Arctic Biology 2010

Field course in Arctic Biology – University of Copenhagen

Every second year 12 biology students from University of Copenhagen are given the opportunity to experience the Arctic in three-dimensional space and to perform research projects in the vicinity of Arktisk Station at Qeqertarsuaq. This year the projects are centered around two main themes in marine biology (i) diversity and ecology of marine phytoplankton and (ii) physiology of Greenland cod (Gadus ogac) and Greenland shark (Somniosus microcephalus). For these projects we use Porsild to obtain water samples and for setting long lines for shark fishing outside Qeqertarsuaq harbor. Cods are caught from a small vessel. Samples are brought back to the lab for further processing and experimental work. We are using most of the available lab space and the temperature controlled container located next to the lab building.

A course like this can only be efficient and successful with the help of the staff members at Arktisk Station. Therefore we would like to thank Outi Tervo, Frantz Nielsen, Frederik Grønvold, Erik Wille and Lars for all the help that they have provided during our three week long stay (3-24 July).

In addition to the project work, which will be described in more detail below the course participants have also been introduced to other research topics by a series of evening lectures. These have covered (i) “geology of the area” by Gunver and Stig Pedersen, (ii) “shark studies” by Peter Bushnell, (iii) “studies on Pyrola hybrids” by Thure Hauser, and (iv) “bowhead whales” by Outi Tervo and Mads Christoffersen. Finally Per Mølgaard kindly took us on a 3-hour long walk in Østerlien and showed us a huge number of plant species typical for the area. We thank our colleagues for taken time to present parts of their work to all of us.

More detailed descriptions of the five student projects being performed.

Species diversity and abundance of potential harmful marine microalgae

By Maria Laugmann Laubacher, Tine Dencker Bædkel and Hannah Eva Blossom.

Our understanding of the diversity and abundance of potential harmful microalgae in Arctic waters is rather limited. In fact only a single yet unpublished study has measured toxins in one dinoflagellate species. In this project we have collected water samples from a total of 11 stations positioned around Disko Island. At each station water has been collected from 10, 25, 45 and 75 meters. Additionally netplankton has been collected using a 20-µm plankton net. The species diversity is documented using light microscopy of live cells and Lugol fixed samples from 3 to 4 depths are being counted in an inverted microscope using the Uthermöhl method. Individual cells are isolated for single-cell-PCR from either filtered seawater samples collected at specific depths or net hauls. We hope to bring back live samples to our lab at Dept. of Biology for establishing clonal cultures that can be used for more detailed systematic, ecological and molecular studies. At present we have documented potential harmful microalgae from 3 classes: Dinophyceae (7+ species), Bacillariophyceae (2 species) and Haptophyceae (1 species). The counting is ongoing but the data processed up until now reveals low abundances (cells per litre) for all potential harmful species of microalgae.

Arctic HAB team

Biomass and productivity of marine phytoplankton with an emphasis on the contribution by picoplankton

By Signe Lett, Signe Sofie Larsen and Maria Lund Paulsen

To study biomass and productivity of the arctic marine phytoplankton community during the summer bloom seawater samples from specific depth were collected around Disko Island using a Niskin water sampler. During the study period a total of 8 stations have been sampled and from each station water was collected from 3 or 4 depths (viz. 10, 25 45 and 75 m). In order to distinguish the contribution by the net-, nano- and pico-plankton size fractions 2 or 4 liters of seawater from specific depths were filtered through filters with a pore size of 20, 3 and 0.6 µm, respectively. The size fractioned algal biomasses were estimated by ethanol extraction of chlorophylls. The concentration of chlorophyll a was measured using a spectrophotometer. The concentration of phaeopigment has also been measured spectrophotometrically. Productivity experiments have been performed at two stations (one north of Hareø and the other at the mouth of Disko Fjord) by incubating 0.5-liter seawater samples collected at three depths (10, 25 and 45 m). The incubation period lasted 3 hours and we used the 13C isotope. Preliminary results reveal that during the sampling period we see a decrease on algal biomass going from north to south. Additionally picoplankton organisms (here defined as 0.6-3 µm) do not seem to be of insignificant importance in arctic marine waters.

P-B team

Metabolic rates in Greenland cod (Uvak), Gadus ogac

By Daniel Hoffmann and Lea Stenfeldt

The aim of this study is to document the scope at different temperatures between the minimum metabolic rate needed to sustain life (standard metabolic rate) and the active metabolic rate, measured after having forced the fish to swim until exhaustion. The scope is measured at 5˚C and 10˚C in both the Uvak, Gadus ogac and Atlantic cod, Gadus morhua. The Uvak is an exclusive polar species whereas Atlantic cod is to be found in both polar and temperate waters. Comparing the two of them could give an indication of whether the Uvak is metabolically adapted to the cold environment (MCA). Temperature is only one of the major factors having an impact on the metabolic demand of fish. Another impact factor is the water oxygenation level which is known to set the upper limit for metabolism and therefore shows the metabolic framework. Hence the metabolic rate is also measured during hypoxia at both of the aforementioned temperatures.

Greenland cod team 1

Cardio-respiratory and ventilation in Greenland cod: normoxia and hypoxia

By Karina Juhl Rasmussen and Thomas Warnar

Cardio-respiratory synchrony is a characteristic, that until recently was thought to be restricted to mammals only. The purpose of synchrony is to optimise the oxygen uptake at low oxygen concentrations and during exercise. New data have shown, that Atlantic cod living in temperate water have the capability of cardio-respiratory synchrony when exposed to hypoxia. This means, a close coupling between the water flow over the gills, with the blood flow within the gills so the uptake of oxygen via the counter-current system, at the gills can be optimised.  Since fish living in temperate and tropic water have a risk of being exposed to environmental hypoxia, the capability for optimisation of the gas exchange via synchrony of obvious reasons is beneficial. But what about polar fish species, living in cold water and therefore rarely are exposed to low oxygen concentrations, do they have the same capability? In addition, previous research has shown, that polar species are able to show cardiovascular changes to even small oxygen changes. Therefore this study aims to test whether the Greenland Cod is capable of synchronising.

Greenland cod team 2

The Cardiac function of the Greenland cod (Gadus ogac)

By Michael Frisk and Anders Hostrup

The Greenland cod (G. ogac) is a fish species that lives in the fjords and along the coasts of Greenland. The aim of the project is to investigate cardiac function in Greenland cod. These studies are conducted on isolated heartstrips of the species. Force generation in muscles is highly dependent on calcium influx to the individual muscle cells. This influx is possible in two ways, 1: Calcium flow from the extracellular matrix and 2: flow from an intracellular compartment called the sarcoplasmic reticulum (SR). Various hypothesis have been proposed regarding calcium handling in arctic fish, and thus our goal is to investigate whether SR plays an important role in cold acclimated fish or not. So far we finished the experimental part of the project but thorough data analysis and interpretation still remains in order to make sense of the results.

The original idea of our project was to investigate the cardiac function of the Greenland shark (Somniosus microcephalus) a large shark that lives in the cold, deep waters surrounding Greenland. The species still remain largely uninvestigated and therefore we hoped to clarify how this species is adapted to the cold environment in relation to cardiac performance. During the last three weeks we have set benthic long lines in hope to catch Greenland sharks. This has however been without success.

Project supervisors: John Fleng Steffensen and Niels Daugbjerg (Department of Biology).

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