Midwater Ecology Expedition Summer 2019

The ethereal siphonophore, Erenna richardi, was spotted at 850 meters. The nectophores (swimming bells) were purple and the end of the tail (siphosome) was laden with eggs. We estimated it to be a whopping one meter (three feet) long! These gelatinous animals are armed with a battery of powerful stinging tentacles and have been observed ensnaring fish just above the seafloor.

MBARI Expedition #466

Expedition goal: The principal goal of this expedition is to measure oxygen consumption rates of select deep-sea animals using a custom-designed tool, the Midwater Respirometry System (MRS), at both shallow and deep locations. We will also be observing and collecting midwater animals to investigate their ecology, physiology, and behavior in conjunction with onboard collaborators from Stanford University and the Monterey Bay Aquarium.

Expedition dates: June 11- 17, 2019

Ship: R/V Western Flyer

Research technology:  ROV Doc Ricketts, Midwater Respirometer System

Expedition chief scientist: Bruce Robison

The Midwater Ecology Group will continue its research into the respiration rates (oxygen consumption) of deep-sea animals using the Midwater Respirometry System (MRS). The MRS allows the group to measure these animals’ metabolic rates where they live as opposed to in the laboratory at surface pressure. Understanding the energy requirements for these animals will allow a clearer understanding of the biological pump and the energy transfer from the surface, through the ocean’s midwaters to the seafloor. The group’s studies over the last three decades have shown the area of the deep ocean where the oxygen level is lowest is growing. The midwater team has documented the vertical expansion of the oxygen-minimum zone by 60-to 80-meters in relation to ocean warming. This expansion has fragmented the midwater community by shifting the distributions of some midwater animals. Long-term studies like this are necessary for first detecting shifts in communities and then predicting how communities will respond in the future to further changes in the environment

Midwater cruises also include exploration of this large habitat, where light does not penetrate from above, and the seafloor is not in sight below. Such explorations have led to many significant observations and discoveries about this habitat and the animals that live there—and their behavior.

Updates from researchers on the R/V Western Flyer:

Monday, June 17, 2019
Content Manager Nancy Barr

The stunning jellyfish exhibit at the Monterey Bay Aquarium provides visitors a special glimpse into the wondrous diversity of life in the deep sea—the largest habitat on Earth. These animals are part of the intricate marine food web. Successfully exhibiting jellies at the aquarium takes a team of aquarists, including Tommy Knowles, who joined us on this expedition.

Tommy started this cruise with a wish list of specific jellies he was looking for. As the pilots of the ROV Doc Ricketts flew the vehicle hundreds of meters below the surface, the scientists focused on a steady stream of marine snow, looking to pick out the tiny animals scattered among the detritus. When one of these deep-sea experts spotted a jelly, they’d yell “stop!” The pilot then maneuvered the vehicle close to one little jelly. If the jelly was needed for the aquarium, the animal was collected either by suctioning it gently into a bucket or maneuvering the entire vehicle to enclose the animal into a container. This takes an extraordinary amount of skill on the part of the ROV pilots; it’s like trying to catch a butterfly by driving a big truck forward and back, left and right, to track the butterfly until an open window lines up perfectly with the butterfly’s trajectory. In other words—very difficult!

Over several hours of exploring from 200 to 600 meters (about 660 to 2,000 feet) deep, Tommy collected a wide array of jellies. These animals are important to the  aquarium’s research and development on the best ways of caring for jellies, and how to culture them to  keep exhibits well-stocked. This effort helps bring a bit of the deep sea to millions of visitors at the Monterey Bay Aquarium. The aquarium’s jelly collection also helps MBARI’s researchers study important properties like bioluminescence.

Updates from researchers on the R/V Western Flyer:

Monday, June 17, 2019
Vanessa Stenvers, MBARI summer intern
Rondi Robison, manager, Ocean Sciences Department, University of California, Santa Cruz

We have been out for six days on the midwater ecology summer expedition. During this voyage we have been using the ROV Doc Ricketts to observe and sample life in the deep sea. Some dives have had specific missions to collect animals or to identify techniques and ways to observe animals to answer important science questions. We have had a chance to look at species in their natural environment from 200 to 3,000 meters (660 feet to almost two miles) deep.

From Rondi:

The excitement among the participants when we come upon a creature is infectious. Throughout my participation in the cruise my curiosity was piqued in a number of areas that I would not have expected. I was drawn to the excitement of the researchers. One in particular, Vanessa, was willing to share with me examples and knowledge about a couple of tunicates ( Pyrosoma atlanticum and Doliolula equus) we observed and sampled. Although both animals are tunicates, they are very different. I was struck by the firm structure of the pyrosome compared to the delicate doliolid. Both are colonial animals. Pyrosomes only survive as colonies; doliolids are only colonial for part of their life cycle.

First we observed these two animals through the ROV cameras, then the pilots and scientists expertly collected samples so we could observe them firsthand on the ship. By taking a closer look at their structures, many additional questions came out of these initial observations, which are helping Vanessa to identify her summer internship project with the Midwater Ecology Group.

I’m impressed with the knowledge and cooperation in which the scientists, pilots, and ship’s crew work together to make expeditions like this so successful. The data and information that have been collected on this journey will continue to provide insights into this weird and wonderful world.

From Vanessa:

During this cruise we not only got to observe midwater animals in their natural environment, but also got a chance to take an even closer look by bringing them up into the lab.

Many of the animals I had already seen in MBARI’s Deep-Sea Guide and in videos, or read about in academic literature, but being able to see them live (both in the ROV control room and the lab) is truly exciting. I am particularly interested in gelatinous zooplankton, with special emphasis on pyrosomes, as I studied these before coming to MBARI. Seeing pyrosomes bioluminesce (which they do very brightly) and observing their anatomy under the microscope have been a few of the highlights I experienced on this cruise. Moreover, talking to the researchers and pilots on the Western Flyer, who have already answered so many questions about the midwater zone, has provided me with many new insights and made me realize many more research possibilities. Everyone shares a fascination for what lies beneath the ocean’s photic zone, providing an inspiring environment for collaboration and research.

It has been incredible to see how MBARI operates and provides unique information about a difficult-to-reach environment like the deep sea and I could not be more thankful or excited to be part of this research group.

Updates from researchers on the R/V Western Flyer:

Friday, June 14, 2019
Ben Burford, Ph.D. candidate, Hopkins Marine Station, Stanford 

If you spend enough time looking out over the ocean, there is a chance you will see marine mammals of one sort or another; perhaps a whale will spout, or a sea lion will cruise by. But unlike these air-breathers, most animals in the ocean that grow to similarly large sizes do not need to come up to the surface. This is why some of the most impressive animals that exist today are basically unknown to science—they live in the deep ocean.

I live next to the Monterey Canyon in California, where I am neighbor to one of the largest invertebrate species on the planet. But neither I, nor any of my fellow 40,000 residents on the Monterey Peninsula have ever met this neighbor. The robust clubhook squid Onykia robusta—which until recently was called Moroteuthis—is a deep-living species that can grow to over three meters (almost 10 feet) long. Like most squid, it has 10 arms—two of which are elongated to form specialized feeding tentacles. It gets its name from the rows of large hooks at the tips of its tentacles. Behind the giant squid, it is the second largest squid species in the north Pacific.

Large body size has many benefits, including protection from predators. But growing big is a challenge, particularly for squid. By virtue of their molluscan heritage, squid possess a set of traits—including high energy demand, energetically-costly locomotion, and low blood-oxygen-carrying capacity—that presumably restrict most species to smaller adult body sizes. But clearly there are exceptions.

So how does the robust clubhook squid get so big? In order to get at this question, we hope to meet this species face-to-face in its natural deep-sea habitat. It has been seen a handful of times with MBARI remotely operated vehicles (ROVs), so we know it has been in this area. Our search begins along the walls of Monterey Canyon in deep areas rich with potential prey items, such as fish and smaller squids. Should a robust clubhook squid show itself, we will use cameras mounted on the ROV to examine its behavior and how it interacts with its surroundings. How fast can it swim? How much does it breathe? How does it hunt? To what extent could it communicate with members of its species? A glimpse of one of these squid will offer a window into the lifestyle of one of the largest and least understood animals on planet Earth.

Updates from researchers on the R/V Western Flyer:

Wednesday, June 12, 2019
Postdoctoral Fellow Astrid Leitner

Every evening all over the world ocean a mass migration takes place during which animals from the deep swim upwards into the surface ocean to feed under the cover of darkness. When they are full, and the sun begins to light up the surface waters, these animals swim back down to their dark daytime homes mostly around 300 to 400 meters (980 to 1300 feet). These animals are known as diel vertical migrators. I am interested in how this nightly migration is impacted by the dramatic canyon topography here in Monterey Bay.

Canyons and seamounts can result in relatively shallow waters lying right next to the deep ocean, some 500 meters (1,600 feet) deep or more. When this happens we call it “topographic blocking” because such features can prevent the dawn-time descents for those animals that drifted over the shallows at night. I am interested in testing this idea locally and discovering if topographic blocking is a regularly occurring phenomenon on the canyon edges. If the canyon does block these migrators from descending to depth at dawn, we would expect to find vertical migrators “piling up” on or near the bottom, and possibly creating high-density swarms.

Krill are one very common and ecologically important member of the local vertically migrating community, which also includes a variety of small fishes, jellies, and shrimps. One night on this cruise we mapped the vertical migration over a particularly steep section of canyon wall using bioacoustics (similar to a “fish finder” used by fishermen). Then we used MBARI’s remotely operated vehicle Doc Ricketts to film this wall during the dawn descent.

When we arrived at the bottom, close to the edge of the canyon wall at a depth of 200 meters (660 feet) around 7:00 a.m., we were swarmed by krill! Although krill would be attracted to the ROV lights, they could not have swarmed if they hadn’t been there in the first place. The swarm was so thick we could hardly see anything in our cameras, and we observed several rockfish darting through the swarm. If this were a regular occurrence, it would make this an ideal feeding ground for important predators like rockfishes and whales. Time will tell!

Updates from researchers on the R/V Western Flyer:

Tuesday, June 11, 2019
Content Manager Nancy Barr

First order of business for the day was to collect animals to fill the chambers of the Midwater Respirometry System. The jelly Colobonema sericeum (the “silky” jelly) was particularly prevalent today, so we collected several of these small, delicate gelatinous animals and placed them in their designated containers. Once full, the MRS was piloted carefully to the mooring line and skillfully placed on a hanger at 430 meters by the pilots, before being completely decoupled from the ROV. After 24 hours we will return to retrieve the animals, and Kim Reisenbichler will be able to retrieve data on the respiration rates of the animals in the MRS at ambient and enhanced oxygen levels.

Much of the rest of the day involved explorations of the midwater, and a chance for two new members of the midwater team to see the realm of their studies and how the team works there. Scientist Bruce Robison and his team are generous in sharing their time and expertise to mentor the next generation of ocean scientists. Summer Intern Vanessa Stenvers and incoming Postdoctoral Fellow Astrid Leitner were introduced to how the Midwater Ecology Lab uses the remotely operated vehicle and various instruments to study the midwater as they each begin their own research projects at MBARI. As those young scientists go on in their careers, they mentor those coming up behind them, which is evident in the group onboard as both Vanessa and Astrid studied with academic advisors who themselves were postdoctoral fellows with Robison years ago and are now professors (Henk-Jan Hoving GEOMAR in Germany and Jeff Drazen at the University of Hawaii). Also with us on this cruise is Stanford University Ph.D. student Ben Burford, who was once an intern in the MBARI Midwater Ecology Group, and continues to collaborate on research with the team.

MBARI Cruise Participants

Other Cruise Participants:

Tommy Knowles, Monterey Bay Aquarium; Vanessa Stenvers, MBARI summer intern; Ben Burford, Stanford University; Astrid Leitner, University of Hawaii; Rondi Robison, University of California, Santa Cruz