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The Atlanticification of the Ecosystem in Svalbard
The Atlanticification of the Ecosystem in Svalbard
Global warming is having a profound and radical impact on the marine ecosystem of Svalbard, an area that is experiencing an accelerated transformation due to "Atlantification." This phenomenon, characterized by the entry of warmer and saltier waters from the Atlantic, is altering the delicate balance of local marine species [1].
Researchers at the University Center in Svalbard have monitored these changes for three decades, documenting how atlantification is affecting the pelagic ecosystem, a vital component of the marine system that depends on specific interactions between species. The introduction of Atlantic waters has created favorable conditions for the proliferation of some crustaceans, which now thrive in these new, warmer conditions. However, this alteration has cascading consequences on the local food chain [1].
A significant example of this change is the forced adaptation of seabirds, which traditionally fed on species typical of cold waters. As food availability changed, these birds began to include fish from warmer waters in their diet, demonstrating a necessary but worrying adaptation for the long-term sustainability of the ecosystem.
A visible sign of these changes is the drastic reduction in ice cover in the Kongsfjorden fjord, observable by comparing images from 1922 and 2002. The reduction in ice has significant consequences, affecting not only local fauna, but also the entire marine system which depends on the presence of ice to regulate the climate and marine habitats [1].
These changes raise crucial questions about the resilience of species, including humans, in the face of environmental changes that we have helped trigger. The formation of new ecological balances, influenced by global warming, requires further study to fully understand how they will affect biodiversity and, ultimately, humanity. These changes could irreversibly alter marine ecosystems, with long-term impacts still difficult to predict.
Fiordo di Kongsfjorden del 1922 - Credits: Anders Orvin e Christian Aslund/Fram Centre
Fiordo di Kongsfjorden del 2022 - Credits: Anders Orvin e Christian Aslund/Fram Centre
Ice cover has reduced dramatically with implications for the marine ecosystem in the fjord
Oceans: constantly evolving dynamic systems [1]
Weather, currents, tides and seasonality greatly influence marine ecosystems, making it difficult to isolate signals of long-term change from short-term natural variability. To distinguish these signals, scientists conduct long-term sampling campaigns and statistically analyze the collected data, looking for reliable evidence that confirms the observed trends.
In Kongsfjorden, Svalbard, researchers have monitored the marine ecosystem for decades, collecting a vast array of ecological and physical data. These include seabird diet samples, measurements of temperature, sea ice and plankton abundance. Ecosystem changes increasingly reflect physical changes induced by global warming and atlantification.
One of the main indicators monitored is phytoplankton, the study of which dates back to the 1970s, with systematic monitoring every summer since 2009. The data shows three distinct spring bloom scenarios. Until the early 2000s, Kongsfjorden was often covered in ice for long periods, and the phytoplankton bloom occurred in May, dominated by diatoms. With the reduction of ice cover, flowering was brought forward to April, maintaining the dominance of diatoms. However, in warmer years, a third scenario was observed: the influx of Atlantic water during the winter prevented deep mixing and ice formation, leading to delayed flowering dominated by Phaeocystis pouchetti colonies. These changes can significantly affect the marine food web, altering the timing, extent and composition of blooms.
Zooplankton has also been monitored since 1996, with a particular focus on copepods, a key group of small crustaceans. Data indicate an increase in the Atlantic copepod Calanus finmarchicus, related to warming and loss of sea ice. Surprisingly, the abundance of its Arctic cousin, C. glacialis, has not decreased, but has instead shown adaptations that improve its reproductive efficiency and shorten its life cycle, leading to a reduction in body size. These changes could make energy transfer along the food chain more efficient, but could also create challenges for predators that select prey based on size, as smaller copepods may be more difficult to catch, thus reducing the effectiveness of hunting.
Panel a) Svalbard with Atlantic and Arctic currents influencing Kongsfjorden. Panel b) Sea ice index (blue) and ocean temperature (red) records at Kongsfjorden. A lower sea ice index implies less sea ice. Temperature data are from Tverberg et al. (2019) The Kongsfjorden Transect: seasonal and interannual variability in hydrography in The Ecosystem of Kongsfjorden, Svalbard. The figure is modified from Vihtakari et al. (2018).
Changes - West Spitsbergen Current [1]
Changes - West Spitsbergen Current [1]
The marine ecosystems of Svalbard's west coast are particularly vulnerable to climate change due to the influence of the West Spitsbergen Current, a branch of the warm northward North Atlantic Current. This flow of warmer water causes the fjords of Svalbard's west coast to respond to climate change more quickly than other regions of the Arctic.
La corrente di West Spitsbergen
The current Atlanticification process means that warmer and saltier waters penetrate deeper into the fjords than in the past. During the spring bloom, phytoplankton uses solar energy to produce sugars and lipids, which represent an essential source of nutrition for herbivorous zooplankton, such as copepods of the Calanus genus. These copepods are a vital link in the food chain, transferring the energy stored by phytoplankton to higher-order predators.
Atlantic predators such as Atlantic cod (Gadus morhua) are becoming more present in Svalbard waters, placing greater predation pressure on local species, such as polar cod (Boreogadus saida), and on lower trophic levels, including copepods. This invasion of Atlantic species not only alters predatory dynamics, but can also destabilize the structure of the marine ecosystem, causing cascading changes that affect the biodiversity and sustainability of the system.
Significant ecosystem changes in the coastal zone of the seabed [1]
A long-term photographic study, covering a period of 30 years, documented subtidal benthic communities on rocky bottoms in Kongsfjorden and Smeerenburgfjorden, further north. The results show an increase in macroalgal cover since the mid-1990s. This increase is particularly relevant because kelp provides a new habitat for various benthic invertebrates, many of which have become more abundant, while other species have declined. The changes observed in the benthic community have been directly linked to climate change, in particular the reduction of sea ice and warming waters, which have intensified the influence of Atlantic conditions on these ecosystems.
However, the response of muddy bottom species to these changes has not been as consistent. The variations observed over time appear to depend not only on global warming but also on other physical factors whose variability may have influenced these communities. A central element of this research focused on ecological resilience, the ability of Kongsfjorden's marine food web to withstand continuous change.
Data indicates that the 2006 Atlanticification event resulted in a significant loss of ecological resilience, making the system more vulnerable to possible biodiversity loss. However, since 2013, signs of improving ecological resilience have been observed, thanks to changes in the way species feed and interact with each other. Furthermore, increased secondary productivity was found, both in Kongsfjorden and in coastal areas of Svalbard, suggesting the emergence of a new marine food web that is starting to adapt to ongoing climate change.
The changes observed in Svalbard are occurring at an accelerating pace: the fauna of the west coast fjords, once typical of the High Arctic, is becoming increasingly similar to that of the ecosystems present along the Norwegian coast, with food webs that include a number growing Atlantic species. This phenomenon raises concerns about the future of remaining Arctic species, which could gradually decline in abundance until they completely disappear from the ecosystem.
Some Arctic species, such as the copepod Calanus glacialis, seem to show a surprising ability to adapt to the new environmental regime, adopting life strategies similar to those of Atlantic species, thus contributing to the resilience of marine ecosystems in Svalbard. However, it is still too early to determine with certainty the outcome of competitive interactions between Atlantic newcomers and Arctic residents. Scientists are still gathering data and evidence to understand who the losers and winners will be in this great climate experiment.
Deschampsia cespitosa
Ranunculus subborealis subsp. villosus
"Alien" Plants
"Alien" Plants
The growing impact of human activities and climate change are increasing the risk of the introduction and establishment of non-native plant species in Svalbard. This phenomenon is of concern to researchers, especially Kristine Bakke Westergaard, associate professor at the Department of Natural History at the Norwegian University of Science and Technology (NTNU) [2].
Non-native species, which are spreading to different regions of the planet, have the potential to alter the ecological balance of established areas. Svalbard is particularly vulnerable due to its growing appeal as a tourist destination, especially for cruises. Unlike Antarctica, where there are strict biosecurity measures to prevent the introduction of invasive species, there are no adequate controls in Svalbard to monitor whether visitors are carrying seeds or other potentially harmful organisms, for example through contaminated shoes or imported soil [2 ].
Currently, only the most resistant species manage to survive in the archipelago, but with global warming, an increasing number of species could find Svalbard a suitable environment for their settlement. Among the non-native plants with the greatest potential for diffusion in the archipelago, we identify the couch grass (Deschampsia cespitosa), a species of meadow buttercup (Ranunculus subborealis subsp. villosus), and the Alpine saussurea. Climate models predict that almost all areas of Svalbard could develop a climate favorable to the establishment of these invasive plants [2].
To prevent these new species from compromising the ecological balance of Svalbard, researchers highlight the importance of implementing targeted preventive measures. Preventing the spread of non-native species should become a priority to safeguard the Arctic ecosystem, before the situation becomes irreversible and difficult to manage.
Bibliography
[1] https://framforum.com/: Mikko Vihtakari, Haakon Hop, Philipp Assmy, Gary Griffith, Pedro Duarte, Anette Wold and Geir Wing Gabrielsen / Norwegian Polar Institute, Malin Daase, Bodil Bluhm and Else Nøst Hegseth /UiT The Arctic University of Norway, Paul E. Renaud and Janne E. Søreide /University Centre in Svalbard, Børge Moe / Norwegian Institute for Nature Research, October 2019, https://www.unis.no/news/atlantification-of-the-marine-ecosystem-in-kongsfjorden-svalbard/
[2] July 2024, Repubblica, https://www.repubblica.it/green-and-blue/2024/07/26/news/piante_aliene_ecosistema_svalbard-423415524/
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