How Jodie Rummer, PhD, is leading the research on how fish react to changing oceans
When we think of stress, we think of longer and longer to-do lists, traffic when we have an important morning meeting, or perhaps hosting gatherings for our extended families.
For Jodie Rummer, stress is trying to determine what the oceans will look like in the next 100 years. The pH levels are declining as oceans absorb one-third of the carbon dioxide in the environment. Water pollution from development and agriculture is increasing water turbidity, and climate change is increasing water temperatures.
Rummer, Senior Research Fellow and Discovery Fellow at the Australian Research Council’s Center of Excellence for Coral Reef Studies at James Cook University in Australia, is studying the effects of these changes on fish in the tropics. She researches how fish change their behaviors in relation to changing water conditions.
Though Rummer grew up in land-locked Illinois surrounded by cornfields, she was always obsessed with the water. “I grew up with a mask and a snorkel as a kid, watching National Geographic and the BBC Underwater Life. I was good at math in school. I loved picking apart problems and seeing how things worked,” she said.
Rummer, a 2001 initiate of the University of West Florida circle, earned a bachelor’s degree in marine biology and a master’s of science in biology from the same university. The experience that solidified her goal of a career in marine life was a field course in Jamaica studying damaged reefs and sea urchins.
She was fascinated by the world of fish—this group constitutes 28,000 species found on all seven continents. Fish are one of the most evolved and oldest types of animals, having lived on this planet for the past 400 million years. When you compare this to humans—one species, roughly 200,000 years of evolution, you can see how Rummer became captivated by these creatures. Many fish have adapted to very specific niches in their environments; however, they are naturally highly adaptable, which makes them an important group to study.
“The diversity of fish is astounding to me,” Rummer explains. She tells stories of how if the bluefin tuna were to enter the 100-meter race, it could beat Usain Bolts’s 9.58 second world record by six full seconds. Pacific salmon travel 1,000 kilometers to their spawning grounds to reproduce, and clownfish are sequential hermaphrodites, which means all young are born male, and immature males can transform into a female if the dominant female of the school dies or becomes injured.
While conducting research projects to determine just how fish are using their athleticism to adapt to changing ocean conditions, Rummer found her career path. “I realized research is what made me happy; it’s what makes my brain click,” she said. Rummer choose to pursue her Ph.D. at the University of British Columbia where she began to study how fish’s biological processes change as their environments change. Although fish have adapted to nearly every environment on the planet—will they be able to adapt to one changed by humans?
Rummer attempts to answer this question every day. She oversees a lab of ten doctoral students, five masters students, and another handful of undergraduates and staff members, and a list of research projects that is daunting to keep track of. At the ARC Center of Excellence for Coral Reef Studies, Rummer and her team can increase water temperature, decrease oxygen, or change a number of water quality controls on small tanks, and observe fish for changes in their physiology.
She explains, “We can measure how much oxygen fish use at rest, and require for growth, digestion, and reproduction. We are monitoring cellular responses like pH, oxygen transport, ion-regulation and water balance under environmental stresses.” Rummer and her team then measure how these functions are affected by warmer temperatures and ocean acidification.
One of the most important measurements Rummer employs to track fish success is how fish transport oxygen in their bodies. Oxygen is much less readily available in water than in the air, so you might think fish expend more energy just to breathe. However, due to the way fish use hemoglobin, they’re able to deliver oxygen to tissues 50 times more efficiently than air breathers such as humans. It could be this ability that determines how fish adapt to oceans with less available oxygen.
Rummer’s research studies on the Great Barrier Reef, the largest reef in the world, discovered that just a two- or three-degree water temperature increase adds to fishes’ basic maintenance cost to survive. As temperatures increase, gill filaments become covered in mucous and protective cells which reduces their efficiency and capacity for swimming. Warmer temperatures also decrease vegetation, which means fish spend more time looking for their next meal and have less energy for growth and development. This change has implications on the next generation of the species and also effects the entire ecosystem. As oceans continue to change, Rummer and other scientists expect a mass redistribution of species towards higher latitudes seeking refuge from warmer temperatures.
Rummer also studies how fish react to the combination of increased carbon dioxide with ocean acidification—the decrease in pH levels of the water due to this uptake of CO2. As pH levels climb, fish are using more energy to balance pH in their gills. Some fish are less able to smell predators and appear disoriented, which increases their likelihood of being eaten.
With funding from the National Geographic Society, Rummer collaborated with a team of ecologists, biologists, and fish experts to investigate the effects of long-term exposure to elevated carbon dioxide in fishes living in natural carbon dioxide seeps in Papua New Guinea. They found that the fish living in reefs near volcanic seeps exhibited some behavioral impairments, but were seemingly resilient to these conditions. They showed no major difference in numbers, diversity, or physiology than populations on nearby reefs unaffected by the CO2 seeps.
However, overall results from Rummer’s findings are troublesome. Scientists estimate that one-third of coral reefs have already been lost; ocean acidification and carbon levels could eliminate drastic numbers of species. How does Rummer process these often dire predictions?
While she admits that it is sometimes difficult, she is grateful for her career to help make a difference. “I have the freedom to pursue my dreams. I’m very lucky. I go by that saying that ‘luck is preparation meeting opportunity.’ I work really hard and then look for opportunities,” she says.
With a prestigious post at a major university, field projects around the globe, and multiple publications to her name, Rummer isn’t holding back on her dreams or her goal to make a difference. In 2014, Rummer spoke at TEDx in Queensland at the Cairns Institute and urged us all, “Can we devote the time, passion, energy and excitement that we have for human athletes to the rest of the world and the rest of the planet? Can we create and maintain these biological facilities where species are participating in the race for survival? No matter how athletic the athlete, they deserve the very best.”
