Effects of climate change on the Arctic marine fauna

Effects of climate change on the Arctic marine fauna

Top image: An Atlantic cod hiding in a cove at 35 m depth by the Kvadehuken. Cod in these caves were first spotted in 1978 and since spotted every year, even if there have been very little or no cod in the open ocean. The cod probably hide here to avoid being eaten by seals. Photo: Bjørn Gulliksen/UNIS.

UNIS scientists have examined the marine ecosystems of the Svalbard fjords and found several exiting results which can be directly linked to the climate changes in the Arctic.

30 September 2008
Text: Professor Jørgen Berge, Dr. Øystein Varpe, Dr. Janne Søreide, Assoc. Adjunct Professors Paul Renaud and Bjørn Gulliksen, Associate Professor Ole-Jørgen Lønne

This fall six scientists from UNIS have, together with several scientists and students from Norway and abroad, been on a scientific cruise along the western and northern coast of Svalbard with the RV Jan Mayen. We have conducted a series of examinations of the marine ecosystem in the fjords of Svalbard, and we have found a series of exiting results which can be linked to the climate changes in the Arctic.

Among the results found, there is a record amount of Atlantic cod (Gadus morhua), in addition to obvious changes in the benthic fauna along the coast. Both these changes can be directly related to the recent warm winters with minimal ice formation in the fjords.

These trends occur at the same time as most of the fjords in Northern Svalbard are packed with drift ice, which prohibited several ships from entering the fjords on the north side of Nordaustlandet this summer.

Continuous monitoring program
The Norwegian ocean research vessels are sailing each up to 300 days per year, and for the most part they sail in the Northern areas. These annual scientific cruise expeditions play an integral part for the ocean research, environmental – and resource surveillance in the Arctic.

These cruise expeditions in the Svalbard waters have been conducted on a regular basis for the past 30 years. The continuous time series these cruises provide are extremely important for our interpretation of the effects of climate change on the Arctic ecosystems. Scientists and students at UNIS contribute annually to this important collection of knowledge.

Cod population in the fjords
This year there are large amounts of cod in Kongsfjorden and other fjords on the western side of Svalbard. A short trawl haul along the ocean floor produced more than half a ton of cod. Most of the fish were around 60 cm long, and the biggest fish weighed over 4 kilos. The cod lives on shrimp and seemed to have had happy feeding days in the fjord.

The Kongsfjorden has been one of our regular observation areas for years, so we know a great deal about the types of fish and benthic fauna living there. Even if there have been years with irregular influxes of cod into the fjord, the species have become a predominant occupant of the fjord over the last couple of years, compared to the 1980s. As long as the water is warm enough and there is plenty of food, it is no surprise that the cod swim as far north as Spitsbergen to feed.

The main area during the feeding season for the cod is just south of Svalbard, in the Barents Sea. Maybe large amounts of cod will become a regular feature along our west coast in the future.

We also caught spawn and small fish of both cod and other fish species, which are traditionally found further south than Svalbard, such as haddock, catfish and smelt. These observations were done as far north as the ice edge at 80ºN.

A changing ocean floor
The ocean floor around Svalbard is home to a rich and diversified flora and fauna, which reflects the physical conditions in which they live. In the 1970’s, when “the environment” became an important subject, several Norwegian marine biologists were involved in projects where the aim was to map and monitor benthic communities over time.

Along the Norwegian coast and along Svalbard a network of chosen localities were photographed by divers each year. The surveillance systems of Kongsfjorden and Smeerenburgfjorden were established in 1980, and these systems have given us a lot of information about the state of the ocean floor surrounding Svalbard.

A clear trend is that the biodiversity seems to follow both local and global climate variations. From the mid-1990s a more profound change occurred. At that time more algae was observed along the ocean floor than in the previous 15 years of monitoring. The most likely cause is the decreasing amount of fjord ice which resulted in that the sea flora was exposed to more sunlight. The trend has continued over the past two-three years as the amount of algae increases in the monitored areas. However, there have not been registered effects on the marine life structure which can be directly related to human activity.

Ocean floor by Kvadehuken, 1980 (left) and 2008 (right).

Two pictures of the same part of the ocean floor (¼ m2) in Kvadehuken, Kongsfjorden, taken at 28 years’ interval (left image: 1980, right image: 2008). The pictures show the same rocks, but a totally different flora and fauna. Notice the increased amount of algae, but less sea anemones in 2008. Photos: Bjørn Gulliksen, Sten-Richard Birkely.

“Warming” trends despite “cold” summer
Changes in the climate affect the marine ecosystem. As these two examples show, the last years’ more temperate winters have resulted in obvious changes in the ocean floor flora and fauna. The summer of 2008 we had a lot of drift ice on the north side of Svalbard, which might be contributed to that the natural state of things is on its way back to “normal”. But, why do we still observe such changes in the ecosystem when we’ve had a “cold” summer with a lot of drift ice?

The last two winters UNIS has conducted a series of biological investigations in Rijpfjorden in Nordaustlandet. In the beginning of this decade the fjord ice broke up during the month of July, whereas in 2008 the ice started breaking up in mid-August. The areas on the northern side of Svalbard were so filled with ice that the larger research vessels could not enter the fjord this summer. The reason for the greater amount of ice is not due to a larger ice production in the Arctic ocean this summer compared to previous years. In 2008 there is registered about as little ice as in 2007, and a further opening of the Arctic ocean and thinner sea ice have led to higher speed and motion in the ice.

The direct effect of this is most likely observed along our Northern coast where the fjords are packed with drift ice. Another matter is the processes which occur independently of each other in summer and winter.

UNIS scientists have established that wind direction and temperatures previous years have great importance for the formation of sea ice the following winter. Less ice in the winter leads to greater influx of warm water in the summer, which reduces the likelihood of the fjords freezing the following winter. This process is the most likely cause to the observed changes in the ocean flora (red algae) and fauna (cod).

Local and global effects
If the warming of the Svalbard waters continue, we will expect to see more ”southern” species establishing themselves here. The discovery of blue mussels in Isfjorden a few years back is an example of a system in change, where the scientific explanations for these changes seem to be the same as for the significant increase of cod in the fjords.

Another conclusion we can draw, based on the contrast between the development of the cod stock and ocean flora against this year’s “cold” and ice filled summer, is that the coherences in nature are often complicated and very difficult to predict in its entirety.

Changes in the climate might have produced an effect locally (more ice along the Svalbard coast this summer), but a different effect globally (less ice in the polar ocean). The research being conducted both nationally and internationally in the International Polar Year (IPY) will contribute to increased knowledge about how climate changes affect our area in the future.

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