First Real-World Experiment on Future Reef Acidification
Most studies looking at how corals will respond to future increases in ocean acidity are based on laboratory studies. This week in the journal Nature, researchers reported on a large-scale experiment to simulate these conditions in a natural coral ecosystem.
The results showed coral growth slowing even more than previous experiments had suggested.
Off the shores of Australia’s One Tree Island, researchers – including the Carnegie Institution for Science’s Ken Caldeira and the California Academy of Sciences’ Rebecca Albright – devised a way to trap 4,000 gallons (15,000 liters) of seawater and saturate it with carbon dioxide, making the water more acidic. They then introduced some of the water into a nearby area of reef to create the ocean pH conditions that are expected around 2050 or 2060.
They found that reef calcification rates dropped by a third – about twice as much as lab experiments done on individual coral species had found. It is not clear why the rate was so much higher, but the authors told the Australian Broadcasting Corporation that it is likely because reefs are more complex ecosystems than some corals in a tank.
Because their simulated CO2 conditions were done over a short period, a big question that remains is whether some corals could adapt to these kinds of chemical changes over decades. Another recent study in the journal Science showed that corals could start dissolving faster than they can grow if ocean waters acidified enough by 2100.
Should Fishing Vessels Be Allowed to ‘Go Dark’?
The conservation group Oceana published a case study this week looking at commercial fishing vessels that appeared to be hiding their geographic coordinates, raising suspicions of illegal activities.
Oceana used data generated by ships’ Automatic Identification System (AIS) transponders that was compiled by Global Fishing Watch. Public data from AIS – which was originally used to avoid collisions – is now also being used by watchdog groups, researchers and governments to analyze the movements of ships at sea.
Sometimes, AIS transponders are simply turned off aboard ship. This may be for good reason – such as in waters where there is a high risk of piracy – but it could also indicate attempts to hide illegal activities. Oceana identified four examples of fishing vessels “going dark,” including a Panamanian ship near the Galapagos Marine Reserve, an Australian vessel near the Heard Island and McDonald Islands Marine Reserve and a Spanish ship approaching Gambia’s waters.
To increase transparency and aid in monitoring, the group is pushing for flag state governments or regional fishing management organizations to require AIS transponders stay on, or require official notification when they need to be turned off – especially in the waters of developing nations.
Scientists’ Focus Turns to Microfiber Pollution
As scientists from around the world gathered in San Diego this week at the Sixth International Marine Debris Conference, much of the discussion has been about plastic pollution of the ocean. In particular, synthetic microfibers that clothing sheds in washing machines passing through wastewater treatment plants and into the sea.
“We don’t have a good understanding of where all microfibers are coming from,” said Chelsea Rochman, an assistant professor of ecology and evolutionary biology at the University of Toronto, who made one of several presentations on microfiber pollution and its impact on marine life. “Although there is some evidence of effects in lab experiments, we know very little about effects in organisms and we know next to nothing about effects on humans,” she said.
What does seem apparent is that microfiber contamination is widespread.
Lisa Erdle, a PhD student at the University of Toronto, presented research that found that 96 percent of the microplastics discovered in 80 fish she sampled in Lake Ontario were microfibers. Likewise, Ahmet Erkan Kidey of the Middle East Technical University in Turkey found microfibers were the most prevalent microplastics found in fish sampled in the Mediterranean.