After the storm
"Night has always pushed up day
You must know life to see decay
But I won't rot, I won't rot"
- "After the storm" by Mumford and Sons
Back when the wind started (was it really only a few days ago?), it occurred to me that the storm could actually work in our favor. Remember, we're up here to investigate the effects of upwelling Atlantic water on biological communities in an Arctic fjord in mid-winter. We planned our trip at the beginning of January so that we'd be here when warm, salty water from the North Atlantic started coming into the fjord. The idea was to collect samples before and after the upwelling event.
When we first arrived in Ny-Ålesund, it was obvious that the fjord was in its 'normal' winter state, filled with Arctic water - temperature and salinity in the water column were low, sea ice surrounded the harbor, and most of the animals we caught were Arctic species. Well, with gale-force winds blowing down the fjord, some of the surface water was bound to get carried offshore. Anytime surface water is moved, bottom water comes up to replace it, and this process is known as upwelling. If we're lucky, I thought, maybe the winds could cause the Atlantic water to start welling up.
And boy, we were lucky. The water in the fjord is warmer and saltier now than at the beginning of our trip, and I interpret this to mean that the Atlantic water has moved in! I almost can't believe that our plan for the trip is working so well! If there's one thing I've learned about the natural world as a marine biologist, it's that it does not respect human plans. It does what it wants, and you have to keep up. But just this once, nature did what I expected it to, what I wanted it to, and I am so grateful.
You might be wondering how we know the water is warmer and saltier. Well, we use an instrument called a CTD, which stands for Conductivity, Temperature, and Depth. The instrument measures pressure to figure out what depth it's at, temperature, and conductivity, which is essentially how easily electricity is transmitted. Because electricity requires free ions to travel in water, the conductivity is related to how much salt is in the water (remember salt dissociates into ions when it dissolves). The instrument has several integrated sensors and stores its data internally, so you can basically lower it over the side of the boat, bring it back up, stash it in its box, and then download the data back at the lab. It's very convenient.
We can clearly tell from the CTD data that the water in the fjord is different now than it was before. What's really cool is that we're also seeing different species in our plankton samples. Gone are the large comb jellies and arrow worms. Gone are the sea angels. Instead, our samples have many more copepods (tiny shrimp-like things) and warm-water species. We found one jelly, called a hydromedusa, that my colleague, Hongju, recognized. It occurs all over the globe, he said, but he usually sees it in the Kuroshio Current, which has very warm water. The species is usually associated with warm, salty water coming north from the tropics. We think the Atlantic water is bringing warm-water species into the fjord.
Our samples are showing very interesting patterns! I'm excited to continue the analysis and demonstrate the ecological effects of an environmental phenomenon in the Arctic!
You must know life to see decay
But I won't rot, I won't rot"
- "After the storm" by Mumford and Sons
Back when the wind started (was it really only a few days ago?), it occurred to me that the storm could actually work in our favor. Remember, we're up here to investigate the effects of upwelling Atlantic water on biological communities in an Arctic fjord in mid-winter. We planned our trip at the beginning of January so that we'd be here when warm, salty water from the North Atlantic started coming into the fjord. The idea was to collect samples before and after the upwelling event.
When we first arrived in Ny-Ålesund, it was obvious that the fjord was in its 'normal' winter state, filled with Arctic water - temperature and salinity in the water column were low, sea ice surrounded the harbor, and most of the animals we caught were Arctic species. Well, with gale-force winds blowing down the fjord, some of the surface water was bound to get carried offshore. Anytime surface water is moved, bottom water comes up to replace it, and this process is known as upwelling. If we're lucky, I thought, maybe the winds could cause the Atlantic water to start welling up.
 |
| Deploying the CTD on Teisten |
You might be wondering how we know the water is warmer and saltier. Well, we use an instrument called a CTD, which stands for Conductivity, Temperature, and Depth. The instrument measures pressure to figure out what depth it's at, temperature, and conductivity, which is essentially how easily electricity is transmitted. Because electricity requires free ions to travel in water, the conductivity is related to how much salt is in the water (remember salt dissociates into ions when it dissolves). The instrument has several integrated sensors and stores its data internally, so you can basically lower it over the side of the boat, bring it back up, stash it in its box, and then download the data back at the lab. It's very convenient.
 |
| The hydromedusa, a warm-water species, in a dish of sea water in the lab. Photo by Hongju Chen. |
Our samples are showing very interesting patterns! I'm excited to continue the analysis and demonstrate the ecological effects of an environmental phenomenon in the Arctic!
Comments
Post a Comment