Week 3; melting, freezing, Norwegian victory & urchin babiesMay 19, 2009
View up the now mainly ice free fjord this week. Photo: Hannah Wood
A catchy title! It seems to have been a while since I have written a blog. I think because we have settled into life here all the amazing things we do each day seem somehow less newsworthy. However I thought I would give you a general update on the goings on over the past week, both inside the laboratory, and generally about town. So perhaps I should start with the science as this is the bit that occupies most of our waking hours.
Helen and I have been working on the urchin fertilisation experiment this week which has been interesting, hardwork and a lot of fun too. It started off with selecting some urchins to spawn. We chose mainly larger urchins for this in the hopes they would contain more eggs or sperm. One of the main problems we faced is that unlike a lot of animals, particularly mammals, there is no easy way to tell whether a sea urchin is male or female. Because of the way in which they reproduce there is also no particular need for the urchins to be able to tell whether the urchin next to them is male or female. When they reproduce they do so by what is known as broadcast spawning. Based on some cue from the environment (with urchins this is usually a mixture of light levels and temperature increase) the urchins all release their eggs or sperm in a big synchronised event. The sperm then fertilises the eggs in the water column, the eggs develop into larvae which looks very different from an adult sea urchin. Then when they are developed enough the larvae settle on the sea floor and turn into the form a of a sea urchin that you would recognise. Broadcast spawning may not seem the most effective method of reproducing at first glance, particularly as a high degree of synchronicity is required to ensure that the eggs are fertilised. However it is effective and the most common method of reproduction in marine invertebrates; for example the corals on the great barrier reef in Australia all spawn each year in one event so big that if you dive at that time you can hardly see through the water. Anyway enough of that, back to the cold cold waters of the arctic and the urchins. As I said we did not know which urchins were male and which were female. For our experiment we needed to collect the eggs of five females and mix it with the sperm from one male; that way all the developing larvae would be half siblings. Based on our earlier trials I though we’d have plenty of females. So we set up 8 urchins over pots in which we were to collect the eggs, then injected potassium chloride into them; this chemical should be kept well away from humans (it doesn’t have the same effect so no home experiments please) but in invertebrates it makes them spawn their eggs/sperm. We ended up with more males and females on our first attempt. So we started some more and had just the right amount to begin.
Spawning urchins; a male on the left and a female releasing eggs on the right. Photo: Bonnie Laverock
We mixed a known amount of eggs with a drop of sperm in water collected from our tanks- so we had 5 different pH treatments under which we carried this out. Then the hard work began; over the next 24 hours we had to check the stage of development. Initially this was just looking for a fertilisation membrane which shows that the egg has been fertilised. As time progressed we also had to count the cell stages. Just like the beginnings of a baby, the process begins with a single cell dividing into two, and then 4, and then 8 and so on. We have since repeated this experiment at a warmer temperature to see if this too had an impact on the speed of development or survival. Have a look below and see if you can see the ‘halo’ like fertilisation membrane around the yellow looking egg, and then at the 2 cell and 4 cell stages where the fertilised egg has begun to divide:
Top: Urchin eggs with fertilisation membranes & one 2 cell. Bottom: 4 and 8-cell stages. Photos: Hannah Wood
In other news spring has begun here in Ny Alesund- the first sign of which was the melting fjord. Since then we’ve noticed the roads around town turning slushy and eventually revealing the gravel underneath. The Eider ducks have arrived now that there is open water in the fjord and every now and again I hear the honk of a barnacle goose flying by. They will soon be arriving properly from their overwintering site in Scotland to lay eggs and rear their chicks. As the surrounding environment was changing so rapidly, Helen and I took the opportunity to go out and measure the conditions in the slushy seawater just accessible through the ice cracks, and also to see the conditions on the newly exposed rock where Helen’s barnacles are.
Helen Findlay measuring the temperature at the barnacle site. Photo: Hannah Wood
The Sunday just gone was Norwegian National day so the locals (and a few game scientists too) had a day of games and celebrations that began with a ‘wake parade’ with very loud drums banging and a badly played trumpet! There were several people wearing traditional Norwegian costumes and the day ended with a special barbecue at Magrallet Cafe. There were added celebrations when Norway won the Eurovision song contest the night before! It is quite an international community here so we all joined in and helped the Norwegians celebrate.
Ana-Krostoph (Left) and Bendik Helgunset (Right) in traditional Norwegian
costumes in National Day. Photos: Hannah Wood
So that’s us up to date. We put another urchin treatment in today so Thursday and Friday will be very busy sampling. The good news for us is that we have all the urchins we need now so have no more demands to make of the hard working divers. We are even hoping to spend an entire day out of the lab this weekend with a trip to a cabin. . .it’s a good incentive to work hard this week anyway 🙂