June 02, 2025
Day 1 in the field for the project "Fine scale diversity in the lava: genetic and phenotypic diversity in small populations of Arctic charr (Salvelinus alpinus)"
This Monday marked the first field outing of the year for a research project that has been running for 14 years, focusing on the genetic and morphological diversity of small Arctic charr populations living in lava caves around Lake Mývatn, in northern Iceland.
These caves, located between 57 and 500 meters from the lake, host isolated populations that offer a unique opportunity to study evolution at a very fine spatial scale. On this first day, the research team — Bjarni, Camille, Grant, Kari, Krista, and Marie — set traps in several of these caves with the aim of capturing fish for scientific procedures scheduled for the next morning.
Each individual will be:
  • Identified (PIT-tag read if the fish was previously captured),
  • Tagged (PIT-tag inserted if this is the first capture),
  • Measured (total length and weight),
  • Photographed using a standardized protocol to document morphology,
  • Sampled (fin clip collected for DNA analysis).
All fish are anesthetized, carefully handled and released back into their cave of origin after processing, to minimize stress and ensure the continuity of long-term monitoring.
In parallel, substrate samples are collected from each cave. Rocks are extracted and rinsed, and the water sieved to collect macroinvertebrates living on their surface. These samples are then preserved in alcohol for later identification in the lab. This will help us better understand food availability and diet composition of the cave charr in each population.
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A short video summarizes this first day in the field — check it out here!

Want to know more about the project? Have a look at this scientific article we recently published.

Stay tuned — more from Mývatn tomorrow!