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Billefjorden, April 2013; an seasonal ice covered fjord 60km north of UNIS. In 2012-13, we sampled this fjord monthly to document the lifecycle of C. glacialis. Photo JE Søreide.

The research project “Climate effects on planktonic food quality and trophic transfer in Arctic Marginal Ice Zones II” (CLEOPATRA II) studies the degree of match/mismatch of key biological processes at the base of the Arctic marine food web in a changing Arctic. Reduced sea ice cover and earlier sea ice break-up results in more incoming light that will change the timing, quantity and quality of the Arctic spring bloom. We study grazers’ ability to adapt their key life cycle events to a new primary production regime in a warmer Arctic.

Altering sea ice conditions changes the underwater light climate and thus the timing, quantity and quality of primary producers. Currently, two main algal food sources exist in the Arctic: sea ice algae growing within and on the underside of sea ice, and phytoplankton in open waters. Sea ice algae are specialised to grow under very low light and terminate growth when their sea ice substratum melts. In contrast, phytoplankton production starts after the onset of sea ice melting, giving a temporal discontinuity of up to two months between the sea ice algal and phytoplankton blooms. More light may potentially lead to higher total primary production, but not necessarily higher secondary production if grazers are not capable of adjusting their current lifecycle and physiology to a changing primary production and temperature regime in the Arctic.

In CLEOPATRA II, we study the plasticity of the herbivorous copepod Calanus glacialis to tune its seasonal migration, reproduction and growth to a changing light, primary production and temperature regime in Arctic shelf seas. This relatively large (4-5mm) calanoid copepod comprises up to 80% of the zooplankton biomass in Arctic shelf seas. Due to its ability to convert low-energy carbohydrates and proteins in algae into high-energy wax ester lipids, C. glacialis is extremely lipid-rich (50-70% lipids of its dry weight) and thus a very important food item for higher trophic levels, such as fish, birds and mammals. This fat copepod ensures that the essential omega-3 fatty acids − eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) − which are produced exclusively by marine primary producers such as ice algae and phytoplankton, are efficiently channelled to higher levels in the food chain. These omega-3 fatty acids play a key role in reproduction, growth and physiology of all organisms in marine ecosystems, as well as for human health. The fate of this extremely fat and nutritious copepod in a warmer Artic is thus of vital importance to predict the vulnerability of Arctic marine ecosystems to climate change.

Calanus glacialis has a one to two-year lifecycle, depending on temperature and food regime. The lifecycle includes six nauplii and six copepodite stages that follow a pronounced seasonal migration pattern. Females of C. glacialis utilise the high-quality ice algal bloom to fuel early maturation and reproduction, whereas the resulting offspring have access to ample high-quality food during the later occurring phytoplankton bloom. In autumn, C. glacialis fills up its lipid storage and descends towards the deep, entering a dormant state called diapause to survive the long and dark, food-poor winter. It can survive up to ten months without food by reducing its metabolism to an absolute minimum, relying on internal fat stores. Several fjords in Svalbard are now experiencing positive (up to 2°C) in contrast to previously negative (-1 to -1.8°C) bottom sea water temperatures in winter. Warmer winter sea temperatures will increase this copepod’s metabolism during overwintering, with potentially negative consequences for its survival, and thus reproduction, the following spring.

In CLEOPATRA II, we combine extensive field and laboratory investigations with model development to ultimately arrive at an improved understanding of the physiological and life

history adaptations of C. glacialis to a changing climate. The following 3 main tasks have been accomplished:

1) Through field investigations, we have documented the full annual cycle of Calanus glacialis. This will allow for testing of predictions on diapause duration, critical size of lipid storage, and the reproductive success and population abundance of this key Arctic grazer;

2) In laboratory studies, we have obtained fundamental measurements of metabolism and diapause-flexibility of C. glacialis, including testing of predictions on the light, temperature and food-dependence of these traits; and

3) Finally, we have modelled the life history of C. glacialis in order to predict optimal strategies for specified environments and thereby predict how C. glacialis and similar species may respond to climate change in the Arctic.

CLEOPATRA II is now in its final year (ending July 2015), currently being in an intensive analysing and writing phase, preparing for the publication of main project results. News and publications from this and other related projects can be followed at www.mare-incognitum.no.

Fact box 1:

CLEOPATRA II, funded by the Norwegian Research Council, project no.: 216537, 2012-2015, is headed by the University Centre in Svalbard (UNIS) and is one of several projects organised under the Mare Incognitum project umbrella (www.mare-incognitum.no). CLEOPATRA II’s international partners are Germany (Alfred Wegener Institute, AWI), Poland (Institute of Oceanology, Polish Academy of Science, IOPAS) and Russia (Institute of Oceanology, Russian Academy of Sciences, RAS), whereas national partners include the Norwegian Polar Institute (NPI), Akvaplan-niva (APN), University of Tromsø (UiT) and the ARCTOS research network (www.arctosresearch.net).

Fact box 2:

UNIS is the world’s northernmost institution for higher education and research, located at 78°north in Svalbard. At UNIS, students get the opportunity to participate in on-going research, and in CLEOPATRA II we actively involve students in our extensive field and laboratory work. Together with the University in Bergen and the Institute of Marine Research (Norway), the Department of Arctic Biology (UNIS) have established bioCEED, an educational programme which has been awarded status as a Centre for Excellence in Biology Education (for more information, see: http://www.bioceed.no/).

Calanus glacialis – a very important prey item for higher trophic levels in Arctic marine ecosystems. The oil sac almost fills up the entire body cavity in this fat and nutritious copepod. Photo JE Søreide.

Associate Professor Janne E Søreide
Dr. Scient, Marine Biology
The University Centre in Svalbard (UNIS)
Department of Arctic Biology
tel: +47 79023300
[email protected]
www.mare-incognitum.no