08 November 2023

As part of her master’s education in Applied ethology and animal biology, LiU student Ioulia Koliopoulou has chosen to do work on energy requirements in dolphins. For her master's thesis, she is combining research in both Kolmården Wildlife Park and the Oceanografic de Valencia. Ioulia explains that the knowledge on energetic needs in bottlenose dolphins will help understand how changes in the climate may affect survivability and is important to provide appropriate conservation efforts.

a trainer stands on the edge of a dolphin pool measuring exhaled air, a researcher works on a computer at the pool edge Ioulia monitors the test results, while a trainer is measuring the dolphin's exhaled air with a respirometer. Andreas Fahlman

student Ioulia KoliopoulouIoulia Koliopoulou Photo credit private “I have always been fascinated by the sea and marine life, having grown up next to the sea back in Greece where I am from”, says Ioulia. “A job listing for a dolphin trainer in the zoo of my hometown that I had accidentally seen when I first entered high school was what made me realise that with a biology degree, many careers alongside animals were possible and that was what eventually steered me in following this path.”  

Zoo biology course connected her to research

During her bachelor education, Ioulia studied the efficiency of digestion in reptiles, a different animal group, so when the opportunity of continuing work on digestion, this time in marine mammals, came about, she was happy to sign up. She contacted one of her teachers in the Zoo biology - a course organised by LiU in collaboration with Kolmården Wildlife Park - Andreas Fahlman, an expert in marine mammals and head of research at Kolmården Wildlife Park, who offered her an opportunity to work on this project. 

Degree project - a chance to do real research

The Applied ethology and animal biology master's programme is a two-year programme. During year one, the students spend most of their time taking courses that give them a solid theoretical ground. This is also the time when they grow ideas for their degree project. The degree project takes up most of the second year.
Ioulia describes her degree project to be very beneficial and important to her. It gives her the opportunity to plan and execute her own research, and has made it possible to work in collaboration with different organisations. All of this has allowed her to gain more experience in her research field. “I feel exceptionally lucky that I got to work in both Kolmården and Oceanografic, some of the largest zoos and aquariums in Europe.”, she says. 

Ioulia started her degree project by working at Kolmården, under the supervision of Andreas Fahlman, and is now continuing the work in Oceanografic in Valencia, Spain. Her project is investigating the effects of digestion on metabolic rate in bottlenose dolphins. The aim of the project is to measure the increase in metabolic rate, by measuring the oxygen consumption rate. The increase in metabolic rate following a meal, described as heat increment of feeding, is done by measuring the metabolic rate before and after the dolphin has eaten a meal.

Measurements are made with a custom-made respirometer, which is a flow-meter that measures the volume of air the dolphins breathes. A gas analyser samples the air formeasuring with a respirometerResearchers measure exhaled air with a respirometer oxygen and carbon dioxide that flows through the respirometer. These data allow Ioulia to calculate how much oxygen is consumed over the 5 to 10 minutes the dolphin remains inactive at the side of the trainer. “The oxygen consumption is what gives us the metabolic rate. This method is called indirect calorimetry and is one of two ways that we can use to get the metabolic rate, with the other one being direct calorimetry, which quantifies energy expenditure from measured heat production.”, Ioulia says.
The oxygen consumption rate is then converted to number of calories. “Having access to dolphins in managed care is important to obtain this information, as it allows us to perform controlled tests on animals that can decide to participate freely. This is a good example of how zoos and aquariums provide valuable research for conservation efforts”, says Ioulia . 

Important knowledge to be gained

In marine mammals, understanding the bioenergetics of the species is especially important as it can help explain the environmental constraints for survival that come with obtaining one's food underwater when you are an airbreathing mammal. The amount of time available to forage in the underwater environment is limited by the oxygen that is held in the lungs, blood and tissues of the organism, as well as the rate with which those stores are utilised. We can think of the oxygen as the dolphin's salary, and the utilisation rate as the bills that need to be paid each month. With inflation (changes in the environment) the cost of food will increase, but as the salary (amount of oxygen) cannot change, this will reduce the amount of food that they can obtain during each dive.

Thus, the foraging efficiency also depends on factors such as prey density and availability, which in turn are susceptible to environmental changes. Therefore, by understanding the metabolic costs of a dolphin we can better understand and predict how disturbances caused by climate change are possibly affecting them. 

Ioulia will present and defend her master’s thesis at Linköping University in late May 2024. After that she hopes for opportunity to continue working in this very interesting field.

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