Genetic data provides insight into how climate change is affecting white-beaked dolphin distribution, discovering genetically distinct populations across the North Atlantic and presenting new knowledge for conservation management.
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Photograph from Orca Ireland
Human activity and climate change is leading to exacerbating effects on the ocean and its species. Human activity is causing a rise in greenhouse gasses, gasses in the atmosphere that trap heat. This means more heat is being trapped on Earth, creating an increase in sea surface temperature.1 Over the past decade, the mean warming trend of the oceans was 4.5 times higher than the long-term mean, illustrating a rapid increase in sea surface temperature, which has immense negative effects on marine life.2 One of the most significant biological responses to this warming is the shift of marine life towards the poles in an effort to avoid warmer ocean temperatures. While these shifts are often predictable, they can have negative impacts on many types of species and their new environment, as novel competition, predation or prey are introduced.3
White-beaked dolphins (Lagenorhycnchus albirostris) are being disproportionately affected by climate change as they require cold waters to survive. They are typically found in the North Atlantic, but past decades have shown a considerable northward shift in their distribution. As ocean temperatures continue to rise, they will face an increased risk, illustrating a critical need for advanced conservation efforts.4 Writing in Heredity, Gose et al.4 aim to develop improved conservation management as they explore population structure, genetic diversity and gene flow of white-beaked dolphins.
Gose et al. examined 169 tissue samples from archival sources across the North Atlantic. The samples were analyzed via shotgun sequencing, a method of determining the entire DNA sequence of an individual. Once the DNA sequence was established, the authors compared population structures, investigating which groups were most closely related. The authors also examined whether there was gene flow, the transfer of genetic material, between dolphin populations to establish how interconnected populations were. Finally, initial analysis indicated strong intermixing in eastern Scotland, leading Gose et al. to investigate whether there was a possible contact zone at this location, and what it could be in response to. Choosing to study these factors will provide insights into future conservation efforts as population dynamics are better established.
Gose et al. discovered four genetically distinct dolphin populations, which they categorized into the western North Atlantic, Iceland and Barents Sea, western Scotland and Ireland, and the North Sea. Two regions showed significant genetic differences from others. First, the western North Atlantic was significantly differentiated from the North Sea and western Scotland and Ireland individuals. Second, the Iceland and Barents Sea population was significantly differentiated from the North Sea and western Scotland and Ireland. Gose et al. suggest this could be due to geographic isolation by distance, but further research needs to be performed. The coast of eastern Scotland appeared to be a zone for intermixing of dolphins from the North Sea, and dolphins from Ireland and western Scotland, supporting findings of high gene flow between regions. Gose et al. assert these findings present strong evidence that ecological factors are influencing dolphin population structures in the North Atlantic. Ecological differences may be partially responsible for genetic differentiation between neighboring regions. Furthermore, Gose et al. argues the eastern Scotland contact zone could reflect responses to environmental change in the species and any changes in behavior.
While Gose et al. provide insightful knowledge into the population structure of white-beaked dolphins, further studies need to be done on their movement, behavior and ecology to fully understand the drivers of their structure and create more targeted conservation efforts. While these drivers are being explored, Gose et al. argue lawmakers should reconsider local management based on population structures and what is currently known about white-beaked dolphins.4 For example, lawmakers could better enforce policies against the production of greenhouse gasses to prevent further increases in sea surface temperature.
Genomics data can have positive impacts on conservation management efforts, but it is important to be aware of several things when monitoring marine mammal populations. With no current regulations in place for white-beaked dolphins5, releasing data on their locations and genetics could cause them to be targeted as a food source. Furthermore, if regulations are put in place as a result of these findings, daily management needs to be considered. Oceans can be particularly difficult to manage as they take up a large area offshore; legislation needs to ensure protection is enforceable. As human activity and climate change continue to negatively impact ocean populations, governments will need to consider enacting legislation to protect these ecosystems that have a massive impact on the human populations along their shores.
References
- Irving, D. B., Wijffels, S. & Church, J. A. Anthropogenic Aerosols, Greenhouse Gases, and the Uptake, Transport, and Storage of Excess Heat in the Climate System. Geophysical Research Letters 46, 4894–4903 (2019).
- Garcia-Soto, C. et al. An Overview of Ocean Climate Change Indicators: Sea Surface Temperature, Ocean Heat Content, Ocean pH, Dissolved Oxygen Concentration, Arctic Sea Ice Extent, Thickness and Volume, Sea Level and Strength of the AMOC (Atlantic Meridional Overturning Circulation). https://www.frontiersin.org/articles/10.3389/fmars.2021.642372/full (2021).
- Sunday, J. M., Bates, A. E. & Dulvy, N. K. Thermal tolerance and the global redistribution of animals. Nature Clim Change 2, 686–690 (2012).
- Gose, M.-A. et al. Population genomics of the white-beaked dolphin (Lagenorhynchus albirostris): Implications for conservation amid climate-driven range shifts. Heredity 1–10 (2024) doi:10.1038/s41437-024-00672-7.
- White-beaked dolphin. Whale & Dolphin Conservation USA https://us.whales.org/whales-dolphins/species-guide/white-beaked-dolphin/.
Written by Maddie Marquardt. Contact the author at mamarquardt@davidson.edu.
© Copyright 2022
Department of Biology, Davidson College, Davidson, NC 28036.
This is a great summary! Understanding how organisms adapt, or fail to adapt (as seen in my butterfly extinction paper), to our changing world is so interesting. I especially like your mention of potential policy-based change that could help mitigate some of the effects of climate change on these dolphin species. While I agree that global climate-change legislation is urgently needed to bring down ocean temperatures, I wonder what kind of local coastline policy might be required to help these dolphins. After some quick Google searches, it looks like dolphin hunting is not a huge issue, especially in the regions where the white-beaked dolphins are found. However, I could see high fishing quotas in their habitats being a potential food source issue for the dolphins. As climate change is a human issue, we are undoubtedly responsible for mitigating the effects as much as possible, and any number of policy changes, whether large or small, are super important!
I appreciate that you took the time to include possible difficulties and caveats to proposed regulations that would help the dolphins! It’s important to take all the limitations into account so that any measures implemented can have their desired effect on conservation efforts instead of any unforeseen harm to the species and the environment. You did a great job summarizing the article in a way that makes it accessible for a wider audience and guides the reader through the study and conclusions.