feigenbaum D (1982) Feeding by the chaetognath, Sagitta elegans, at low temperatures in Vineyard Sound, Massachusetts. Limnol. Oceanogr. 27(4): 699-706.

Iguchi N, Ikeda T (1998) Elemental composition (C, H, N) of the euphausiid Euphausia pacifica in Toyama Bay, southern Japan Sea. Plankton Biol. Ecol. 45(1): 79-84.

Mauchline (1998) The biology of calanoid copepods

Sameoto DD (1972) Yearly respiration rate and estimated energy budget for Sagittu elegans. J. Fish. Res. Bd. Can. 29: 987-996.

Coral Reef Adventures

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No, the EMLab is not heading to Bermuda (at least not yet).  Instead, the post is to clue our reader(s) in on the continuing adventures of rogue SMS professor, Bob Steneck.

Bob has been studying coral reefs for a long time, and he is also an avid sailor.  He is also one of the most creative scientists I've met.  The latest evidence of his creativity: he has managed to combine sailing and coral reef ecology into an awesome sabbatical (assuming he survives).  

He has sailed his boat Alaria, a 34' cutter-rigged Pacific Seacraft, from Maine to Bermuda.  He will soon be on his way to the Antilles, where he will spend several months studying the reefs there.  You can keep tabs on his adventures through his blog.

Cod in the Gulf of Maine

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This is a very challenging time to be a cod fisherman in the Gulf of Maine, and presumably, it's also a tough time to be a cod.  Fisheries managers have drastically reduced the amount of cod fishermen will be allowed to catch next year, and this follows a large reduction last year. Like many of us working at the intersection of oceanography and fisheries, I'm interested in what's up with cod?  There are a lot of hypotheses being kicked around, but as you might imagine, I'm interested in whether changes in temperature or other environmental factors are playing a role.  Here's a quick and dirty take on whether recent warming could be impacting cod.

First, temperature.  I began with the AVHRR OI data set that I've been using to characterize the 2012 story.  I grabbed the pixel near NERACOOS Buoy E off of the central Maine coast.  Here is the temperature pattern at that location:
GOMSSTanomaly.jpg
The thin blue line is the daily anomalies (smoothed over 15 day window).  The gray circles are the mean for each year.  The black line is the overall trend.  The trend is significant, but there is considerable year-to-year variability.  A trend of 0.026° per year is pretty consistent with the general global warming trend.  This would project to a 1° increase by 2050 and 2.3° by 2100.  The really striking pattern in the figure are the last three, extremely warm years.  If you fit a line to the 2004-2012 anomalies, you get a trend that is 10 times faster than the long term trend. I'm getting on statistically dubious grounds with this calculation, but it does suggest that we may have entered a new temperature regime.

Most of the published relationships between temperature and cod use some form of bottom temperature.  I used the 2002-2012 temperature data from buoy E to develop a simple statistical model for the temperature at 50m as a function of the surface temperature and the day of the year. The long-term mean temperature at this location was 6.89°C, which is a bit lower than the "standard" 8° value that most people report.  So, I added 1.11° to the annual bottom temperatures to get the mean close to right:
GoMBottomTemps.jpg
Why the big deal about 8°?  Well, Ken Drinkwater's 2005 paper on cod and climate change suggests that for regions above 8°, additional warming tends to reduce the fitness of cod.  For regions below 8°, warming increases fitness.  Using this benchmark, we had a period from 1999-2002 when cod reproduction may have been reduced by temperature.  The 10°C value for 2012 is getting scarily close to the 12°C point where Drinkwater says "cod stocks are not observed much."  

The red line in the figure is the September-October mean (not adjusted).  I then applied a relationship from Fogarty et al. (2008) relating the probability of catching a cod in the NMFS bottom trawl survey with the September-October bottom temperature. 
ProbCod_50mSO.jpg
Not surprising, this has many of the same patterns as the temperature values.  There is a gradual long-term trend (probability declines by 0.004 per year) and a much faster trend over the last 8 years (0.02 per year).  While the trends are interesting, I'm interested in what appears to be a shift in the mean in 1999.  Before 1999, the values are centered around 0.42.  After 1999, the mean probability appears near 0.37.  By this metric, 2012 looks very, very scary.  The probability of finding a cod this year was about half what it was in the early 1980s

The Wonders of Copepods

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SeascapeModeling is still waiting for copepod jokes to hit the mainstream.  In the meantime, here's a short video produced by UMaine featuring my views on why copepods are important.  The video was featured on NSF's news site last week.  The video was produced about a year ago and foreshadows some of the work going on in the lab, notably, Karen's work on copepods and carbon and Walt's work on bluefin tuna condition.  

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!

blue_ice_comp.JPG
An ice and skyscape, tweeked blue.
Lookout: "Ice berg right ahead!"

BW_ice_comp.jpg
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.

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

net_ice_comp.JPG
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.

orcas1_comp.jpg
Three killer whales in a pod of around 10 individuals.  

orcas2_comp.jpg
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."

saddle_patch_comp.jpg
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.

sunrise_comp.JPG
A sunrise with some distant icebergs.

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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.

petri_dishes_comp.JPG
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_expt_comp.JPG
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.  

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

salps.JPG
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.

sun_comp.JPG
A lovely sunset
Editor's note: sunset pic inserted to counterbalance the poop.


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

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