Diseased dolphin populations are being put at increasing risk of starvation and are using their muscles as an energy source to survive due to man-made factors including tourism and shipping, a conservation study has found.
The disruption of feeding due to human activity in the ocean is one of many conservation concerns for all marine mammals. A new study, funded by the US Office of Naval Research, US, has found that dolphins with poorer health had lower levels of amino acids, the building blocks for muscles, and that they may use those building blocks to substitute the short fall in energy they have to fight the disease.
Read the study published in Comparative Biochemistry & Physiology
According to Professor David Lusseau from DTU Aqua humans can impact the health of dolphins to such a degree that it can even lead to less offspring being born.
“To prevent this, we are measuring the health of dolphins by estimating how much fat they have. This is the same principle as in humans where we don’t have enough fat stores, the body tries to survive by shutting down non-essential mechanisms such as our ability to reproduce.”
“However, in dolphins we have found that only looking at their fat stores does not give us the full picture about their health as they also use fat stores to keep them warm, to dive and for buoyancy. We desperately need novel health markers if we want to protect these precious species. Our study is the first step towards finding those novel health markers,” says David Lusseau and continues:
“When in good ‘health’, individuals might be able to accommodate exposure to stressors but when in a poor health, individuals will lack the resilience to cope physiologically and/or behaviourally with those stressors and their effects will impact life functions. Our results show that this might indeed be the case and that dolphins may struggle in time to have the energy necessary to both survive and keep producing offspring.”
Comparing the blood profile
Researchers from DTU Aqua, the University of Aberdeen, Medical University of South Carolina, and Georgia Institute of Technology have collaborated on comparing the blood profile of bottlenose dolphins who were sick with those that were healthy of two wild populations at Charleston Harbour and the Indian River Lagoon, US.
By increasing the understanding of the cetacean’s physiology, conservationists can better assess how to mitigate the risks posed by human activity.
Dr Patricia Fair from the Medical University of South Carolina and Dr Davina Derous from the University of Aberdeen’s School of Biological Sciences have said the study provides a vital benchmark for measuring the health of dolphin populations and will be highly effective in influencing conservation policy.
Dr Davina Derous from the University of Aberdeen’s School of Biological Sciences explains: “This study gives us vital insight into how diseased animals regulate their metabolism and how further impact by humans may cause even more issues to their health. Energy metabolism plays a key role in our ability to understand the consequences that human disturbances might have for the conservation of whale and dolphin species. Human activities can disrupt the foraging ability of cetaceans, reduce their food intake, and can impact how much energy they can invest in reproduction or growth. Predicting these ecological consequences is limited by our understanding of cetacean energy metabolism and what a healthy dolphin looks like".