Ragupathy Kannan: Salps to Shearwaters, August 22, 2019


NOAA Teacher at Sea

Ragupathy Kannan

Aboard NOAA Ship Gordon Gunter

August 15-30, 2019


Mission: Summer Ecosystem Monitoring

Geographic Area of Cruise: Northeast Atlantic Ocean

Date: August 22, 2019

Weather Data from the Bridge

Latitude: 40.74767
Longitude: -70.41857
Water temperature: 25.3°C
Wind Speed: 7.18 knots
Wind Direction: 229 degrees
Air temperature: 24°C
Atmospheric pressure: 1014 millibars
Sky: Cloudy

Science and Technology Log

Life aboard this research vessel is fast-paced and absorbing.  I feel like I am a child in a toy shop, eager to learn and blog about so many of the happenings around me!  I spend much of my time high above in the flying bridge (above the bridge) with a panoramic 360 degree view of the horizon, documenting seabirds and mammals with colleagues—more on this later.  We suspend our surveying when the ship reaches a sampling station.  We have about 150 random sampling stations out in the ocean, ranging from close to coast (depth about 15 m) to right at the edge of the continental shelf (up to 500 m so far).  Cruising about 9 knots (about 10 mph), the ship zigzags along a predetermined track, stopping anywhere between 15-30 minutes at each sampling station. 

sampling station map
A map of our sampling stations. The black circles indicate plankton sampling sites; Dots show oceanographic stations where conductivity and temperature measurements are taken along with water samples for carbonate chemistry and nutrient analyses

At each station, an array of measurements are taken or specimens sampled.   

In my previous blog, I described a state-of-the-art device called the Imaging FlowCytoBot (IFCB).  But plankton are also sampled using more traditional methods.  We deploy Bongo Nets for plankton sampling.  Can you guess why they are called Bongos?  See the photo below. 

bongo nets
Bongo nets being pulled out after sampling. The chief bosun and student volunteers are on watch.

Note that there is a pair of bigger bongos and a pair of “baby” bongos.  These nets are lowered by a j-frame (arm that can be extended off the side of the ship) and winch, at various depths into the water and towed for particular distances through the water.  The time spent inside the water (5 minutes minimum) and the depth traversed (up to 200 meters) varies with station depth, but there is a Flowmeter at the mouth of each net that counts volume of water sampled.  So all measurements are standardized by volume.  The mesh size is 333 microns (1 micron = 1 millionth of a meter; 1 meter = 3.3 feet), meaning anything over 333 microns will be trapped.  (To put that in perspective, most cells in your body are about 100 microns).

flowmeter
A flowmeter at the mouth of a bongo net–-note the spinning fins that activate the water volume counting device

When they are pulled out, research personnel swing into action.  Most of them are undergraduate volunteers from various universities eager to get their hands wet (literally and figuratively) doing marine science.  The bigger bongo nets are hosed to flush all organisms to the bottom.  Then the bottom is opened and contents flushed into a sieve.  These samples are then preserved in formalin for future examination in labs on the mainland. 

Jessica rinses bongo nets
Jessica, an undergraduate volunteer, spraying the bigger bongo nets to flush plankton to the bottom
David rinses baby bongos
David (another undergraduate volunteer) sprays the smaller bongos
TAS Kannan rinsing nets
I lend a helping hand spraying the nets
emptying bongo nets
Jessica opens the bottom of the net and empties contents into a sieve
net contents
Much of the contents are Salps: jelly-like planktonic tunicates
salps and larval hake
Closer look at Salps with a larval hake fish (probably a Red Hake) near the center. More on hakes below.
Facts about Salps
The abundant salps are a vital component of the ecosystem. Source: archives.nereusprogram.org
crustacean
We even caught this beautiful planktonic crustacean (amphipod or isopod). It’s related to our rolly-pollies.
arrow worms
We also get some tiny arrow worms in our plankton samples. These torpedo-shaped worms belong to a phylum of predatory marine worms called Chaetognatha (“bristle jaws”). Photo courtesy Zatelmar
plankton jars
Plankton from the bigger bongos are preserved in 5% formalin for future analyses in mainland labs.

What happens to the contents of the pair of smaller bongos?  Our Chief Scientist Harvey Walsh freezes the sample from one of them into small ziplock bags for a Florida lab which will conduct Stable Isotope Analyses.  The other one’s contents are preserved in ethanol for genetic testing (Ethanol is far easier on DNA than formalin) to determine such aspects as taxonomy and phylogenetic (evolutionary) relationships and use in larval fish age and growth studies.

sample bag
Chief Scientist Harvey Walsh bags a sample for freezing
labels
All specimens are carefully labeled and catalogued

So what are Stable Isotope Analyses?  If you are a beginning college student, you may be unaware of this sophisticated and widely-used technique.  (My ecology students should be well aware of this!).  Basically, the ratio of isotopes of a chemical element in a given sample is used to yield insights into aspects such as food preferences of the organism or to reconstruct its past environmental conditions.  It can also be used to determine where the plankton originated and thus get insights into ocean circulation.  The analyses are done with a device called mass spectrometer. 


Career Corner

I spoke with our Chief Scientist Harvey Walsh about his career, research, and his advice for students.

Q. Harvey, tell us how a man from land-locked Minnesota ended up as a top marine biologist.

A. When I graduated from college I looked for a job with the Minnesota Department of Natural Resources, but they were very competitive. So I applied for several NOAA positions from North Carolina down to the gulf coast. I got a job offer in NC.  This was after my B.S. in Aquatic Biology from St. Cloud State University.

Q. You did an M.S. while working with NOAA?

A. Yes, I went back to school part-time and got my Masters. I then went to Woods Hole Oceanographic Institute [WHOI]

Q. From WHOI you came back to NOAA?

A. Yes.

Q. Has ocean acidity changed since NOAA started EcoMon?

A. It is hard to say because of seasonal variability.  We need more long-term data.

Q. Is ocean acidity world-wide increasing?

A. That’s what I see in the scientific literature.

Q. How about temperature?

A. Yes, the Northeast has seen an increase in water temperatures, especially in the Gulf of Maine, where it has increased about 0.9°C in about 4 decades.

Q. Has EcoMon helped document declines in sharks or whales?

A. Again, we need long-term data for that.

Q. Can you name one recommendation from EcoMon that has benefited sea life?

A. We get larval fish data.  Recently we started calculating Atlantic Mackerel Egg Index in collaboration with Division of Fisheries and Ocean Canada and the data indicated that there is a decline in the adult population.  This aided in the determination to lower catch limits for that species.

Q. Has the politics of climate change influenced your work?

A. No.  I have not had anyone try to change my research or findings in any way.  We have within NOAA good scientific integrity rules. We feel we have the ability to publish sound science research without any interference.

Q. You are highly published.  One of your papers on larval fish otoliths was with my former student Michael Berumen.  How are larval otoliths helpful in research?

A. One of the projects we have is trying to use larval hakes to examine stock structure (fish stock is a group of fish of the same species that live in the same geographic area and mix enough to breed with each other when mature) and estimate spawning stock biomass (the amount of mature fish).  We have interns in the lab who remove otoliths and get daily growth increments. That allows us to estimate age of the larva and spawning seasonality. 

Q. Can you tell based on this where they hatched?

A. That’s where we are headed.  Once we get information on when they were born and where they were collected, we hope to use oceanographic conditions to see if we can back-calculate where they may have come from and thus plot spawning locations to aid in stock structure analysis.

Q. One of the findings of past warming episodes is shrinking of foraminiferans and other small shelled organisms.  Is NOAA monitoring size of plankton?

A. We are.  That’s one of the projects we have just started: estimating size of Calanus finmarchicus, or Cal fin [see photo below].  This is a copepod crustacean and an important food for the endangered Right Whales. We have a 40-yr time series and have seen evidence of declining size of late-stage and adult Cal fin. We are trying to see if this has resulted in a decline in their energetic value.  They are a lipid-rich zooplankton.  If their size is related to their lipid storage they may be less nutritious for their predators.

Q. One of your papers indicated that about a third of fish and plankton species assessed in the northeast are vulnerable to climate change.  Is that trend continuing?

A.  Yes, as we monitor we continue to see shifts in fisheries, plankton, seabirds, and mammals.

Q.  What is your advice to early college undergraduates interested in marine science? 

A. Be flexible.  When I first started I thought I’d stay in Minnesota and work on adult fish stocks. I ended up working on larval fish and zooplankton.  Not focusing on one skill set and being able to adapt and look at various aspects will help you in the long run.

At the end of the interview, Harvey gave me this card and encouraged students to contact him for volunteer opportunities with NOAA. 

information card
Information Card from NOAA’s Oceans and Climate Branch
Calfin
Calanus finmarchicus, a subject of Harvey Walsh’s research. From: https://www.st.nmfs.noaa.gov/nauplius/media/copepedia
food web slide
Harvey also kindly shared this slide explaining the locations of Calfin, Baleen Whales, and even you, in the food web. The highly endangered North Atlantic Right Whale feeds on plankton like calfins by filtering them through a sieve (baleen) in their mouths (slide: courtesy Harvey Walsh)


Personal Log

One of the best aspects of this voyage is the daily spectacular views of sunrises and sunsets.  I spend a lot of time high up on the fly bridge assisting in sea bird, sea mammal, and sea turtle surveys.  It’s also a treat to look around 360 degrees and see nothing but the horizon, nothing man-made except this big old ship gently bobbing up and down in the center, leaving a wide frothy wake behind.  Yet, in the vastness of the ocean, we are but a mere speck. It really is humbling to experience this vista.

The ship crew are very serious about safety.  We have periodic Fire and Emergency, Abandon Ship, and Man Overboard drills.  A billet posted on my door advises where to report in each of these scenarios.  We have “muster” points, meaning, where to meet, for each.  I was trained to get into my Anti Exposure Suit in less than two minutes.  That was easier said than done!

Kannan in survival suit
Here I am in my Anti Exposure Suit. I felt like an astronaut in it

The food continues to be sumptuous and delicious, cooked by two expert stewards Margaret and Bronley.  Never did I dream I will enjoy eggplant curry and coconut jasmine rice on a NOAA Ship far out into the sea.

Dinner menu
Dinner menu posted in the mess
stewards Margaret and Bronley
Margaret and Bronley are the two great cooks on board. Margaret makes her own Garam Masala, putting her unique fingerprint into her curry dishes (and delighting my Indian-American tongue)!
gym
I even get my daily work out in the ship’s small but well-appointed gym


Did You Know?

Hakes (see photo above) are lean whitefish belonging to the Cod family.  They are known as Gadoids (Order Gadiformes) and are grouped with cods, haddocks, whiting, and pollocks.  They are much sought-after for their delicate texture and mild flavor.  We get some hake larvae in our plankton tows.  Hake larvae are used by scientists for all kinds of studies.  For example, their otoliths (tiny ear bones) can enable identification of species and even help determine where they were hatched (by Stable Isotope Analysis—see above).  This information, combined with data on ocean currents and circulation, can help determine hotspots for hake reproduction to enable conservation and sustainable fisheries. 

Interesting animals seen lately

Fish:

Hammerhead Shark

Whale Shark

Tuna sp.

Mammals:

Pilot Whales

Minke Whales

Common Dolphins

Bottle-nosed Dolphins

Spotted Dolphins (riding the bow!)

Sea Birds:

Great Shearwater

Manx Shearwater

Cory’s Shearwater

Sooty Shearwater

Audubon’s Shearwater

Wilson’s Storm-petrel

Band-rumped Storm-petrel

Leach’s Storm-petrel

Black-capped Petrel

Red-necked Phalarope

Northern Gannet

In addition, several land birds on their south-bound autumn migration rested briefly on the ship.  I was not expecting to see Prairie Warblers, Red-winged Blackbirds, and Brown-headed Cowbirds on a pelagic (=ocean) cruise!

2 responses to “Ragupathy Kannan: Salps to Shearwaters, August 22, 2019

  1. Microns are cool I know – but many of us are old school with some gray hair, so a translation at the end to inches would be appreciated and save me some extra work

    thanks

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