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.   

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.  

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.

Blog posted for Jeff Plumlee:

Howdy from the Blazing Seven!

Success! We have completed our mission, with all gear intact, and two days ahead of schedule. We finished 12 stations today towing both the neuston and bongo nets. Our day started at station 37 at 06:00 hours and finished at 21:00 at station 48. Sargassum mats were still very present throughout the day but diminished towards the end. The majority of the fishes we had found in previous trawls, however, a few fish expanded our list of families, such as porcupinefish (Diodontidae) and pipefish (Syngnathidae). We continued to find billfish and flying fish larvae when sorting through the Sargassum mats.

Another group of people, aside from the scientists, that needs recognition for our success is our crew. Warm meals, posh rooms, and a fully functioning vessel, all are attributable to the hard work of the crew of the Blazing Seven.

Thomas Tunstall - Captain
Stephan Tunstall
Brandin Busch
Eric Castagnetta

All of them played many different roles  throughout this trip, and all of them have put forth their best efforts to get us home safe and sound. Thanks again guys.

Well, this is my last update. We head home to Galveston, TX tomorrow morning with samples in hand. Stay tuned for our second ichthyoplankton cruise in July - we can only hope that it goes as smoothly. Cheers!

Jeff