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Megan Ehlers

Megan Ehlers

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We finished up the last few sampling sites yesterday.  Kendall and I can’t thank the group from Texas A&M and the Blazing Seven crew enough for making the cruise so enjoyable.  I’ll miss my time on the boat, but I’m excited to return to my position at Sarasota High School and share my experience with my students!  


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Though it may take longer to sort through a sample inundated with sargassum, we’ve been seeing some really unique organisms.  Pictured below is a sargassum fish, an ambush predator, that has the perfect camouflage. 



We’ve also been collecting filefish, crustaceans, and jellyfish that are taken out of the samples by Carlos Ruiz and Veronica Quesnell.  


Right after they help pull up the nets they search each sample for organisms to take back with them to the Texas A&M Galveston Shark Biology and Fisheries Lab run by David Wells, PhD.  


Carlos came back to his alma mater of TAMU after finishing a M.S. from Auburn University.  A research technician, he has an integral part in the lab and assisting graduate students on their projects.  The position allows him to take part in a wide variety of research and to be out in the field frequently, which he enjoys.  It would be a great opportunity after graduation for any student with an affinity for research .  




Veronica usually isn’t out on the field, and instead gets samples for her research on swordfish from NOAA and commercial fisheries.  Along with other courses she’ll be teaching fisheries techniques in a field ichthyology course.  In addition to being a researcher, student, and teacher, Veronica is the mother to a beautiful girl named Abby.  



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We’ve had some exciting visitors in the past 24 hours.  Last night we saw two pygmy whales, and a sperm whale and this morning a pod of dolphins.


Onto the fish!  Picture the excitement of pulling up a Mahi mahi, the same thing happens here, but instead of holding up the fish with two hands these guys fit on a finger. 



This tuna is distinguishable by the dark mark on its dorsal fin.  When the fish is too small determine the species by sight scientists rely on DNA analyses. 



The fishes below didn’t need DNA identification.  The sailfish on the left, and swordfish on the right are starting to display characteristics of the adult fishes.  



Each sliver of silver below is a fish to be sorted and collected. 



Scattered in the samples are these copepods.  Familiiar shape, but a striking color!



I’ve previously written about the large amount of sargassum in the water around us.  As Jay Rooker, PhD predicted before we towed, when we were in clear water with a high salinity we started to see the billfish. On the left is clear blue water where we found mahi, tuna, and billfish.  On the right the water in this picture is heavily influenced by the freshwater input of the Mississippi river which gives it a greenish hue.  The salinity in this area has dropped down to 21 ppt even though we’re still quite a ways offshore (remember you can see where we are here). 




Water from rivers brings with it nutrients creating prime environment for algae.  We’ll be in this “green water” for the rest of the trip.   

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Yesterday was another beautiful day on the Blazing Seven.  We’re still running across a significant amount of sargassum while using the neuston net.  Our captain, Thomas Tunstall, tries to avoid the floating masses during the tows. 


Deploying her own plankton net at every other site is Jillian Gilmartin.  She came to Texas A&M (TAMU) from NC State with degrees in Meteorology and Marine Science.  She just brought up a sample with lots of jellyfish.  She explains that this area, the middle of the loop current, is warmer and has low biological productivity.  Jillian is collecting the plankton samples for her thesis.  Her research focuses on tropical species found in the Gulf of Mexico that arrive there via the loop current off of the Yucatan. 


When I asked what I should tell my students who are interested in pursuing a career in Marine Science she suggested getting involved during your undergraduate degree by interning or working in a lab. The work she did outside of her major is actually what led to her current research with Dr. Rooker.   


Cori Meinert is a brand new graduate student at TAMU.  She is an Environmental Science major from Ohio that worked in a freshwater lab last summer.  She came across an article by Dr. Rooker during her studies, emailed him, and then made the decision to start her Masters degree at TAMU.  She had just arrived in Texas and then traveled the very next day to the ship for this research cruise.  What a way to dive into your graduate degree!  In the picture below Cori is recording the pH, salinity, and other characteristics of the surface water at each site. 


Near the end of the day the sargassum started to clear.  This time the neuston net sample contained the billfish that we had not seen in the previous tows.

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One of the goals of this cruise is the research done by Jay Rooker, PhD and his lab on pelagic fishes, such as billfish and tuna.  This ties in the data being collected by DEEPEND with information from the epipelagic zone.  When I picture a billfish what usually comes to mind is the adult stage that recreational fisherman target for sport.  It’s easy to forget that they all start out as zooplankton, and we’ve been finding a few in each of the tows. The image below depicts a sailfish on the top and a blue marlin on the bottom. 


Attached to each of the plankton nets is a flowmeter, which looks similar to a rocket.  


It measures the volume of water flowing through the net.  This allows researchers to calculate the number of fish and other organisms collected per unit volume of water and make estimations about a larger area. 


Since the neuston net is towed at the surface, it frequently contains large amounts of sargassum.  Dr. Rooker explained that areas with high amounts of sargassum usually yield low amounts of these epipelagic fish. We saw evidence of this during our last tow. 

This floating macroalgae is carefully searched for specimens by the group and then weighed.  It’s been very impressive to see the sharp eyes of those around me pick out fish from a heap of sargassum no more than 1 mm long. 


The tiny dot below is on the finger of Maelle Cornic, a PhD student.  Maelle looks at early life stages of tuna in the Gulf of Mexico.  She’s got some of the sharpest eyes on the ship and is consistently finding the smallest critters hiding in the sargassum.  Maelle is from France, where she says being around water sparked her interest in fish from an early age. 


Another PhD student in Dr. Rooker's lab is Mike Dance, an avid fisherman.  Part of his research uses acoustic telemetry, a tracking technology using tags, to monitor the behavior of juvenile red drum in Texas estuaries.  In addition to finding out where the fish are spending their time, Mike determines the type of habitat (oyster bed, seagrass, etc.).  Mike focuses on red drum ages 2-18 months.  Models based on the data collected will shed new insight into the nursery habitats of the fish.


Our last plankton tow of the night once again yielded a diverse group of organisms.  Among those collected was a viperfish, Chauliodus sloani.  Kendall is busy counting the photophores using a stereoscope that projects onto the computer.  This allows pictures and video to be collected of organisms before they're preserved to help with identification later on.  


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When I left last we one more site to sample from, which was done at night with the help of flood lights on the deck.  Once again the bongo and neuston nets were deployed.  This last stop of the night stood out from the others since we deployed a bongo net this time reaching a depth of 500 meters.   This sample was taken in the middle of the mesopelagic zone which spans vertically from 200 to 1000 meters.  This zone is sometimes referred to as the “twilight zone”, because some light still penetrates. Fellow Floridian, Kendall Lord, has been a big help identifying the deeper living fish. He is graduate student and research assistant at Nova Southeastern University. He works with Dr. Tracey Sutton, his advisor and the DEEPEND Consortium Director. Kendall is working on his Masters degree in Marine Science. His thesis will cover the history of research in the bathypelagic zone (> 1000 meters below the surface).  He’s using research starting with the 1870’s with reports from the HMS Challenger all the way up to the Census of Marine Life from 2000-2010. 










One of the first organisms pulled out was a purple jellyfish that Kendall informed me was a Periphylla  periphylla, the helmet jellyfish.



We also found a bristlemouth fish (Cyclothone sp.), the most abundant vertebrate on Earth! Some of these little guys are serial hermaphrodites, specifically protandrous, meaning they are males first and then turn into females. Clownfish change their sex in the same way.


Many of the zooplankton collected were either clear, red, or black. This is part of their camouflage to help them hide from predators. The red shrimp pictured below stands out amongst the other organisms on deck, seemingly a contradiction. The reason some organisms in the deep are red in color is because it doesn’t penetrate as deeply as the other colors.  Those bright red shrimp actually appear black in the mesopelagic zone where we are sampling. The clear organism that you can see only part of in the picture above is a larval eel, or leptocephali. 



Perhaps the most exciting organism collected was a heteropod.  In hand it appeared to be a gelatinous blob.  When placed into a small tank for observation we were able to observe the mollusk’s unique swimming behavior that earns it the nickname “sea butterfly”.  You can see video here.  This unique gastropod is quite the predator! We later witnessed it feeding on the eel larvae which was easily 10 times its size.


After collecting the samples we went into one of the labs to take pictures and sort the organisms into Whirl-Paks.  The fish in the picture below is a hatchetfish.



We began again this morning around 6:30 am.  The weather is fully cooperating and the plan is to get through 12 sampling sites today.


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Greetings from the R/V Blazing Seven! I'm your current teacher at sea from Sarasota, FL.  I'm very excited to be joining scientists and students from Texas A&M Galveston and Nova Southeastern University to sample the larvae and juveniles of pelagic fishes using plankton nets.  You can read more about the research done by Jay Rooker, PhD here. 

We left Port Fourchon, LA early this morning and just made it to our first sampling site to collect plankton.  Plankton are tiny (usually) plants or animals that drift with the currents.  The focus of this cruise is animal plankton, referred to as zooplankton. The basic design of a plankton net is a large area of mesh that ends in a collection bucket. The two nets we will be using during this cruise will sample at different depths and have different mesh sizes. 

The first net, rightfully named a bongo net, is deployed from the stern. The reason it has two nets is that one net has a mesh size of 333 microns and the other has a mesh size of 500 microns allowing us to sample two different sizes of zooplankton. The bongo net is hoisted off the back of the boat using a winch.  After entering the water it sinks down to a depth of 100 meters (328 feet)! When the nets are brought back up to the surface they are carefully rinsed with seawater to ensure that all of the organisms make it into the collection buckets at the bottom.


The second, a neuston net, is deployed from the side of the ship and samples at the water's surface. 


Each sample from the plankton nets contain algae and a wide variety of of organisms from copepods to larval tuna. The samples are placed in a freezer for identification at a later date. We collected a larval tuna and a sargassum fish! 


In addition to targeting larval and juvenile pelagic fishes, we are collecting samples for other labs involved with the DEEPEND Consortium for their research as well. I’ll get into that more later.  Our next stop is coming up soon! 




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