Small Differences Have Big Consequences to Keep the Oceans Happy

Swimming away from the rocky shores out to sea Grace Klinges, a 2nd year PhD student in the Vega-Thurber Lab, is surrounded by short green sea grasses swaying in the waves, multi-colored brown sand and occasional dull grayish-brown corals dot the floor as she continues her research dive. However, the most interesting thing about this little island reef off the coast of Normanby Island, Papua New Guinea, is the forest of bubbles that envelopes Grace as she swims. Bubbles curiously squeak out everywhere along seafloor between sand grains and even eating their way through the corals themselves. It reminds one of how thick the fog can be in the Oregon hills, and like a passing cloud, the bubbles begin to dissipate the further away you swim from the shore, revealing an increasingly complex web of life wholly dependent on the corals that look more like color-shifting chameleons than their dull-colored cousins closer to the shore.

Grace took ~2,000 photos for each of 6 transects moving away from the carbon dioxide seeps. She is rendering these photos using a program called PhotoScan, which identifies areas of overlap between each photo to align them, and then generates a 3D model by calculating the depth of field of each image.

These bubbles emanating from the seafloor is part of a naturally occurring CO2 seep found in rare parts of the world. While seemingly harmless as they dance up the water column, they are changing ocean chemistry by decreasing pH or making the water more acidic. The balance of life in our oceans is so delicate – the entire reef ecosystem is changing in such a way that provides a grim time machine into the future of Earth’s oceans if humans continue emitting greenhouse gasses at our current rate.

Corals are the foundation of these ocean ecosystems that fish and indigenous island communities rely on for survival. In order for corals to survive they depend on a partnership with symbiotic algae; through photosynthesis, the algae provide amino acids and sugars to the corals, and in return, the coral provides a sheltered environment for the algae and the precursor molecules of photosynthesis. Algae lend corals their magnificent colors, but algae are less like colorful chameleons and more like generous Goldilocks that need specific water temperatures and a narrow range of acidity to survive. Recall those bubbles of CO2 rising from the seafloor? As the bubbles of CO2 move upward they react with water and make it slightly more acidic, too acidic in fact for the algae to survive. In an unfortunate cascade of effects, a small 0.5 pH unit change out of a 14 unit scale of pH, algae cannot help corals survive, fish lose their essential coral habitat and move elsewhere leaving these indigenous island inhabitants blaming bubbles for empty nets. On the grander scale, it’s humans to blame for our continuous emissions rapidly increasing global ocean temperatures and lowering ocean pH. The only real question is when we’ll realize the same thing the local fishermen see now, how can we limit the damage to come?

 

The lovely Tara Vessel anchored in Gizo, Solomon Islands.

Grace Klinges is a 2nd year Ph.D. student in the Microbiology Department who is using these natural CO2 seeps as a proxy for what oceans could look like in the future, and she’s on the hunt for solutions. Her research area is highly publicized and is part of an international collaboration called Tara Expeditions as a representative of the Rebecca Vega Thurber Lab here at Oregon State, known for diving across the world seeking to better understand marine microbial ecology in this rapidly changing climate. Grace’s project is studying the areas directly affected by these water-acidifying CO2 seeps and the surrounding reefs that return to normal ocean pH levels and water temperatures. By focusing her observations in this localized area, about a 60-meter distance moving away from shore, Grace is able to see a gradient of reef health that directly correlates with changing water chemistry. Through a variety of techniques (GoPro camera footage, temperature sensors, pH, and samples from coral and their native microbial communities) Grace hopes to produce a 3D model of the physical reef structures at this site to relate changing chemistry with changes in community complexity.

Tara scientists spend much of the sailing time between sites labeling tubes for sampling. Each coral sample taken will be split into multiple pieces, labeled with a unique barcode, and sent to various labs across the world, who will study everything from coral taxonomy and algal symbiont diversity to coral telomere length and reproduction rates. Photo © Tara Expeditions Foundation

One of the main ideas is that as you move further away from the CO2 seeps the number of coral species, or coral diversity, increases which often is expressed in a huge variety of physical structures and colors. As the coral diversity increases so should the diversity of their microbiomes. Using genetic and molecular biology techniques, Grace and the Vega Thurber lab will seek to better understand which corals are the most robust at lower pH levels. However, this story gets even more complicated, because it’s not just the coral and algae that depend on each other, but ocean viruses, bacterial players, and a whole host of other microorganisms that interact to keep this ecological niche functioning. This network of complicated interactions between a variety of organisms in reef systems requires balance for the system to function. Affectionately named the “coral holobiont“, similar to a human’s microbiome, we are still far from understanding the relative importance of each player which is why Grace and her labmates have written a series of bioanalytic computer scripts to efficiently analyze the massive amounts of genetic information that is becoming more available in the field.

Grace was overjoyed after taking a break from sampling to swim with some dolphins who were very curious about the boat. Photo © Tara Expeditions Foundation

With the combination of Grace’s field work taking direct observations of our changing oceans, and her computer programming that will help researchers around the world classify organisms of unknown ecosystem function, our knowledge of the oceans will get a little less murky. Be sure to listen to the interview Sunday January 14th at 7PM. You can learn more about the Vega Thurber lab here.

You can also download Grace’s iTunes Podcast Episode!

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