10 March 2011


(High-temperature white smokers emitting liquid carbon dioxide from the Champagne vent in the Marianas Trench Marine National Monument. Credit: NOAA, via Wikimedia Commons.)

It's possible the first life on Earth evolved at remote "extremophile" ecosystems like deep-sea hydrothermal vents.

These otherworldly ecosystems were discovered only in 1977 by a group of marine geologists exploring the Galapagos Rift. From Deep Blue Home:

[Hydrothermal vents] form at fissures torn into Earth’s crust by our planet’s persistent rebuilding of its house, by its slow-motion rearrangement of ocean basins and continents. Much of this building takes place down the spine of the longest mountain range on Earth, the 45,000-mile underwater chain threading through the center of all the ocean basins and connecting one to the next.

 (Credit: NOAA.)

Hydrothermal vents run on a different engine than sunlight. Instead of photosynthesis, microbes use chemosynthesis to make life from nonlife inside the superheated waters of the vent. The results are incredible.

[H]ydrothermal vents are closed systems—aquariums, really, contained by walls built by temperature differences and by minerals emitted from the vents: sulfides, barium, silicon, calcium. They support highly specialized and uniquely adapted species that exist in relatively low diversity but in enormous plenty, up to 100,000 times the density of life forms on the surrounding deep-sea floor—bioabundance in an invisible box.

In this short video you can see some of the strange life forms at a deep-sea vent—including the giant tube worms whose bacterial symbionts perform the chemosynthesis fueling the foodweb here.

This is much the same relationship, btw, as the coral-zooxanthella relationship in the sunlit zone. The coral animals harbor—or enslave, depending on your point of view—symbiotic algae (the zooxanthellae) whose photosynthesis fuels the foodweb of the coral reef.

(Image courtesy of Pacific Ring of Fire 2004 Expedition, NOAA Office of Ocean Exploration, Dr. Bob Embley, NOAA PMEL, Chief Scientist.)

In the photo above, taken in 2004, scientists for the first time found hydrothermal-vent and coral-reef communities overlapping at 190 meters/623 feet. This was in the Mariana Arc region of the western Pacific. 

The image shows chemosynthetic microbial mats covering photosynthetic red algae and coral. It doesn't get any weirder or more wonderful than that.

(NW Eifuku Volcano. Squat lobsters, shrimp, and vent mussels dispersed over the bottom. Image courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program.)

But for the most part, deep-sea vents live pretty isolated from the world above. Until now, that is, when they're experiencing the ultimate alien invasion—repeatedly visited and probed by beings from above.

An interesting paper forthcoming in Conservation Biology addresses the uncertain future of these deep-sea ecosystems:

Within the last 10 years, deep-sea tourism has become established at certain vent fields, and exploration has begun to measure the potential for extraction of the massive stores of sulfides in deep-sea vents that are enriched with copper, zinc, lead, silver, gold, and barium. Currently, the primary and expanding activities in vent systems are scientific, and hydrothermal vents are sometimes considered as one of the most important biological discoveries of the past century.

(A hermit crab with seep-associated fuzzy bacterial filaments on its claws, from New Zealand Seeps, a cold seep site. Image courtesy of NOAA/NIWA.)

So what impact are these visitors having on the invisible aquariums of the deep?

In 2007 the nonprofit InterRidge published a code of conduct known as the ISRRP (The InterRidge Statement of Commitment to Responsible Research Practices at Deep-Sea Hydrothermal Vents). The statement was the consensus of 2,000 researchers from more than 27 nations engaged in vent research. They concluded:

In the interest of environmental stewardship, it must be the goal of research scientists to minimize disturbances as much as possible, while still gathering the information necessary both to understand the systems and to form a basis for sustainable use strategies. Therefore, marine scientists should always evaluate their research plans from a conservative standpoint, and choose the most environmentally friendly research approach.

(Image courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program.)

The authors of the paper in press in Conservation Biology are advancing the conversation with three questions:

  • What's the value of hydrothermal vents for the global scientific community?
  • Is there evidence that scientific activities are having deleterious effects on the vents?
  • How to ensure a sustainable scientific use of vents?

Using a statistical analysis of the published scientific literature, the authors compared vents to two highly-studied marine ecosystems: coral reefs and seagrass beds. The idea here is that the quantity of published papers reveals one measure of scientific value. Sure enough, vents are extremely valuable to science:

Scientific literature on hydrothermal vents is abundant, of high impact, international, and interdisciplinary and is comparable in these regards with literature on coral reefs and seagrass beds. 

(Conservation Biology. DOI: 10.1111/j.1523-1739.2010.01642.x)

The authors then surveyed scientists engaged in deep-sea research and found that although they were aware of the ISRRP code of conduct, and believed it to be relevant to conservation, they lacked confidence that other researchers were respecting it.

Respondents thought it would be difficult to be familiar with research in an area and to avoid activities that would compromise on-going studies. To facilitate adherence to this guideline, InterRidge lists locations of field campaigns and ongoing, site-specific experiments and observations, but listings are voluntary, brief, and not up to date. 

(Cable from scientific instruments, hydrothermal plume, and CO2 bubbles.  Image courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program.)

Finally, the authors asked for suggestions on ways to make the ISRRP a better environmental management tool. Based on the feedback from scientists they conclude:

We believe... that scientific activities should be managed for conservation for the same reasons mining, harvesting, or tourism are managed... Scientists are often involved in evaluation of status of world natural heritage sites and, together with other stakeholders, can evaluate the status of hydrothermal vents. Because scientists benefit from these living libraries and have the potential to degrade them, they are stakeholders and we believe they have a special responsibility for exemplary behavior.

Here's a long but luminous voyage to the world of hydrothermal vents with Sir David A.

The paper:

GODET, L., ZELNIO, K., & VAN DOVER, C. (2011). Scientists as Stakeholders in Conservation of Hydrothermal Vents Conservation Biology DOI: 10.1111/j.1523-1739.2010.01642.x

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