Cara Nelson: Methot Madness, September 14, 2019

NOAA Teacher at Sea

Cara Nelson

Aboard USFWS R/V Tiglax

September 11-25, 2019

Mission: Northern Gulf of Alaska Long-Term Ecological Research project

Geographic Area of Cruise: Northern Gulf of Alaska – currently sampling in Prince William Sound

Date: September 14, 2019

Weather Data from the Bridge:

Time: 16:10
Latitude: 59º19.670’
Longitude: 146º07.196’
Wind: East 5 knots
Air Temperature: 14.5ºC (58ºF)
Air Pressure: 1010 millibars
Clear skies

Science and Technology Log

A Methot net is not your typical plankton net.  This large net hooks to a stainless-steel frame and has a mesh size of 3mm.  Its purpose: large jellyfish collection!  The Methot is unique not only for its size but also in its method of deployment.  The net must be craned off the starboard (right side) of the ship and submerged just under the water.  It is then towed for 20 minutes at the surface. Similar to the smaller plankton nets, there is a “cod-end” bucket that helps collect the jellies as the water filters out of the net. 

The setup of the Methot is tricky.  The frame that we are using was fabricated locally for these nets so there isn’t a manual for setup and a lot if trial and error is involved in the setup process.  This entails a lot of wrenching on shackles to connect the net to the frame, trying out a setup and then trying again once it is in place and we can watch the positioning and motion of the net in the water.  Fortunately, we have an amazingly positive team so we were able to meet each challenge and come up with a solution.  Our fourth time in resetting the net seems to be the charm.

Heidi Islas is our onboard jellyfish guru.  I have never met anyone who loves jellyfish more than Heidi, and this passion and enthusiasm translates directly toward her commitment to her research.  She is currently working on her master’s degree at UAF with Russ Hopcroft as her advisor.  Her specific research thesis is, “the abundance and distribution of gelatinous zooplankton in the Northern Gulf of Alaska (NGA).”  Currently there is no baseline data on the type and biomass of the large jellies in the NGA so Heidi’s work is so important in helping identify not only what is present but how these jellies may be playing a role in this ecosystem particularly as predators on small fish. 

Our typical sampling includes running either a Bongo net or Multinet off the stern (back) of the boat to collect zooplankton, and then immediately following we lower the Methot net for its 20-minute tow.  One of the deckhands, either Dave or Jen, run the crane for us, while the four of us help move and position the net into and out of the water.  At the end of the tow, we hose down the net and then open the cod-end to see what we have collected.  Our first few tows had only a few jellies but a little more variety.  Last night however, as we moved into deeper water south of Middleton island, we had a large number of jellies to process.  We assist Heidi in measuring the diameter of bells of the jellies, as well as collecting volume and mass measurements.  We then preserve any zooplankton and fish we collect for analysis by fisheries scientists back in the lab. 

Many people might ask, why should we care about the jellyfish?  It all comes back to the food web connectivity.  For example, it is known that jellies will feed on smaller zooplankton, such as copepods and euphausiids (krill), but also on fish larvae, such as pollock.  The commercial pollock fishery is very interested in identifying any factor that may impact the adult pollock numbers.  Additionally, very little is known about what else the jellies are eating, or in what quantity.  So many questions arise about how these jellies might be impacted food availability for other species as well as serving as a food source themselves. 

Another very interesting piece of research for Heidi apart from her thesis focus is how are jellies responding to climate change.  A current hypothesis was that jellies increase in number during warming events, suggesting that they may become more abundant as our climate changes with even greater impact other species.  In her research on this topic, Heidi came across a paper published in 2013 that challenges this hypothesis.  It demonstrated that jellyfish actually follow a natural cycle of growth and decline with a peak in abundance every 19 years.  Heidi decided to analyze data that NOAA Fisheries had collected over a 38-year period from bottom trawls in the NGA.  She too saw the same cycle emerge.  Although this is exciting data, it leads to many more questions for her to explore. Such as what is driving this cyclic pattern?

In both the scientific and non-scientific world it is easy to see a correlation of cause and effect and jump to a conclusion.  What I am realizing from the research going on aboard R/V Tiglax is that numerous variables must be considered before true causes can be determined from the data.  This is why collaboration in research is so important.   Physical, chemical and biological oceanographers along with fisheries biologists must work together to gain more holistic view of this NGA ecosystem to help unravel its secrets. 

Personal Log

Fortitude is my word for the past few days.  I have learned so much on this trip so far, including two important pieces of information about myself.  One is that my body does not like to work nights.  The days are blurring together for me as I adjust to my shift work.  I can say that it is definitely not an easy transition because the transition requires more than just adjusting sleep times, but also eating patterns as well.  On Friday night, due to the nature of our stations, we were not able to start our shift work until 1am.  By 5:30 in the morning as we began our last sample, I literally fell asleep on the rales of the ship waiting for our Bongo net to surface.  I think in another day or two, I will have it figured out.

A second piece of information I learned about myself, I am allergic to the scopolamine patch!  Early on Friday, I realized I was developing a rash, which soon spread.  The itching was becoming a problem and so I immediately discontinued an antibiotic I was taking thinking it was the culprit.  After the rash worsened, I then realized it was likely the patch.  After speaking with Captain John, he confirmed that this is a nasty side effect for some people.  I removed the patch Saturday and transitioned back to my usual medicine for motion sickness prevention: Bonine. Unfortunately, 24 hours later, the rash and itching persists.  Russ and John joke that they will be taping my fingers soon, so I better behave. 

After the first storm passed we were lucky enough to have several days of beautiful and surprisingly warm weather as we started along the Middleton line.  I was able to spend time on the fly bridge with Dan birding and mammal monitoring.  I will definitely highlight more on this in a later blog.  From Friday to Saturday I was fortunate enough to watch both amazing sunsets and sunrises as well as enjoy the beauty of the full moon. 

Another storm is forecast to be upon us by late Sunday evening, so our plan is to finish the Middleton line tonight and be in transit to GAK1 (just outside of Resurrection Bay) overnight.  Currently it is calling for East 40 knot winds and 11-13 foot seas.  It should be a fun ride.

Did You Know?

The jellies we are sampling all started out in the benthic (bottom) habitat in what is known as a polyp stage of their life cycle.  These polyps are attached to the bottom and will asexually bud off into the water column.  At this point, the jellies are only approximately a half of a centimeter in size.  It is estimated that it takes approximately a year for the jellies to grow to the full adult medusa stage.  The medusa is the bell-shaped, free floating stage that everyone recognizes as a jellyfish.  This amount of growth requires a lot of energy input, and thus these jellies must feed continuously to reach the adult sizes.  It is not known for sure, but it is estimated that the jellies will spend approximately a year in this phase in which they sexually reproduce.  The larva will then settle back to the benthic environment and start the cycle all over again.