CTD’s and why we filter water

Throughout the cruise, we have cast a lot of CTD’s. CTD stands for conductivity (or salinity), temperature, and depth. In oceanography, a CTD is a regularly used instrument that is dropped vertically in the water column to measure water properties (the C, T, and D) at different depths. CTD’s are usually attached to large bottles that collect sea water at different depths. In the video below, the crew brings up the CTD rosette, and Martí and Peter begin filtering water.

Why do we need to know the properties of ocean water? To learn more about where certain animals live in the ocean, we use instruments like CTD’s to determine different water properties at various depths. We can then use this type of data and correlate it to the type of animlas or plants we find there, and further study how tiny marine critters can survive in different areas (or habitats) of the ocean.

Phytoplankton (tiny ocean plants) are essential for many marine animals. By filtering sea water, we can collect these small plants (as well as dead organic material) on filters with microscopic holes. Therefore, filtering water can give an indication of the amount of food available to small marine life (as Coralie mentioned in her post). Martí filters water for his project to learn more about the microbial food web during the polar night.

CTD data can also be used to compare water properties at similar locations through time. The water in western Svalbard is influenced by warmer and saltier water from the Atlantic Ocean moving its way northward into the Arctic Ocean. To determine if some of the fjords in western Svalbard will be ice-covered this year, researchers can investigate water temperatures using a CTD (see figure below). Some of the researchers on our cruise have summarized their findings on this University Centre in Svalbard (UNIS) page.

A temperature profile obtained from a CTD. Here you can see that surface water temperatures in 2016 were colder than in 2017 in Isfjord (IsK). What this indicates is that there is more Atlantic water inside Isfjord than last year, so the chances of an ice-covered Isfjord is unlikely this winter. Graphic credit: Ragnheid Skogseth/UNIS.
Coralie, Peter, and Martí around the CTD rosette.
Peter is boss when it comes to water filtration!

-Erin Kunisch (PhD candidate, UiT)

Echosounder preparations

As the weather calms down around the cruising path of the R/V Helmer Hanssen, Max prepares to operate the new Kongsberg echosounder. This is a wide band acoustic transducer EK80. What is unique and novel about it is that it chirps (which is like whistling for brief periods), instead of pinging (which is similar to honking on a car). Together with the AZFP (stands for Acoustics, Zooplankton, and Fish Profiler) echosounder from the ASL Environment Company, both echosounders will tell the team where the plankton and fish are located in the waters outside of the Ny Ålesund research station. Before that happens, the Arctic ABC team needs to know how to operate it, test that all its cables and connections are working, and come up with a plan on how best to install both instruments in the water.

Max with echosounder.

-Pedro De La Torre (Engineer, NTNU)

Our second sampling station

We are now at 75N. Yesterday we encountered rough seas, with winds at approximately 30 meters/second (!!). Some people were more sick than others, but we all managed to pull through and are in good spirits!

The zooplankton teams are getting ready to deploy another CTD, and a few more nets (WP3, WP2, multinet) for biological sampling. The samples taken from these nets will be used for a variety of studies. Two in particular will be assessing zooplankton community composition of small copepods, and behavioral studies of Calanus species (a copepod found in Arctic and sub-Arctic seas).

After we finish sampling, Jon Cohen (University of Delware) will deploy a light sensor into the water. This light sensor measures the bioluminescence of organisms found within these waters. Since organisms can be quite sensitive to non-natural light sources, the R/V Helmer Hanssen will move a bit away from the zooplankton sampling and turn off its exterior lights before deploying the sensor. That way, more of these smaller zooplankton animals will stay closer to the surface of the water, and the sample will be more representative of the polar night.

Malin enjoying the weather at 12 noon.

We plan on being in Van Mijen fjord this evening. Our first scheduled stop is in Longyearbyen on Sunday.

-Erin Kunisch (PhD candidate, UiT)

First research activities

Research activities started immediately after lunch onboard. A CTD (conductivity, temperature, and depth sensor for seawater), and two sampling nets (multinet and WB3) provided the first insight into the environmental and biological characteristics of the ocean outside the sheltered continental area. The first crate sent from the Scottish Association for Marine Science (SAMS) was opened, and it was like Christmas all over again.

The Arctic ABC technology team (the A in ABC) did not waste any time and setup a mini electronics lab in the instruments room onboard to begin testing the ICE-POPES (electronic sampling devices, which stands for Ice-tethered Platform Cluster for Optical, Physical, and Ecological Sensors, so not the Catholic kind) that will be deployed at Ny Ålesund in Svalbard. We hope that you can appreciate the looks on everyone’s faces–the engineers in charge were happy to see not only that the equipment made it, but that their tools and spare parts were right where they were supposed to be.

-Pedro De La Torre (Engineer, NTNU)



The A in Arctic ABC

The ‘A‘ in Arctic ABC stands for applied technology. Scientists have developed and will be deploying autonomous drifting sensors in the Arctic sea ice. These sensors will observe and monitor the ice-associated biological communities during the winter (polar night) and spring seasons. Data collected from these sensors will provide a better understanding of how Arctic biological communities will respond to climate change.

In January, the Arctic ABC team will be installing sensors in Ny Ålesund, Svalbard (situated at 78° 55′ N, 11° 56′ E). Artur Zolich and Sturla Haltbakk, researchers from NTNU (Norwegian University of Science and Technology) are working with instruments that measure light throughout the year. The data that is harvested from these sensor instruments will be complimentary to the underwater measurements of light for the instruments that will be tested later on in January. Stay tuned!

Ny Ålesund town center
Ny Ålesund at 12 noon, during the polar night period.
two people standing next to light dome sensor
Artur and Sturla, two researchers involved with the Arctic ABC project, standing next to the light dome sensor.
Light dome with sensors.
Light dome with sensors.

-Pedro De La Torre