by Emily Li
Watching educational programs like Animal Planet or That’s My Baby—a series that documents pregnant animals—might evoke memories of flickering classroom projectors for most. But for Jasmin Graham, an intern with the Smithsonian Environmental Research Center (SERC), these shows were her childhood. Her love for marine science and wildlife followed her through high school science fairs and university research on shark genetics at the College of Charleston. Now, at an internship with SERC’s Ocean Acidification Lab, she studies acidification not in the open ocean, but in a far more dramatic arena, where the marine celebrities she grew up with may be at risk.
The coast isn’t clear
As we release more and more carbon dioxide (CO2) into the air, it’s not just the atmosphere that’s taking the hit—it’s our oceans, and they pay the price in the form of rising acidity. In the open ocean, acidification is a widely acknowledged environmental threat. In coastal estuaries, where freshwater and seawater meet, the issue is far murkier.
A major reason for this difference is because the estuarine environment is so dynamic. In the ocean, the pH, or the measure of the water’s acidity levels, stays at a relatively constant 8.1; in estuaries, this fluctuates drastically. From tides to light conditions, phytoplankton activity, wind, and time of day, estuaries possess a range of factors that can vary separately or compound each other’s effects on the water’s chemistry.
“There haven’t been a lot of studies on CO2 concentrations in estuaries because it fluctuates so much,” Graham said. ”Scientists know now that ocean acidification is happening out in the open ocean because they’re actually seeing the changes in pH, but it’s a little different in estuaries because there’s always a lot of CO2 fluctuations … It just depends on a lot of different factors.”
To fill this gap, Graham is monitoring three creeks along the Rhode River, a tributary that runs through SERC’s campus. She’s keeping an eye on CO2 and alkalinity, the water’s ability to resist a change in pH when an acid, like CO2, is added. Hopefully, her research will help establish what a range of “normal” acidification levels in estuaries look like. Without this link, it’s nearly impossible for scientists to determine how rising carbon emissions are affecting them.
Getting into murky waters
Given how complicated her research is, it’s a good thing Graham isn’t working by herself. Not only does she have lab technician Amanda Reynolds, but she also has help from SERC equipment, even if it’s a bit high-maintenance. Because they can’t directly measure CO2 in the water, the water samples must first be fed through a special equilibrator that the lab designed, which leaves the air with the same concentration of CO2 as the water. Then, these air samples can be run through the project’s “brains”—an infrared gas analyzer—that reads the air’s CO2 levels.
Besides technical difficulties, nature provides its own obstacles. They have to eliminate microscopic marine plants called phytoplankton, which can alter readings. For alkalinity readings, this just means using a filter. For CO2 surveys, it’s a not-so-simple matter of cleaning all the equipment weekly. The days between scrubbings is long enough for a crowd of creatures to move in, from polychaete worms, to carpet-like bryozoans, tiny crabs and one unlucky spider with a web in the wrong place. Graham and Reynolds arm themselves with scrapers and what look like metal pipe cleaners to remove the organisms nestled within the piping.
“Unfortunately, a big part of working in the Chesapeake Bay is that the Chesapeake Bay is very fertile,” Reynolds said with a laugh. “It grows a lot of stuff—so we have to do a lot of cleaning.”
But the hard work is already paying off, as Graham’s preliminary observations reveal. She expected tides to have the most impact on CO2 levels, but this wasn’t reflected in her data. Instead, she now suspects photosynthesizing phytoplankton were responsible for a large degree of fluctuation. But they weren’t acting alone—other factors affecting photosynthetic activity, like light intensity and time of day, also had high impacts.
“We have to tease apart the variables and figure out, this variable is important, this variable is not so important, and it makes for a very interesting but a very complicated story,” said Reynolds.
Nobody is certain how this story ends. In the ocean, acidification is setting marine life up for tragedy, by breaking down the calcium carbonate that shelled organisms rely on. In estuaries, the plot is less clear. Because fluctuation is so common, it’s possible that estuarine animals may have an easier time adapting.
“Some of our animals here may have evolved to deal with the big changes in pH, more so than an ocean creature that lived in the same sort of pH environment for thousands and millions of years,” Reynolds said. “So we may have a more robust system since they see a lot more variation in their lives. But we don’t know who’s going to be the winner and who’s going to be the loser here.”