Exploring evolutionary and ecological solutions to DHA deficiency during colonization of freshwater by marine fish in South Greenland
Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz - EAWAG
Lay summary
Polyunsaturated fatty acids (PUFAs) are essential nutrients, but they differ in abundance within and between habitats. They are abundant in marine environments, but less so in freshwater, and this poses a challenge for fish species that colonize freshwater from the ocean. As the environment changes, it is likely that we will observe range expansions and colonizations by marine fish. This is particularly relevant in the Arctic, where the melting of glaciers will create new freshwater habitats that lack fish. To survive in these new habitats, fish must evolve adaptations to obtain the essential nutrients that they need. One important PUFA, docosahexaenoic acid (DHA), is crucial for its role in neural development of vertebrates, and is essential for survival. Organisms can either obtain DHA directly from their diet, or synthesize it from other fatty acids. Some fish species have shown a duplication in the FADS2 gene, which helps them synthesize more DHA, while others are morphologically adapted to forage on DHA rich prey. With this project, we aim to investigate these two evolutionary adaptations that fish evolve to obtain DHA when colonizing freshwater habitats. The melting of glaciers and associated changes in sea level have provided opportunities, and created barriers, for species to shift their range or colonize new habitats. Threespine stickleback (Gasterosteus aculeatus) are a marine fish species that have repeatedly colonized freshwater around the northern hemisphere. In Greenland, freshwater habitats only became accessible to fish after the melting of glaciers, between 20,000-12,000 years ago, so we have a rough estimate of the age of freshwater populations. During this field campaign, we plan to collect freshwater stickleback from populations of different age throughout Southern Greenland. Once back in the lab we will determine the number of FADS2 genes they possess, compare this to their DHA content from muscle tissue, and measure morphological traits related to prey capture efficiency. By studying Greenlandic stickleback populations, we will learn more about how aquatic organisms evolve when faced with nutritional constraints.
Details
| Regional focus | Arctic |
| Location | Greenland – Narsarsuaq / Quassiarsuk |
| Funded amount | 15,000 CHF |
| Project dates | 1st May 2020 – 30th November 2021 |
| Category | Polar Access Fund |