The Polar Retrospective – A migrating pike, an ancient eruption, and an Arab state with Polar ambitions | Polarjournal
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The Polar Retrospective – A migrating pike, an ancient eruption, and an Arab state with Polar ambitions

Polar Journal AG Team 20. January 2025 | Arctic, Science

An Icelandic delegation in Abu Dhabi. Image : The Arctic Circle Assembly / ADSW

The Polar Retrospective looks at recent stories from around the world’s polar regions. On the menu this week: an ancient volcanic eruption, a Polar-curious Arab country, and a freshwater fish on salty migrations.

The Polar Retrospective is a collaborative effort by the Polar Journal team. Each writer chooses a topic they found interesting and important in the past week. The intitials at the end of each section indicate the author. We hope you enjoy it.


Northern pike cross marine corridors to migrate between freshwater systems

Northern pike (Esox lucius) Photo: Wikimedia / HalbsHännile,
CC BY-SA 4.0

A new study has revealed that pike, typically considered pure freshwater fish, migrate through salt water to colonize new habitats. This discovery was made by researchers from the University of Alaska Fairbanks (UAF) and the Alaska Department of Fish and Game (ADFG) through the analysis of ear stones, known as otoliths. 

These otoliths, which retain chemical signatures of the waters the fish traverse, provided clear evidence that pike migrate through Cook Inlet near Anchorage, Alaska, to reach other freshwater systems.

This finding sheds new light into the ongoing spread of pike in the region. Native to Interior and Western Alaska, pike were illegally introduced into the Susitna River Basin in the 1950s. Since then, they have established themselves in over 150 lakes and rivers, impacting native fish species such as salmon.

Previously, the ocean was considered a natural barrier that prevented the dispersal of pike between freshwater systems. However, the study shows that the Cook Inlet and possibly other ocean-connected waterways act as migration corridors, complicating efforts to control this invasive species.

While the results are concerning, they also provide crucial information for managing the pike’s spread. “Confirming northern pike can use this pathway gave us the information we needed to now focus on preventing this spread and protecting valuable habitats,” said Parker Bradley, an invasive species biologist at ADFG, in a UAF news release. Kristine Dunker, who leads ADFG’s pike management efforts in Southeastern Alaska, added that the findings will help target resources to regions at the highest risk of invasion. J.H.

Link to the study: Matthew J. Wooller, Parker Bradley, Karen J. Spaleta, Robert L. Massengill, Kristine Dunker, Peter A. H. Westley. Estuarine dispersal of an invasive Holarctic predator (Esox lucius) confirmed in North America. PLOS ONE, 2024; 19 (12): e0315320 DOI: 10.1371/journal.pone.0315320

Emerging polar strategy for the United Arab Emirates

Former Icelandic President Ólafur Ragnar Grímsson and H.E. Prof. Ebrahim Al Hajri, president of Khalifa University. Image : The Arctic Circle Assembly / ADSW

Last week, The Arctic Circle Assembly, a forum for cooperation and scientific exchange in the Arctic, organized a two-hour event during The Sustainability Week, an economic forum dedicated to renewable energy and technological advancements in Abu Dhabi, the capital of the United Arab Emirates. Former Icelandic President Ólafur Ragnar Grímsson, president of The Arctic Circle Assembly, met there with H.E. Prof. Ebrahim Al Hajri, president of Khalifa University. The United Arab Emirates is developing a polar strategy based on scientific diplomacy.

Last August, a delegation of Emirati representatives, including H.E. Prof. Ebrahim Al Hajri, visited the University of Tromsø, which has established collaboration agreements with Khalifa University. The polar segment was among the areas of collaboration, and the delegation visited the IC3 laboratory. In October, the Emirati Meteorological Center signed a partnership with the Bulgarian Antarctic Institute.

The state from the Arabian Peninsula then officially launched its polar program in early November and sent scientists to Antarctica with the 33rd Bulgarian mission at the St. Kliment Ohridski station. Finally, in December, the United Arab Emirates joined the Antarctic Treaty system on December 11 and formally acceded to it on December 24. A month ago, the Emirati polar program signed a partnership with the Indian Ministry of Earth Sciences.

Mariam Al Mheiri, head of the Office of International Affairs of the Presidential Court and chair of the steering committee for the UAE’s polar missions, stated to the press: “Joining the Treaty allows us to forge new collaborations and partnerships to conduct coordinated research on the factors of change in polar regions. It also enables us to conduct international polar missions and actively contribute to the protection of the region.” Among the country’s stated objectives is the installation of a polar station in Antarctica. C.L.

Ice core analysis rules out volcano as cause of Younger Dryas cooling 

The Herbstlabyrinth cave in Germany contains geological formations known as speleothem. These allowed scientists to gain a glimpse of the ancient climate in the region and conclude that the Lacher See eruption did not start a global cooling event. Photo: Wikimedia Commons
The Herbstlabyrinth cave in Germany contains geological formations known as speleothem. These allowed scientists to gain a glimpse of the ancient climate in the region and conclude that the Lacher See eruption did not start a global cooling event. Photo: Wikimedia Commons

About 13,000 years ago the northern hemisphere experienced a period of sudden cooling known as the Younger Dryas. Within a few decades, average air temperatures are estimated to have fallen by around 3 degrees celcius in North America, 2-6 degrees in Europe and up to 10 degrees in Greenland

Some have speculated that this event may have been caused by a volcanic eruption, particularly the Lacher See eruption in the Rhineland-Palatinate state of present-day Germany. 

But a new study from Heidelberg University rules out this theory. Through its analysis, the study concludes that the ancient eruption happened about 150 years before the Younger Dryas onset and thus could not have been the cause. 

To come to this conclusion, scientists compared two different ancient climate records. One from an ice core drilled out of the Greenland Ice Sheet, and the other from the Herbstlabyrinth cave near Hesse, Germany.  O.E.

Link to the study: Sophie F. Warken et al., Discovery of Laacher See eruption in speleothem record synchronizes Greenland and central European Late Glacial climate change.Sci. Adv.11,eadt4057(2025).DOI:10.1126/sciadv.adt4057

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