In summer 2021 a team of Explorers Club members will venture to Roatan Honduras to explore the ocean off the northern coast and the wildlife that resides in the deep. The expedition maintains three goals:
- Develop operational procedures of tagging sharks at depth for future research opportunities.
- Provide Hexanchus griseus (six gill shark) tracking data for Dr. Dean Grubbs of Florida State University to support his paper on six gill migratory patterns.
- Tag three, six gills with timed tracker releases at 6 months, 9 months and 12 months to better understand long term migration movements.
In 2019 an expedition was mounted by Dr. Grubbs and shared in a great article in National Geographic by Haley Cohen Gilliland.
Gilliland writes, ” Believed to be descendants of sharks that inhabited Earth’s waters even before pterodactyls and T. rexes roamed its lands, bluntnose sixgills spend most of their time at profound depths, sometimes swimming to 4,500 feet below the ocean’s surface.
This predilection for deep water makes bluntnose sixgills a difficult bunch to study. When asked what remains mysterious about them, Simon Thorrold, a senior scientist at the Woods Hole Oceanographic Institution laughs, explaining: “It will be way quicker to go over what we do know. And that is almost nothing.”
The International Union for Conservation of Nature’s Red List of Threatened Species classifies bluntnose sixgills as “near threatened,” but there is not enough data to estimate their population or discern whether it is increasing or dwindling. Females tend to be larger than males—measuring up to 18 feet at maturity—and give birth to 40 to 110 pups at a time, but we don’t know where they breed or how long they gestate. While bluntnose sixgills appear to be rather cosmopolitan, having been spotted near the coasts of every continent but Antarctica, it is unclear whether they’re highly migratory or merely spread out. (Original article found here.)
Though the tracking expedition aboard the Ocean X vessel was successful in tagging the six gills, it has been confirmed by Dr. Dean Grubbs that the one successfully placed tag at depth didn’t end up transmitting. Thus the data was lost.
The Science
From our initial conversations with Dr. Grubbs, he shared that six gill sharks are able to withstand being pulled from depth to the surface. He has tagged a multitude of sharks using this method. However once the sharks are released, during the first 48 hours their daily depth migrations reflect some sort of “freak out” period. You can visualize this assumed recovery period in the charts below. Notice from the left side of Figure 1 the six gill would migrate daily below the surface from 200m to 400m then 250 to 400, 250 to 450, before returning to a deeper more stable pattern.
By tagging these animals at their native depths we hope to better understand if the sharks still maintain some sort of “freak out” period when they are not brought to the surface. Figure 2 supplied by Dr. Grubbs shows the a similar pattern taken from different expeditions from 2006 to 2011.
The Expedition
Each team member will rotate through the deep sea submersible Idabel to depths between 500 to 2000ft in order to support not only the six gill research but also record data for a deep sea marine and micro-plastics survey.
In July of 2013, the R/V Falkor mapped much of Roatán’s coastline using Kongsberg EM302 and EM710 multibeam echosounders. These data were processed in CARIS HIPS/SIPS to generate 10 meter resolution bathymetry and QPS-Fledermaus to generate backscatter for habitat characterization. Once processed, the surfaces were imported into ArcGIS to examine several key habitat features, including slope and substrate character.
The team will dive about one to two miles off the coast and use these maps to determine and track their dive sites and data collection points.
The Outcome
The Next Generation of Ocean Leaders Use Submarines to Explore the Deep.
“We compiled this expedition with large goals”, expedition leader Trent Tresch says. “Using lasers and a custom sampling device we collected data on ocean microplastics from 100 ft to 2000 ft underwater.”
Micro plastics are plaguing our planet. By studying deep sea water samples, we can uncover if and how these particulates are impacting benthic environments. Similarly, by scanning the water column with special lasers we will try to identify plastics by using glossy polymer reflection.
Working in conjunction with Dr. Dean Grubs, Phd. at Florida State University’s Coastal and Marine Laboratory, the team of Explorers Club members tagged sixgill sharks from the submersible.
“We know very little about the deep ocean and thus very little about six gill sharks that reside there. By tracking these sharks we will be able to understand their migration patterns if they have any. By understanding animal migration patterns we can potentially locate their breeding grounds and support legislation to protect these areas.”
“To be the first to accomplish anything is very special, especially this day in age. We are in a time when it’s easy to think there is nothing left to explore. This successful tag deployment and recovery shows how much left there is to understand about our world. The future of science and exploration belongs to the curious.” -David DeBerard
We were able to accomplish 1) Initial creation of a new cost effective way to collect deep sea water samples from submarines or drop lines 2) Tag and successfully recover some of the only data ever on deep sea sharks by submarine 3) Enable a local plastics scientist 4) Share our work with students from around the world.
With the help of Zara Zuniga at the Bay Islands Conservation Associate we were able to unfortunately detect small amounts of plastics in our water samples. At this point there isn’t a definitive way to fully prove our collection device was active solely at the depths prescribed (1300ft – 2000ft) but with the work we completed we have laid the foundation to further develop the technology and gain better data on future expeditions.
As mentioned, we were also able to deploy two of the five animal tracking tags. One tag, as per our lead scientist’s recommendation, was set to 30 days recovery. Meaning from the date of deployment it would detach from the shark and surface 30 days later. The other was set for 360 days.
From our initial dive location off the North coast where the sharks were tagged, our first transmissions were about 7-8 nautical miles away on the south coast. You can see the pings to the Argos satellites in the map below. The furthest east green dot was where the tag first popped up. The cluster of red/yellow/green on the coast and in the bay are less accurate transmissions but leads us to believe the unit is located in that bay. Karl went on a recovery mission to try and retrieve the unit but so far we haven’t had any luck. In his words, everything that washes into the bay enters a very complex area of rocks and mangroves without a defined shoreline. Nearly impossible to find the tracking unit. We may be able to get our hands on a radio receiver that can catch the 401 mhz pings which would make it easier to find but right now we are looking visually.
Nevertheless we were still able to obtain depth data on the sharks which is what our scientist Dean was interested in. If any of you recall, to better understand these animals scientists would pull them up to the surface to place a tracking unit. This caused the animals to have a 48 hour “freak out” period when they were reaclimatizing to their normal depths. You can visualize this in the above charts shared by Dean.
48 hour “freak out period” / recovery chart before returning to normal daily migration patterns.
I have attached the depth tracking data for you to take a look at if you’re interested. But in short it seems that the animal had a minimum depth close to 255m and a maximum depth of 1114m. As more data comes in we will be able to graph the measurements and add to the 10 years of data Dean has collected. The only difference is that ours will be the only data that was initiated from a submarine!
In other news, our very own Dr. Payne believes he may have witnessed a new species of comb jelly. Alec shares, “I have a video of what could be a new species of comb jelly that James and I saw from the sub. These types of jellies are often identified by just video (no holotype or actual collected specimen). My video is not high quality, but I’ll ask some experts and see what they say.
With comb jellies, it’s actually possible to identify the exact species using just morphological characteristics. I’m interested in comb jellies because they’re really unique, and they form an entire phylum, Ctenophora, containing only about 150 recognized species. For comparison, the phylum Cnidaria (which includes true jellyfish) has 9,000 species, so identifying exact species there is really hard. Most described ctenophores are from shallow waters, but they’re also abundant at depth. Ctenophores look a lot like true jellyfish, but they’re not closely related. Ctenophores are characterized by “comb rows” of cilia which they beat to move around (you can see these in my video–the comb rows have flashes of color coming off them, which is common for the phylum). Ctenophores also have between 0 and 2 tentacles with no stinging cells. If you think you have videos or pictures (especially anything high quality) of a ctenophore, please send it to me! If you have any other jelly pics, especially siphonophores, I’d like to see those too.
As for my video, I’ve gone through all the literature and taxonomic keys I could find on Ctenophora, and I know this particular jelly has to be a cydippid (order Cydippida), but I can’t even find a possible family it could be in. I’ve checked every possible genus, and nothing matches. The closest would be the genus Euplokamis, but it doesn’t seem to have the right tentilla structure (side branching of tentacles) or spacing among tentillae to fit into this genus. I’ll have to ask an expert about this.
The interesting thing about the type of jelly in my video is that their mouth is actually on the side opposite from the tentacles, unlike true jellyfish. So, they catch prey with their sticky tentacles, and then they have to flip around to put it in their mouths. It looks like there is a bright yellow piece of tentacle in its stomach (stomodaeum). I wonder if somehow a piece of its tentacles came off in its stomach while doing this flip maneuver while feeding. This jelly also has asymmetrical tentacles, but this could be innate as they do sometimes naturally have asymmetrical tentacles.”
“The unique combination of deep sea submarine exploration, microplastic research, lasers, shark tagging and coral conservation just proved to be too compelling of an opportunity to miss and early steps were taken to produce a documentary. Between the talented cast of scientists/explorers and a stunning underwater wonderland, it was hard to find a frame which didn’t just jump out at you during filming! The mysteries of our oceans are just fascinating and I’m certain a wide audience will appreciate watching this dynamic story of discovery. The project is currently undergoing post production in Los Angeles, CA. Please like the Submarine Trip Facebook Page to learn more and look out for updates about the film as we move into the next phase.” Gregory Taylor MN’19
The Explorers carried the Club Flag #211. Flags have been carried by Members on a myriad of other firsts including the first expedition to the summit of Mt. Everest, the bottom of the Mariana Trench, the North and South Pole, and the surface of the moon.
We would like to thank the Explorers Club, Sustainable Oceans Alliance , and Karl Stanley for their support of this expedition. Without our community’s help this project wouldn’t be possible.
Expedition members list: Alec Payne SM’19, Alec Shumate MN’18, Breezy Grenier MN’17, Collin Bettis MN’20, Cassia Patel, Chase Cornell, David DeBerard MN’18, David Busch, Devin Gilmartin, Elon Gordon MN’20, Francesca Cohn SM’19, Fabrice Lays, Gregory Taylor MN’19, Genevieve Carlson, Greg Naing, Heather Philpot, Jeff Orlowski, James Carew, Karl Stanley, Kai Staats, Marshall Hayes, Philip Busch, Stephen Daire MN’18, Tyson Anderson FOTC