Guest blog by SOI educator and Oceanographer Daniele Bianchi
After a few hours of sustained wind, the sea is finally quiet enough to let us venture into the mouth of the Coutts Inlet, along the northeast coast of Baffin Island. On the zodiac, about ten students will take up different roles while participating in the oceanography workshop. They will measure profiles of temperature and salinity by operating a Conductivity-Temperature-Pressure instrument (CTD), estimate the turbidity of the water by dropping and retrieving a Secchi disk, and use two plankton nets to sample tiny animals and plants that live in the inlet. We stop the zodiac a few hundred meters offshore, and while we drift gently with the current, the students start taking notes: local time, GPS coordinates, and meteorological conditions.
Despite the current, we manage to keep track of the Secchi disk as it sinks through the blue-green water. This simple instrument has been used for more than a century to measure water turbidity, which tells us not just how much sediment is suspended in the water, but also how many microscopic algae are living in it. In the inlet, the Secchi disk disappears after sinking to a depth of less than ten meters: a far cry from clear open waters, and a sign of the amount of sediment suspended in the current. We guess that the fine silt that clouds the water comes from melting glaciers and streams that run down the mountains to feed the inlet.
Temperature and salinity profiles tell us another piece of the story. In the first few meters the water is fresh and cold, more than what we expect for typical seawater. Just a few meters deeper, the water is warmer and saltier. As guessed by the students, the shallow lens of freshwater comes from the same meltwater that brings the sediments to the inlet. Because it is less dense than salty oceanic water, it floats on top of it, barely mixing as the currents transport it to the open sea. If we were able to measure temperature and salinity across the inlet, we would be able to tell the paths of the currents, and the melting rate of the glaciers that run into it.
After measuring temperature and salinity, we set out to sample the the minute organisms that live in the water. Unlike on land, most of these plants and animals are microscopic; to collect them, we use plankton nets with very fine meshes. We use the coarser net, with a mesh of about half a millimetre, to sample zooplankton: tiny animals that float with currents, and the source of food for many fish and birds of the Arctic. The finer net has a mesh of less than a twentieth of a millimetre: it feels like silk at the touch and is fine enough to retain phytoplankton, the microscopic, single-cell algae that form the base of the marine food web. After towing the nets at the sides of the zodiac, the students recover the samples: in the cod-ends the concentrated water appears like a yellow soup, dotted by tiny, wiggling specks. The water is filled with a myriad of living organisms with elaborate shapes and delicate textures. We can readily identify some of them: copepods, sea angels and sea butterflies, jellyfish and comb-jellies. But many organisms are still invisible, too small to be seen with naked eyes.
In the second part of the workshop, we take the samples onboard the Ocean Endeavour. Like previous years, the crew helped us set up a Science Lab, where students can observe and experiment with the samples collected during the Expedition. Fish tanks, microscopes, pipettes and petri dishes are scattered around the space on many tables. The students gather around the aquaria to observe the catch of the day: sea butterflies rising and sinking through the water, clouds of copepods, jellyfish gently pulsating. We prepare microscope samples by squeezing drops of water between glass slides. This year we upgraded the Science Lab by wiring a microscope to a digital camera provided by Lumenera, a partner of the Students on Ice Foundation. With the help of the camera, we stream the images directly to a laptop, taking snapshots and videos of tiny plankton, as we follow them moving across the screen. The new setup pays off: a landscape of alien creatures, many of which we had never observed before, materializes on the screen. They are alive, crawling, wiggling, and zipping across the screen. Many are single-celled species, others are small larvae of larger animals. We observe dinoflagellates with their three horns, long chains of spiny diatoms, and individual ones, like disks of glass with elaborate patterns. The variety of shapes and behaviours is staggering: copepods, giants under the lens of the microscope, disappear with sudden jumps; larvae swim along microscopic currents, propelled by multiple lines of cilia; minuscule clams filter the water by wiggling bundles of hairs, their minute shells intact.
Students and staff stop by, curious about the alien world on the screen, and end up staring at it mesmerized. After the workshop is over, chatting with the students over dinner or on the deck, we comment on the variety of creatures that we found in waters that many of us thought inhospitable and lifeless. The Arctic Ocean is much more than clear water with sprinkled salt and ice: it is the living home to diverse, wondrous creatures that we are just learning to explore and appreciate.
Video of microzooplankton as seen under microscope. This video was captured using the Lumenera INFINITY1-2 camera.
Daniele Bianchi, PhD is an Oceanographer and Assistant Professor in the Atmospheric and Oceanic Sciences Department at the University of California Los Angeles.
Daniele’s research focuses on interactions between climate, ocean circulation and marine life. He is particularly interested in the mechanisms that regulate marine ecosystems, and how marine organisms, from microscopic phytoplankton up to zooplankton and fish, respond to changes in their environment, both natural and due to human activities. For his research, he use a range of oceanographic data, from in situ measurements to satellites, together with mathematical models that describe the physics, chemistry and ecology of the ocean.
Originally from Italy, Daniele completed his Ph.D. in Atmospheric and Oceanic Sciences at Princeton University, and worked as a postdoctoral fellow at McGill University in Montreal and University of Washington in Seattle before joining the University of California Los Angeles.