gatesj3 – The Larval Lab

Digo’s Nautical Adventures

gatesj3 on February 10, 2024February 19, 2024

By Digo Zúñiga

Our collaborators, the Mullineaux lab group, conducted a HiPPO larval behavior experiment onboard. Released from COVID prison at the beginning of the cruise and no longer on COVID parole, Mullineaux Research Assistant Digo Zúñiga writes:

“No, we are not referring to the terrestrial mammal. Fun fact though (!): the closest living relative to deep sea diving whales isn’t the manatee or the seal, it’s actually the hippopotamus. For our purposes though, HiPPO stands for ‘High Pressure Plankton Observatory’. It’s a pressure chamber that allows us to observe larvae from the deep sea onboard the ship in pressures they naturally live in. Like COVID jail, it’s small and constrained, but unlike COVID jail it keeps deep sea larvae alive and happy long enough for us to record their behavior with a high-speed video camera. How the larvae swim in our HiPPO chamber tells us a little about how they can undergo long journeys to find different hydrothermal vent homes in a dark and vast ocean– currently a mystery to deep sea biologists. In other words, the HiPPO chamber is the closest us land creatures can get to watch deep sea baby animals in their natural habitat.

Digo and Dr. Lauren Mullineaux with the HiPPO. “The larvae go here.”

Copepods and polychaete explore the HiPPO chamber under pressure (3650 psi).

For those curious about what COVID quarantine is like on a research vessel, for me: it was not the worst thing imaginable. Luckily I got the booster vaccine a couple of weeks ago, and my case was pretty mild. The isolation was really the worst of it and each con had its corresponding pro. Though I got stuck in a windowless room for a week, I had it all to myself and didn’t have to share my bathroom with anyone (a rare premium on boats). I didn’t get to socialize with anyone during lunch, but I got room service for every delicious meal. And although I had to find what little energy my body could muster to get the occasional breath of fresh air, the view on the deck was a spectacular one– nothing beats that salty ocean breeze. I’m proud to say that the strict adherence to protocol was all worth it, and that nobody else got sick. I’d argue that the best way to experience COVID (other than to not get it at all), is in the middle of the Pacific with a great group of well-spirited, considerate fellow sea lovers.

Signed – Digo

EPR Biofilms4Larvae project is a multi-institutional NSF grant: OCE-1948580 (Arellano), OCE-1947735 (Mullineaux), OCE-1948623 (Vetriani).
Also find us on Instagram! @larvallab, #Biofilms4Larvae
The Inactive Sulfides project is a multi-institutional NSF grant: OCE-2152453 (Mullineaux & Beaulieu), OCE-2152422 (Sylvan & Achberger).
Also find us on Instagram! @jasonsylvan, #LifeAfterVents

You are connected to the seabed right now

gatesj3 on February 3, 2024February 6, 2024

By Rose Jones, WHOI

Most people, if they thing about the seafloor at all, think about it rather like another planet; a distant, hostile place full of strange creatures. The seabed can be these things, which is why we need a ship and vehicles like Alvin to get to them.

However, the seabed is increasingly seen as a vast source of untapped resources in our resource-hungry era. You are holding some of those resources right now, in the rare metals in your electronics and rechargeable batteries. You have a stake in the future of the seabed.

Image of Alvin working from a lander, Cruise AT42-21 (2019). Jason Sylvan, Chief Scientist, Texas A&M; Alvin Operations Group; National Science Foundation; @Woods Hole Oceanographic Institution

Humans have always had an economic relationship with the sea, from early humans hunting for food through to its use as trade highways and as a source of gas and oil. Whether this is a good thing or not depends on what side of the often-competitive nature of that particular use your personal history falls. Now, technology like ROV’s are putting the seabed within reach of more than just those of us lucky enough to study and participate in it.

Alvin recovery at sunset, AT50-20. Shawn Arellano, Chief Scientist, Western Washington University; Alvin Operations Group; National Science Foundation; @Woods Hole Oceanographic Institution. Photo by Rose Jones

A controversial new use is deep sea mining. Our need for rare metals like cobalt and lithium for your rechargeable batteries is outstripping Earth’s supply. Equally, the way these metals are mined on land can be controversial and cause pollution. Some industries are considering mining the vast, untapped ores on the seabed to avoid the issues associated with land mining. Currently manganese nodules (fields of potato sized lumps of ore formed in some seabed areas) are the primary focus but mining inactive hydrothermal vent deposits is under consideration too. East Pacific Rise won’t be one of the sites mined but other sites like it might be.

Inactive hydrothermal vent chimney sample, AT50-20. Photo by Rose Jones

There are many arguments for and against mining the seafloor, from the debatable renewability of seabed resources to speculation on the extent of pollution and disruption to potentially unique ecosystems, and risking causing the extinction of valuable sources of new bio-technologies. DNA technology and all the medical advances that rely on it being a prime example, as one of the keys to DNA extraction is an enzyme from a hydrothermal vent microbe.

The main problem though, is that much of what we’re basing arguments on is merely speculation. We have at least four thousand years of experience with how land mining can change and damage an ecosystem and humans. However, we have barely any of the data we would need to make informed, evidence-based decisions on how to mine seabed resources. Most sites are barely explored, yet alone understood. We can’t yet even say if mining the sea would create the same disruption it does on land. Although, the laws of chemistry and physics are universal, so there is a reasonable chance that some of the same impacts are very possible. More information on these sites and how they react to disturbance is greatly needed.

We need to understand these places better before we make the decision on whether to go ahead with mining or not. We’re risking destroying so much before we ever knew it was there.

A ship-based jacuzzi for deep-sea invertebrates

gatesj3 on January 25, 2024February 3, 2024

By Stephane Hourdez

All species on Earth are affected by the temperature they encounter in their environment. Ectotherms are especially sensitive to temperature variations as their internal temperature follows that of their environment. As a result, these species’ distribution correlates with latitude on land and in coastal marine environments (e.g. temperate species will not occur in polar or equatorial regions). In the deep-sea, temperatures are much more homogenous, cold, and should not significantly affect species distributions. Deep-sea hydrothermal vents, however, are a notable exception. There, the hot hydrothermal fluid (up to 400˚C) exits the seafloor in focused areas and mixes with the deep-sea, very cold (2-3˚C), water. Depending on the proportion of hydrothermal fluid mixed with the seawater, the whole range of temperature is possible. If some microorganisms can grow at up to 113˚C, metazoans cannot withstand temperatures much higher than 50˚C. Over very short distances, species can experience sharp temperature variations. Other conditions (pH, oxygen concentration) near hydrothermal vents can also be very challenging and affect species distribution. Our observations have shown that there are distinct species assemblages and that their thermal environment is different. What is the role of temperature in the distribution of these species? Are other conditions important as well or is temperature the only driver?

During this cruise, we carried out experiments on a diversity of invertebrate species to determine their tolerance to temperature. We are working with deep-sea species and most would not survive at atmospheric pressure. We therefore need to reproduce the pressure to which they are exposed in situ (250 times the atmospheric pressure at 2500 m). The animals are placed into a pressure vessel (photo) through which sea-water flows to minimize oxygen depletion. We start the experiments at the temperature of the surrounding deep-sea and raise it by 1 ˚C every 10 minutes. The top window allows us to observe the animals and determine when they can no long withstand the conditions. Some species will die at 10˚C while others can withstand at least 20˚C more. These tolerances reflect values for short term tolerances, long term tolerances are roughly 8˚C lower.

Figure legend: Scaleworms (annelids of the family Polynoidae) from the Tica vent site on the East Pacific Rise in a pressure vessel at 250 times the atmospheric pressure.

Overall, the tolerances we measured correlate well with the in situ measurements made near the assemblages where their usually live. Some species, however, have higher tolerances than expected. This could mean that we have not properly documented their natural environment or that other parameters affect these species’ distribution.

Stephane Hourdez is a marine biologist working as a researcher at CNRS (Centre National pour la Recherche Scientifique) in France. He works on the evolution of adaptations to hypoxia (low oxygen concentrations) and variable temperature.

Progress on our Polynoid Pilgrimage

gatesj3 on January 15, 2024January 17, 2024

By Jack Gates

This week, the larval lab set out on the final research cruise for our EPR Biofilms 4 Larvae project! We are en route to the East Pacific Rise where the hydrothermal vents lie. While our field experiments on the relationship of microbial biofilms to larval settlement continue, masters student Mel will also be investigating a deep-sea polynoid worm, Branchipolynoe.

A summary of our work for those new to the blog:

Being dotted sometimes miles apart, locating hydrothermal vents on the vast seafloor is a big feat for a small larva. The Biofilms 4 Larvae project aims to understand the role microbial biofilms might play in helping these larvae find a place to settle. Chemosynthetic microbes are characteristic of hydrothermal vents; while plants and algae at the surface create energy from sunlight to support our ecosystems, microbes at hydrothermal vents use the mineral-rich water erupting from vents to create energy through chemical reactions. With these microbes at the heart of hydrothermal vent communities, they could be a cue for the larvae of vent species to settle. The larval lab is investigating how larval settlement is impacted by the presence of microbial biofilms.
(Sunset photo by Mel Lemke)

Our days-long transit gives us time to prepare for our experiments. Rocking back and forth with the waves in the R/V Atlantis’ main science lab, we have been busy constructing tools, measuring preservative chemicals, and reviewing dive plans. This work involves building ‘sandwiches,’ stacks of square polycarbonate plates. See Mel modelling a completed sandwich to the left.

These will be deployed on the seafloor for larvae to settle upon. Sandwiches deployed last year are waiting for us on the seafloor—these are contained in mesh ‘purses’ that keep larvae from entering but allow microbial biofilms to grow. Using the submersible Alvin, we will remove these purses and deploy microbe-less sandwiches, so we can see how larvae settle on biofilms versus on bare surfaces.

We are also building tube traps: upright cylinders that preserve any small critters descending toward the seafloor. These give us an idea of how many larvae in the water column are going toward the benthos to settle. When we arrive on site, Alvin will descend to thousands of meters depth to deploy these, alongside our sandwiches, amidst the hydrothermal vents.

Left: Laura screws the weighted base on to a tube trap. Right: (from left to right) Tanika, Dexter, and Laura build sandwiches.

Alvin will also be collecting samples. Mel is hoping to bring up Polynoids (also known as scaleworms) living inside of deep-sea mussels to investigate their ecology. In addition to studying the adults, we have a worm nursery on board for raising Polynoid larvae. Pressure vessels called HiPPOs allow larvae to be raised in the high-pressure environment they are accustomed to in the deep sea. By observing these little worms, we can better understand their development.

Temperatures are rising as we draw farther south, as is excitement as we near our first dive. We are joined by flying fish, a flock of boobies, and the occasional dolphin, each skimming the surface of the ocean. Soon, we will get to see what lies far beneath. The larval lab is excited to share the rest of our voyage with you!

Jack

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About me: I’m Jack. I’m a WWU student working in the larval lab as an REU intern. As a fan
of creatures and the ocean, I’m excited to share my experience on a deep-sea
research cruise!

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EPR Biofilms4Larvae project is a multi-institutional NSF grant: OCE-1948580 (Arellano), OCE-1947735 (Mullineaux), OCE-1948623 (Vetriani).

Also find us on Instagram! @larvallab, #Biofilms4Larvae

The Inactive Sulfides project is a multi-institutional NSF grant: OCE-2152453 (Mullineaux & Beaulieu), OCE-2152422 (Sylvan & Achberger).

Also find us on Instagram! @jasonsylvan, #LifeAfterVents