Tuesday, January 24, 2012

Introducing: The Bio Team

One of the most exciting parts of this cruise has been seeing what lives in these depths and bringing sample organisms back to the surface to study them in greater detail. This is the first time that a significant amount of biology has been brought up from this site.

Bio Team at work
The Bio Team on board is dedicated to the study of macrofauna (large animals) on this expedition and includes five people: the principle investigator, Cindy Van Dover from Duke University, her post doc Sophie Plouviez, and grad student Jameson Clarke, as well as Paul Tyler from the University of Southampton and his grad student, Verity Nye.

Several others are also involved with the Bio Team’s work and together they have collected many samples to distribute to different labs once we return to port. The team instructs Jason’s pilot which animals to sample using the vehicle’s manipulator arms. The pilot then places the samples in the biobox on the front of the vehicle and closes the lid before surfacing. Smaller animals such as shrimp he collects with a device aptly named the “slurp,” which sucks up anything near its nozzle, much like a vacuum cleaner.

After every Jason dive, the team forms an assembly line, where they take an inventory of their samples, image them, and slice up pieces of the animals to be used for genetic study later. Verity Nye described the process: “First we preserve the whole animal in formalin to take it back to our lab. We look at the whole animal very closely to see if it is something already described or if it’s something new to science.”

Tubeworm out of its tube. The black part is
full of symbiotic bacteria that feed the worm.

Vent sites have very unique biodiversity. At the bottom of the food chain are the microbes. They are mainly chemosynthetic bacteria able to make a living off of the chemical-rich fluids coming out of the vent. These bacteria sustain larger animals in a symbiotic relationship. The bacteria thrive on vent fluids, even if they live inside the gut of a tubeworm or on a shrimp. This is why the symbionts (animals that depend on another organism to survive) live in such close proximity to vents or seeps—so the larger host animals can keep their microbes healthy. In return, they get a full belly of nutrients. Otherwise, the larger animals wouldn’t be able to survive here.

The Bio Team is mainly concerned with sampling macrofauna at the two main hydrothermal vent fields: Von Damm (2300 meters deep) and Piccard (5000 meters deep). The team will be analyzing, categorizing, and prepping the samples for phylogenetic studies in their respective labs.

So far the Jason Team has brought back incredible samples from the depths that are a real treat to look at. These include three species of shrimp, two species of tubeworms, star fish, sea cucumbers, coral, mussels, clams, sea anemones, squat lobsters, gastropods (snails) and even some fish.
Following the InterRidge code of conduct, this team is choosing to sample only a small fraction of the total number of each species present at the seafloor in order to minimize any impact on the populations they find there.

A Mystery Lurks Below

These active hydrothermal sites on the Mid-Cayman Rise are unique and especially important to study because of the recent discovery of tubeworms and shrimp here. If you aren’t an avid vent fauna researcher or enthusiast then you might miss the significance of these two species being found together (as I did). I learned that tubeworms are seen in the Pacific vent sites and at cold seeps in the Gulf of Mexico, while shrimp are only found in the Atlantic. Shrimp and tubeworms have never been seen together at vents until Chris German and Paul Tyler first dived at these sites using the Little Hercules ROV aboard the NOAA ship Okeanos Explorer in August 2011.

This raises several questions regarding the origin of the tubeworms. From where did they migrate? Are they related to the tubeworms found at cold seeps in the Gulf of Mexico or the Pacific Ocean? If they resemble Pacific tubeworm species, then how and when did the first tubeworm larvae make it to the Caribbean? Did their predecessors arrive via the Panama Canal or before the North and South American landmasses joined together about three million years ago? “It is not well known how far tube worm larvae can travel,” said Plouviez.

These are questions that the bio team hopes to answer through detailed studied morphologic (physical differences) and phylogenetic (molecular differences) of these tubeworms. 

Cindy and Jameson
Cindy’s grad student, Jameson Clarke, is interested in linking the genetic information of the biology at these vents with similar information about species in other geographic locations. As Jameson told me, his main interest on this cruise is to investigate the genetic connectivity and biogeographic relationship between the sites to study the extent to which the sites are exchanging genetic information. They also aim to know where tubeworm sites have been colonized through evolutionary time. This may shed light on how ocean currents and ocean nutrient cycling plays a roll in the migration of isolated species, not just at vent sites, but globally, as well.


Another exciting moment for the Bio Team was the identification of three different species of shrimp. At the shallower Von Damm site, the shrimp are much larger than their cousins at the deeper Piccard site. The discovery of three different species is especially exciting for Cindy, as she’s had a long history of studying the biology of vent sites since vents were first discovered. In 2002, Cindy published a paper grouping similar biologic life at different vent regions (indicated by dots of the same color on the map, left). After an in-depth study of the biology at this site, she hopes to understand which regions share similarities to the Cayman site. 

Shrimp with eggs.
Paul and Verity, from the University of Southampton, are interested in how and when vent species reproduce. For Paul, the most interesting thing about the cruise so far has been finding female shrimp carrying eggs. He explained that the last time shrimp were sampled was during the summer months at the Mid-Atlantic ridge, few if any of the shrimp carried eggs. Perhaps information form these shrimp will help determine if there is a seasonal periodicity of reproduction. As Paul put it, “reproduction maintains population, it gives opportunities for vent species to colonize new vents.”

How the tiny larvae of vent fauna locate and populate vents in the vastness of the deep ocean remains one of the important questions in vent biology Research like that of the Bio Team will contribute towards finding these answers. This expedition so far has been a truly rich experience for all of the teams.

“One of the things I love about this project is the teams of scientists, and the bigger picture of life in the oceans,” said Cindy. “There have been very interesting conversations. It’s like being at summer camp for scientists.”

1 comment:

  1. Wow, looks like everyone had a fun trip. Great finds!