Sustainably exploring life in the deep ocean through chemistry

Thursday, April 23, 2020

Crabs near the Alba hydrothermal centThree thousand meters below sea level, hydrothermal vents spew black smoke into the dark ocean. No light ever reaches these depths, yet surprisingly, these areas are rich with life. Crabs, shrimp, and other small organisms and bacteria call this strange habitat home.

Without light to photosynthesize, these organisms rely on a process called chemosynthesis to get their energy. While the term photosynthesis describes using photons of light to make energy, chemosynthesis describes organisms using chemicals to make energy. These chemicals are the ones spewing from the hydrothermal vents, and make this life possible.

To understand the unique nature of life this far below the ocean’s surface, it is imperative to understand the chemistry of the water surrounding the hydrothermal vents. This is one of the projects that University of Waterloo chemistry professor Janusz Pawliszyn is studying.

As a diver, Pawliszyn has always been interested in underwater environments, studying the chemistry of coral reefs and sea sponge purification in the past. The deep-sea environment has attracted his attention specifically because this environment is similar to the types of environments that existed at the beginning of Earth’s creation.

“Understanding the ecology and chemistry around these vents could eventually give us information on how life originated,” said Pawliszyn.

The chemistry of these unique ecosystems is commonly analyzed by using rovers to take water samples up to the surface of the ocean. There, these samples would undergo an extraction process, where a significant amount of organic liquids would be required to separate the carbon-based molecules from the deep-sea water. This creates a significant amount of chemical waste.

Additionally, by bringing the sea water to the surface, the sample is exposed to vastly different light and pressure conditions than exist near the hydrothermal vents. Some compounds can undergo chemical changes simply by shining light on them, while others can become gases when the pressure decreases. These differences have the potential to change the molecules in the sample before they are studied.

Instead of bringing samples to the surface, Pawliszyn has used a sampling technique called solid phase microextraction (SPME) to collect samples underwater directly at the vent site. SPME was invented by Pawliszyn in the early nineties, and uses a thin film coating to directly absorb small carbon-based molecules in a sample.

Remotely operated vehicle at the botom of the ocean sampling the water using solid phase microextraction

This research, Unique Solid Phase Microextraction Sampler Reveals Distinctive Biogeochemical Profiles among Various Deep-Sea Hydrothermal Vents, was recently published in Scientific Reports by Jonathan James Grandy, Bora Onat, and Pawliszyn from the University of Waterloo, in conjunction with Verena Tunnicliffe from the University of Victoria, and David Butterfield from the National Oceanic and Atmospheric Administration.

SPME is a much more environmentally responsible way of studying these hydrothermal vents, because the sampling is done right at the vent site. “When taking water samples to the surface, you actually remove something, including the microorganisms in the water – it’s like taking a biopsy of the water,” said Pawliszyn. “We’re not doing this, so it’s less invasive to the deep-sea ecosystems.”

Moreover, the use of SPME removes much of the wasteful extraction process that usually happens with water samples, and eliminates any errors based on changing environmental conditions that occur when samples are brought to the surface, making it a truer representation of the water chemistry around these vents.

“We’ve been able to measure lipids, organo-sulfur compounds, and other organic molecules which are an indication of life in these ecosystems,” Pawliszyn described. After testing three unique hydrothermal vent sites, researchers found that each site contained unique mixtures of compounds, many of which can be correlated with different microorganisms and animals around the vents.

This research shows that SPME can be used to help us understand deep-sea ecology and chemistry around hydrothermal vents, and gives us a new method of exploring our wonderful and mysterious world in exciting, sustainable ways.