Volcanic rock to replenish marine life?

On August 15, 2019, Michael and Larissa Hoult, an Australian couple, were sailing to Fiji. As they sailed near Tonga, they encountered a “total rock bubble slick made up of pumice stones [ranging] from marble to basketball in size” floating in the ocean. Days earlier, NASA’s Earth Observatory (NASA EO) picked up an image that matched what Michael and Larissa saw. NASA EO states that the floating raft of pumice originated from an underwater volcanic eruption which occurred near the Pacific island of Tonga on August 7, 2019.

Scientists around the globe argue that this floating raft of pumice, currently headed to Australia, could potentially replenish marine life at the Great Barrier Reef.

According to Hobart M. King, a geologist and Ph.D. graduate in geology, pumice is a light-colored, extremely porous igneous rock that forms during volcanic eruptions. Pumice can be found in multiple everyday products such as skin exfoliators and traction enhancement materials in rubber tires.

Dr. Paul Ashwell, geology professor at the University of Toronto Mississauga, describes the floating pumice as an anchor for organisms to attach themselves.

“When corals spawn, they give off very small larva. These larva float around in ocean currents, and that’s where the floating pumice comes in,” explains Ashwell.  “The larva, along with other organisms, attach themselves to the pumice rock. This allows [the larva] to move and introduce themselves to other environments.” Ashwell argues that these organisms can either act as an invasive species or colonize new volcanic areas that previously had no corals.

Ashwell disagrees with other scientists about the possible beneficial impact of the pumice raft on the Great Barrier Reef. He says to “think of [the Great Barrier Reef] as a forest with toxic soil. No matter how many trees you plant in this toxic soil, the trees will still die. Climate change is destroying coral reefs in general and not just the Great Barrier Reef.” Ashwell argues that all theories of this raft replenishing marine life are unlikely considering the Great Barrier Reef’s current condition. “First, we solve climate change. Once that’s done, maybe we’ll see an increase in coral reefs,” he remarks.

Climate change, such as the increase of global temperatures and greenhouse gases, affect marine life in many ways. Temperature and greenhouse gases are directly correlated: the higher the level of greenhouse gases, the higher temperatures rise. The heat is trapped inside Earth by greenhouse gases and transfers to the ocean. This is problematic for corals which “are very susceptible to temperature change.”

Corals provide shelter for marine life, assist in carbon and nitrogen fixing, help with nutrient recycling, and most importantly, have a symbiotic relationship with algae. Corals receive their energy from algae. “Temperature change stresses corals out,” Ashwell explains. “As a result, that relationship with algae dies off. Once the algae dies, so does the coral.”  Unfortunately, temperature rise isn’t the only factor negatively impacting corals.

Along with causing rising temperatures, greenhouse gases acidify the ocean through a process called acidification. Acidification happens when there is an excess of greenhouse gases. The excess gases transfer to the ocean due to equilibrium which namely describes how the more gases there are in the atmosphere, the more gases there will be dissolved in the ocean. Carbon dioxide (CO2), a common greenhouse gas, is very soluble in water.

“When CO2 reacts with water, it produces carbonic acid,” Ashwell explains. “Carbonic acid reacts with the coral’s skeleton—which is mostly made of calcium carbonate—to produce more acid. This causes the ocean to become more acidic.” Under acidic conditions, corals have to struggle more to create their skeletons.

Students can fight climate change in two steps. “The first step is to realize your own impact on the environment. You can do this by checking your carbon footprint,” advises Ashwell. “From there, you can work on reducing that footprint.”

According to Ashwell, the average Canadian carbon footprint per person is about 15 tonnes. “Most of it comes from the transportation sector,” Ashwell states. “But meat and dairy consumption also plays a huge part.” According to National Geographic, cattle contribute to about 40 per cent of the annual methane budget. “If the demand for meat and dairy decreases, so will its production,” says Ashwell.

For those who love meat, Ashwell discusses an alternative solution. “The second step is to vote,” he affirms. “Right now, the most important thing to work on is climate change.” Ashwell encourages students to research political parties that have a legitimate and effective solution to reduce Canada’s greenhouse gasses emissions.

Students can also learn more about climate change and its impact on Earth in Ashwell’s course ERS111: Earth, Climate, and Life.